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1
Meacham, Robert Ian. "Sorption-effect chromatography." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/27095.
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The objective of this work has been to develop an understanding of the changes in volumetric flow rate that occur during chromatography so that flow rate measurements can be used as the basis of an analytical method. It is suggested that the total amount of gas which adsorbs on a column equals the total amount of gas which elutes from the end of the column.
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Mwamila, Luhuvilo. "Arsenic (V) and Phosphate sorption to Swedish clay soils - Freundlich sorption modelling." Thesis, KTH, Miljögeokemi och ekoteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96100.
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This thesis is an attempt to analyze and interpret the behavior of the two elements arsenic and phosphorus when released into the environment. Both of them may occur naturally in the environment but also may be added to the environment for certain purposes e.g. as pesticides and fertilizers respectively or through anthropogenic sources. When in excess, arsenic can be toxic to plants and organisms in the soil and some of it when leaches to groundwater or transported to surface water bodies through runoffs may pose a threat to aquatic organisms. Likewise, phosphorus when in excess result into eutrophication of surface water bodies and groundwater as well which has been a major problem in the Baltic Sea. In order to be able to predict their mobility a study on their chemical and physical characteristics under different conditions is important. The soil composition is an important aspect of nutrient management because some of the minerals present i.e. hydr(oxides) of aluminium and iron tend to hold and store both arsenic and phosphorus in the soil, while plant uptake and harvest may remove them (especially phosphorus) from the soil. This study was focused on Swedish agricultural soils and the samples for investigation were collected from two locations, one is Broknäs from which samples were collected from different horizons i.e. A 0-30 cm, C 60-90 cm and C 47-67 cm samples from an area known as Bogesundslandet, NE of Stockholm (59°24’N, 18°18’E) and E21:2 was collected from the county of Östergötland (58°27’N,14°57’E), southern Sweden not far from Lake Vättern, from where the A horizon was collected. Batch experiments were performed to check pH and concentration dependence of the sorption/desorption of As and P. Two varieties of the Freundlich equation (Basic and Competitive) were used to model the results obtained. It was observed that the dependence of arsenate and phosphate sorption/desorption on pH show a similar but not identical trend for both anions. At low pH, the dependence of dissolved P and As did not agree, for unknown reasons. Possibly, the low pH value may mobilize otherwise un-reactive P that at higher pH are blocked by some aluminium/iron precipitate. The Freundlich modeling results showed that there is direct competitive adsorption between As and P ions, at least in the A horizon. However use of the competitive Freundlich equation did not result in meaningful results in the C horizon, which may indicate different As and P sorption mechanisms. However, further studies on this are recommended.
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Marais, Charles Guillaume. "Thermodynamics and kinetics of sorption /." Link to the online version, 2008. http://hdl.handle.net/10019/1944.
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Bachmaf, Samer. "Uranium sorption on clay minerals." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2010. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-62404.
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The objective of the work described in this thesis was to understand sorption reactions of uranium occurring at the water-clay mineral interfaces in the presence and absence of arsenic and other inorganic ligands. Uranium(VI) removal by clay minerals is influenced by a large number of factors including: type of clay mineral, pH, ionic strength, partial pressure of CO2, load of the sorbent, total amount of U present, and the presence of arsenate and other inorganic ligands such as sulfate, carbonate, and phosphate. Both sulfate and carbonate reduced uranium sorption onto IBECO bentonite due to the competition between SO42- or CO32- ions and the uranyl ion for sorption sites, or the formation of uranyl-sulfate or uranyl-carbonate complexes. Phosphate is a successful ligand to promote U(VI) removal from the aqueous solution through formation of ternary surface complexes with a surface site of bentonite.
In terms of the type of clay mineral used, KGa-1b and KGa-2 kaolinites showed much greater uranium sorption than the other clay minerals (STx-1b, SWy-2, and IBECO montmorillonites) due to more aluminol sites available, which have higher affinity toward uranium than silanol sites. Sorption of uranium on montmorillonites showed a distinct dependency on sodium concentrations because of the effective competition between uranyl and sodium ions, whereas less significant differences in sorption were found for kaolinite. A multisite layer surface complexation model was able to account for U uptake on different clay minerals under a wide range of experimental conditions. The model involved eight surface reactions binding to aluminol and silanol edge sites of montmorillonite and to aluminol and titanol surface sites of kaolinite, respectively. The sorption constants were determined from the experimental data by using the parameter estimation code PEST together with PHREEQC. The PEST- PHREEQC approach indicated an extremely powerful tool compared to FITEQL.
In column experiments, U(VI) was also significantly retarded due to adsorptive interaction with the porous media, requiring hundreds of pore volumes to achieve breakthrough. Concerning the U(VI) desorption, columns packed with STx-1b and SWy-2 exhibited irreversible sorption, whereas columns packed with KGa-1b and KGa-2 demonstrated slow, but complete desorption. Furthermore, most phenomena observed in batch experiments were recognized in the column experiments, too.
The affinity of uranium to clay minerals was higher than that of arsenate. In systems containing uranium and arsenate, the period required to achieve the breakthrough in all columns was significantly longer when the solution was adjusted to pH 6, due to the formation of the uranyl-arsenate complex. In contrast, when pH was adjusted to 3, competitive sorption for U(VI) and As(V) accelerated the breakthrough for both elements.
Finally, experiments without sorbing material conducted for higher concentrations of uranium and arsenic showed no loss of total arsenic and uranium in non-filtered samples. In contrast, significant loss was observed after filtration probably indicating the precipitation of a U/As 1:1 phase.
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Higgo, J. J. W. "Radionuclide sorption by marine sediments." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37725.
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Marais, Charl Guillaume. "Thermodynamics and kinetics of sorption." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1810.
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Rimas, Zilvinas. "Sorption in disordered porous media." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/268094.
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The lattice-gas model of sorption in disordered porous media is studied for a variety of settings, using existing, updated and newly developed numerical techniques. Firstly, we construct an efficient algorithm to calculate the exact partition function for small lattice-gas systems. The exact partition function is used for detailed analysis of the core features exhibited by such systems. We proceed to develop an interactive Monte Carlo (MC) simulation engine, that simulates sorption in a porous media sample and provides real-time visual data of the state space projection and the 3d view of the sample among other parameters of interest, as the external fields are manipulated. The use of such tool provides a more intuitive understanding of the system behaviour. The MC simulations are employed to study sorption in several porous solids: silica aerogel, Vycor glass and soil. We investigate how the phenomena depend on the microstructure of the original samples, how the behaviour varies with the external conditions, and how it is reflected in the paths that the system takes across its state space. Secondly, we develop two methods for estimation of the relative degeneracy (the number of microstates that have the same value of some macroscopic variables) in the systems that are too large to be handled exactly. The methods, based on a restricted infinite temperature sampling, obtain equidegenerate surfaces and the degeneracy gradient across the state space. Combined with the knowledge of an internal energy of a microstate, it enables us to construct the free energy map and thus the equilibrium probability distribution for the studied projection of the state space. Thirdly, the jump-walking Monte-Carlo algorithm is revisited and updated to study the equilibrium properties of systems exhibiting quasi-ergodicity. It is designed for a single processing thread as opposed to currently predominant algorithms for large parallel processing systems. The updated algorithm is tested on the Ising model and applied to the lattice-gas model for sorption in aerogel and Vycor glass at low temperatures, when dynamics of the system is significantly slowed down. It is demonstrated that the updated jump-walking simulations are able to produce equilibrium isotherms which are typically hidden by the hysteresis effect characteristic of the standard single-flip simulations. As a result, we answer the long standing question about the existence of the first-order phase transitions in Vycor. Finally, we investigate sorption in several distinct topology network representations of soil and aerogel samples and demonstrate that the recently developed analytical techniques for random networks can be used to achieve a qualitative understanding of the phenomena in real materials.
