Journal articles: 'Aqueous solution methods'

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Persson, Ingmar, Josephina Werner, Olle Björneholm, Yina Salamanca Blanco, Önder Topel, and Éva G. Bajnóczi. "Solution chemistry in the surface region of aqueous solutions." Pure and Applied Chemistry 92, no. 10 (October 25, 2020): 1553–61. http://dx.doi.org/10.1515/pac-2019-1106.

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AbstractSolution chemistry is commonly regarded as the physical chemistry of reactions and chemical equilibria taking place in the bulk of a solvent, and between solutes in solution, and solids or gases in contact with the solution. Our knowledge about such reactions and equilibria in aqueous solution is very detailed such as their physico–chemical constants at varying temperature, pressure, ionic medium and strength. In this paper the solution chemistry in the surface region of aqueous solutions, down to ca. 10 Å below the water–air interface, will be discussed. In this region, the density and relative permittivity are significantly smaller than in the aqueous bulk strongly affecting the chemical behaviour of solutes. Surface sensitive X-ray spectroscopic methods have recently been applicable on liquids and solutions by use of liquid jets. This allows the investigation of the speciation of compounds present in the water–air interface and the surface region, a region hardly studied before. Speciation studies show overwhelmingly that neutral molecules are accumulated in the surface region, while charged species are depleted from it. It has been shown that the equilibria between aqueous bulk, surface region, solids and/or air are very fast allowing effective transport of chemicals over the aqueous surface region.

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Shapovalov, Serghiy, and Yana Kiseliova. "Association of Thymolsulfonephthalein and Cresolsulfonephthalein Anions with Cationic Cyanines in Aqueous Solution." Chemistry & Chemical Technology 4, no. 4 (December 15, 2010): 271–76. http://dx.doi.org/10.23939/chcht04.04.271.

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The formation of associates between one- or two-charged anions of sulfonephthalein dyes – thymolsulfonephthalein, cresolsulfonephthalein – and cyanine cations (pinacyanol, quinaldine red) has been considered in aqueous solution. Equilibrium association constants have been determined using spectrophotometric data. By semiempirical methods the enthalpy of formation and the eventual structure of ions and associates have been established.

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Fateev, A. I., S. I. Krivosheev, V. A. Kvitsinnsky, and T. G. Shendrik. "METHODS FOR THE DETERMINATION OF SODIUM IN THE PROCESS OF WATER WASHING OF SALTY COAL." Energy Technologies & Resource Saving, no. 1 (March 20, 2020): 19–26. http://dx.doi.org/10.33070/etars.1.2020.2.

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Coal with high content of alkaline and alkaline earth metals (salty coal) occupies its definite place in an energy reserve of the country. Standard methods to assess the dynamics of the release of salts (mainly sodium chloride) into the aqueous solution during the desalting of salty coal were used. The advantages and disadvantages of existing methods for determining the sodium content in aqueous solutions are considered. The principle of operation of the upgraded spectral complex KSVU-5 based on the determination of the content of alkali metals in aqueous solutions by the method of atomic emission analysis is presented. The remarkable reproducibility of the measurements results on the spectral complex of small and large concentration of Na in solution is shown. The results of an experimental study of the desalting process by water washing of salty coal samples of various size classes (in the range 0-5 mm) and analysis of the obtained solutions by the spectral complex KSVU-5 are presented. Comparison of the sodium concentration in solutions during the desalting of salty coal obtained by atomic absorption and atomic emission analysis was performed. The possibility of using express analysis (Conductivity/TDS) to determine the concentration of sodium in solution is shown. Ref. 8, Fig. 6.

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Polishсhuk, Viktor, Svetlana Tarasenko, Ievgen Antypov, Nataliya Kozak, Andrii Zhyltsov, and Oleksandr Okushko. "Study of Methods of Biodiesel Neutralization with Aqueous Solution of Lymonic Acid." E3S Web of Conferences 154 (2020): 02007. http://dx.doi.org/10.1051/e3sconf/202015402007.

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At the article is to determining an effective way to neutralize biodiesel and install optimal and rational parameters of biodiesel neutralization. The investigation of the efficiency of biodiesel neutralization was carried out by mixing it with aqueous citric acid solution (volumetric method) and by spraying an aqueous solution of citric acid over a layer of biodiesel (aerosol method).

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Ullah, Rafique, Biplob Kumer Deb, and Mohammad Yousuf Ali Mollah. "Studies on the Treatment of Wastewaters Containing Cr⁶⁺ with Iron Oxide-Silica Composite Materials Prepared by Different Methods." Defect and Diffusion Forum 353 (May 2014): 33–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.353.33.

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Chromium (VI) is known to be carcinogenic to humans and thus it is important to ensure the removal of Chromium (VI) from aqueous solutions and industrial effluents. The present study introduces a good alternative method for Cr (VI) removal from aqueous solutions at ambient temperature by adsorption, allowing the development of newer, lower operational cost, and more efficient technology than other processes already in use. Adsorption was found to be dependent on pH and initial concentration of Cr (VI) solution. Results of adsorption studies suggest that pristine iron oxide and silicon (IV) oxide removes 72.10% and 24.73%, respectively. The iron oxide – silicon (IV) oxide composite, prepared in this work, removes 93.88% Cr (VI) in 20 minutes from aqueous solution at an initial concentration of 50 mgL-1at pH 4.8 ± 0.2. The effect of concentration, contact time, adsorbent dose and solution pH on the adsorption of Cr (VI) were studied in detail in batch experiments. Studies of the sorption kinetics shows that equilibrium adsorption was attained in 20 minutes depending on other experimental conditions. The kinetic data justified Lagergren’s first-order kinetic equation. Adsorption isotherm study showed that the results fulfilled the Langmuir Model of adsorption isotherm. The maximum adsorption (98.28%) was recorded at pH 3 in 90 minutes for the initial Cr (VI) concentration of 50 mg L-1. Therefore, it can be concluded that iron oxide – silicon (IV) oxide composite is a potential adsorbent for adsorption of Cr (VI) from aqueous solution.

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Terazima, Masahide, and Seung Min Park. "Photoinduced cooling of Eu3+ aqueous solution probed by the photothermal methods." Chemical Physics Letters 228, no. 4-5 (October 1994): 398–402. http://dx.doi.org/10.1016/0009-2614(94)00954-6.

