Dissertations / Theses on the topic 'Elektroliza'

Metalne nanočestice spadaju u nanomaterijale sa širokim spektromprimena u plazmonici, elektronici, katalizi i biomedicini.Razvijene su brojne metode njihove fabrikacije. U ovoj disertacijipredstavljena je mogućnost sinteze metalnih nanočestica korišćenjemjednog novog metoda, u kojem se koristi granični sloj elektrolita iplazme. Niskotemperaturni joni iz plazme se pomoću električnog poljauvode u elektrolit sa prekursorskim materijalom. Ovako uvedeni joniiniciraju oksido-redukcione reakcije sa prekursorom metala unanometarski tankom sloju na površini elektrolita.Razvijen je generator niskotemperaturne plazme baziran nakonfiguraciji dielektričnih barijernih pražnjenja. Urađena je njegovakarakterizacija i merenje struje formiranih reaktivnih jona. Metod jeverifikovan na primeru nanočestica srebra i platine.
Metallic nanoparticles are nanomaterials with wide range of applications inplasmonics, electronics, catalysis and biomedicine. Thus, a number ofmethods for their fabrication exist. In this dissertation a possibility ofsynthesis of metallic nanoparticles using а new method, which exploits aninterface between plasma and electrolyte. By means of an electric field, lowtemperatureions from plasma are introduced into the electrolyte withprecursor material. The ions from plasma start redox reactions with metalprecursor ions within a nanometer-thin layer on the surface of the electrolyte.Nonthermal plasma generator based on dielectric barrier discharges wasdeveloped and characterized. Currents of generated reactive ions weresubsequently measured. The developed method was verified by synthesis ofsilver and platinum nanoparticles.

Analysis of the working capital of the company Elektroline based on historical data and sugestions for improves in the area of the working capital. Short financial analysis of the company Elektroline and suggestions for further analysis in some specific areas.

The work is concerned with a production of hydrogen and oxygen through by the help of electrolytic process in a device called electrolyzer. The basis of the work is assurance of the best efficiency of this process by testing a variety of materials and surfaces of electrodes, and testing different types of alkalic electrolytes.

Darbo pavadinimas: „Kraujo plazmos elektrolitų spektro pokyčiai vartojant mineralinį vandenį“. Darbo tikslas buvo įvertinti kraujo plazmos elektrolitų koncentracijos pokyčius vartojant Lietuvoje išgaunamą natūralų mineralinį vandenį „Tichė“. Darbui atlikti buvo suformuluotas užvadinys: Įvertinti kraujo plazmos elektrolitų (Na+, K+, Cl-, Ca2+ (bendro ir jonizuoto), bei Mg2+) koncentracijų pokyčius vartojant mineralinį vandenį „Tichė“. Kraujo elektrolitų tyrimai buvo atlikti Vilniaus universiteto ligoninės Santariškių klinikų Laboratorinės diagnostikos centro biochemijos laboratorijoje. Per šį laikotarpį buvo ištirta 30 atsitiktinai atrinktų 19-20 metų amžiaus asmenų. Tyrimo metu tie patys tiriamieji vartojo mineralinį ir natūralų šaltinio vandenį. Tyrimas buvo suskirstytas į 4 etapus. Jiems 4 kartus buvo imamas veninis kraujas: pirmą kartą - prieš eksperimentą, antrą kartą – po dvidešimties dienų mineralinio vandens vartojimo, trečią kartą – po dviejų savaičių pertraukos, ketvirtą kartą – po dvidešimties dienų šaltinio vandens vartojimo. Atlikus eksperimentą ir apskaičiavus gautus rezultatus gavome tokias išvadas: Natrio jonų koncentracija kraujo plazmoje vartojant mineralinį nepakito. Chloridų jonų koncentracija kraujo plazmoje vartojant mineralinį vandenį statistiškai reikšmingai sumažėjo. Visų tiriamųjų natrio ir chloridų koncentracija neviršijo rekomenduojamų normos ribų. Kalio jonų koncentracija kraujo plazmoje vartojant mineralinį vandenį taip pat nepakito. Vienam... [toliau žr. visą tekstą]
Report title: „Changes in electrolytes spectrum of blood plasma under consumption of mineral water“. The aim of the study was to assess the plasma concentration of electrolyte changes, which are using natural mineral water „Tichy“ extracted in Lithuania. The goal of the work: To evaluate the plasma electrolytes (Na+, K+, Cl-, Ca2+ (general and ionized), and Mg2 +) concentration changes in the use of mineral water „Tichy“. Blood electrolyte tests were carried out at Vilnius University Hospital Santariškių Clinics. Centre of Laboratory Diagnostics, Laboratory of Biochemistry. During this period, 30 randomly selected individuals of the age of 19-20 years were examined. The study used the mineral water, and the natural spring water. The study was divided into four stages. Venous blood of the investigated study participants was charged four times: the first time - before the experiment, the second time - after twenty days of consumption of mineral water, the third time - after a two-week break, the fourth time - after twenty days of spring water consumption. After the experiment and calculation of the results the following conclusions were obtained: Consumption of mineral water had no influence on the concentration of sodium ions in blood plasma. Concentration of chloride ions, on the other hand, statistically significantly decreased. Both sodium and chloride ion concentration did not exceed the recommended rate limits. Potassium ion concentration in blood plasma using mineral... [to full text]

Bakalauro darbą „Plazmoelektrolitinio proceso stabilumo sąlygų tyrimas“ sudaro įvadas, 3 skyriai, išvados, literatūros sąrašas, priedai ir 1 kompaktinis diskas. Darbo apimtis 39 puslapiai. Darbe pateikti 26 paveikslai, 1 lentelė. Įvade iškeliama darbo problema, pagrindinis tikslas ir uždaviniai. Pirmąjame skyriuje pateikiami pagrindiniai teoriniai teiginiai apie procesus sudarančius vandenilio plazminę elektrolizę: elektrolizę ir plazmą. Antrąjame skyriuje analizuojami ir aptariami moksliniai straipsniai, kuriuose kalbama apie atliktus vandenilio plazminės elektrolizės proceso tyrimus. Išryškinami tyrimai, kurie susiję su šio proceso stabilumo stebėjimais. Trečiajame skyriuje aptariami atlikto plazmoelektrolitinio proceso stabilumo sąlygų tyrimo rezultatai ir pateikiama jų analizė.
The Bachelor paper “The investigation of the stability conditions of plasma electrolysis process ” consists of introduction, three chapters, conclusions, literature source, additions and 1 CD. The volume of this work is 39 pages. There are 26 pictures and 1 table in this work. Work problem, objective and goals are provided in the introduction. The first chapter is provided main theoretical propositions about processes which take part in hydrogen‘s plasma electrolysis: electrolysis and plasma. Second chapter analyze and review scientific articles about hydrogen’s plasma electrolysis research. The paper underlines studies, related to mentioned process and it’s monitoring of stability. In the third chapter a reader will find the results and their analysis about stability conditions of plasma electrolysis process.

U ovoj doktorskoj disertaciji ispitivani su elektroliti na bazi jonskih tečnosti pogodni zaprimenu u litijum  jonskim baterijama. Fizičko-hemijska svojstva binarnih smešajonskih tečnosti sa dicijanamidnim i bis(trifluorometilsulfonil)imidnim anjonima imolekulskih rastvarača ispitana su u celom opsegu molskih udela i na različitimtemperaturama. Na osnovu izmerenih gustina, viskoznosti i električne provodljivostiizračunati su različiti fizičko hemijski parametri i diskutavne interakcije između komponenata smeša. Ispitana je termička i elektrohemijska stabilnost odabranihelektrolita. Dodatkom litijumove soli u odabrane binarne smeše dobijeni su ternarnisistemi koji su okarakterisani u zavisnoti od koncentracije litijumove soli. Odabranielektroliti upotrebljeni su za  ispitivanje performansi litijum  jonske ćelije sa anatasTiO2  nanotubularnim elektrodama.Cikličnom voltametrijom i galvanostatskimcikliranjem su ispitane performanse ćelije u toku 150 ciklusa punjenja i pražnjenja. Naosnovu ciklovoltametrijskih merenja izračunati su koeficijenti difuzije i energija aktivacije za difuziju.
In this doctoral dissertation, Ion liquid-based electrolytes were tested for use in  lithium-ion batteries. The physicochemical properties of binary mixtures of ionic  liquids with dicyanamide and bis (trifluoromethylsulfonyl) imide anions and  molecular solvents were examined throughout the range of molar proportions and at different temperatures. Based on the measured densities, viscosity and electrical conductivity, various physical chemical parameters and discrete interactions between  the components of the mixture are calculated. Thermal and electrochemical stability of selected electrolytes was examined. By addition of lithium salt to the selected binary mixtures, ternary systems were characterized which were characterized by the concentration of lithium salt. The selected electrolytes were used to test the performance of the lithium-ion cell with anatomic TiO2 nanotubular electrodes. Cyclic voltammetry and galvanostatic cycling tested the cell's performance during the 150 charge and discharge  cycles. Based on cyclotoltametric  measurements, the diffusion coefficients and activation energies for diffusion were calculated.