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Alajmi, Faleh. "Water sorption of flowable composites." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/367584.
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Oral BiologyM.S.
ABSTRACT Objectives: Flowable composites are characterized by lower filler loading and a greater proportion of diluent monomers in their formulation. These composites were traditionally created by retaining the same small particle size of the conventional hybrid composites, but reducing the filler content and allowing the increased resin to reduce the viscosity of the mixture However, their various mechanical properties such as flexural strength and wear resistance have been reported to be generally inferior compared to those of the conventional composites. Dental restorative materials are in continuous contact with fluids and saliva in the patient’s mouth. Consequently, the water sorption and solubility of these materials are of considerable importance. Resin based materials demonstrate water sorption in the oral cavity, which is the amount of water absorbed by the material on the surface and into the body while the restoration is in service. The water intrusion in the dental material can lead in a deterioration of the physical/mechanical properties, decreasing the life of resin composites. Water uptake can promote breakdown causing a filler-matrix debonding. Water sorption affects the physical and mechanical properties of resin composite such as dimensional change, decrease in surface hardness and wear resistance, filler leaching, change in color stability, reduction in elastic modulus, and an increase in creep and a reduction in ultimate strength, fracture strength, fracture toughness, and flexural strength. In addition, penetration of water into the composite may cause release of unreacted monomers (solubility) which may stimulate the growth of bacteria and promote allergic reactions. The effect of water sorption on conventional composites has been extensively studied and reviewed in the dental literature. However , there are no published studies on the water sorption of flowable composites. Water sorption increases as the amount of resin matrix increases and filler content decreases, since the filler particles do not absorb water. Thus, it is of utmost importance to study the water sorption of flowable composite. Hence the aim of this study was to evaluate and compare water sorption and solubility values of different light-activated flowable composite materials in solutions with varying pH values. And, since water filled porosities in the flowable composites may form small incubation chambers, a second related objective was to compare and correlate water sorption values of the various flowables to their ability to form Streptococcus mutans and Streptococcus sanguis single species biofilms in/on their surfaces. Methods: In this study, water sorption and solubility tests were performed according to the ISO standards (International Organization for Standardization specification 4049:07-2009- Dentistry- Polymer Based Restorative Materials [available at http://www.iso.org/iso/home/store.htm]). Three disc-shaped specimens of each flowable composite were made in a jig consisting of a Teflon mold (15 mm in diameter by 1 mm in thickness) compressed between 2 glass slabs with mylar strips used as separating sheets. The flowable resin was inserted in the Teflon mold in a single increment. All specimens were cured with a light-emitting diode curing unit. According to the ISO standard, discs were weighted every day for 35 days using the same balance, with a repeatability of 0.1 mg, until a constant mass (M1) was obtained. Once a constant M1 was obtained, the volume (V) was then calculated in cubic millimeters as follow: V =π(d/2)2h, where π=3.14; d is the mean diameter of the specimen; and h is the mean thickness of the specimen. After M1 was achieved, each flowable composite resin group of 3 discs was placed into buffers of pH = 4.0,5.5 and 7.0. After 24 hrs, specimens were wiped free of excess buffer with absorbent paper and weighed. This cycle was repeated at one week , one month, and six months. When a constant mass was achieved it was designated M2. Mass gain (Mg) was defined as follows: (M2 –M1). Per cent mass gain (%Mg) was defined as follows: (M2-M1/M1). Finally, the specimens were reconditioned to constant mass, once again following the above-mentioned procedure. This constant mass was recorded as M3. Water sorption (Wsp) was calculated in micrograms per cubic millimeter for each of the specimens by using the following equation provided by ISO 4049 standard: Wsp=(M2-M3)/V, where M2 is the mass of the specimens in micrograms after immersion in buffer for 30 days; M3 is the reconditioned mass of the specimen, in micrograms; and V is the volume of the specimen in cubic millimeters. Water solubility (Wsl) was calculated in micrograms per cubic millimeter for each of the specimens, using the following equation, provided by ISO 4049 standard: Wsl=(M1-M3)/V, where M1 is the conditioned mass of the specimen in micrograms before immersion in buffer; M3 is the reconditioned mass of each specimen in micrograms, and V is the volume of the specimen in cubic millimeters. For biofilm experiments, flowable discs were prepared as described above. Each disc was then sectioned into three equal portions using high speed and low speed handpieces , a diamond bur, and sandpaper discs, such that the three samples of each flowable had the same mass to within 0.3 mg. The samples were sterilized by dipping in 1.2% sodium hypochlorite (Chlorox), followed by rinsing with sterile distilled water, and then conditioning to a constant mass as described above, inside a desiccator that was wiped with 1.2 % Chlorox. Biofilm experiments were conducted as follows: three equal mass specimens of each flowable composite were placed in a series of wells of a sterile culture disc. Then sterile BHI broth (2 ml) was added to each well. One well served as control and no growing bacteria were added to it. To the other specimens was added 40 μl log phase S. mutans or S. sanguis cells. The culture dishes were then placed on a rotator at 37C for six hrs. Biofilm formation was measured by staining attached cells with crystal violet, destaining with 30% acetic acid, and measuring the satin spectrophotometically. Results: The pH of the solution influenced the % mass gain, as all samples gained more mass at pH 4.0 as compared to pH 5.5 and 7.0. The flowable resin SureFill showed the least % mass gain at each pH. However, there was no statistical difference in % mass gain based on pH of storage buffer for any of the flowable composites (P=.05) . Time had a significant influence on the % mass gain for the first week for all samples, with minor gains thereafter, and became steady after 1 month. Surefill showed the least water sorption when stored in buffer for 30 days, however it was not significant compared to the other flowables (P= 0.05). Filtek showed the least water solubility, but is not significant compared to the other flowables (P=0.05). The highest significant values (P< 0.05) for water sorption and solubility were observed for Virtuoso. Two trials indicated that strains of S. mutans and S. sanguis form biofilm readily on the surface of the composites, with S. sanguis having a higher predilection to form biofilm on all composites (Figure 6). However, no correlation was found between water sorption and solubility values of the flowable composites and biofilm formation. Conclusions: Within the limitations of this study the following is concluded: Time and storage conditions are important to the % mass gain due to water, with all flowable composites showing more mass gain at low PH. Due to its hydrophilic nature, as well as to the filler characteristics, the flowable composite Virtuoso exhibited significantly higher values of water sorption and water solubility than the other flowable composites that were tested. All flowable composites formed S. sanguis and S. mutans single species biofilm on their surfaces, with S. sanguis forming higher concentrations of biofilm on all samples. There was no clear correlation to water sorption and biofilm formation characteristics of the composites.
Temple University--Theses
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Molinarolo, Susan L. "Sorption of xyloglucan onto cellulose fibers." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/5760.
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Xyloglucan is a hemicellulose found in the primary cell walls of many plant species. Found adjacent to the cellulose, it is believed to function as a cementing material which contributes crosslinks and rigidity to the cellulose framework. The only noncovalent linkage reported in the primary cell wall cellulose-hemicellulose-pectic polysaccharide matrix of the cultured tissues is that between xyloglucan and cellulose. Therefore, the xyloglucan:cellulose association has been of great interest to researchers.