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Reytblat, Irena, Keren Keinan-Adamsky, Jordan H. Chill, Hugo E. Gottlieb, Aharon Gedanken, and Gil Goobes. "NMR studies of DNA microcapsules prepared using sonochemical methods." Physical Chemistry Chemical Physics 17, no. 3 (2015): 2235–40. http://dx.doi.org/10.1039/c4cp04312j.

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Wu, Xi Long, Li Mao, Da Ke Qin, and Shen Zhou Lu. "Impact of Sterilization Methods on the Stability of Silk Fibroin Solution." Advanced Materials Research 311-313 (August 2011): 1755–59. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1755.

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Different sterilization techniques such as Co(60) gamma irradiation and autoclaving were used to treat the regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions. The effect of the two above mentioned sterilization methods on the conformational changes and gelation rate of RSF was studied. According to the analysis of circular dichroism spectroscopy, gamma irradiation may initiate the conformational transition from random coil to β-sheet for RSF, while autoclaving shows less significant influence on the structure changes of RSF in aqueous solutions. The results also indicate that gelation time decreased to 5 days after γ-irradiation treatment while gelation time increased to 31 days after autoclave treatment. Moreover, particles of RSF in solutions changed larger and gelation time increased when autoclaving treatment time extended. However, no detectable changes of RSF secondary structure were found investigated by XRD and FTIR. Which indicated that under both sterilization methods, the RSF structure was transformed from random coil to β-sheet structure after gelation.

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Xu, Binkai, Xiangdong Liu, and Bo Zhou. "Calculation Methods of Solution Chemical Potential and Application in Emulsion Microencapsulation." Molecules 26, no. 10 (May 18, 2021): 2991. http://dx.doi.org/10.3390/molecules26102991.

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Several new biased sampling methods were summarized for solution chemical potential calculation methods in the field of emulsion microencapsulation. The principles, features, and calculation efficiencies of various biased Widom insertion sampling methods were introduced, including volume detection bias, simulation ensemble bias, and particle insertion bias. The proper matches between various types of solution in emulsion and biased Widom methods were suggested, following detailed analyses on the biased insertion techniques. The volume detection bias methods effectively improved the accuracy of the data and the calculation efficiency by inserting detection particles and were suggested to be used for the calculation of solvent chemical potential for the homogeneous aqueous phase of the emulsion. The chemical potential of water, argon, and fluorobenzene (a typical solvent of the oil phase in double emulsion) was calculated by a new, optimized volume detection bias proposed by this work. The recently developed Well-Tempered(WT)-Metadynamics method skillfully constructed low-density regions for particle insertion and dynamically adjusted the system configuration according to the potential energy around the detection point, and hence, could be used for the oil-polymer mixtures of microencapsulation emulsion. For the macromolecule solutes in the oil or aqueous phase of the emulsion, the particle insertion bias could be applied to greatly increase the success rate of Widom insertions. Readers were expected to choose appropriate biased Widom methods to carry out their calculations on chemical potential, fugacity, and solubility of solutions based on the system molecular properties, inspired by this paper.

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Korenkova, O. B., A. V. Radkevich, and N. I. Voronik. "Radionuclide 106Ru behavior in aqueous solutions by ion exchange, ultrafiltration, and centrifugation methods." Proceedings of the National Academy of Sciences of Belarus, Chemical Series 57, no. 3 (September 5, 2021): 331–39. http://dx.doi.org/10.29235/1561-8331-2021-57-3-331-339.

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The paper presents the results of 106Ru radionuclide behavior regularities study in aqueous solutions in a wide pH range by ultrafiltration, ion exchange and centrifugation methods. The regions of 106Ru various species existence in solution have been established: cationic 106Ru species at pH < 3.5; the transition region of non-ionic species formation in the range of pH 3.5–4.2 and the region of non-ionic species predominant formation at pH > 4.2. A characteristic feature of the studied solutions is the formation of non-ionic particles by microconcentrations of 106Ru via pseudocolloids at lower pH values as compared to ruthenium solutions with a concentration of 10-6–10-4 mol/dm3. The established regularities of the behavior of ruthenium radionuclides can be utilized to increase the efficiency of ion exchange and membrane separation methods at nuclear and radiation facilities for technological solutions and liquid radioactive waste treatment.

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Osmanbegovic, Nahla, Lina Yuan, Heike Lorenz, and Marjatta Louhi-Kultanen. "Freeze Concentration of Aqueous [DBNH][OAc] Ionic Liquid Solution." Crystals 10, no. 3 (February 26, 2020): 147. http://dx.doi.org/10.3390/cryst10030147.

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In the present work, freeze crystallization studies, as a novel concentration method for aqueous 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) ionic liquid solution, were conducted. In order to find the appropriate temperature and composition range for freeze crystallization, the solid–liquid equilibrium of a binary [DBNH][OAc]–water compound system was investigated with differential scanning calorimetry (DSC). Results of this analysis showed that the melting temperature of the pure ionic liquid was 58 ℃, whereas the eutectic temperature of the binary compound system was found to be −73 ℃. The activity coefficient of water was determined based on the freezing point depression data obtained in this study. In this study, the lowest freezing point was −1.28 ℃ for the aqueous 6 wt.% [DBNH][OAc] solution. Ice crystal yield and distribution coefficient were obtained for two types of aqueous solutions (3 wt.% and 6 wt.% [DBNH][OAc]), and two freezing times (40 min and 60 min) were used as the main parameters to compare the two melt crystallization methods: static layer freeze and suspension freeze crystallization. Single-step suspension freeze crystallization resulted in higher ice crystal yields and higher ice purities when compared with the single-step static layer freeze crystallization. The distribution coefficient values obtained showed that the impurity ratios in ice and in the initial solution for suspension freeze crystallization were between 0.11 and 0.36, whereas for static layer freeze crystallization these were between 0.28 and 0.46. Consequently, suspension freeze crystallization is a more efficient low-energy separation method than layer freeze crystallization for the aqueous-ionic liquid solutions studied and, therefore, this technique can be applied as a concentration method for aqueous-ionic liquid solutions.

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Tyunina, Elena Yu, Valentin G. Badelin, and Valentina S. Egorkina. "INTERACTION OF NICOTINIC ACID WITH L-PHENYLALANINE IN BUFFER SOLUTIONS: HEAT CAPACITY AND VOLUME PROPERTIES STUDY." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 4 (May 12, 2017): 33. http://dx.doi.org/10.6060/tcct.2017604.5548.