U  ovoj  doktorskoj  disertaciji  ispitivani  su  elektroliti  na  bazi binarnih  smeša  imidazolijumovih  jonskih  tečnosti  i  laktona  koji su  pogodni  za  primenu  u  litijum-jonskim  baterijama.  Fizičkohemijska  svojstva  binarnih  smeša  jonskih  tečnosti  na  bazi imidazolijum katjona i bis (trifluorometilsulfonil)imidnog anjona i laktona ispitana su u celom opsegu molskih udela i na različitim temperaturama.  Na  osnovu  izmerenih  gustina,  viskoznosti  i električne  provodljivosti  izračunati  su  različiti  fizičko-hemijski parametri i diskutovane  interakcije između komponenata smeša. Ispitana  je  termička  i  elektrohemijska  stabilnost  odabranih elektrolita.  Na  osnovu  dobijenih  rezultata,  prvo  je  odabran odgovarajući  lakton  koji  je  kasnije  kombinovan  sa  jonskimtečnostima  na  bazi  imidazola,  koje  se  međusobno  razlikuju  u dužini  bočnog  niza  katjona.  Na  osnovu  fizičko-hemijskih svojstava  na  različitim  temperaturama  i  pri  različitim  sastavima binarnih  smeša  diskutovan  je  način  organizacije  njihovihkomponenata.  U  binarne  smeše  koje  su  se  pokazale  kao najperspektivnije  sa  stanovišta  električne  provodljivosti, viskoznosti,  elektrohemijske  stabilnosti  i  (ne)zapaljivosti  dodata je litijumova so. Tako dobijeni ternarni sistemi su okarakterisaniu zavisnosti od koncentracije litijumove soli. Odabrani elektroliti upotrebljeni su za ispitivanje performansi litijum-jonske ćelije sa elektrodama  na  bazi  anatas  TiO₂  nanocevi.  Cikličnom voltametrijom  i  galvanostatskim  cikliranjem  ispitane  superformanse ćelije u toku 350 ciklusa punjenja i pražnjenja. Na osnovu   ciklovoltametrijskih  merenja  izračunati  su  koeficijenti difuzije jona Li  ⁺ i energija aktivacije za difuziju.  Kombinacijom jonskih  tečnosti  i  laktona  moguće  je  dobiti  elektrolite  smanjene viskoznosti,  povećane  električne  provodljivosti,  povećanetermičke  stabilnosti  usled  međusobnog  stabilizacionog  efekta laktona na imidazolijumove jonske tečnosti.
In  this  doctoral  dissertation,  binary  mixtures  based  on  imidazolium  ionic  liquids  with  lactones  were  tested  for  use  in lithium-ion  batteries.  The  physicochemical  properties  of  binary  mixtures  of  imidazolium  based  ionic  liquids  with  bis (trifluoromethylsulfonyl)imide  anions  and  lactones  were  examined  throughout  the  whole  composition  range  and  at  different temperatures. Based on the measured densities, viscosity  and electrical conductivity, various physical chemical parameters  and discrete interactions between the components of the mixture are  calculated.  Thermal  and  electrochemical  stability  of  selected  binary  mixtures  were  examined.  Based  on  obtained  results  was  selected lactone  which is later combined with imidazolium based  ionic liquid,  differing from each other in the length of the cation. Based  on  the  physico-chemical  properties  at  different  temperatures and in the different compositions of binary mixtures, the way of organizing their components is discussed. Lithium salt  is added to the binary mixtures that have been shown as the most perspective  from  the  standpoint  of  electrical  conductivity, viscosity,  electrochemical  stability  and  (non)flammability.  The  resulting  ternary  systems  are  characterized  according  to  the concentration of lithium salt.  The selected electrolytes were used to test the performance of the lithium-ion cell with anatase TiO₂ nanotubular  electrodes.  Cyclic  voltammetry  and  galvanostatic  cycling  tested  the  cell's  performance  during  the  350  charge  and discharge  cycles.  Based  on  cyclic  voltammetric  measurements, the  Li ⁺ ion  diffusion  coefficients  and  activation  energies  for diffusion  were  calculated.  Combination  ionic  liquid  and  lactone could  be  obtained  electrolytes  with  lower  viscosity,  higher electrical  conductivity,  improved  thermal  stability  due  to stabilization effect of lactone on imidazolium based ionic liquids.

Przeprowadzono analizę literatury poświęconej metodom wytwarzania i właściwościom powłok tlenkowych uzyskiwanych na aluminium i jego stopach na potrzeby sformułowania tezy i postawienia celów dysertacji doktorskiej. Zapoznano się z opracowaniami na temat nowoczesnych metod komputerowych i ich wykorzystaniu w modelowaniu i symulacji warstwy tlenkowej, a także analiz numerycznych wspomagających komputerowe badania tribologiczne. Zakres pracy doktorskiej obejmował wytworzenie warstw tlenkowych Al2O3 na stopie aluminium w elektrolitach trójskładnikowych dla zmiennych warunków anodowania twardego. Ukształtowane warstwy tlenkowe poddane zostały komputerowej analizie obrazu na podstawie wykonanych zdjęć SEM. Uzyskane z pomiarów wartości użyto do zbudowania modelu warstwy i zaprogramowania aplikacji symulującej ułożenie włókien. Przeprowadzono komputerowe badania tribologiczne dla węzła tarcia kostka-płytka z zastosowaniem różnych materiałów próbek dla warunków odpowiadających pracy siłowników pneumatycznych. Osiągniętymi celami pracy doktorskiej było poznanie i wyjaśnienie mechanizmów formowania i wzrostu warstwy Al2O3 przy użyciu mikroskopu skaningowego na podstawie zdjęć powłok. Symulacja i modelowanie nanostruktury warstwy tlenkowej Al2O3 wytwarzanej na stopie aluminium w elektrolicie trójskładnikowym. Analiza numeryczna naprężeń, odkształceń i przemieszczeń węzła tarcia tribologicznego w skojarzeniach ślizgowych. Przedstawiona rozprawa doktorska stanowi oryginalne i nowatorskie rozwiązanie problemu wykorzystania metod komputerowych do wspomagania badań tribologicznych węzłów tarcia modyfikowanych materiałów polimerowych w skojarzeniu ze stopem aluminium EN AW-5251 na którym wytworzono warstwy tlenkowe w procesie anodowania. Zamodelowano trójwymiarową warstwę tlenkową wytwarzaną w elektrolitach trójskładnikowych, a także opracowano autorski programu symulujący wygląd morfologii warstwy tlenkowej wytwarzanej w zmiennych warunkach anodowania twardego. Odpowiednie dane wykorzystane na potrzeby modelowania i symulacji uzyskano z KAO zdjęć SEM. Przeprowadzono badania tribologiczne wspomagane modelowaniem CAD i symulacjami komputerowymi wykorzystującymi obliczenia MES, w których zastosowano różne materiały polimerowe dla skojarzenia ślizgowego kostka-płytka celem zastąpienia czasochłonnych i kosztownych badań stanowiskowych.

Postoperative atrial fibrillation (AF) after cardiac surgery with cardiopulmonary bypass (CPB) remains unresolved problem. Some authors noticed that there were changes in electrolyte balance after coronary artery bypass grafting (CABG) surgery with CPB. The changes in serum magnesium level and their relation with the rate of postoperative AF are usually analyzed in scientific publications. The aim of the study has been to estimate the relationship between the rate of postoperative AF and the changes in serum electrolyte concentration and their urinary excretion after CABG surgery with CPB. The goals: 1) To estimate the rate and the character of postoperative AF and its influence on haemodynamics after CABG surgery. 2) To estimate changes in serum K+, Na+, Mg++, Ca++, Cl–, P– concentration and compare them between the patients who received, and who did not receive magnesium sulphate supplementation during the surgery. 3)To estimate changes of urinary excretion of K+, Na+, Mg++, Ca++, Cl–, P– and compare them between the patients who received, and who did not receive magnesium sulphate supplementation during the surgery. 3) To evaluate the effects of intraoperatively infused magnesium sulphate on the rate of postoperative AF in the early postoperative period. In our study the rate of postoperative AF was 27.4 %. AF in 91.3 % of cases was tachyarrhythmic, but haemodynamic remained stabile. Serum Mg++ level was > 1.05 mmol/l during the suregry in all patients. The infusion of... [to full text]

Baigiamajame darbe nagrinėjama vidaus degimo variklio galimybė dirbti naudojant elektrolizės būdu gautą vandenilį kaip kuro priedą. Buvo atlikta mokslinės literatūros analizė siekiant nustatyti galimus teigiamus ir neigiamus variklio charakteristikų pokyčius naudojant vandenilį, išsiaiškinta elektrolizės aparato konstrukcija ir veikimo principas. Baigiamąjį darbą sudaro dvi dalys: praktinė ir teorinė. Praktinio darbo metu buvo nustatytos variklio kuro sąnaudos, išmetamųjų dujų temperatūros pokyčiai naudojant vandenilį ir kiti parametrai. Šie parametrai buvo panaudoti variklio teorinių charakteristikų skaičiavimui, taip nustatant jo galimybes dirbti su vandeniliu. Įvertinus gautuosius rezultatus buvo atlikti elektrolizės sukeliamų energijos nuostolių skaičiavimai, bei sudarytos rekomendacijos vandenilio kaip kuro priedo naudojimui aviaciniuose varikliuose. Darbo apimtis: 85 psl. be priedų, 27 iliustracijos, 3 lentelės, 22 bibliografiniai šaltiniai. Prie darbo pridedamas mokslinis straipsnis.
The final thesis provides possibility for internal combustion engine to work using hydrogen as fuel additive. Analysis of scientific literature has been performed during research work. Main reason was to gain knowledge of possitive and negative engine characteristics while using hydrogen extracted from water during electrolysis process. The final thesis is made from two parts: practical experiments and theoretical calculations. Fuel consumption, exhaust gass temperature and other parameters have been established during practical experiments. These parameters were used in theoretical calculations to establish possibility for engine to work using hydrogen. Energy losses were calculated and recomendation for internal combustion engine have been prepeared after evaluation of parameters. Volume of the final thesis: 85 pages without appendixes, 27 pictures, 3 tables, 22 bibliographical entries. Memoir is included to appendix.