Xyloglucan can be bound to cellulose in vitro to simulate this in vivo relationship. Previously, the sorption of xyloglucan fragments onto cellulose under non-physiological conditions had been studied, but little information was available on xyloglucan polymer sorption onto cellulose under more natural conditions. This thesis examined the sorption of the xyloglucan polymer isolated from Tamarindus indica onto cellulose fibers (cotton linters) in an aqueous environment.
The structure of the xyloglucan isolated from Tamarindus indica in this thesis resembled that of other tamarind xyloglucans reported in the literature. Due to the milder isolation procedure employed, the molecular weight of this polymer was much larger than those previously found. No acetyl, pyruvate, methoxyl, or carboxyl groups were found. The molecular weight and certain structural features (e.g., no fucose units) also differed from the xyloglucan found in plant primary cell walls.
When sorbed onto well characterized cotton linters, this xyloglucan exhibited equilibrium sorption within 24 hours. The equilibrium adsorption isotherm was defined. Monolayer sorption occurred. A maximum specific sorption value of 3.9 milligrams of xyloglucan sorbed per gram of cotton linters was calculated using Langmuir's adsorption isotherm theory. This value was compared with other values found in the literature for similar polymer adsorption studies. The effect of molecular weight on sorption equilibrium was also examined and found to be insignificant over the molecular weight range of the polymer isolated in this thesis.
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Ajmani, Manu. "Sorption of veterinary antibiotics to woodchips." Kansas State University, 2011. http://hdl.handle.net/2097/13169.
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Master of ScienceDepartment of Civil Engineering
Alok Bhandari
In the upper Midwest, subsurface tile drainage water is a major contributor of nitrate (NO[subscript]3–N) coming from fertilizers and animal manure. Movement of NO[subscript]3-N through tile drainage into streams is a major concern as it can cause eutrophication and hypoxia conditions, as in the Gulf of Mexico. Denitrifying bioreactors is one of the pollution control strategies to treat contaminated tile drainage water. These bioreactors require four conditions which are: 1) organic carbon source, 2) anaerobic conditions, 3) denitrifying bacteria and 4) influent NO[subscript]3-N. This research focuses on investigating fate of veterinary antibiotics in woodchips commonly used in in-situ reactors. Tylosin (TYL) and sulfamethazine (SMZ) are two veterinary antibiotics which are most commonly used in the United States and can be found in tile water after manure is land applied. Partition coefficients of TYL and SMZ on wood were determined by sorption experiments using fresh woodchips and woodchips from an in situ reactor. It was concluded that the woodchips were an effective means to sorb the veterinary antibiotics leached into the tile water after application of animal manure. Linear partition coefficients were calculated and phase distribution relationships were established for both the chemicals. The fresh woodchips gave inconclusive data but predictions could be made by the information determined in the experiments using woodchips from a ten year old woodchip bioreactor. Desorption was also studied and the likelihood of desorption was predicted using the Apparent Hysteresis Index. Overall, it was found that the old woodchips allowed for quick sorption of both antibiotics. It was also found that SMZ had reversible sorption on old woodchips. Thus, it was concluded that the woodchip bioreactor would not be effective for removal of veterinary antibiotics from tile drainage. More research is required for the fate of TYL and to confirm the conclusion.
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Lee, Sangwha. "Transient sorption and permeation in fluoropolymers /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487862399448826.
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Vithayaveroj, Viriya. "Atomic force microscopy for sorption studies." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-09282004-121825/unrestricted/vithayaveroj%5Fviriya%5F200412%5Fphd.pdf.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.Dr. Rina Tannenbaum, Committee Member ; Dr. Michael Sacks, Committee Member ; Dr. Sotira Yiacoumi, Committee Chair ; Dr. Costas Tsouris, Committee Co-Chair ; Dr. Ching-Hua Huang, Committee Member. Vita. Includes bibliographical references.
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Silvertooth, J. C., and B. R. Gardner. "Phosphate Sorption of Several Arizona Soils." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/204831.
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Phosphate (P) adsorption of 6 agriculturally- important Arizona soils was studied by use of adsorption isotherm experiments and with conventional Langmuir and Freundlich adsorption models. Adsorption experiments were conducted at 25°C where each soil was placed in a 10:1 (solution:soil) ratio using 0.01M CaCl₂ as a background solution. Each soil was subjected to 4 levels of inorganic P addition using Ca(H₂PO₄)₂H₂O as the P source. Use of the Langmuir model was significant in all cases (P ≤ 0.05) with r² values ranging from 0.93 to 0.99. Capacity parameter estimates obtained from the models indicated P adsorption potentials of up to 357 lb. acre⁻¹ (818 lb. P₂0₅ acre⁻¹) for the soils studied. Application of the Freundlich model revealed r² values of 0.88 to 0.99 with all models proving to be significant (P ≤ 0.05).
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Pariti, Uma Mahesh 1969. "Coal sorption behavior using gas mixture." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291953.
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This thesis discusses an experimental study involving sorption studies using methane, carbon dioxide, and a multicomponent gas mixture representative of in situ gas composition. Using the isotherms for pure methane and carbon dioxide, isotherm and variation in gas composition with desorption for gas mixture were established using a numerical technique. When using gas mixture, composition of the desorbing gas at each pressure level was monitored. Results indicate that during desorption, methane concentration decreased as the pressure was decreased while carbon dioxide concentration increased. Experimental results for sorption and variation in gas composition of the gas mixture compare very well with the theoretically obtained results. It is, therefore, possible to establish the sorption isotherm, Langmuir constants for gas mixtures and estimate the variation in gas composition with desorption theoretically, if the sorption isotherms for individual component gases are available and the in situ gas composition is known.
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Müter, Dirk. "Sorption von Fluiden in mesoporösen Silikamaterialien." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16121.
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Die geordneten mesoporösen Silikamaterialien SBA-15 und MCM-41 zeichnen sich durch lange zylindrische Poren aus, die auf einem 2D-hexagonalen Gitter arrangiert sind. Auf Grund dieser Eigenschaften finden sie vielfach Anwendung in der Industrie, bieten jedoch auch die Möglichkeit Sorptionsvorgänge und die dadurch induzierten Verformungen auf der Nanometerebene zu untersuchen. Dazu werden im ersten Teil dieser Arbeit Kleinwinkelröntgenstreuungsdaten mit Hilfe eines Formfaktormodells angefittet, um die Adsorption von Fluid in den Poren in Abhängigkeit vom Dampfdruck nachvollziehen zu können. Basierend auf diesen Ergebnissen wird ein Gittermodell eingeführt, welches die Vorgänge während der Sorption mit Hilfe heuristischer Füllmechanismen reproduziert und im Abgleich mit experimentellen Daten Auskunft über die Verteilung der Porosität auf Mikro- und Mesoporen in SBA-15 gibt. Weiterhin wird der Einfluss der begrenzten Geometrie auf die Selbstassemblierung von Tensiden in SBA-15 untersucht. Hierzu werden Neutronenstreudaten durch die Kombination eines Formfaktormodells für die Bragg-Streuung und des Teubner-Strey-Modells für die diffuse Streuung modelliert und interpretiert. Der zweite Teil der Arbeit beschäftigt sich mit den elastischen Verformungen der mesoporösen Materialien durch die Fluidsorption. Dazu wird eine Molekulardynamik-Simulation eines Lennard-Jones-Fluids in einer Schlitzpore vorgestellt, um den Ursprung dieser Verformungen auf der mikroskopischen Ebene zu untersuchen. Diese Ergebnisse fließen anschließend in ein makroskopisches Modell eines ganzen Kristalliten des mesoporösen Materials ein, wodurch ein einfaches Multiskalenmodell entsteht. Die makroskopische Ebene wird dabei durch eine Finite-Elemente-Simulation beschrieben, die im Abgleich mit experimentellen Daten weitere Aussagen über die elastischen Eigenschaften des Materials erlaubt.The ordered mesoporous silica materials SBA-15 and MCM-41 consist of long cylindrical pores arranged on a 2D-hexagonal lattice. Due to these features, they are used for a range of industrial applications but provide also a possibility to study sorption processes and sorption-induced deformations on the nanoscale. In the first part of this work small-angle X-ray scattering data are fitted with a form factor model in order to examine fluid adsorption in the pores. Based on these results a lattice model is introduced which reproduces the sorption process using heuristic filling mechanisms and clarifies how the porosity of SBA-15 is composed out of micro- and mesopores. Furthermore, the influence of the confined geometry on the self-assembly of surfactants in SBA-15 is studied. For this, neutron scattering data are modeled and interpreted by the combination of a form factor model for the Bragg scattering and the Teubner-Strey model for the diffuse scattering. The second part of this work focuses on the elastic deformations caused by fluid sorption in the mesoporous materials. A Molecular Dynamics simulation of a Lennard-Jones fluid in a slit-pore is presented in order to reveal the origin of these deformations on the microscopic scale. These results are subsequently implemented into a macroscopic model of whole crystallite, thereby creating a simple multi-scale model. The macroscopic scale is modeled with a Finite Elements simulation, which by comparison with experimental data delivers further insights into the elastic properties of the material.