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Thermodynamic and physicochemical properties of multicomponent aqueous solutions containing biologically active solutes are important in various areas of applied chemistry and are essential for understanding the chemistry of biological systems. Interactions between nicotinic acid (NA) and L-phenylalanine (Phe) were studied in aqueous phosphate buffer solutions (pH=7.35) by differential scanning calorimetry and volume methods. Heat capacities and densities of nicotinic acid-buffer, L-phenylalanine-buffer, and nicotinic acid-L-phenylalanine-buffer mixtures were determined at T=(288.15, 298.15, 308.15 and 318.15) K using the microdifferential scanning calorimeter SCAL-1 (Pushchino, Russia) and the density meter DSA 5000 M (Anton Paar). The apparent molar heat capacities (fCp) and apparent molar volumes (Vφ,NA) of nicotinic acid in buffer solution and in buffer 0.0120 mol×kg-1 amino acid solutions were evaluated. The concentration of NA was varied from (0.0079 to 0.036) mol×kg-1. The first and second differentials values were determined for NA in an aqueous buffer solution and for NA in an aqueous amino acid buffer solution. The interaction of NA with Phe is accompanied by complex formation. NA molecules in an aqueous buffer solution are water structure breakers, then the structure breaking effects of NA decrease as a result of interactions with Phe molecules during the complex formation in an aqueous amino acid buffer solution. The results were discussed in terms of various interactions taking place in this system.Forcitation:Tyunina E.Yu., Badelin V.G., Egorkina V.S. Interaction of nicotinic acid with L-phenylalanine in buffer solutions: heat capacity and volume properties study. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 33-39.

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Huang, Yuxin, Chen Wang, Jianyuan Qin, Wendao Xu, Min Chen, Jianxiang Du, Lijuan Xie, and Yibin Ying. "Feasibility Study on Rapid Analysis of Doxycycline Hydrochloride Aqueous Solution by Terahertz Time-Domain Spectroscopy." Transactions of the ASABE 62, no. 1 (2019): 205–12. http://dx.doi.org/10.13031/trans.12493.

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Abstract. Antibiotics have been extensively applied in the treatment of infections in food-producing animals. However, the residues of these agents create a potential risk to human health. Among the methods available for rapid detection of antibiotics, terahertz time-domain spectroscopy (THz-TDS) has emerged as a technique with unique advantages over other methods. In this study, we demonstrate that rapid analysis of doxycycline hydrochloride (DCH) aqueous solutions could be achieved with THz-TDS through transmission, attenuated total reflection (ATR), and reflection with minimum detectable concentrations of 5000, 10, and 80 mg L-1, respectively, indicating that the ATR and reflection methods are superior to the transmission method for low-concentration aqueous solutions. This study is an effort to promote the development of rapid analysis of antibiotic residues in an aqueous matrix using THz spectroscopy. Keywords: Attenuated total reflection, Doxycycline hydrochloride solution, Reflection, Terahertz, Transmission.

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Zayats, Mikhail F., and Sergey M. Leschev. "The development of methods for the determination of residues of the herbicide halauxifen-methyl in barley and rape." Journal of the Belarusian State University. Chemistry, no. 1 (February 28, 2018): 59–65. http://dx.doi.org/10.33581/2520-257x-2019-1-59-65.

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Optimal conditions for the extraction of halauxifen-methyl from grain, straw and green mass of barley; seeds, oil and green mass of rape, as well as the conditions for the purification of extracts were selected on the basis of the distribution constants (P) and distribution coefficients (D) experimentally determined at a temperature of (20 ± 1) °C. At the first stage, acetonitrile, or acidified acetonitrile, or a mixture of water and acetonitrile were used to extract the pesticide. Halauxi fen-methyl was found to be a weakly hydrophobic substance and it exhibits the properties of a weak base in aqueous solutions. For the purification of plant material extracts hexane – 1 mol/L aqueous solution of hydrochloric acid and hexane – 10 % K2HPO4 aqueous solution were successfully used (to neutralize the acid and increase the extraction constant due to the salting out effect). The samples obtained after purification are sufficiently pure. So, the residual amounts of halauxifen-methyl can be determined by widespread liquid chromatography with diode array (ultraviolet) detection at the level, which is equal or lower to the maximum allowable content of herbicide in barley and rape.

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Rybarczyk, Piotr, and Bożenna Kawalec-Pietrenko. "Simultaneous Removal of Al, Cu and Zn Ions from Aqueous Solutions Using Ion and Precipitate Flotation Methods." Processes 9, no. 2 (February 5, 2021): 301. http://dx.doi.org/10.3390/pr9020301.

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This paper presents the results of investigations concerning the simultaneous removal of Al(III), Cu(II), and Zn(II) from dilute aqueous solutions using ion and precipitate flotation methods. The effects of initial solution pH, surface active substance concentration, and the gas velocity on the flotations’ efficiency and course are studied. Experimental results are discussed in terms of physicochemical aspects related to aqueous solutions of metal salts. The results indicate that satisfying simultaneous flotations of aluminum, copper and zinc species are observed if the pH value ranges between 7.0 and 9.0. It was found that an increase in collector concentration results in a decrease in the flotation rate constants. An increase in the gas velocity results in an increase in the ion and precipitate flotation rates.

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Yubuchi, So, Akane Ito, Naoki Masuzawa, Atsushi Sakuda, Akitoshi Hayashi, and Masahiro Tatsumisago. "Aqueous solution synthesis of Na3SbS4–Na2WS4 superionic conductors." Journal of Materials Chemistry A 8, no. 4 (2020): 1947–54. http://dx.doi.org/10.1039/c9ta02246e.

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We report a facile synthetic protocol from aqueous solution for Na₃SbS₄-Na₂WS₄ superionic conductors with sodium-ion conductivity of 4.28 mS cm⁻¹ at 25 °C, which is the highest one in reported sulfide electrolytes prepared via liquid-phase methods.

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Bayiermingda, Cong Li, and Zhang Yan. "The Review of NDMA Removal in Aqueous Solution." Applied Mechanics and Materials 316-317 (April 2013): 614–17. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.614.

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The paper is an overview of some new issues that are connected with the removal of N-Nitrosodimethylamine (NDMA) by some water technology. NDMA is the most frequently detected member of extremely carcinogens, the N-nitrosamines. In this paper, the recent new methods for removing NDMA are introduced and proposed the future direction of the research about the removal of NDMA.