The thesis deals with water electrolysis focusing in particular on pulse electrolysis. The theoretical part characterizes hydrogen and its properties as well as the ways of its use and storage. It also analysis various methods of hydrogen generation. It examines in details water electrolysis and its energetic and chemical balance. There is also an evaluation of water electrolysis efficiency and its improvement followed by pulse electrolysis description. Laboratory equipment for direct current and pulsed direct current hydrogen production are suggested. Theoretical expectations are tested experimentally. Finally the thesis presents the results of measurements, compares and summarizes the data. It points out the contribution of this type of electrolysis with its effectiveness. It proposes uses of electrolysis and the subsequent research.

Thesis deals with study of separators and membranes, suitable for using in alkali electrochemical applications like fuel cells or electrolysis. As basic material for membranes production is used polyvinylalkohol (PVA). Various methods of PVA cross linking are introduced in the thesis. PVA membranes are also doped by various types of additives to improve the attributes of the membranes like mechanical stability and or conductivity. The aim of the work is verification of parameters of membranes, doped by alkali hydroxides KOH, NaOH and LiOH at various temperatures. These hydroxides are added to the membrane especially for increasing of membrane conductivity.

This work deals with the production of hydrogen and oxygen by electrolysis. Aims of this thesis are to measure different types of membranes and choose the best for use in elektrolyzer for hydrogen and oxygen production. Properties of membranes were tested in the laboratory electrolyzer in the short and long operation. The emerging gases from elektrolyzer were also tested on a gas chromatograph to determine the purity of produced hydrogen. At the same time are also tested different concentrations of KOH elektrolyte and the effect of concentrations on efficiency of electrolyzer.

Zn redukcija iš šarminių elektrolitų vyksta per tarpinę oksido/hidroksido fazės susidarymo stadiją. Dalis oksidinių junginių gali būti neredukuojami, todėl terptis į metalinę dangą. Impulsinės elektrolizės taikymas Zn dangų nusodinimui yra vienas iš būdų modifikuoti metalo struktūrą ir tuo pačiu pagerinti dangų korozinį atsparumą. Nemetalinių intarpų kiekis impulsine elektrolize nusodintose Zn ir jo lydinių dangose nėra tyrinėtas. Nemetalinių intarpų kiekis buvo nustatytas dangų anodinio tirpinimo Na2SO4 + Na2 EDTA tirpale ir Rentgeno fotoelektronų spektroskopijos metodais. Nustatyta, kad oksidinių intarpų kiekis impulsine elektrolize nusodintose Zn ir Zn-Ni dangose buvo didesnis, lyginant su nuolatinės srovės dangomis, taip pat į Zn dangas, lyginant su lydinių, įsiterpia daugiau oksidinių junginių. Nuolatine srove nusodintose Zn dangose ZnO kiekis yra didesnis už Zn(OH)2, tačiau impulsinė elektrolizės taikymas didina hidroksido kiekį dangoje. Nuolatine srove nusodintose Zn-Ni dangose oksido ir hidroksido intarpų kiekiai yra panašūs, tuo tarpu impulsinė elektrolizė ženkliai padidina hidroksido kiekį dangoje.
Electrodeposition process of Zn in alkaline solutions occurs through oxide/hydroxide phase formation, which under certain conditions could not be totally reduced and therefore formation of non metallic (oxide/hydroxide) inclusions can take place. Pulse plating of metal coatings is widely used as the method for metal structure modification in order to enhance the corrosion resistance of Zn and Zn alloy coatings, however the amount of inclusions in pulse plated Zn and Zn-Ni coatings was not investigated up to date. The amount of non-metallic inclusions was determined from anodic dissolution curves, obtained in Na2SO4 + Na2 EDTA solution and from X-ray photoelectron analysis of the sample surfaces after Ar ion sputtering. The amount of the oxide phase in Zn and Zn-Ni coatings was determined to be higher in the pulse plated coatings with respect to direct current ones, while in Zn coatings this amount was also higher with respect to the alloy. The amount of ZnO in the inclusions of direct current plated Zn coatings is higher than that of Zn(OH)2, however, application of pulse deposition increases the amount of the latter compound. Oxide and hydroxide amounts in the direct current plated Zn-Ni coatings are similar, meanwhile, the pulse plating increases significantly the amount of hydroxide phase.

This master’s thesis deals with Power to Gas technology. In this concept electrical energy is used for hydrogen production via electrolysis. Hydrogen can be injected in limited amount into natural gas grid, used for power generation via fuel cells or as a reactant for methanation process. Characteristics of hydrogen and ways of hydrogen production, storage and transport are described. Fuel cells are described as a device which uses hydrogen for power production. Crucial part of this thesis consists of a description of Power to Gas concept and a design of Power to Gas unit with electrical power of 9,5 kW. Three different units were designed for three different times of day operation. Efficiency and economical assessment was carried out for these three Power to Gas units.

Disertacijoje yra nagrinėjama, kokią įtaką ličio katijonų ir deguonies vakansijų (Vo) kietųjų elektrolitų elektrinėms savybėms daro jų struktūra ir elementinė sudėtis. Darbe yra aprašomos technologinės superjoninių junginių (SJ) keramikų ir sluoksnių gamybos sąlygos, lemiančios jų mikrostruktūrą, bei pateikiami SJ paviršių, temperatūrinio stabilumo ir elektrinių savybių tyrimo rezultatai. Li+ SJ priklauso monoklininei, ortorombinei arba romboedrinei singonijoms. Keramikų mikrostruktūra labiausiai priklauso nuo jų kepinimo temperatūros. LiCe2/3PO4 keramiką paveikus elektriniu lauku, XPS buvo parodyta, kad šioje medžiagoje vyksta Li+ jonų pernaša. Kompleksinės varžos spektroskopijos tyrimai parodė, kad sistemose Li1+xScxZr2-x(PO4)3, Li1+xZr2-2xAlxTix(PO4)3 ir Li1+xGe2-2xAlxTix(PO4)3 (čia x = 0,1, 0,2, 0,3), didinant x, didėja kristalitiniai keramikų laidžiai, o jų aktyvacijos energijos mažėja. Li3Sc2–xBx(PO4)3 junginiuose vykstančio superjoninio fazinio virsmo temperatūra priklauso nuo x. Li3-xSc2-x-yYyZrx(PO4)3 sistemoje kai x = 0,1, y = 0, 0,1 temperatūrinėse kristalitinio laidžio prieklausose yra stebimos anomalijos, susijusios su superjoniniais faziniais virsmais šiose medžiagose, o kai x = 0,2 tirtame temperatūrų intervale faziniai virsmai nevyksta. Magnetroninio dulkinimo metodu suformuotų YSZ storųjų sluoksnių joninis laidis ir šio laidžio aktyvacijos energija priklauso nuo jų paruošimo technologinių sąlygų. Didinant NiO-CGO sluoksnių, suformuotų purškimo pirolizės... [toliau žr. visą tekstą]
The influence of the structure and elemental composition of lithium ions’ and oxygen vacancies’ (Vo) solid electrolytes (SE) on their electrical properties are investigated in the dissertation. The technological conditions of SE ceramics’ and films’ fabrication, which influence their microstructure, are described. The results of the investigation of the surfaces, temperature stability, and electrical properties are presented. Li+ SE belong to monoclinic, orthorhombic, or rhombohedral symmetries. The microstructure of the ceramics is mainly influenced by the temperature of their sintering. It has been shown by XPS that LiCe2/3PO4 ceramic is Li+-ion conductor. Complex impedance spectroscopy investigation showed that the increase of x in the systems Li1+xScxZr2-x(PO4)3, Li1+xZr2-2xAlxTix(PO4)3, and Li1+xGe2-2xAlxTix(PO4)3 (where x = 0.1, 0.2, 0.3) leads to the increase of bulk ionic conductivity of the ceramics and to the decrease of its activation energy. Phase transition temperature in Li3Sc2–xBx(PO4)3 compounds depends on x. The anomalies of temperature dependencies of bulk conductivity of Li3-xSc2-x-yYyZrx(PO4)3 system were observed when x = 0.1, y = 0, 0.1. The anomalies are related to superionic phase transitions in the materials, but no phase transitions have been detected for x = 0.2 compound in the studied temperature range. Ionic conductivity and its activation energy of YSZ thick films prepared by magnetron sputtering depend on their preparation’s technological... [to full text]