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Koulouris, George. "Sorption characteristics of electrolytic manganese dioxide." Thesis, Queensland University of Technology, 1995.
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Parker, Robert Watson. "Sorption of dog attractants on montmorillonite." Thesis, Queensland University of Technology, 1994.
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Sorption studies of Dingo/wild dog chemical attractants on montmorillonite were undertaken. The study focused on the use of montmorillonite for the controlled release of volatile organic chemicals.
Adsorption isotherms for ethanoic, propanoic and butanoic acids, on sodium and calcium montmorillonite, showed comparable monolayer capacities to activated charcoal. Acid concentration increased with polarisation of the exchangeable cation (Ca2+ > Na+) and decreased with increasing molecular weight.
Diffuse Reflectance Fourier Transform Infrared Spectroscopy was used to determine organic chemical interactions and concentrations in powdered organicmontmorillonite complexes. Of those complexes studied, interactions were observed for propanoic and 4-methylpentanoic acid, heptanal, trimethylamine, hexylamine, 2- mercaptoethanol and ethylhexanoate but not dimethyldisulphide.
With increasing propanoic acid adsorbed on montmorillonite, the amount of adsorbed propanate anion reached a maximum of 0.54 mol. kg-1, corresponding to 6.6 x lo23 binding sites per kg. Exposure of this complex to the atmosphere resulted in decreasing acid concentration, whilst the concentration of adsorbed propanate remained constant. Propanoic acid loss was also found to have an initial (0-24 hours) rapid decline, followed by a more steady decline phase (24-240 hours). During the latter, concentration change was 4.4 x 104 mol.kg-1.h-1, and rate of diffusion 2.2 mol.kg-1.m-1.
Exposure of an equal part mixture of propanoic acid, heptanal, trimethylamine and dimethyldisulphide adsorbed on montmorillonite showed an exponential rate of decline for all components except dimethyldisulphide which followed a linear rate of decline.
Similar trials using a mixture of 9 carboxylic acids showed exponential decline rates for each acid. Acid desorption rate constants were found to be higher for odd over even numbered carbon chains, straight over branched chains, and high over low initial concentrations. Water uptake occurred for both complexes and was a function of organic and initial clay hydrations. Exposed organo-montmorillonite complexes and blank montmorillonite showed net weight gains, which were attributed to water uptake.
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Lu, Yeong-Wei. "Sorption of organic compounds on oil shale materials and sorption of selected chemicals on a Western soil." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91135.
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The sorption capacity of a raw shale (Anvil Points), three spent shales, (Antrim, Oxy 6, and Run 16), and a western soil for three organic compounds (2-Hydroxynaphthalene, 1,2,3,4-Tetrahydroquinoline, and 2,3,5-Trimethylphenol) was evaluated by batch and column sorption studies. In addition, the sorption capacity of the western soil for selected inorganic agents (arsenic, cadmium, calcium, potassium, iron, ammonium, fluoride, and sulfate) was also determined.
The results of the study showed that the sorption capacity of oil shales for organic compounds varied with the retorting conditions of spent shales, the characteristics of sorbates, and the number of different sorbates present. The overall sorption capacity of the oil shales and the soil were greatly enhanced in multi-sorbate solutions. On the other hand, mutual inhibition for sorption of individual compounds was evident throughout the study.
The western soil, in general, exhibited a better sorption capacity for organic compounds than Anvil, Oxy 6, and Run 16 shale, yet Antrim shale appeared to be the best sorbent. Sorption of inorganic ions by soil was closely related to the pH of the solution, and was greatly affected by the interactions between ion species in multi-sorbate solutions. The soil had good affinity for arsenic, cadmium and iron, but little sorption capacity for ammonium and sulfate. Desorption of calcium and potassium from the soil was evident.M. Eng.
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Bi, Erping. "Sorption and transport of heterocyclic aromatic compounds in soils." Tübingen : Inst. für Geowissenschaften, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015518432&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Houssein, Taher Ahmad. "Water Sorption Isotherms Of Libyan Date Paste." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608276/index.pdf.
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water sorption isotherms of destoned and ground saiadey Jaul type dates were obtained at 30,40.50 C.using the gravimetric methods.Data were analyzed by applying the GAB,BAT ,Smith,Iglesias and Chrife,Halsey ,Henderson and Oswin Models.Isosteric heat of sorption value was calculated using the Clausius-Clapeyron Equation and tried to be as afunction of moisture content of dates. It was found that the experimental data fitted well to ,smith ,I glesias and Chirife ,Halsey, Henderson and Oswin equation, which are suitable for high sugar foods.Isosteric heat of sorption for dates varied from 0,9 to - 1,84 KJ/mol as moisture content changed from 11,0 to 18,0%.
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Ali, Baraa Abbas. "Sorption Of C8 Aromatics On Mcm-41." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611983/index.pdf.
Full textAbstract:
The discovery of MCM-41 materials have attracted substantial research attention due to the remarkable features of these materials including a narrow pore size distribution, high surface area, high pore volume, and high thermal and hydrothermal stability, as well as, parallel hexagonal arrangement of uniform cylindrical pores without pore channel intersection. These well-defined structural characteristics make them ideal media to study the adsorption, catalysis, ion exchange, and separation.