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Presto, Sabrina, Damien Giraud, Andrea Testino, Carlo Bottino, Massimo Viviani, and Vincenzo Buscaglia. "Growth of polycrystalline nickel hydroxide films from aqueous solution. Solution chemistry, deposition methods, film morphology and texture." Thin Solid Films 552 (February 2014): 1–9. http://dx.doi.org/10.1016/j.tsf.2013.12.008.

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Zhang, Li Fang, and Min Wang. "Removal of Neutral Red from Aqueous Solution by Pretreated Penicillium Sp." Advanced Materials Research 383-390 (November 2011): 3969–75. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3969.

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The biosorption of neutral red, from aqueous solutions by Penicilium sp. biomass was studied in a batch system with respect to pretreatment methods, contact time, pH, initial dye concentration and temperature. The NaHCO3- treated biomass exhibited maximum dye uptake at pH 5-6. A larger amount of dye was removed by the pretreated biomass in the first 10 min of contact time and the equilibrium was established in 60 min for 50 mg/L of initial dye concentration. The optimum biosorption temperature was determined as 40 °C. Biosorption played main role in dye removal from aqueous solution in this study. The results indicate that the pretreated Penicilium sp. biomass can be used as an effective biosorbent to remove neutral red from aqueous solution.

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RAO, FENG, SHAOXIAN SONG, and ALEJANDRO LOPEZ-VALDIVIESO. "ELECTROKINETIC STUDIES OF MINERALS IN AQUEOUS SOLUTIONS THROUGH ELECTROACOUSTIC MEASUREMENT." Surface Review and Letters 16, no. 01 (February 2009): 65–71. http://dx.doi.org/10.1142/s0218625x09012305.

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Electrokinetic property of various minerals in aqueous solutions has been studied through electroacoustic measurement in the present work. This study was carried out on the particles of calcite ( CaCO 3), magnetite ( Fe 3 O 4), quartz ( SiO 2), and galena ( PbS ) in an aqueous NaCl solution. Electrophoretic measurement was also applied to magnetite and quartz particles for the comparison of the two methods. The experimental results have shown that the point of zero charges (PZCs) of calcite, magnetite, and galena were at pH 12.5, 3.8 and 2.8, respectively, while no PZC for quartz appeared in the pH range of 1.5–11. The electroacoustic and electrophoretic measurements have obtained the same PZC and similar curves of zeta potential vs pH for magnetite and quartz particles in aqueous solutions. In addition, it has been found that a specific adsorption of Na + cation was applied to magnetite surfaces in aqueous solutions if the electrolyte ( NaCl ) concentration in the solution is high enough, leading the isoelectric point to shift rightward. This observation might be more remarkable in electroacoustic measurement than electrophoretic measurement.

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ALIAKSEYEU, Yuri, Algimantas BUBULIS, Vladimir MINCHENYA, Aleksandr KOROLYOV, Vladimir NISS, and Rasa KANDROTAITĖ JANUTIENĖ. "Plasma Electrolyte Polishing of Titanium and Niobium Alloys in Low Concentrated Salt Solution Based Electrolyte." Mechanics 27, no. 1 (February 24, 2021): 88–93. http://dx.doi.org/10.5755/j02.mech.25044.

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Today, world enterprises specializing in the production of titanium and niobium alloy products and having modern high-tech equipment are still forced to use outdated, costly and environmentally unsafe methods of polishing and surface cleaning, based on electrochemical treatment in toxic solutions. The complex geometric shape of the processed products does not allow the use of mechanical polishing methods, due to high labor costs and low efficiency. These materials are difficult to process, and the processes of their polishing require the use of toxic electrolytes. An alternative to existing methods of electrochemical polishing is plasma electrolyte polishing in aqueous solutions of salts with a concentration of up to 5%. We have developed fundamentally new modes of plasma electrolyte polishing of products from titanium and niobium alloys using simple electrolytes based on an aqueous solution of fluoride salt, the use of which can significantly increase the surface quality class. The advantage of the plasma electrolyte polishing over classical electrochemical polishing is its safety due to the use of an electrolyte based on an aqueous solution of salt. The paper presents the results of an investigation of the characteristics and morphology of the surface after processing using the developed method. Modes that provide the maximum change in roughness with minimal metal removal were obtained.

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Álvarez, Pedro M., Diego H. Quiñones, Isidro Terrones, Ana Rey, and Fernando J. Beltrán. "Insights into the removal of terbuthylazine from aqueous solution by several treatment methods." Water Research 98 (July 2016): 334–43. http://dx.doi.org/10.1016/j.watres.2016.04.026.

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Derikvand, Ehsan, Seyyed Mehdi Borghei, Amir Hessam Hassani, Seyyed Ahmad Mirbagheri, and Amir Hosein Javid. "Comparison of Ozonation and Aeration Methods in Removal of Naphthalene from Aqueous Solution." Asian Journal of Chemistry 25, no. 16 (2013): 9135–37. http://dx.doi.org/10.14233/ajchem.2013.15053.

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Pitarch, Jes�s, Juan-Luis Pascual-Ahuir, Estanislao Silla, I�aki Tu��n, and Manuel F. Ruiz-L�pez. "Modeling ?-lactam interactions in aqueous solution through combined quantum mechanics-molecular mechanics methods." Journal of Computational Chemistry 20, no. 13 (October 1999): 1401–11. http://dx.doi.org/10.1002/(sici)1096-987x(199910)20:13<1401::aid-jcc7>3.0.co;2-m.

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Noon AA Kamil, Shaza W Shantier, and Elrasheed A Gadkariem. "Torsemide Analysis Using Derivative Spectrophotometric Methods." International Journal of Research in Pharmaceutical Sciences 11, SPL4 (December 21, 2020): 1847–52. http://dx.doi.org/10.26452/ijrps.v11ispl4.4388.

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An accurate stability-indicating method has been developed for the analysis of Torsemide (TOR) in bulk and pharmaceutical dosage forms. The methods used the zero-order spectrum (0D) of TOR aqueous solution (measured at 285 nm) and the instrumentally differentiated first (1D) and second (2D) derivative spectra (measured at 311 nm and 282 nm, respectively). The effect of light, acid (HCL) and alkali (NaOH) on the stability of TOR were studied using the new methods. ICH guidelines were used to validate the new methods. Regression analysis of Beer's plots showed a good correlation coefficient not less than 0.998. These methods reported great inter-day and intra-day precision. Excipients interference was not detected due to the achievement of good recovery percentages (97.60 - 101.45 ± 2.7 %, n=3). Good assay results ranged from 99.0 ± 1.7% to 100.0 ± 2.5%; the developed methods obtained n=3. The 2D model proved its ability to be used as a stability indication method of TOR analysis. TOR was unstable in acids and bases with or without heating. Its degradation follows the first-order kinetics. However, its aqueous solution was proved to be stable under sunlight. The established methods demonstrated good precision, sensitivity and accuracy at 95% confidence level.