The influence of the structure and elemental composition of lithium ions’ and oxygen vacancies’ (Vo) solid electrolytes (SE) on their electrical properties are investigated in the dissertation. The technological conditions of SE ceramics’ and films’ fabrication, which influence their microstructure, are described. The results of the investigation of the surfaces, temperature stability, and electrical properties are presented. Li+ SE belong to monoclinic, orthorhombic, or rhombohedral symmetries. The microstructure of the ceramics is mainly influenced by the temperature of their sintering. It has been shown by XPS that LiCe2/3PO4 ceramic is Li+-ion conductor. Complex impedance spectroscopy investigation showed that the increase of x in the systems Li1+xScxZr2-x(PO4)3, Li1+xZr2-2xAlxTix(PO4)3, and Li1+xGe2-2xAlxTix(PO4)3 (where x = 0.1, 0.2, 0.3) leads to the increase of bulk ionic conductivity of the ceramics and to the decrease of its activation energy. Phase transition temperature in Li3Sc2–xBx(PO4)3 compounds depends on x. The anomalies of temperature dependencies of bulk conductivity of Li3-xSc2-x-yYyZrx(PO4)3 system were observed when x = 0.1, y = 0, 0.1. The anomalies are related to superionic phase transitions in the materials, but no phase transitions have been detected for x = 0.2 compound in the studied temperature range. Ionic conductivity and its activation energy of YSZ thick films prepared by magnetron sputtering depend on their preparation’s technological... [to full text]
Disertacijoje yra nagrinėjama, kokią įtaką ličio katijonų ir deguonies vakansijų (Vo) kietųjų elektrolitų elektrinėms savybėms daro jų struktūra ir elementinė sudėtis. Darbe yra aprašomos technologinės superjoninių junginių (SJ) keramikų ir sluoksnių gamybos sąlygos, lemiančios jų mikrostruktūrą, bei pateikiami SJ paviršių, temperatūrinio stabilumo ir elektrinių savybių tyrimo rezultatai. Li+ SJ priklauso monoklininei, ortorombinei arba romboedrinei singonijoms. Keramikų mikrostruktūra labiausiai priklauso nuo jų kepinimo temperatūros. LiCe2/3PO4 keramiką paveikus elektriniu lauku, XPS buvo parodyta, kad šioje medžiagoje vyksta Li+ jonų pernaša. Kompleksinės varžos spektroskopijos tyrimai parodė, kad sistemose Li1+xScxZr2-x(PO4)3, Li1+xZr2-2xAlxTix(PO4)3 ir Li1+xGe2-2xAlxTix(PO4)3 (čia x = 0,1, 0,2, 0,3), didinant x, didėja kristalitiniai keramikų laidžiai, o jų aktyvacijos energijos mažėja. Li3Sc2–xBx(PO4)3 junginiuose vykstančio superjoninio fazinio virsmo temperatūra priklauso nuo x. Li3-xSc2-x-yYyZrx(PO4)3 sistemoje kai x = 0,1, y = 0, 0,1 temperatūrinėse kristalitinio laidžio prieklausose yra stebimos anomalijos, susijusios su superjoniniais faziniais virsmais šiose medžiagose, o kai x = 0,2 tirtame temperatūrų intervale faziniai virsmai nevyksta. Magnetroninio dulkinimo metodu suformuotų YSZ storųjų sluoksnių joninis laidis ir šio laidžio aktyvacijos energija priklauso nuo jų paruošimo technologinių sąlygų. Didinant NiO-CGO sluoksnių, suformuotų purškimo pirolizės... [toliau žr. visą tekstą]

The Master’s thesis reviews the topic of hydrogen in within European and Czech energy industry. Hydrogen’s usage in gas industry, heating industry and power engineering may play a significant role in meeting European Union’s ambitious goals aiming to reduce emission production. This work identifies specifications of technologies used to produce, transport, and use of hydrogen and their impact on today’s energy systems and safety. The technical, economic, and political context is emphasized. The technical part covers the topic of injecting hydrogen into natural gas and it’s impact on physico-chemical properties of gas. The work analyses concentrations of 0, 5, 10, 15, 20 and 25 molar percent of hydrogen in real composition of natural gas measured on a handover point of transition system. Furthermore, calculations for these mixtures have been done to determine a change in characteristics of a heat exchanger. The results show, that with higher concentrations of hydrogen, the power of heat exchanger rises, while the power of a burner decreases due to lower calorific value of gas mixture. The last chapter follows up on a economical analysis of fuel and emission allowance costs for above-mentioned concentrations of hydrogen in gas mixture. Specific values of combined cycle gas plant Počerady from year 2019 were used for calculations. The results show, that in all of the three considered scenarios of emission allowance price predictions, replacing hydrogen with natural gas did not have a positive economic impact.

In my diploma work i focus on the production hydrogen by electrolysis of water using by electrolyzer. Especially, i concentrate on preparation electrodes for laboratory electrolyzer. I work on principles of increasing electrodes area, increasing functional surface of electrodes, by Nickel – Zinc coatings. By electroplating or chemical plating we spread microlayer of Nickel-Zinc onto electrodes made of steel plate. Then, in alkali - hydrate oxide, we will corrode Zinc components off the alloy and this is how we create pore surface of electrode. From macroscopic view, electrode has same geometrics propositions, however from microscopics view, the electrode has bigger surface area. The hydrogen production increases with unchanget sizes of electrolyzer.

The diploma thesis is focusing on the seasonal energy storage in synthetic fuels and the Power to Gas system (P2G). The P2G enables the conversion of electrical energy in times of electricity surplus, for example by using the surplus from renewable energy sources to produce synthetic gas, particulary hydrogen and synthetic methane. The main focus is on the technical and economic assessment of P2G of the Gazela natural gas pipeline. Furthermore, it identifies the limits of production, transportation, and storage capacities of these synthetic gases. The technical analysis assumes the injection of hydrogen of a certain molar concentration, according to the four proposed scenarios, into the natural gas transmission system in the Gazela pipeline. The results have showen that an increase in the molar fraction of hydrogen in natural gas will cause problems in gas transport and will lead to an increase in the pressure losses, an increase in flow rate, and a decrease in the storage capacity of the pipeline. The economic analysis examines the use of P2G technology in Czech conditions. It demonstrates the amount of production costs for the production of 1 MWh of synthetic gas depending on the electricity price and the operating time of the production facility. The sensitivity analysis has shown that neither hydrogen nor synthetic methane is competitive next to cheap natural gas unless measures like an increased price of emission allowances or a carbon tax are taken.

This thesis deals with Sector coupling problematics. First, it deals with the development and present situation in the generation and consumption of electric power and the development and present situation in the extraction and consumption of natural gas in the Czech Republic and in the European union. Further, the thesis deals with Sector coupling, this concept is explained, and it is adumbrated what questions it deals with. Then, the technologies that can be achieved in the future of Sector coupling are introduced. Pilot projects of these technologies are presented as part of the discussion about these technologies. Finally, a consideration of the future use of Sector coupling technologies in the Czech Republic is given.

Hydrogen, as a form of storage for the excess energy from renewable sources, is a technically and economically viable option. However, the technology is not mature enough to compete with the other renewable energy possibilities. In this thesis, a study based on coupling two 330 kW wind-turbines with an NELP. 40 electrolyzer this connection should improve the utilization of wind power. In this thesis are two options of energy utilization. The energy produced by the wind-turbine is stored in the form, of hydrogen and is then delivered for consumption at variable power through a fuel cell, second option is use of produced hydrogen as alternative fuel for cars. This study is a general introduction for the wind energy system with hydrogen storage. Future studies should be more complex and detailed in order to understand and model the system with greater accuracy and to increase the possibility for the utilization of wind energy to generate hydrogen. This would enhance wind power competitiveness and sustain the continuously changing world energy demands.

In the last couple of years there has been a great need for finding alternative, cleaner burning fuel sources. This search has led to the development of various hydrogen technologies. The reason for this is that when burnt, hydrogen gas only forms water and oxygen as products. One of the methods used in the production of hydrogen gas is that of the electrolysis of sulphur dioxide which is facilitated by a sulphur dioxide depolarized electrolyzer. The electrolysis of sulphur dioxide has the advantage of requiring lower cell voltages in the electrolysis process when compared to the electrolysis of water. This type of electrolyzer unfortunately suffers from low hydrogen gas production volumes. It was thought that by linearly increasing the reactions active area of the electrolyzer, the production volumes can be increased. A linearly upscaled 100cm2 cell was designed by using computer aided design software, such as SolidWorks, Cambridge Engineering Selector, EES and ANSYS. The cell was then constructed and tested to determine the effects of linearly upscaling. The results of the 100cm2 cell were compared to the results of a similar 25cm2 cell and results obtained from the literature. The 100cm2 cell exhibited very poor performance when compared to the other cells. The 100cm2 cell showed lower hydrogen production volumes at higher energy inputs than the 25cm2 cell and an 86cm2 stack assembly. It was concluded that creating stack assemblies with cells with smaller active areas would be much more efficient than linearly upscaling the active area of the cells.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.