MCM-41 sample used in this study was synthesized in (Chemical Engineering Department, Gazi University). The MCM-41 was synthesized by using sodium silicate (0.0705 mol, 27% Silica) as a source of silica and surfactant cetyltrimethylammoniumbromides (CTMABr) (0.036 mol) as template. A characteristic feature of this direct hydothermal synthesis was relatively long synthesis time (96 hour at 120°C). MCM-41 was characterized by using XRD, and nitrogen physisorption analysis techniques. The characteristic peak in the low-angle region corresponding to 2&
#952
= 2.406°
was obtained for MCM-41 sample indicating high structural ordering of the MCM-41sample. The BET, surface area was found as (492.2 m /g), with an average pore diameter (25 Å
). In this study the sorption equilibrium of C aromatics (p-xylene, m-xylene, o-xylene, and ethylbenzene ) on MCM-41 at different temperatures (30°
C, 50°
C, 65°
C, 80°
C) was investigated by using an automated gravimetric electrobalance system. It was found that the amounts of each sorbate (p-xylene, m-xylene, o-xylene, and ethylbenzene) adsorbed at a given relative pressure on MCM-41 decreased when the temperature of the adsorption isotherms increases. The adsorption isotherms were type V, according to IUPAC isotherm classification due to the mesoporous nature of the MCM-41 sample. The hysteresis are associated with condensation-evaporation within a narrow distribution of mesopores with each adsorption isotherms. It was shown that as the temperature for the adsorption isotherms increases the size of hysteresis decreases for each sorbate. The volume of sorbates (V ) were obtained from the mass uptake at maximum relative pressure by taking the normal liquid density at the adsorption temperature for all sorbates. These values are significantly lower than that obtained from low-temperature nitrogen isotherm. The reason of this difference is that the density of the adsorbed phase is unlikely to be exactly the same as that of the liquid adsorptive and curvature of some isotherms at high relative pressure leads to uncertainty in the location of the upper limit for pore filling.
22
Burkhart, John F., and John F. Burkhart. "Sorption behavior of formaldehyde to ice grains." Thesis, The University of Arizona, 2000. http://hdl.handle.net/10150/626770.
Full textAbstract:
The equilibritun partitioning of fonnaldehyde between air and snow was studied in a senes of
laboratory experitnents conducted at -S"C, -15"C and -35()C, with the intention of developing a
quantitative relationship of the ternperature dependence of the bulk partitioning transfer coefficient,
K0 , for fonnaldehyde in polar snow. The results of the experitnents it1dicate that the original field
based paratneterization of the n1odel does use realistic values for both the partitioning coefficient,
K0 , and the pseudo-fust order transfer rate coefficient, k1 ,. Measurements of K0 were 1.75, 1.97, and 2.39 (Log 1nol L-1 atm-) for -5°C, -15oC and -35()C, respectively. Estitnates of k1 , for the satne three tetnperatures in units of s-1 were 4.11 x 10-4, 1.07 x 10-4, and 1.08 x 1 o s, respectively. Attnospheric
tneasuretnents of fonnaldehyde in polar regions reveal concentrations that are higher than predicted
frotn current 1nodelll1g. Additionally, firn and firn-air concentrations of fonnaldehyde i11 the polar
snow pack have been observed to have a unique profile of preserved concentrations that are not
consistent with other reversibly deposited species. These experitnents help to further define the
behavior of fonnaldehyde sorption to ice, and the preservation of it in the snow. It has been shown
that fonnaldehyde observations it1 fun can be 1nodeled solely through the use of a parameterized
tnodel of tetnperature dependent sorption
23
Al-Asheh, Sameer. "Sorption of heavy metals by biological materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26101.pdf.
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Hadialhejazi, Golshid. "Assessment of vanadium sorption by different soils." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171798.
Full textAbstract:
Vanadium is a white bright metal that belongs to group 5 in the periodic table of elements. It can exist in different oxidation states from -2 to +5 although the forms can be found naturally in the environment are (III), (IV) and (V). As vanadium is toxic at high concentrations, and as vanadium is a common contaminant from e.g., steel slags, more detailed knowledge on the environmental behavior of this metal is required. One important property is its sorption to soils, as this will determine the bioavailability and the risk of leaching from soils. In surface soils vanadium(V) is commonly the predominating redox species. Therefore the purpose of this study was to determine vanadium(V) sorption in 7 different soils in order to investigate the factors determining vanadium(V) sorption and to estimate the capacity of the soils to bind vanadium. From laboratory adsorption experiments, vanadium sorption has been studied as a function of pH, vanadium(V) concentration, and phosphorus status. The adsorbed vanadium(V) of investigated soils was compared on the basis of the Freundlich parameters m and log Kf. The clay content of the soil and the content of oxalate soluble iron and aluminum were two important factors for the vanadium(V) sorption behavior. The higher the values of these soil properties, the stronger was vanadium(V) sorption. Among the soils investigated here the sorption strength was highest for the Kungängen A3 soil and then decreased in the following order Säby, Kungsängen D3, Pustnäs, Termunck, Guadalajara and Zwijnaarde. It is notable that the three soils with the strongest vanadium(V) sorption were clay soils, whereas the other four were sandy or silty soils. The pH dependence of vanadium sorption was also determined. The results show that the percentage sorbed vanadium(V) increases with decreasing pH. This is due probably to the anion properties of vanadium(V) (i.e. vanadate) in combination with increased positive surface charge on the soil colloids at lower pH. Moreover there is a competition between phosphate and vanadium(V) for sorption sites, which will cause less vanadium(V) sorption in soils. Therefore both the pH value and the phosphorus status are two additional factors that influence the vanadium sorption properties of soils.
25
Nocon, Melody Schwartz. "Inorganic Sorption in Polymer Modified Bentonite Clays." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3850.
Full textAbstract:
In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite lining systems. In some applications an additive (polymer) is mixed with the bentonite to increase performance, especially in those that have low concentrations of sodium bentonite (EPA 2001).Studies showing significant increases in hydraulic conductivity values for bentonite in the presence of high salt concentrations are frequently documented and there is a risk of early breakthrough due to performance failure of the GCL clay component. (Ashmawy et al, 2002). It has also been stated that sodium, potassium, calcium, and magnesium have such a high affinity for the clay's surface other chemical species have little chance of attenuation (EPA 2001).
For these reasons, researching sorption in the presence of major salt cations and polymers gains great importance.Distribution coefficients were extrapolated from Linear, Freundlich and Langmuir sorption isotherms for sodium and calcium cations modeled from data collected from batch tests of sodium bentonite and various manufactured and custom mixed polymer modified bentonites. Surface characterization before and after calcium or sodium solution exposure of all tested media was accomplished by use of scanning electron microscopy and energy dispersive x-ray analysis.
26
Hong, Sung-Yoon. "Calcium silicate hydrate : crystallisation and alkali sorption." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310573.
Full textAbstract:
Homogeneous single C-S-H gels have been prepared for the investigation of alkali binding potential and crystallisation. A distribution coefficient, Rd, was introduced to express the partition of alkali between solid and aqueous phases at 25°C. Rd is independent of alkali hydroxide concentration and depends only on Ca:Si ratio over wide ranges of alkali concentration. The trend of numerical values of Rd indicates that alkali bonding into the solid improves as its Ca:Si ratio decreases. Reversibility is demonstrated, indicating a possibility of constant Rd value of the material. Al has been introduced to form C-A-S-H gels and their alkali sorption properties also determined. Al substituted into C-S-H markedly increases Rd, indicating enhancement of alkali binding. However, the dependence of Rd on alkali concentration is non-ideal with composition. A two-site model for bonding is presented. Crystallisation both under saturated steam and 1 bar vapour pressure has been investigated. It has been shown that heat treatment by saturated steam causes crystallisation of gels. The principal minerals obtained were (i) C-S-H gel and Ca(OH)2 at ~55°C, (ii) 1.1 nm tobermorite, jennite and afwillite at 85-130°C, and (iii) xonotlite, foshagite and hillebrandite at 150-180°C. Properties of crystalline C-S-H were also reported for reversible phase transformation, pH conditioning ability, seeding effect and solubility. At 1 bar pressure, crystallisation is slower than in saturated steam due to lower water activity. Tobermorite-like nanodomains develop during reaction at low Ca/Si ratios. In some Ca-rich compositions, Ca(OH)2 is exsolved and occurs as nano-sized crystallites.