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Bowling, Frank L., Ryan T. Crews, Eleanna Salgami, David G. Armstrong, and Andrew J. M. Boulton. "The Use of Superoxidized Aqueous Solution versus Saline as a Replacement Solution in the Versajet Lavage System in Chronic Diabetic Foot Ulcers." Journal of the American Podiatric Medical Association 101, no. 2 (March 1, 2011): 124–26. http://dx.doi.org/10.7547/1010124.

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Background: The removal of necrotic tissue from chronic wounds is required for wound healing to occur. Hydrodebridement (jet lavage) and superoxidized aqueous solution have been independently used for debriding wounds. We sought to investigate the use of superoxidized aqueous solution with a jet lavage system. Methods: Twenty patients with diabetic foot ulcers were randomly assigned in a 1:1 ratio to receive jet lavage debridement with either superoxidized aqueous solution or standard saline weekly. Results: There was no significant difference between the two treatments in the reduction of bacterial load or wound size in 4 weeks. No adverse reactions were reported for either treatment. Conclusions: The use of superoxidized aqueous solution for jet lavage debridement seemed to be as safe and effective as saline. Future investigations should concentrate on whether superoxidized aqueous solution may reduce the bacterial air contamination associated with hydrodebridement. (J Am Podiatr Med Assoc 101(2): 124–126, 2011)

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Romanenko, О., Т. Tkachuk, and B. Blyshchyk. "Ultraviolet radiation treatment of the drug «KENO CID 210»." Energy and Automation, no. 4 (September 23, 2020): 116–21. http://dx.doi.org/10.31548/energiya2020.04.116.

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The effectiveness of the process of photoactivation of aqueous solutions has been proven by studies conducted in the article. As a method of exposure, UV radiation is low-cost and natural, so there is a need to study the effect of ultraviolet radiation on aqueous disinfectant solutions and to determine effective methods of irradiation. Accordingly, there is a need to investigate the effect of UV radiation on disinfectants, in particular on their antimicrobial properties and to determine the effective effect of ultraviolet radiation on the tool. The high pressure mercury arc lamp DRT-400 lamp was used as a source of ultraviolet radiation. The surface of the aqueous solution was at a distance of 0.25 m under a source of UV radiation. The photoactivated liquid was applied to the agar medium immediately after inoculation of bacteria. The growth of colonies of microorganisms was recorded 24 hours after application of the treated disinfectant solution. At the Department of Electrical Engineering, Electromechanics and Electrical Technologies of NULES of Ukraine measurements of pH, redox potential of disinfectant solutions immediately after irradiation were carried out. Graphical dependences of changes of disinfecting properties are received. It is established that ultraviolet radiation significantly changes the pH and redox potential of aqueous solutions of disinfectants. The intensity of the parameter change is characteristic of ultraviolet radiation at an exposure of 5-15 minutes. Irradiation of сoncentrated disinfectant based on quaternary ammonium and glutaraldehyde «Keno Cid 210» solution for 5 minutes effectively inhibits the growth properties of microorganisms. The concentration of the irradiated aqueous disinfectant solution can be 5 times lower than the concentration of the non-irradiated.

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Yao, Takeshi. "Synthesis of functional ceramic materials from aqueous solutions." Journal of Materials Research 13, no. 5 (May 1998): 1091–98. http://dx.doi.org/10.1557/jmr.1998.0150.

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Methods for synthesizing ceramic materials from aqueous solutions at ordinary temperature and pressure are advantageous because of the applicability to making films with wide areas and/or complicated shapes with no requirement of vacuum or high temperature, and because of lower cost. Powder of ZrO2 or LnMeO3 (Ln = La, Nd; Me = Cr, Mn, Fe, Co) perovskite was dissolved in hydrofluoric acid and a solution of fluoro-complex ions was obtained. Boric acid was added to the solution, the fluoride ions were consumed by the formation of BF4-, and then the fluoro-complex ions were hydrolyzed to ZrO2 or LnMeO3 in order to increase the amount of fluoride ions. A number of synthesized particles of ZrO2 or LnMeO3 were observed on the substrates in scanning electron microscope images.

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Mathpal, S., and N. D. Kandpal. "Colorimetric Estimation of Ni(II) Ions in Aqueous Solution." E-Journal of Chemistry 6, no. 2 (2009): 445–48. http://dx.doi.org/10.1155/2009/913767.

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A rapid and accurate colorimetric method has been proposed for the estimation of nickel(II) in aqueous solution. It is found that nickel(II) ions have maximum absorbance at 393 nm in distilled water and in aqueous sucrose solution (0.3 mol dm-3). In both case, the Beer’s law was obeyed over the range from 0.04 to 0.08 mol dm-3of nickel(II).The value of molar absorpitivity was constant 5.13±0.03 mol dm-3. This method is more rapid than the existing spectrophotometeric methods for the estimation of nickel(II). The variation in the results obtained by the method is ±2.1%.

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Hui, Qian, and Li Peiyue. "Mixing Corrosion of CaCO3in Natural Waters." E-Journal of Chemistry 8, no. 3 (2011): 1124–31. http://dx.doi.org/10.1155/2011/891053.

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The methods of aqueous speciation calculation, pH calculation and the solubility (precipitability) calculation of CaCO3were used to study the mixing corrosion of CaCO3in natural waters. Mixing processes were done between two unsaturated (with CaCO3) solutions, two oversaturated solutions and between an unsaturated solution and an oversaturated solution, respectively. Results show that the mixing corrosion can be divided into two different levels: mixing corrosion in strict sense and mixing corrosion in broad sense. When mixing corrosion occurs, the HCO3-concentration in one end member solution is usually higher than that in the other solution, and the Ca2+concentration in the former solution is also usually higher than that in the latter one.

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Cloutier, Caroline R., Akram Alfantazi, and Elod Gyenge. "Physicochemical Properties of Alkaline Aqueous Sodium Metaborate Solutions." Journal of Fuel Cell Science and Technology 4, no. 1 (April 17, 2006): 88–98. http://dx.doi.org/10.1115/1.2393310.

