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Chromatography is a widely used separation technique including many different modes, for example supercritical fluid chromatography (SFC) which uses a supercritical fluid as mobile phase. A supercritical fluid is achieved when a substance is subjected to a temperature and pressure above the critical point and the boundary between the liquid phase and gas phase is erased. The interest for SFC has increased in recent years, mainly for separation of chiral molecules in the pharmaceutical industry. What makes SFC interesting is that it is a quick, cost-efficient and green method. This is in part due to less organic solvent used in the mobile phase in SFC compared with liquid chromatography and that the carbon dioxide that represents the major part of the mobile phase is a by-product from other processes. In SFC modifiers, often small alcohols, are added to carbon dioxide based mobile phase in order to increase the solubility of polar compounds. In this study the adsorption of methanol to two different stationary phases; Kromasil-Diol and chiral Lux Cellulose-4 were studied. Adsorption is a phenomenon where surface interactions crate a higher density of molecules at the surface than in the bulk. The aim of this work has been to study the adsorption of modifier (methanol) to the stationary phase both to determine the extent of adsorption and the kinetics for system equilibration. These findings were then put into perspective of normal use of SFC for separation of molecules. There are a number of techniques for measuring adsorption; in this study the tracer pulse method is used. This is a pulse method where a concentration plateau is created and an isotope labelled molecule is injected. This was performed in the mobile phase composition from pure carbon dioxide to pure methanol. In addition to the tracer pulse experiments the isotope effect, the eluent flow, equilibration times for the column and retention times for a set of analytes were measured. For the Diol column no large isotope effect was observed, the method was also proved to be highly reproducible since several runs gave consistent results. Calculations based on the experimental data showed that a 6.3 Å thick layer was built up at a methanol fraction of 13% (v/v), corresponding to a monolayer. Changes of the methanol fraction below the saturation level has has greater effect on the retention factor for the analytes than at higher methanol fractions, when the monolayer was saturated. The conclusion of this is that SFC is more stable in the area where the layer has been built up. A preliminary study has been made for the chiral Lux Cellulose-4 column which was not as conclusive as for the Kromasil-Diol column. This type of column needs further studies to confirm the deviating observations and to investigate the cause for these.

>Magister Scientiae - MSc / Titanium dioxide (TiO2) has potential as an adsorbent within the 68Ge/68Ga generator context. To function effectively, three basic requirements are required: optimum 68Ga elution efficiency, stability and removal of the 68Ge breakthrough. After analysis of the 68Ga elution efficiency and the 68Ge breakthrough, two models are proposed, namely; surface modification and molecular imprinted polymer, to address factors influencing 68Ga elution efficiency and minimize 68Ge breakthrough. The surface modifiers that were investigated are 3-aminopolypropyltriethoxy silane (3-APTES), 3-mercaptopropyltrimethoxy silane (3-MPTMS), bis(3-aminopropyl)amine (BAPA) and 2-chloro-4,6-dimethoxy-1,3,5-triazine silane (CDMT). / 2023