The diploma thesis deals with the principles of operation of lithium ion batteries and their properties when using deposited thin films. The thesis is mainly focused on the formation of thin films using the electrolytic method and subsequently testing the properties of the thin film in an electrochemical cell. The test criteria are mainly the value of the capacity of the prepared electrode and the impact of cycling on the electrode layer itself, where the deposited layer is assessed before cycling and after cycling on an SEM microscope..

The main object of this thesis is the diagnostics of the diaphragm discharge generated in water solutions containing supporting electrolytes (mostly NaCl), and description of particular processes before and after discharge breakdown by DC non-pulsed voltage up to 2 kV. Although many applications of electric discharge in liquids have been developed during the last years, the exact mechanism of the discharge ignition is not sufficiently known up to now. Based on this reason, this work is focused on the investigation of processes before the discharge ignition, breakdown parameters and the discharge itself both in the irregular and stable regime. The theoretical part of the work presents proposed mechanisms of the discharge generation in water solutions including the description of particular kinds of known discharges. Diaphragm discharge is one of many possible configurations of electrical discharges in liquids. In fact, electrical discharge in water forms non-thermal plasma, which is generated by high voltage, and many physical and chemical processes are started in plasma channels (so-called streamers). Among physical processes, high electrical field, shock waves and last but not least emission of electromagnetic radiation in visible and ultra-violet radiation belongs. The most important chemical processes are generation of various active species as hydrogen peroxide, and OH radical. Three batch plasma reactors using a diaphragm configuration with different total volume (4 l, 100 ml and 50 ml) are employed in the presented work. The discharge is created in an orifice (a pin-hole) in the dielectric barrier separating two electrode parts of the reactor. DC non-pulsed high voltage up to 4 kV is used for the discharge generation. Electrodes are made of stainless steel or platinum, and they are installed in parallel to the diaphragm in a variable distance from the dielectric barrier in each reactor part. The dielectric barrier is made of PET or Shapal-MTM ceramics with the variable thickness (0.2?2 mm). One pin hole st the diaphragm center with diameter of 0.2?1.5 mm are used in contemporary experiments. Time resolved characteristics of current and voltage are recorded using four-channel oscilloscope which detected their output values. Parameters are measured by the constantly increasing DC voltage with a step of 100 V. The solutions containing sodium chloride electrolyte are used at five different conductivities. Recorded time resolved characteristics determine breakdown moment, and describe current and voltage in particular parts within the static current-voltage curve. The breakdown appeared at lower applied voltage when the electrode distance is enhanced. However, the electrode distances higher than 4 cm does not induce any significant change of the breakdown voltage. The influence of pin-hole diameter is less obvious in the studied range, but a slight enhancement of breakdown voltage is observed with the increasing pin-hole diameter. Current-voltage characteristic curve moves towards lower voltage with the diaphragm thickness enhancement. The work compares the influence of conductivity change on current-voltage characteristics as well as the effect of inorganic salt kind. By the conductivity enhancement, the measured current-voltage curve moves towards lower voltage which means that the breakdown voltage is decreased. Sizes of the reactors do not have any effect on the processes before and after discharge breakdown.

Thematic interrelation is an underdeveloped field of inquiry in Lukan studies. The design and elegance of Lukan theology begs for guided investigation into a possible system of organisation that governs history and theology, that is, narrative and theme. Based on the Greimasian Actantial Model, morpho–syntactical structural–critical analysis of Luke and Acts reveals that the covenant concept in its operative aspect of service functions as an organising principle, structuring the narratives and facilitating thematic interrelation. A survey of representative Lukan research consisting of five methodologically determined approaches shows a commonality regarding Lukan purpose. These all share the “plan of God” as a fundamental concept, thus intimating its plausibility as a common organisational principle in the text. This observation encourages further analysis of Lukan narrative and meta–narrative as relevant subject matter. Investigation into the purpose and goals of Ancient Jewish and Ancient Greek literature suggests that the concepts of piety/holiness and justness combined with a notion of divine order and expectation demonstrates organisational capacity. Under the terms and conditions of the Old Covenant three non–exclusive themes/concepts hold organisational functionality and ability to facilitate thematic interrelation: Exodus typology, the covenant concept and the eschaton idea. Exodus typology connects narrative with theme, developing Israel’s story. The covenant idea frames stories using parallelism and gives the meta–story progression. The eschaton idea presents the Day of YHWH as an organisational principle guiding the story of judgment to restoration. It is observed that the covenant concept is the most prevalent of these themes/ideas. Assuming the conceptual unity of Luke and Acts and adopting a morpho–syntactical structuralist approach, it was observed that the covenant concept in its operative aspect of service occurred as Helper at ten places, determining the development and structure of the meta–narrative. According to the Greimasian Actantial Model, Israel failed to fulfil its covenant–based mandate to serve God and shine God’s light of mercy to the nations. Jesus, Israel’s new Helper, becomes the Subject and by his covenant–based ministry, characterised as the greatest service, resolves the problem that prevents Israel from carrying out its divine mandate and sets the stage for its fulfilment. In Jesus Israel is given new leaders, an ethical platform of discipleship and the Holy Spirit. The apostle Paul as the epitomised and exemplary witness and servant of Jesus fulfils what Israel could not. He is vindicated in righteousness and shares in the Isaianic ministry of Jesus, to bear witness to leaders and to shine God’s light to the nations. Paul is unhindered in this ministry. Additionally, in thematic–critical terms, the key placement of the covenant concept in its operative aspect of service at plot–defining junctures features its catalytic dynamic as a “template” concept advancing the re–conceptualising of themes and providing a platform for meaningful relation. The evidence thus suggests that the covenant concept in its operative aspect structures the conjoined narratives of Luke and Acts. It also provides a basis for relation between the divine and humans in the context of the history of God’s salvation, linking history and theology, and makes possible a discernible means to thematic interrelation. The SO2 electrolysis was performed by supplying the anode of the cell with SO2 gas, while the water was fed to the cathode using graphite plates as flow fields. Initial experimental work was done at ambient pressures on the anode (SO2 gas–fed) and cathode (water–fed) after which the water pressure was increased from ambient to 1 bar. Various parameters were evaluated for SO2 electrolysis at ambient conditions, including operating temperature, membrane thickness and catalyst loading. The operating temperature was increased from 50oC to 80oC which resulted in a significant voltage improvement from 0.78V to 0.64V at 300mA/cm2. Operating the cell with thinner membranes (86 vs 170um) also resulted in an improved overall cell performance, while the catalyst loading (1 vs 0.5mgPt/cm2) had a negligible effect on the operating voltage. SEM images and EDX analysis were performed on the best performing MEA (N1135) which showed that no degradation of the MEA had occurred.
Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.

This diploma thesis is involved in possible development of different types of milling molds coated with modern plows. The first part is devoted to an analysis of contemporary trends in forms production technology. The analysis includes the different types of machines and tools for making various kinds of molds and dies. Another part deals with design of dies for sheet metal shears. The thesis continues by design of the production procedure after heat treatment and finishing die by miling. For milling of die are designed miling tools, the NC program and the possible development of manufacturing the die using a new machining center and the possibility of production optimization. The penultimate point of the thesis is technical and economical evaluation of the direction of development and comparison of positives and negatoves of each method. At the final evaluation is all summed up.

This diploma thesis is focused on the study of the influence of advanced oxidation processes on degradation of organic dyes. The field of AOP – very effective physically-chemical methods of wastewater treatment – includes application of strong oxidation agents, UV and ionizing radiation and electrical discharges. For this thesis, two of these methods were chosen – the application of oxidation agent (ozone) and UV radiation. Along with electrolysis, which is mentioned rather marginally in this thesis (it is the subject of the previous thesis), these phenomena are products of electrical discharge in water, where they participate in the processes of degradation in a different way. For all measurement series, two direct azo dyes were chosen as model substances – C.I. Direct Blue 106 and C.I. Direct Red 79. The ozonizer, in which either oxygen or synthetic or technical air were loaded as carrier gases, was used for degradation of dyes by ozone. The generated ozone was loaded into the bubbling vessel with dye solution of different initial concentration (10–130 mg.dm-3), which was followed by other bubbling vessel with KI solution for the next analytical determination of the amount of generated ozone. The other parameters changed were the gas flow (1–2 dm3.min-1), ozonizer output (minimal and maximal), type of dye, pH value of the solution (neutral or acid) and additional electrolyte (NaCl, Na2SO4 or any). The reactor for the study of the influence of UV radiation on degradation of dyes was an UV sterilizer into which the equivalent volume of dye solution was added. The possibilities of experimental settings were limited and only the type of dye, an additional electrolyte and pH value of the dye solution were adjusted (as in the case of ozone). Several series of samples were measured with various input conditions which more or less influenced the degradation of investigated dyes in this experiment. It was found that for both used methods the Direct Blue 106 dye was more degradable (with significantly better results for ozone than for UV radiation). The degradation of Direct Red 79 dye proceeded only by ozone treatment, in the case of the application of UV radiation no degradation occurred. By investigation of the influence of initial concentration of dye on its degradation, it was confirmed that with the initial concentration enhancement the final concentration rises as well, whereas in low concentrations (10–50 mg.dm-3) the initial concentration has no effect. The addition of an electrolyte had an accelerating effect on dye degradation in both methods (NaCl and also Na2SO4 showed similar results though the degradation proceeded in different ways). The addition of HCl accelerated the degradation only in the case of UV radiation; during the application of ozone the pH level of the system did not have any influence on the degradation. Oxygen and synthetic air had the strongest effect on ozone degradation (comparable results); in the case of technical air the final dye concentration was higher up to 30 %. The gas flow of 1.5 dm3.min-1 was stated as optimal with the ozonizer output 30 W (maximal). At minimal power the ozonizer produced very low amount of ozone.