27
Jones, D. W. "Vapour sorption by latex bonded carbon particles." Thesis, Nottingham Trent University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372741.
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Donner, Erica. "Sorption and fixation of zinc in soils." Thesis, University of Reading, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440079.
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Calmiano, Mark Daniel. "Computer simulation of molecular sorption in zeolites." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249244.
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Jacobi, David Louis. "Sorption studies of caesium by complex hexacyanoferrates." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46841.
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Davie, Scott Warren. "Design of a gas sorption measurement system." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13059.
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Onyango, MS, J. Kittinya, N. Hadebe, V. Ojijo, and A. Ochieng. "Sorption of melanoidin onto surfavtant modified zeolite." Chemical Industry & Chemical Engineering Quarterly, 2011. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000753.
Full textAbstract:
Melanoidin is responsible for the dark brown color of distillery wastewater. Discharge
of colored wastewater has a major environmental impact on the biota of
the receiving water body. Consequently, this study explores the removal of melanodin
from aqueous solution. The equilibrium, kinetics and thermodynamics
of melanoidin sorption are studied by varying initial solution pH, initial concentration,
adsorbent dose and temperature. Kinetically, the melanoidin removal
from solution by a surfactant modified zeolite is rapid and the amount adsorbed
is dependent on pH, initial concentration, adsorbent dose and temperature.
The equilibrium sorption data are fitted to the Freundlich and Langmuir models
while the sorption kinetics are described by the Ho pseudo-second order and
Elovich models. The thermodynamic analysis indicates that the sorption is
spontaneous and endothermic in nature. The FTIR spectra analyses show no
new peaks or shift in peaks after sorption indicating that the melanoidin sorption
may have occurred by a physical process. The results from desorption studies
showed that melanoidin eluted back easily to the solution using distilled
water which corroborates the physical sorption mechanism.
33
Scott, Thomas Bligh. "Sorption of uranium onto iron bearing minerals." Thesis, University of Bristol, 2005. http://hdl.handle.net/1983/3602a415-20b2-4d52-8f86-32b35d6b378a.
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Patterson, Andrea. "Sorption of Anionic Organic Contaminants to Goethite." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543427642730863.
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Forsling, Scott A. "Sorption and biodegradation of phenanthrene in soils." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020357/.
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36
Jalaludin, Zaihan. "The water vapour sorption behaviour of wood." Thesis, Edinburgh Napier University, 2012. http://researchrepository.napier.ac.uk/Output/4905.
Full textAbstract:
The water vapour sorption properties of several commercial tropical hardwoods and temperate softwood species as well as thermally modified wood and acetylated wood has been studied. A dynamic vapour sorption apparatus was used for this investigation to give data on the sorption isotherms under equilibrium conditions as well as sorption kinetic behaviour. Small differences in the sorption isotherms were found between the wood species, but modification resulted in substantial changes to the sorption isotherms. The sorption isotherms were analysed using the Hailwood-Horrobin model. Sorption kinetics behaviour was found to be accurately described using the parallel exponential kinetics (PEK) model. This model has only recently been applied to wood and this work represents a much more comprehensive study of the applicability of the model. Until now the favoured approach has been based upon Fickian models. The conventional interpretation of the PEK model relies upon the idea of different types of sorption sites, but his work has shown (partly based upon Hailwood-Horrobin analyses of the isotherms) that this interpretation is not applicable. Instead, an interpretation based upon relaxation limited kinetics has been adopted. These ideas are commonly employed in the polymer science literature, but have hardly been used in wood science. The model employed was that involving two Kelvin-Voigt elements in series, from which cell wall moduli and viscosities have been determined. The values of the moduli appear sensible, but the model is only tentative at this stage. The kinetic data has also been used to determine activation energies, entropies and Gibbs free energy of sorption. This is the first time that the entropy and Gibbs free energy of sorption have been studied. The purpose of this work was to understand the phenomenon of sorption hysteresis and in particular to examine if there was a link between sorption hysteresis and sorption kinetics.
37
Houde, A. Y. "Sorption and permeation of gases in polymers." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1991. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3006.
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Hammer, Heiko. "Sorption organischer Chemikalien an Huminstoff-Komponenten – Experimentelle Analyse, pH-Abhängigkeit und Modellierung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-197276.
Full textAbstract:
Das Verfahren zur Bestimmung von Koc-Werten nach OECD Richtlinie 121 ist zur Abschätzung der Sorptionskoeffizienten einzelner Stoffklassen gut geeignet. Die komplexen Wechselwirkungen eines Stoffes mit einer Matrix bei dem Sorptionsprozess konnten durch die Erweiterung des Kalibrierdatensatzes und den zusätzlichen stationären Phasen besser dargestellt werden. Die empirische Annahme der Kapazitätsfaktorensumme aus Cyano-Phase, Diol-Phase und Amino-Phase berücksichtigt die Wechselwirkungen von polaren Stoffen mit polaren Phasen und kann zur Bestimmung des Sorptionskoeffizienten weiterer Stoffklassen (z.B.: Amine, Alkohole) unter OECD-Bedingungen angewendet werden. Der Vorteil dieser Bestimmungsmethode ist, dass der Sorptionskoeffizient Koc unter umweltrelevanten Versuchsbedingungen ermittelt wurde und weitere Parameter wie zum Beispiel die pH-Wert-Abhängigkeit untersucht werden können. Auch eine hohe Reproduzierbarkeit des Verfahrens ist gewährleistet, da die verschiedenen HPLC-Säulen kommerziell erhältlich sind. Ein großer Nachteil der Bestimmungsmethode ist die einfache Struktur der Sorbensmatrizes, welche die Komplexität der Umwelt- bzw. Bodenmatrix nur bedingt wiedergeben können. Weiterhin ist die Bestimmung des Sorptionskoeffizienten mittels der drei unterschiedlichen HPLC-Säulen zeitaufwendiger als Sorptionsversuche mit einem Sorbensmaterial. Aus diesem Grund wurde in weiteren Sorptionsversuchen ein Sorbens gesucht, welches die natürlichen Sorptionsprozesse besser abbildet.
Für das Beurteilen des Sorptionsverhaltens von organischen Verbindungen an natürlichen Sorbentien wurden in Batchversuchen die Sorptionskoeffizienten bestimmt. Mit dem Festlegen der Sorptionsparameter (z.B.: Sorptionskinetik, Sorbensmenge, Extraktionszeit) liegt ein valides Verfahren zur Aufnahme von Sorptionsisothermen vor. Von den verschiedenen Sorptionsmatrizes bilden die Huminsäuren den Sorptionsprozess von organischen Stoffen an natürlichen Böden am besten ab. Die Aldrich-Huminsäure wurde als Sorbens für die Durchführung von Säulenversuchen ausgewählt, da für diese Sorptionsmatrix die Sorptionskoeffizienten mit Literaturdaten am besten übereinstimmen.