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Background: The transition to a hydrogen fuel economy is hindered by the lack of a practical storage method and concerns associated with its safe handling. Chemical hydrides have the potential to address these concerns. Sodium borohydride (sodium tetrahydroborate, NaBH4), is the most attractive chemical hydride for H2 generation and storage in automotive fuel cell applications, but recycling from sodium metaborate (NaBO2), is difficult and costly. An electrochemical regeneration process could represent an economically feasible and environmentally friendly solution. Method of Approach: We report a study of the properties of concentrated NaBO2 alkaline aqueous solutions that are necessary to the development of electrochemical recycling methods. The solubility, pH, density, conductivity, and viscosity of aqueous NaBO2 solutions containing varying weight percentages (1, 2, 3, 5, 7.5, and 10wt.%) of alkali hydroxides (NaOH, KOH, and LiOH) were evaluated at 25°C. The precipitates formed in supersaturated solutions were characterized by x-ray diffraction and scanning electron microscopy. Results: All NaBO2 physicochemical properties investigated, except solubility, increased with increased hydroxide ion concentration. The solubility of NaBO2 was enhanced by the addition of KOH to the saturated solution, but decreased when LiOH and NaOH were used. The highest ionic conductivity (198.27S∕m) was obtained from the filtrate of saturated aqueous solutions containing more than 30wt.%NaBO2 and 10wt.% NaOH prior to filtration. At 10wt.% hydroxide, the viscosity of the NaBO2 solution was the highest in the case of LiOH (11.38 cP) and lowest for those containing NaOH (6.37 cP). The precipitate was hydrated, NaBO2 for all hydroxides, but its hydration level was unclear. Conclusions: The use of KOH as the electrolyte was found to be more advantageous for the H2 storage and generation system based on NaBO2 solubility and solution half-life. However, the addition of NaOH led to the highest ionic conductivity, and its use seems more suitable for the electroreduction of NaBO2. Further investigations on the impact of KOH and NaOH on the electroreduction of NaBO2 in aqueous media have the potential to enhance the commercial viability of NaBH4.

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Palimąka, Piotr, Stanisław Pietrzyk, Michał Stępień, Katarzyna Ciećko, and Ilona Nejman. "Zinc Recovery from Steelmaking Dust by Hydrometallurgical Methods." Metals 8, no. 7 (July 18, 2018): 547. http://dx.doi.org/10.3390/met8070547.

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Hydrometallurgical recovery of zinc from electric arc furnace dust was investigated on a laboratory scale, using aqueous sodium hydroxide solution as a leaching agent. Special attention was paid to the effect of NaOH concentration, temperature and liquid/solid phase ratio on the zinc leachability. It was found that all tested factors increased the leachability, with the maximum efficiency of 88% obtained in a 6 M NaOH solution at a temperature of 80 °C and the liquid/solid phase ratio of 40. The test results confirmed the high selectivity of the zinc leaching agent. In spite of this, complete recovery of zinc from steelmaking dust has proved to be very difficult due to the occurrence of this element in the form of stable and sparingly soluble ZnFe2O4 ferrite. Purification of the solution by cementation and electrolysis gave zinc of purity 99.88% in powder form.

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Shinoda, Kozo, Eiichiro Matsubara, Masatoshi Saito, Yoshio Waseda, Tetsuji Hirato, and Yasuhiro Awakura. "Structural Study of Poly-Molybdate Ions in Acid Mo-Ni Aqueous Solutions." Zeitschrift für Naturforschung A 52, no. 12 (December 1, 1997): 855–62. http://dx.doi.org/10.1515/zna-1997-1204.

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The atomic structure of poly-molybdate ions formed in acid Ni-Mo aqueous solutions has been determined by applying anomalous X-ray scattering (AXS) and EXAFS methods. In a solution containing only molybdenum ions, we found only a poly-molybdate ion consisting of seven edgesharing MoO6 octahedra. In a solution containing both Mo and Ni ions, there exists another polymolybdate ion consisting of 6 edge-sharing MoO6 surrounding an Ni ion. The total coordination number of Mo and Ni ions around a molybdenum ion is reduced by half when introducing citric ions into the Ni and Mo solution. This indicates that the large poly-molybdate ion is decomposed to smaller molybdate ions when forming citric complexes. Since molybdenum-nickel alloys can not be electrodeposited from solutions without citric ions, we propose a view that the structural change of the poly-molybdate ions in the solutions is closely related with the mechanism of induced codeposition of molybdenum and nickel alloy. The results of small-angle X-ray scattering (SAXS) measurements also support this conclusion.

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Golub, Maksym, Adrian Kölsch, Artem Feoktystov, Athina Zouni, and Jörg Pieper. "Insights into Solution Structures of Photosynthetic Protein Complexes from Small-Angle Scattering Methods." Crystals 11, no. 2 (February 19, 2021): 203. http://dx.doi.org/10.3390/cryst11020203.

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High-resolution structures of photosynthetic pigment–protein complexes are often determined using crystallography or cryo-electron microscopy (cryo-EM), which are restricted to the use of protein crystals or to low temperatures, respectively. However, functional studies and biotechnological applications of photosystems necessitate the use of proteins isolated in aqueous solution, so that the relevance of high-resolution structures has to be independently verified. In this regard, small-angle neutron and X-ray scattering (SANS and SAXS, respectively) can serve as the missing link because of their capability to provide structural information for proteins in aqueous solution at physiological temperatures. In the present review, we discuss the principles and prototypical applications of SANS and SAXS using the photosynthetic pigment–protein complexes phycocyanin (PC) and Photosystem I (PSI) as model systems for a water-soluble and for a membrane protein, respectively. For example, the solution structure of PSI was studied using SAXS and SANS with contrast matching. A Guinier analysis reveals that PSI in solution is virtually free of aggregation and characterized by a radius of gyration of about 75 Å. The latter value is about 10% larger than expected from the crystal structure. This is corroborated by an ab initio structure reconstitution, which also shows a slight expansion of Photosystem I in buffer solution at room temperature. In part, this may be due to conformational states accessible by thermally activated protein dynamics in solution at physiological temperatures. The size of the detergent belt is derived by comparison with SANS measurements without detergent match, revealing a monolayer of detergent molecules under proper solubilization conditions.

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Abedi, Mostafa, and Hossein Farrokhpour. "Acidity constants of some sulfur oxoacids in aqueous solution using CCSD and MP2 methods." Dalton Transactions 42, no. 15 (2013): 5566. http://dx.doi.org/10.1039/c3dt33056g.