This Diploma thesis is focused on physical and chemical effects which contribute to the decomposition of organic dyes by diaphragm discharge generated in water solutions. Due to the application of DC high voltage source in continuous regime, there is an effect of electrolysis contributing to the dye decomposition by diaphragm discharge. The aim of this work was to find out when the electrolysis is running (or when is the moment of discharge breakdown) and which factors influence the breakdown. The other goal was decomposition of selected textile and food organic dyes by electrolysis itself. In the theoretical part, theory about creation of electrical discharges in aqueous solutions is noted and various types of underwater discharges are described. Background researches about underwater electrical discharges used in the world are mentioned as well as the use of diaphragm discharges and various ways how to remove organic dyes from wastewater. Finally, theories of electrolysis, UV-VIS spectroscopy and basis of other analytical methods useful for detection of organic molecules are described. Experimental part is oriented to experiment procedure which was carried out in a reactor with separated electrode areas. Separation was made by dielectric diaphragm with a pinhole in the centre. Its initial diameter was 0.4 mm. Used chemicals and course of experiments are described in this part, too. First, the breakdown moment in the reactor was investigated (i. e. determination, when only electrolysis was operating) by formation of hydrogen peroxide and measurement of dynamic (time resolved) electrical characteristics. Next, decomposition of selected dyes by electrolysis was carried out. As the decomposition was related to decolorization of the solution, UV-VIS spectroscopy in the range of 350–700 nm was used for determination of dye concentration. Next part focused on results presents various factors which had an effect on breakdown of diaphragm discharge. These factors are kind of used electrolyte, initial conductivity of solution, kind of dye, temperature of solution and type of reactor (or solution volume). From the result, the most important factor is initial solution conductivity. After the determination of the breakdown moment, the electrolysis of organic dyes was performed. The applied current was 10 mA, initial conductivity was 500 µS/cm and used electrolyte was NaCl. Moreover comparison of dye decomposition in dependence on the different applied power was realized. From this comparison one can assume, there is no significant contribution of electrolysis (the efficiency is approximately 15 %) to the diaphragm discharge in aqueous solution.

The Ceratium species occurring in the Vaal River since 2000, was identified as Ceratium hirundinella (O.F. Müller) Dujardin as proposed by Van Ginkel et al (2001). Ceratium hirundinella is known to cause problems in drinking water purification and has been penetrating into the final drinking water of Rand Water since 2006. Ceratium hirundinella is associated with many other water purification problems such as disrupting of the coagulation and flocculation processes, blocking of sand filters and algal penetration into the drinking water. Ceratium hirundinella also produce fishy taste and odorous compounds and causes discolouration of the water. The aims of this study were to determine the main environmental factors which are associated with the bloom formation of C. hirundinella in the source water and to investigate the influence of C. hirundinella on the production of potable water. In order to optimise treatment processes and resolve problems associated with high C. hirundinella concentrations during the production of potable water, jar testing and chlorine exposure experiments were performed. Multivariate statistical analyses were performed to determine the main environmental variables behind C. hirundinella blooms. Ten years data (2000 - 2009) from the sampling point C–VRB5T in the Vaal River, (5 km upstream from the Barrage weir) were used for this investigation, because C. hirundinella occurred there frequently during the ten year period. In this study, it was found that C. hirundinella was favoured by high pH, Chemical Oxygen Demand (COD), orthophoshapte (PO4), and silica concentrations, as well as low turbidity and low dissolved inorganic nitrogen (DIN) concentrations. No correlation was found between C. hirundinella and temperature, suggesting that this alga does not occur during periods of extreme warm or extreme cold conditions, but most probably during autumn and spring. The results of the multivariate statistical analysis performed with historical data from Vaalkop dam, indicate that the dinoflagellate C. hirundinella seems to be favoured by low temperature and turbidity, and high DIN, Fe, Methyl–orange alkalinity, Cd, PO4, Conductivity, pH, hardness and SO4 concentrations. In order to optimise treatment processes such as coagulation, flocculation and sedimentation, jar testing experiments were performed to investigate different coagulant chemicals namely: cationic poly–electrolyte only, cationic poly–electrolyte in combination with slaked lime (CaO) and CaO in combination with activated silica. Water from four different sampling localities were chosen to perform the different jar testing experiments: 1) sampling point M–FOREBAY (in the Forebay, connecting the canal to the Zuikerbosch Purification plant) near Vereeniging due to its proximity to the Zuikerbosch treatment plant, 2) M–CANAL_VD (upstream from the inflow of the recovered water from Panfontein) to determine the influence of (if any) the recovered water from Panfontein on Forebay source water, 3) source water from Vaalkop Dam (M–RAW_VAALKOP) and 4) source water from Rietvlei Dam (water from both Vaalkop and Rietvlei Dams contained high concentrations of C. hirundinella at that time of sampling) to determine which coagulant chemical is the most effective in removing high concentrations of C. hirundinella cells during the production of drinking water. The jar testing experiments with Vaalkop Dam and Rietvlei Dam source water (rich with C. hirundinella) indicated that using cationic poly–electrolyte alone did not remove high concentrations of C. hirundinella efficiently. However, when CaO (in combination with cationic poly–electrolyte or activated silica) were dosed to Vaalkop Dam source water a significant decrease of C. hirundinella concentration was observed. This indicates that the C. hirundinella cells were “shocked or stressed” when exposed to the high pH of the CaO, rendering it immobile and thereby enhancing the coagulation and flocculation process. However, when 10 mg/L CaO in combination with poly–electrolyte was dosed to Rietvlei Dam source water the turbidity and chlorophyll–665 results indicated that this coagulant chemical procedure was ineffective in removing algal material from the source water. The jar testing experiments using the cationic poly–electrolyte alone or cationic poly–electrolyte in combination with CaO on M–FOREBAY and M–CANAL_VD source water, showed a decrease in turbidity, chlorophyll–665 concentration, and total algal biomass, with an increase of coagulant chemical. When CaO in combination with activated silica was dosed, the inherent turbidity of the lime increased the turbidity of the Vaalkop Dam, M–FOREBAY and M–CANAL_VD source water to such an extent that it affected coagulation negatively, resulting in high turbidity values in the supernatant. Regardless of the turbidity values, the chlorophyll–665 concentration and total algal biomass (C. hirundinella specifically in Vaalkop Dam source water) decreased significantly when CaO was dosed in combination with activated silica. Therefore it was concluded that a cationic poly–electrolyte alone is a good coagulant chemical for the removal of turbidity, but when high algal biomass occur in the source water it is essential to add CaO to “stress” or “shock” the algae for the effective removal thereof. However, when CaO in combination with activated silica was dosed to Rietvlei Dam source water a decrease in turbidity and chlorophyll–665 concentration was found with an increasing coagulant chemical concentration. These results confirm the fact that coagulant chemicals may perform differently during different periods of the year when water chemistry changes and that certain coagulant chemicals may never be suitable to use for certain source waters. For the effective removal of algae during water purification, it is recommended that cationic poly–electrolyte in combination with CaO are used as coagulant chemical at the Zuikerbosch Water Purification Plant. Turbidity is not a good indication of algal removal efficiency during jar testing experiments. If problems with high algal concentrations in the source water are experienced it is advisable to also determine the chlorophyll–665 concentrations of the supernatant water during the regular jar testing experiments, since it will give a better indication of algal removal. Chlorine exposure experiments were performed on water from Vaalkop Dam (M–RAW_VAALKOP) and Rietvlei Dam source water, to determine the possibility of implementing pre– or intermediate chlorination with the aim to render the cells immobile for more effective coagulation. The chlorine exposure experiments with Vaalkop Dam and Rietvlei Dam source water showed similar results. The chlorine concentration to be dosed as part of pre– or intermediate chlorination will differ for each type of source water as the chemical and biological composition of each water body are unique. When the effect of chlorine on the freshwater dinoflagellate C. hirundinella was investigated, it was found that the effective chlorine concentration where 50 % of Ceratium cells were rendered immobile (EC50) was approximately 1.16 mg/L for Vaalkop Dam source water. For the source water sampled from Rietvlei Dam, it was found that the EC50 was at approximately 0.87 mg/L. Results of analyses to determine the organic compounds in the water after chlorination revealed that an increase in chlorine concentration resulted in increase in total organic carbon concentration (TOC), as well as a slight increase in MIB and trihalomethanes (CHCl3). Pre– or intermediate chlorination seem to be an effective treatment option for the dinoflagellate C. hirundinella to be rendered immobile and thereby assisting in its coagulation process. The use of pre– or intermediate chlorination to effectively treat source waters containing high concentrations of C. hirundinella is a viable option to consider. However, the organic compounds in the water should be monitored and the EC50 value for each source water composition should be determined carefully as to restrict cell lysis and subsequent release of organic compounds into the water.
Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2012.