Für die Anwendung eines weiteren Analysenverfahrens wurde die Säulenmethode mit einer immobilisierten Aldrich-Huminsäure-Silikagel-HPLC-Säule durchgeführt. Die Aldrich-Huminsäure-immobilisierte-stationäre-Phase wurde durch eine mehrstufige organische Synthese unter inerten Bedingungen hergestellt. Zur Verifizierung der eingesetzten Huminsäure-Säule wurden die Stabilität der Matrix mit der theoretischen Bodenzahl N, des Säulendrucks und der Kapazitätsfaktor eines Kontrollstoffes erfolgreich überprüft. Die Porösität der Säulenmatrix, der organische Anteil des Sorbens und die Leitfähigkeit der mobilen Phase wurden als weitere Versuchsparameter überprüft, und es wurde darauf geachtet, dass umweltrelevante Bedingungen bei den Sorptionsversuchen vorliegen. Das HPLC-Verfahren wurde durch die hohe Übereinstimmung zwischen experimentellen Koc-Werten der Aldrich-Huminsäure und den Koc-Literaturwerten aus Batchversuchen mit Böden für neutrale organische Stoffe verifiziert. Auch beim Vergleich der Sorptionsergebnisse von verschiedenen Huminstoff-Matrizes besitzt die Aldrich-Huminsäure die Koc-Werte mit der größten Übereinstimmung mit Literaturdaten. Zur Beurteilung des Sorptionsverhaltens eines Stoffes in der Umwelt wurde die Einteilung von Höltig erweitert. Zum Treffen einer Aussage über das Sorptionsverhaltens eines Stoffes wurde neben dem log Kow auch der log Koc verwendet und für ionische Stoffe in Sorptionsklassen eingeteilt. Für 30 umweltrelevante und toxische Stoffe ohne Sorptionskoeffizient wurde ein Koc-Wert ermittelt und das Sorptionsverhalten nach dem erweiterten Hölting-Modell abgeschätzt. Dabei zeigten 2,6-Di-t-butyl-p-benzochinon, Epoxiconazol und Chalconepoxid nach dem Modell ein relevantes Sorptionsverhalten (log Koc= 2,39 bis 3,18). Für einen Koc-Datensatz von 85 Stoffen wurde mit dem Aldrich-Huminsäure-Säulenverfahrens ein Abraham-Modell aufgestellt. Das Modell liefert die signifikanten Phasenparameter e, s, b, v und und hohe Regressionskoeffizienten (r2=0,91, q2cv= 0,89). Demnach ist das aufgestellte Abraham-Modell für 16 Stoffklassen sehr gut geeignet, die Sorptionskoeffizienten vorherzusagen. Auch der Vergleich mit dem Abraham-Modell von Nyguyen (2005) zeigt, dass die Aldrich-Huminsäure die Sorptionseigenschaften von Böden sehr gut abbilden kann. Für eine Vielzahl an Stoffen lagen keine Literaturwerte vor, so dass mit Hilfe der HPLC-Säulenmethode zeitnah weitere Stoffklassen in das Abraham-Modell implementiert werden können.
Für 40 organische Basen mit einem pKs-Bereich von 0,50 bis 10,69 und einem logKow- Bereich von -0,02 bis 5,51 wurde der Sorptionskoeffizient bei 3 pH-Werten ermittelt. Für 9 organische Basen, welche im untersuchten pH-Wertbereich ausschließlich neutral vorliegen,
wurde kein signifikanter Einfluss des pH-Werts auf den Sorptionskoeffizienten ermittelt. Für kationisch vorliegende organische Basen wurde mit steigendem pH-Wert ein zunehmender Sorptionskoeffizient bestimmt. Eine Erhöhung des Sorptionskoeffizienten bei pH 5 und pH 7 beruht auf zusätzlichen ionischen Molekül-Matrix-Wechselwirkungen zwischen organischen Basen und Sorbens. Auch für die organischen Basen, welche im pH-Bereich von 3 bis 7 mit beiden Spezies vorliegen, konnte bei dem pH-Wert 5 oder pH-Wert 7 die größten Sorptionskoeffizienten ermittelt werden. Die starke Zunahme der Sorptionskoeffizienten kann neben hydrophoben Wechselwirkungen auf dem Maximum an ionischen Bindungen bei pH 5 oder pH 7 zwischen der kationischen Spezies der Base und den anionischen Carboxyl-Gruppen der Aldrich-Huminsäure basieren. Für 16 organische Basen, welche im pH-Wertbereich bei pH 7 neutral und bei pH 3 ionisch vorliegen, wurde ein linearer Zusammenhang zwischen log Koc.n und log Koc.ion aufgestellt. Für die Annahme, das für einen Stoff der Sorptionskoeffizient einer Spezies ermittelt wurde, gilt die Näherung dass mindestens 90 Prozent der Spezies vorliegen müssen.
Das Modell zur Berechnung des pH-abhängigen Sorptionskoeffizienten beruht auf 55 log Koc(pH)-Werten von organischen Basen. Für die Anwendung des Modells muss eine organische Base im untersuchten pH-Wertbereich als neutrale Spezies vorliegen. Bei einem Vergleich der experimentellen Sorptionskoeffizienten mit den berechneten Werten von Franco stellte sich heraus, dass das Literaturmodell zur Vorhersage des Koc(pH) nur bedingt geeignet ist.
In zukünftigen Arbeiten kann das erstellte Abraham-Modell für eine noch bessere praxisbezogene Anwendung auf weitere umweltrelevante Stoffklassen erweitert werden. Zur Erstellung eines Gesamtmodells für ionisch und neutral vorliegende organische Basen müssen pH-abhängige Sorptionskoeffizienten weiterer Basen ermittelt werden.
39
Hobson, John T. "The Mechanics Involved in Removing Copper Ions Using Hydrochars, Activated Carbons, and Resins." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1328.
Full textAbstract:
According to the World Health Organization around 785 million people do not have a good source for their drinking water. [1] The lack of clean water comes from a lack of access to proper water treatment methods, and the presence of heavy metals in rivers and coastal areas, due in a large part, to industrial run-off. Sorption techniques that use different materials including hydrochars, activated carbons, and resins can be used to clear heavy metals and organic compounds from water. Biomass is a cost effective supply due to its large abundance and when carbonized, yields chars that can be used as adsorbents. Hydrothermal carbonization (HTC) is the process where biomass is converted to hydrochar. In this work, hydrochars were compared to traditional adsorbents for the removal of copper ions in a copper nitrate solution. Incorporating acids such as acrylic acid and vinyl sulfonic acid into the HTC process was done to see how adding an acid affects the performance of the hydrochars ability to remove copper ions. These hydrochars were then activated with a base solution, which improved the hydrochar’s ability to remove copper ions. Lastly, FTIR and titration of sorption materials was done to understand how adsorption of copper ions is related to the material’s acid concentration. The results showed that hydrochars exhibit a strong intensity of carboxylic acids on their surface. In addition, activation helped to ionize the hydrochars’ acid sites to give the char a more negatively charged surface to adsorb the positively charged copper ions. Overall, activated hydrochars have adsorption capacities that are comparable to traditional adsorption materials and that there is promise in exploring these materials as adsorbents in wastewater treatment.
40
Wingenfelder, Ulla Geraldine. "Sorption of metals by natural and modified zeolites /." [S.l.] : [s.n.], 2004. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15743.
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Thomé, Stefan. "Untersuchungen zur Sorption von Innenraum-Luftschadstoffen durch Wolle." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980970725.
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Hoerstermann, Henning. "Computersimulation der Sorption von kleinen Molekülen in Polymernetzwerken." Wuppertal Universitätsbibliothek Wuppertal, 2010. http://d-nb.info/1003249310/34.
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Gustafsson, Åsa. "Sorption and weathering properties of naturally occurring chlorites." Licentiate thesis, KTH, Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1819.
Full textAbstract:
Chlorite is a ferrous silicate mineral occurring as afracture filling mineral in the Swedish granite bedrock thatsurrounds the area of the candidate Swedish geologicalrepositories for nuclear waste.