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Gugulothu, Rajanna, Arun Kumar Macharla, Kranthi Chatragadda, and Anuj A. Vargeese. "Catalytic decomposition mechanism of aqueous ammonium dinitramide solution elucidated by thermal and spectroscopic methods." Thermochimica Acta 686 (April 2020): 178544. http://dx.doi.org/10.1016/j.tca.2020.178544.

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Yasuoka, Takashi, Tadahiko Kidokoro, and Shunmei Mitsuzawa. "Methods for Observing the Deformation of an Aqueous Paramagnetic Solution in a Magnetic Field." Bulletin of the Chemical Society of Japan 58, no. 10 (October 1985): 3023–24. http://dx.doi.org/10.1246/bcsj.58.3023.

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Jensen, Jan H. "Predicting accurate absolute binding energies in aqueous solution: thermodynamic considerations for electronic structure methods." Physical Chemistry Chemical Physics 17, no. 19 (2015): 12441–51. http://dx.doi.org/10.1039/c5cp00628g.

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Lilja, Christina, Iva Betova, and Martin Bojinov. "Electrochemical methods to study hydrogen production during interaction of copper with deoxygenated aqueous solution." Electrochimica Acta 202 (June 2016): 333–44. http://dx.doi.org/10.1016/j.electacta.2015.12.159.

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40

Reli, Martin, Miroslava Edelmannová, Marcel Šihor, Petr Praus, Ladislav Svoboda, Kateřina Kutláková Mamulová, Hana Otoupalíková, et al. "Photocatalytic H2 generation from aqueous ammonia solution using ZnO photocatalysts prepared by different methods." International Journal of Hydrogen Energy 40, no. 27 (July 2015): 8530–38. http://dx.doi.org/10.1016/j.ijhydene.2015.05.004.

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Nasri, Khouloud, Chaker Chtara, Hassen Chekir, and Hafed EL Feki. "Solubility Study and purification Of Industrial triple superphosphate in aqueous solution." JOURNAL OF ADVANCES IN CHEMISTRY 9, no. 2 (April 7, 2013): 1943–52. http://dx.doi.org/10.24297/jac.v9i2.2348.

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Triple Superphosphate (TSP) is a chemical fertilizer, acknowledged by its important content of phosphorus, necessary element for plants. It’s obtained by adding phosphoric acid to phosphate ore, consisting of calcium phosphate containing many impurities. TSP was dissolved at different temperatures and in various amounts of water, filtered to remove insoluble compounds. Then the ionic conductivity was monitored for each solution as a function of the added amount of TSP. Aqueous solutions were evaporated to dryness and analyzed the P2O5. The starting materials and final products were analyzed by several methods (XRD, IR, NMR, SEM) confirming that after dissolution the product was purified.

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Alagta, Abdulmajed, Ilona Felhősi, and Erika Kálmán. "Hydroxamic Acid Corrosion Inhibitor for Steel in Aqueous Solution." Materials Science Forum 537-538 (February 2007): 81–88. http://dx.doi.org/10.4028/www.scientific.net/msf.537-538.81.

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The selected dihydroxamic acid derivatives, namely oxalyl-dihydroxamic acid (C2) and pimeloyl-1,5-di-hydroxamic acid (C7) have been synthesized and evaluated as corrosion inhibitors for carbon steel in neutral aqueous solution by potentiodynamic polarization and ac impedance methods. C2 molecule acts as good inhibitor with inhibition efficiency value reached 91%; it is well adsorbed most likely throughout the two hydrophilic groups, and forms a protective film on the metal surface. C7 has moderate inhibition efficiency probably due to the presence of long single hydrocarbon chain in the molecule, negatively affect the adsorption process. Addition of Ni2+ to C7 significantly improve the inhibition efficiency, throughout the formation of a dense compact layer of complexes between Ni2+ and C7.

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Dahl, Gregor Thomas, Jan-Dominik Krueger, Sebastian Döring, Horst Weller, and Tobias Vossmeyer. "Seeded Growth Synthesis of Zirconia@Gold Particles in Aqueous Solution." Nanomaterials 10, no. 6 (June 19, 2020): 1197. http://dx.doi.org/10.3390/nano10061197.

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Metal-ceramic composite particles are of increasing interest due to their potential applications in photonic metamaterials as well as next-generation catalysts. The zirconia-gold system has received little attention due to the lack of controllable preparation methods. Well-known methods for the deposition of gold nanoshells on silica spheres, however, should be adaptable for similar zirconia-based materials. Here, we present a novel synthetic approach to the well-controlled deposition of gold on the surface of sol-gel derived zirconia mesoparticles by a stepwise method involving the immobilization of gold nanoparticles and repeated seeded-growth steps. We show that the immobilization efficiency is strongly enhanced by acidification with hydrochloric acid and additional employment of aminomethylphosphonic acid as coupling agent. The optimum conditions are identified and the subsequent incremental growth by seeded reduction of gold is demonstrated. The results shed light on the parameters governing the preparation of zirconia@gold composite particles and our synthetic approach provides a promising tool for future developments in complex nanomaterials design.

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Xu, Yan, Yue Hua Wen, Jie Cheng, Gao Ping Cao, and Yu Sheng Yang. "Electrochemical Reaction Mechanism of Tiron in Acidic Aqueous Solution." Advanced Materials Research 396-398 (November 2011): 1730–35. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.1730.

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Electrochemical oxidation of tiron in the presence of H2O as a nucleophile in strongly acidic aqueous solutions was studied by cyclic voltammetry, controlled-voltage coulometry and spectrometric investigations. The mechanism of electrochemical reaction is confirmed by spectrophotometric tracing in various times of controlled-voltage coulometry. The voltammetric and spectrophotometric foundations indicate that a 1,4-Michael addition of H2O from its hydroxy moiety to the position 4 of electrochemically derived o-quinone is occurred. The electrochemical oxidation and reduction of tiron has been successfully accomplished by controlled-voltage coulometry in a redox flow-through type cell and the final electro-reduced product was characterized by spectrophotometric, 1H NMR and mass spectrometric methods. It is demonstrated that the electro-oxidation of tiron follows an ECE mechanism in acidic aqueous solutions, leading to formation of a new compound of para- benzoquinone derivative.

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Shapovalov, Serghey, and V. Ponomariov. "Interaction of Dyes with Cationic Surfactants in Solutions: Determination of Critical Micelle Concentration." International Letters of Chemistry, Physics and Astronomy 81 (February 2019): 27–34. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.81.27.