My diploma thesis is focused on a comparison of direct-current and high frequency (15-80 kHz) electric discharge, which generates non-thermal plasma in water solution of sodium chloride. Mainly current-voltage and Lissajous charts are discussed in the first part of this thesis. These charts describe different discharge phases: electrolysis, bubble formation, discharge breakdown and discharge regular operation in a pin-hole of a dielectric barrier. Influence of frequency, electrolyte conductivity, thickness of the diaphragm (or length of the capillary) and pin-hole diameter on discharge breakdown and bubble generation was studied, too. Measurements were realized in a polycarbonate reactor with total volume of 110 ml, which was divided by a changeable polyacetal insulating wall. This wall divided the reactor into two approximately equal spaces with one stainless steel planar electrode in each part. The Shapal-MTM ceramic discs (thickness of 0.3–1.5 mm and diameter of the central pin-hole of 0.3-0.9 mm) were mounted in the centre of the insulating wall. Initial conductivity of sodium chloride solution was chosen within the interval of 100900 S/cm. The second part of my thesis compares an influence of the direct-current (DC) and high frequency (HF) power sources on physical solution properties (conductivity, pH and temperature) and generation of hydrogen peroxide. A plasma reactor with total volume of 4 l and with mixing set up was divided into two equal spaces with one planar platinum electrode in each part. Diaphragm with thickness of 0.6 mm and pin-hole diameter of 0.6 mm was installed in the middle of the separating wall. Experiment was held at discharge operation of 45 W for 40 minutes with both power sources. Detection of hydrogen peroxide was realised by using a titanium reagent forming a yellow complex, which was analysed by absorption spectroscopy. If HF discharge power is plotted as a function of applied frequency, exponential decrease of frequency with increasing power can be observed. Higher breakdown voltage is necessary for thicker dielectric barriers, on the other hand for bigger diameter of the pin-hole lower breakdown voltage and higher power is needed in DC as well as in HF regime. Breakdown voltage is decreased by the increasing conductivity in both regimes; due to more charge carriers in the higher conductivity lower breakdown voltage is needed. However frequency in HF regime and DC discharge power increases. HF discharge power is decreased by the increasing conductivity. Solution conductivity and temperature are increased by initial conductivity value in both discharge regimes. Solution pH drops to acidic conditions when HF or DC positive regime is applied due to the generation of reactive species and electrolysis (in DC regime). However solution becomes alkaline when DC negative regime is applied. Concentration of hydrogen peroxide is produced linearly when HF or DC negative regime is applied and it depends on initial solution conductivity.

Purpose of this thesis is wisdom accumulation from current area of energetic use of hydrogen and future systems. In overview is presented possible processes where dominate steam methane reforming. In main part of thesis, steam methane reforming will be analyzed and electrolysis also. Actual results will be discussed. Next part is about energetic use of hydrogen based on thermochemical properties and safety. Used of hydrogen will be divided to areas thermal generation as burner‘s section, electric generation as fuel cell‘s section, mechanical energy as combustion engine’s section and finally chemical transportation of energy. At the end will be made a promising energy systems using hydrogen as fuel which can be applied in a large scale.

The exact mechanism of the discharge in liquids ignition is not sufficiently known up to now. Although during the last years was achieved the great progress and overloading which some of them are written in this theoretical part of thesis. This thesis is divided into two experimental parts. When the first part deals with diagnostics of diaphragm discharge in electrolyte solutions and the second part is focused on its use for uncoiling (higher homogenization) of carbon nanotubes in solutions. In experiment 1, three different sized (4 l, 100 ml, 50 ml) diaphragm discharge configurations were used to diagnose diaphragm discharge in electrolyte solutions. Diagnostics is done through current and voltage waveforms with the addition of synchronized ICCD camera images that have been connected to a four-channel oscilloscope. The V-A characteristic can be described by three events occurring in the electrolyte solution with a gradual increase in voltage. Slowly increasing of the voltage in the solution leads first to electrolysis. The next phase is the formation of microbubbles or bubbles, which is characteristic of the curve by a slight decrease in the increase of the current passing between electrodes. The sudden increase in the current flow is characteristic of the last phase, namely the discharge phase. The distance of the electrodes from the diaphragm does not significantly affect the V-A characteristic. The higher diameter of the pin hole, therefore, has a higher voltage, but this does not affect the origin of bubble generation or breakdown. The higher thickness of diaphragm, the higher voltage is needed to the beginning of the bubbles generation, and consequently the discharge breakdown. Comparison of the voltage of the start generation of the bubbles and breakdown for PET diaphragms and diaphragms from the ceramic there was no mark able difference. One of the most important parameters is the conductivity of the electrolyte solution. The lower voltage is needed for the start generation of the bubbles at the higher solution conductivity, and also the discharge generation is observed at a lower breakdown voltage. The second experimental part is focused on the study of the diaphragm discharge effect on carbon nanotubes. A specially designed U-shaped reactor is used to modify carbon nanoparticles. Tap water and aqueous solutions of organic compounds are used as the electrolytic solutions. The discharge is generated by a non-pulsed DC high source with a voltage in the range of 0-2.8 kV supplied to platinum electrodes located in the electrolyte solution. The experimental results have shown that the diaphragm discharge has positive effects on the disintegration of clusters and agglomerates of carbon nanotubes. The primary effect on disintegration is probably the shock waves generated by the discharge. It turned out that it depends on the electrode configuration, where the treatment in anode space has far greater effects than the treatment in cathode half of the reactor. Effects of carbon nanotubes disintegration in solution are long-lasting and the treatment effect is not loosed after several months. There were detected no significant changes in the structure of plasma-treated nanotubes by Infra-red spectroscopy.