To investigate the importance of chlorites as a naturalbarrier for radionuclide migration sorption of Ni(II) onto anatural chlorite was chosen as the studied system. The sorptionbehaviour was studied using batch technique under differentexperimental conditions by varying the concentration ofbackground electrolyte, pH and initial nickel concentration.Our experiments showed that sorption is dependent of pH; belowpH 4 no sorption occurs and in the pH range 7-11 the sorptionmaxima was found. The sorption shows no dependence of ionicstrength in our experiments and together with pH dependency weconclude that the sorption of nickel to chlorite is mostlyoccurring through surface complexation. The distributioncoefficient, Kd, was determined for our results and in the range formaximal sorption the Kdis approximately 103cm3/g.
Our experimental data were described using a diffuse doublelayer model, including strong and weak surface sites, in thesoftware PHREECQ and the results obtained from PHREEQC werealso used for a fit of the data in the software FITEQL. Thesurface complexes that dominate the sorption of nickel tochlorite from our model are Chl_ONi+(weak) and for pH above 9 Chl_ONi(OH)-(weak). Flow-through technique was used in ourinvestigations regarding the dissolution rate of a naturalchlorite and the experimental results show that the dissolutionrate of chlorite is strongly pH dependent and at pH 2 thehighest dissolution rate (RSi) could be determined to 7• 10-11mol/(m2s) based on silica data.
Keywords:chlorite, nickel, sorption, surfacecomplexation, dissolution rate.
44
Fernández, Esther Ochoa. "CO2 Acceptors for Sorption- Enhanced Steam Methane Reforming." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1936.
Full textAbstract:
Sorption-enhanced steam methane reforming (SESMR) is an emerging technology for H2 production from fossil fuels with CO2 capture. The aim of the present work has been to study SESMR with a multiscale approach and to gain insight into certain aspects of the process. Specail attention has been given to the development of new high-temperature CO2 acceptors and their impact on the workability of SESMR. The preparation and CO2 capture properties of Li2ZrO3, potassium promoted Li2ZrO3, and Na2ZrO3 have been studied in detail. A novel soft-chemistry route has been developed with success for the synthesis of mixed oxides. This method involves intimate mixture of the precursors and requires lower temperatures than conventional solid-state routes, forming nanosized crystals with high purities. The properties of the powders such as capture rate of CO2 and regeneration conditions have been significantly improved. Nanocrystalline tetragonal Li2ZrO3 could hold CO2 in amounts equivalent to 27 wt%, and saturation was reached in less than 5 min at 848 K and 100% of CO2. These results represent important improvements in the carbon dioxide capture rates compared to monoclinic Li2ZrO3 prepared by solid-state reactions. However, low capture rates were observed when operating at CO2 partial pressures lower than 0.2 bar. Controlling the Li:Zr ration, and especially ensuring the presence of free ZrO2, allowed improved uptake rates. More beneficial was the promotion of oxide with potassium due to the presence of molten carbonates. It is generally accepted that doping with potassium favours the diffusion of CO2 through the Li2CO3 layer that is formed at the surface of the acceptor during the capture reaction. On the other hand, nanocrystalline monoclinic Na2ZrO3 showed superior uptake kinetics and the ability to work efficiently at CO2 partial pressure as low as 0.025 bar. However, Na2ZrO3 requires higher temperatures for regeneration.
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Fabritius, T. (Tapio). "Optical method for liquid sorption measurements in paper." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514284045.
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Abstract
This thesis presents an effective optical method for measuring liquid sorption into paper. From the two tested methods, based on a streak-camera and optical coherence tomography (OCT), the last-mentioned proved very promising for investigating dynamical paper-liquid interactions as spatially and temporally dependent processes.
The streak-camera measurements were performed to explore the relationship between paper properties and light migration in dry and refractive index matched paper in general. Based on streak-camera measurements, a novel procedure for determining the average refractive index of cellulose fibre tissue was also presented here. In addition, the streak camera method lent itself to paper porosity determination.
Results of the performed OCT measurements proved that liquids cannot penetrate into paper before filling the pores and pits of the paper surface. As a liquid penetrated into paper, the border between the wetted and dry area could be investigated in the depth direction. The liquid penetration velocity seemed to be slower at the beginning and end of the process. Liquid absorption into paper fibres could be investigated concurrently. For the first time, the location and moment of structural changes in paper could be determined during wetting, and the effect of three different coexistent subprocesses related to paper wetting could be detected. OCT only fell short of detecting the effect of liquid migration along fibres.
Despite the limitations of the utilized method (resolution, probing depth and depth scanning rate), the obtained OCT measurement results are very promising for the development of an effective paper wetting measurement device for industrial applications. Even if this thesis focused on paper wetting, it is reasonable to assert that the presented ideas and obtained results have more general value in terms of explaining liquid penetration into porous structures and offer an alternative method of evaluating that process.
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Winterle, James Richard, and James Richard Winterle. "Sorption Kinetics of Hydrogen Peroxide to Ice Grains." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/626794.
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Li, Jian-Xin. "Case II sorption in glassy polymers, penetration kinetics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0009/NQ35222.pdf.
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Gustafsson, Åsa. "Sorption and weathering properties of naturally occurring chlorites /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1819.
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Xu, Kai Harper Willie F. "Thermodynamics of steroid estrogen sorption to activated sludge." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/FALL/Civil_Engineering/Thesis/Xu_Kai_29.pdf.
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Chu, Kuang-Chi Kevin Yelias. "Landfill Leachate Sorption Potential of Kate Valley Soils." Thesis, University of Canterbury. Civil Engineering, 2014. http://hdl.handle.net/10092/10041.
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Kate Valley is a municipal waste landfill situated in Waipara, Northern Canterbury. It is a joint venture between the 6 local regional councils and Transwaste Canterbury Ltd to help dispose of waste quantities generated in the wider Canterbury region. Landfill waste disposal also generates waste streams. Major waste streams can include methane gas production and liquid leachate. One practice which can turn liquid leachate waste streams into a nutrient source for plants is land irrigation. It is important to have a thorough understanding of the interactions involved with leachate, soil structure, soil microbiology, flora. This thesis investigates the sorption mechanisms between Kate Valley soil and leachates, through batch and column experiments.
Sorption mechanisms between leachate and soil were investigated through batch and column tests. Ex-situ soil samples were extracted from Kate Valley, along with raw leachate samples for batch tests at a soil to liquid ratio of 30 g vs. 70 ml respectively. Tested dilution leachate strengths ranged from raw to 50x raw leachate dilution; meanwhile soil samples were categorized into 3 groups based on soil depth: 0-20 cm, 20-40 cm, and 40-60 cm.
Column tests were conducted on 3 extracted in-situ soil column monoliths. Column test irrigation conditions included: control case, 2x and 10x raw leachate dilution, and 200 mg/L KBr (bromide column), where the same soil column was used for bromine testing after control testing had ceased.
Batch results suggest deeper soils are less effective at sorption of ammonia, where partitioning coefficient ranged from 9.5x*10-7 to 6.4*10-7 L/mg for 0-20 cm soil to 40-60 cm soil respectively. Column results generally showed lower partitioning capacity than batch results, at 4*10-8 and 5*10-8 L/mg for 10x and 2x dilution leachate irrigation respectively.
Discrepancies in experimental data have been attributed to: different dilution leachates tested between batch and column tests, making it difficult for direct comparison; extreme soil to liquid ratios employed in experiments; direct data comparison between the “full-contact” experimental data (between leachate and soil), obtained from batch tests with column results, where not all soil may have been fully exposed for shrinkage of boundary layers of soil particles; and oxygen exposure of samples during testing and sampling, possibly encouraging nitrification.