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Interactions of sulforhodamine B or ethyl eosin (as the anionic dye) with cetylpyridinium bromide (as a cationic surfactant) have been investigated by visible spectroscopy in aqueous solution. The object of research is the association between an anion of dye and of cationic surfactant in aqueous solutions and its features. Computer simulation of these interactions was carried out with the use of AM1 and PM3 semi-empirical methods. A new spectrophotometric method was developed for determination of critical micelle concentration of cationic surfactants.

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Саркисов, Yu Sarkisov, Сидоренко, G. Sidorenko, Лаптев, B. Laptev, Горленко, N. Gorlenko, Антошкин, and L. Antoshkin. "Evaluation of changing the structure of aqueous solutions in the near-wall layers with using dielectrometry and resonance method." Journal of New Medical Technologies. eJournal 9, no. 2 (July 6, 2015): 0. http://dx.doi.org/10.12737/11249.

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In this work the authors evaluated changes of the structure of aqueous solutions of chlorides of sodium and potassium in various concentrations in the parietal layer by means of the dielectrometry and resonance method. In experiments at 20 ° C, the concentration of sodium and potassium chloride concentration of 0.01 M to 1 M in thenear-wall layer "glass - water solutions" height of less than 1000 microns observed multiple reduction of capacitance of solutions, and Q of an oscillatory circuit and a multiple increase coefficient KS which allows to evaluate the structure of the solutions. It is shown that the structure of the solutions in the wall layer depends on the solution concentration, the nature of the solute and the material of surface. Methods of dielectrometry and resonance are informative in the interpretation of the processes in the fluid layer at the interface, "solid – aqueous solution".

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Cassagneau, T. P., B. Sweryda-Krawiec, and J. H. Fendler. "Rectifying Self-Assembled Ultrathin Films." MRS Bulletin 25, no. 9 (September 2000): 40–46. http://dx.doi.org/10.1557/mrs2000.178.

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“Soft solution processing” is rapidly becoming a viable approach for the fabrication of advanced nanostructured materials. It involves the use of environmentally friendly chemicals and preparation methods with minimum energy input. Construction of ultrathin films by the room-temperature, layer-by-layer self-assembly of dilute aqueous solutions (or dispersions) of polyelectrolytes (or polymers), nanoparticles, and nanoplatelets is clearly soft solution processing (see the articles by Yoshimura et al. in this issue).

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Chokradjaroen, Chayanaphat, Jiangqi Niu, Gasidit Panomsuwan, and Nagahiro Saito. "Insight on Solution Plasma in Aqueous Solution and Their Application in Modification of Chitin and Chitosan." International Journal of Molecular Sciences 22, no. 9 (April 21, 2021): 4308. http://dx.doi.org/10.3390/ijms22094308.

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Sustainability and environmental concerns have persuaded researchers to explore renewable materials, such as nature-derived polysaccharides, and add value by changing chemical structures with the aim to possess specific properties, like biological properties. Meanwhile, finding methods and strategies that can lower hazardous chemicals, simplify production steps, reduce time consumption, and acquire high-purified products is an important task that requires attention. To break through these issues, electrical discharging in aqueous solutions at atmospheric pressure and room temperature, referred to as the “solution plasma process”, has been introduced as a novel process for modification of nature-derived polysaccharides like chitin and chitosan. This review reveals insight into the electrical discharge in aqueous solutions and scientific progress on their application in a modification of chitin and chitosan, including degradation and deacetylation. The influencing parameters in the plasma process are intensively explained in order to provide a guideline for the modification of not only chitin and chitosan but also other nature-derived polysaccharides, aiming to address economic aspects and environmental concerns.

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Rahman, Mohammad Arifur, Tamanna Azam, and A. M. Shafiqul Alam. "Removal of Phosphate Ions from Aqueous Solution Using Anthracite." Dhaka University Journal of Science 60, no. 2 (July 31, 2012): 181–84. http://dx.doi.org/10.3329/dujs.v60i2.11490.

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Anthracite was used as an adsorbent to remove excess phosphate from wastewater. Anthracite used in the present study is environmentally friendly and of cost effective. The adsorption study was carried out using different particle size of adsorbents, different concentration of phosphate solution ranging from 25.0 mg/L to 100.0 mg/L, different pH values ranging from 0.5 to 11.5 along with different adsorbent amount from 1.0 g to 5.0 g. Flow rate was also varied in the range of 0.6 mL/min to 1.8 mL/min. Adsorption column methods show the optimum removal of phosphate under the following conditions: initial phosphate concentration 25 mg/L, initial volume 25.0 mL, flow rate 1.0 mL/min adsorbent amount 2.0 g, particle size, < 90?m. This removal method may provide a solution to the removal phosphate from wastewater in Bangladesh as well as other countries of the world.DOI: http://dx.doi.org/10.3329/dujs.v60i2.11490 Dhaka Univ. J. Sci. 60(2): 181-184, 2012 (July)

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Beuermann, Sabine, Michael Buback, Pascal Hesse, Frank-Dieter Kuchta, Igor Lacík, and Alex M. van Herk. "Critically evaluated rate coefficients for free-radical polymerization Part 6: Propagation rate coefficient of methacrylic acid in aqueous solution (IUPAC Technical Report)." Pure and Applied Chemistry 79, no. 8 (January 1, 2007): 1463–69. http://dx.doi.org/10.1351/pac200779081463.

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Critically evaluated propagation rate coefficients, kp, for free-radical polymerization of methacrylic acid, MAA, in aqueous solution are presented. The underlying kp values are from two independent sources, which both used the IUPAC-recommended technique of pulsed-laser-initiated polymerization (PLP) in conjunction with molar mass distribution (MMD) analysis of the resulting polymer by size-exclusion chromatography (SEC). Different methods of measuring the MMD of the poly(MAA) samples have, however, been used: (i) direct analysis via aqueous-phase SEC and (ii) standard SEC with tetrahydrofuran as the eluent carried out on poly(methyl methacrylate) samples obtained by methylation of the poly(MAA) samples from PLP. Benchmark kp values for aqueous solutions containing 15 mass % MAA are presented for temperatures between 18 and 89 °C. The Arrhenius pre-exponential and activation energy of kp at 15 mass % MAA are 1.54 × 106 L mol-1 s-1 and 15.0 kJ mol-1, respectively. Also reported are critically evaluated kp values for 25 °C over the entire MAA concentration range from dilute aqueous solution to bulk polymerization.

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Journal articles on the topic 'Aqueous solution methods'

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