STRESZCZENIE PRACY Celem niniejszej pracy było zbadanie wpływu temperatury i składu elektrolitu na proces elektrosorpcji wodoru w stopie wodorochłonnym typu AB5 o składzie LaMmNi4,1Al0,2Mn0,4Co0,45 (LaMm – mischmetal bogaty w lantan). Badany stop jest potencjalnym materiałem do zastosowań jako anoda w ogniwie niklowo-wodorkowym (Ni-MH). Badania prowadziłam technikami elektrochemicznymi (chronowoltamperometria cykliczna, chronoamperometria i chronopotencjometria). Pomiary wykonywałam w roztworach zasadowych (wodorotlenki litowców). Wyniki badań elektrochemicznych porównałam z wynikami uzyskanymi dla sorpcji wodoru z fazy gazowej (PCT). Dodatkowo przeprowadziłam serię analiz fizykochemicznych (IPS, XRD, XPS, SEM-EDS, TGA, DSC) w celu szczegółowego scharakteryzowania badanego materiału. Aby ocenić przydatność stopu wodorochłonnego do zastosowań w ogniwach Ni-MH, należy zbadać parametry takie jak pojemność elektrochemiczna i współczynnik dyfuzji wodoru w tym stopie. Podczas swojej pracy zaobserwowałam, że parametry te zależą od szeregu czynników, m.in. temperatury, rodzaju elektrolitu i jego stężenia, wartości prądu ładowania i rozładowania oraz procesu aktywacji materiału wodorochłonnego przed pomiarami. Elektrody pracujące przygotowywałam przez wprasowanie stopu w matrycę złotą, co pozwalało uzyskać elektrodę o ograniczonej objętości (LVE – Limited Volume Electrode). Wykazałam, że tak przygotowana elektroda zachowuje się jak zbiór mikroelektrod, co umożliwia pełniejszą analizę badanego procesu dyfuzji wodoru. Wykazałam, że współczynnik dyfuzji wodoru (DH) maleje nieliniowo ze wzrostem stopnia nasycenia elektrody wodorem (SOC) i zależy od składu elektrolitu. W temperaturze pokojowej najwyższe wartości DH przyjmuje dla wodoru absorbowanego z roztworu KOH. Współczynniki dyfuzji w temperaturze pokojowej rosną w elektrolitach w kierunku LiOH < NaOH < KOH, a później maleją w kierunku KOH > CsOH > RbOH. Wpływ jonów litowców na proces dyfuzji biegnący w ziarnie stopu można tłumaczyć silnym oddziaływaniem jonów litowców z zaabsorbowanym wodorem. Prawdopodobne jest również wnikanie litowców do warstwy powierzchniowej elektrody, co modyfikowałoby znacznie właściwości stopu. Analiza XPS częściowo potwierdziła ten postulat. Wykazałam też, że wartości współczynnika dyfuzji wodoru rosną ze wzrostem temperatury, co świadczy o tym, że proces dyfuzji wodoru jest aktywowany termicznie. Silny wpływ jonów litowców przejawia się w zmianach energii aktywacji procesu dyfuzji wodoru. Zgodnie z uzyskanymi przeze mnie wynikami wartość energii aktywacji zależy od SOC, co jest wynikiem obsadzania różnych luk międzywęzłowych w kolejnych stadiach nasycenia elektrody wodorem. Dla SOC = 1 wyznaczone energie aktywacji zawierają się w przedziale 20–60 kJ/mol. Zmiany energii aktywacji zależą też od rodzaju zastosowanego elektrolitu. Analogicznie do współczynnika dyfuzji wodoru zmienia się pojemność stopu w zależności od składu elektrolitu. W temperaturze pokojowej najwyższą pojemność uzyskałam podczas badań w roztworze KOH, a później kolejno coraz mniejszą w roztworach NaOH > LiOH > RbOH > CsOH. Wartość pojemności wyznaczona w roztworze 6M KOH w temperaturze pokojowej (280 mAh/g) jest bliska wartości maksymalnej uzyskanej podczas sorpcji wodoru z fazy gazowej (289 mAh/g). To oznacza, że zastosowane procedury elektrochemiczne pozwalają na pełne wysycenie materiału wodorem z roztworu 6M KOH. Wykazałam również, że elektroda pracująca w roztworze wodorotlenku sodu wykazuje największą odporność na wielokrotne cykle ładowania i rozładowania oraz na prądy rozładowania o dużej gęstości. Niezależnie od zastosowanego elektrolitu pojemność elektrody maleje z obniżaniem temperatury. Zmiany pojemności w zależności od składu elektrolitu tłumaczę wpływem elektrolitu na powierzchnię stopu (korozja materiału elektrody). Wykazałam, że zmiany na powierzchni ziaren są najmniejsze w roztworze wodorotlenku potasu, a najsilniejsze – w roztworze wodorotlenku rubidu. Jako produkty korozji po pracy elektrody we wszystkich elektrolitach zidentyfikowałam wodorotlenki niklu, kobaltu i lantanowców. Dodatkowo zauważyłam, że po pomiarach prowadzonych w roztworze RbOH powierzchnia elektrody jest wzbogacona w metaliczny nikiel oraz związki RbLaO2 i Rb2CeO3. Na podstawie uzyskanych danych stwierdziłam, że produkty korozji obecne na powierzchni ziaren stopu są barierą dla procesu elektrosorpcji i powodują spadek pojemności oraz spowolnienie dyfuzji wodoru. Przeprowadziłam badania elektrochemiczne również w roztworach mieszanych. Jako roztwór bazowy zastosowałam 4M KOH, a dodatkiem był każdorazowo wodorotlenek innego litowca (łączne stężenie jonów OH− wynosiło 6 mol/dm3). Zaobserwowałam, że dodatek jonów litu poprawia właściwości elektrody w wysokich temperaturach, natomiast dodatek jonów sodu poprawia jej odporność na pracę w niskich temperaturach. Uzyskane informacje sugerują, że właściwości elektrody wykonanej ze stopu wodorochłonnego LaMmNi4,1Al0,2Mn0,4Co0,45 zależą w dużym stopniu od składu elektrolitu, w którym prowadzone są procesy elektrochemiczne. Przeprowadzone przeze mnie badania są istotne ze względu na możliwość opracowania nowych elektrolitów do zastosowań w ogniwach niklowo-wodorkowych.
In this dissertation I describe an investigation of the influence of temperature and electrolyte composition on hydrogen electrosorption in LaMmNi4,1Al0,2Mn0,4Co0,45 hydrogen storage alloy (LaMm – La-rich mischmetal). The investigated alloy is an anodic material for potential use in construction of nickel-metal hydride batteries (Ni-MH). I performed electrochemical measurements using standard techniques (cyclic voltammetry, chronoamperometry, chronopotentiometry) in alkaline solutions (alkali metal hydroxides). I compared the electrochemical results with the study of gaseous hydrogen absorption by the hydrogen storage alloy (PCT). I performed additional physicochemical analyses (IPS, XRD, XPS, SEM-EDS, TGA, DSC) for better characterisation of the material. In order to verify the usability of the LaMmNi4,1Al0,2Mn0,4Co0,45 hydrogen storage alloy in construction of Ni-MH batteries it is necessary to investigate the electrochemical capacity of the material and the hydrogen diffusion coefficient in it. I have observed that these parameters depend on a number of factors, like temperature, composition and concentration of the electrolyte, the density of charge and discharge currents or the initial electrochemical activation of the material. I prepared the working electrodes by compressing the powder alloy into a gold mesh matrix. Such procedure allows to produce LVE-type electrodes (Limited Volume Electrode). I showed that the electrode behaves like a set of microelectrodes, which allows more accurate investigation of hydrogen diffusion process. I observed that hydrogen diffusion coefficient (DH) nonlinearly decreases with an increase of the state of charge (SOC) of the electrode and it depends on the electrolyte composition. At room temperature the highest values of DH can be observed for KOH solution. When comparing different alkali metal hydroxide solutions the hydrogen diffusion coefficients first increase in the direction LiOH < NaOH < KOH, and later decrease KOH > CsOH > RbOH. The influence of the alkali metal cations on hydrogen diffusion process taking place in the alloy particles can be explained by strong interaction of the cations with the hydrogen absorbed. Intercalation of the alkali metal cations into the surface layer of the alloy particles is also probable. Such intercalation (partly confirmed by XPS analyses) might modify the properties of the alloy. I have demonstrated that hydrogen diffusion coefficient increases with rising temperature. This suggests that hydrogen diffusion process is thermally activated. The activation energy of hydrogen diffusion process is strongly dependent on the electrolyte composition (the presence of alkali metal cations). I have observed that the activation energy also depends on SOC, which is a result of hydrogen filling of interstitial sites of different energies during the absorption process. For SOC = 1 activation energy determined for all the solutions varies in the range of 20–60 kJ/mol. The electrochemical capacity of the hydrogen storage alloy is strongly dependent on the electrolyte composition, like it was observed for hydrogen diffusion coefficient. At room temperature the highest capacity can be observed for the solution of KOH, and it decreases in the direction NaOH > LiOH > RbOH > CsOH. The capacity of the alloy obtained in 6M KOH solution (280 mAh/g) is comparable with maximum equilibrium capacity of the alloy determined from the experiments of absorption of gaseous hydrogen (289 mAh/g). This suggests that used electrochemical procedures result in full hydrogen charge of the material when charging in concentrated KOH solution. I have also observed that in 6M NaOH solution the electrode shows the highest resistance to the multiple charging and discharging procedure and to high rate discharge. The capacity of the alloy decreases with lowering the temperature in all investigated electrolytes. The decrease of the electrochemical capacity of the alloy observed in other electrolytes can be explained by strong interaction of the electrolyte with the surface of the alloy (mainly corrosion). I have observed the surface modifications during electrochemical measurements – the mildest in KOH solution, the most intensive in RbOH solution. I have identified hydroxides of nickel, cobalt and lanthanides as corrosion products. After measurements in RbOH solution, on the surface of the alloy particles I have also observed metal nickel clusters and large (ca. 10 μm) crystals of RbLaO2 i Rb2CeO3. According to my observations I have concluded that surface corrosion products constitute a barrier for hydrogen electrosorption and cause a significant decrease of electrochemical capacity and decay of hydrogen diffusion in the material. I have performed electrochemical analyses of the hydrogen storage alloy also in mixed solutions containing more than one alkali metal cation. I used 4M KOH electrolyte as a base for the mixed solutions. To the basic solution, I was adding a portion of a different alkali metal hydroxide (the total concentration of OH– anions was equal to 6M). I have observed that addition of lithium cations improves properties of the electrode at high temperatures, while addition of sodium cations improves the properties at low temperatures. The results obtained suggest that the properties of the electrode made of the hydrogen storage alloy (LaMmNi4,1Al0,2Mn0,4Co0,45) highly depend on the composition of the electrolyte. The presented electrochemical study is important in view of designing new electrolytes to be used in Ni-MH batteries.

This thesis deals with the oxidative degradation of the active pharmaceutical substance ticagrelor, which is used together with acetylsalicylic acid as a prevention against atherothrombotic events in adult patients. In this thesis, oxidation was studied both in the traditional way using hydrogen peroxide and the new electrochemical approach. The oxidation was performed with a 3% solution of hydrogen peroxide at 50 řC in various solvents. An electrochemical method for the oxidation of ticagrelor was developed as part of the thesis. This method was then optimized to achieve the highest possible oxidation efficiency. The thesis also investigated the effect of excipients on the oxidation rate. Degradation products were evaluated using the ultra-high performance liquid chromatography. The structures of all the degradation products formed were identified using a QDA mass detector. Key words: UPLC, electrolysis, degradation studies, pharmaceuticals