<p> Rate of adsorption data for gases on molecular sieve·s and coals have been interpreted using equations for unsteady state diffusion derived from Fick's law for spheres usually, ignoring the amount adsorbed and the shape of the adsorption isotherm. These inappropriate equations result in calculated diffusivities that are too low and activation energies that are too large. </p> <p> Numerical. solutions of Fick's law were made for diffusion and adsorption in a porous sphere of radius R by finite difference methods for the following conditions: a. Diffusion is the rate-controlling step, and the diffusivity, D, is constant. b. Within an increment of the particle the total amount of adsorbate per unit volume, T is related to the "effective" concentration, c, by a Langmuir-like isotherm T = abC/(1 + bC). c. At zero tine the particle containing no adsomate is surrounded by adsozbate of concentration, Co, which remains constant throughout the rate process, and d. Equilibrium is established immediately at the periphery of the sphere. </p> <p> The solutions are obtained in terms of Z = Q/Q and T=(DCo/QR^2) t = kt, where t is time, k is a constant equal to the term within the brackets, and Q and Q are the amounts adsorbed per unit volume at time t and at equilibrium. The quantity within brackets is also a valid expression for linear and Freundlich-like adsorption isotherms and probably holds for other isotherms. Plots of z as a function of T shift systematically as the parameter B = bCo increased from 0, corresponding to a linear adsorption isotherm, to large values; the value of Z at a given T increasing with increasing values of B. For B = 0 the numerical solution is identical with analytical solution for the linear adsorption isotherm which for values of z <0.87 is given by kt = (2/π) { (-1 - πZ/6) - (1 ~πZ/3) ^1/2 } where k = DCo/R^2Q. For large values of B the numerical solutions approach as a limit the parabolic law kt = (1/2) {(1- 2Z/3) - (1- Z) } The value of (1/k~) o.zidt~ at short times increases fran 3.385 for B = 0 to 4 .. 243 for very large values of B.. From experimental data the value of k derived using the equation for B = 0 is 1.56 larger than for the parabolic equation. Hence the values of D obtained from the initial linear portions of t.he rate curve change by only a factor of 1.56 when the type of isotherm is changed from linear to rectangular. </p> <p> Rates of adsorption and the adsorption isotherm were determined for N2 , CH4, co2 , and C2H6 on samples of Linde 4A molecular sieve at several temperatures from -78° to +50°C in a manostatic volumetric aborption apparatus. The Langmuir equation satisfactorily approximatedthe isotherms and the values of B were moderately large at the lower temperatures of each series of experiments, eg., for N2 at -78°C, 10.6; for CH4 at -78°C, 7.3; for co2 at 0°C, 64; for Ci!6 at 0° and 30°C, 37 and 10.3. </p> <p> The rate data plotted as Z against t^1/2 were not linear at short times but curved upward initially before becoming linear. The initial (, nonlinear portion persisted significantly longer than the brief uncertain period at the beginning of the experiment. This phenomena could result from the equilibration at the periphecy of the particles requiring a finite time rather than being instantaneous. </p> <p> An equation based on the parabolic law model and a first order equilibration process was derived, which fits. the experimental data for 0.05 < Z < 0.95. This equation is appropriate only to data with a large value of B, but is probably a reasonable approximation for other rate data. </p> <p> The rates of adsorption for different molecules were co2 > N2 > CH4 > c2H6 · The activation energies for the diffusivity were found to be 4.1 and 6.0 kcal./nole for methane and ethane. The _heats of adsorption were found to be 7.2 and 8.3 kcal/mole for methane and ethane. </p> / Thesis / Master of Engineering (MEngr)

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Metals sorption in soils is influenced by several factors, including pH, ionic strength, the presence of ionic composition or organic ligands, total amount of metals, and adsorbent loading. These conditions should be considered when evaluating metal sorption capacity of soil material or when applying laboratory results to field conditions. Metal sorption experiments were conducted on Bertie sandy and Starr-Dyke clay loam soils from long-term field studies in which soils received annual applications of copper-rich pig manure for 16 years. Adsorption of Cd, Cu, Pb, and Zn as affected by different background electrolytes at various concentrations was investigated. Electrolytes were Na+, Ca2+, or Al3+ in perchlorate solution, and their concentrations ranged from 0.001 to 0.5 molc L-1. Increasing ionic strength decreased metal adsorption capacity. Electrolyte cation composition had a greater effect on adsorption than did electrolyte concentration. The order of sensitivity to cation composition of the electrolyte was Zn > Cd > Cu > Pb, and this effect was greater in Bertie sandy loam than Starr-Dyke clay loam soils. Little difference in Cu and Pb adsorption was observed between Na+ and Ca2+ in background solution. Most added Cu was adsorbed at low concentrations regardless of pH, but at high concentrations Cu sorption was strongly related to solution pH. Increases in pH resulted in greater Cu sorption due to pH-dependent negative charges and precipitation. The USEPA recommends that soil systems receiving high metal loading rates be maintained at pH 6.5 or above because of the increased metal adsorption. However, pig manure applications to the Bertie soil resulted in greater Cu in soil solution than in control (no manure) soil at pH > 6.5 due to soluble organic matter. Using the Langmuir equation to determine adsorption maxima for soil systems does not always give adequate estimates of adsorption and values from the equations are highly dependent upon soil environmental parameters. Given the limitations in prediction of adsorption maxima, and given that the amount of nonsorbed metal is as important as the adsorbed amount, the isolines of metal remaining in soil solution were provided with a given set of soil environmental factors. / Ph. D.

Les vapeurs organiques émises des solvants utilisés dans le produit chimique / la nourriture / les processus pharmaceutiques, ou des stations d'entreposage de combustible d'hydrocarbure aux terminus de pétrole, peuvent être efficacement capturées par l'adsorption sur les lits de charbon actif. L'objectif général du programme de recherche est les études expérimentales et les études de simulation de l'adsorption et des pas de régénération en cas de l'enlèvement COV qui estime dans les émissions industrielles par l'Adsorption (TSA – Température Swing Adsorption et VTSA -Vacuum Température Swing Adsorption). C'est accompli par les points suivants : établir les données d'équilibre d'isotherme pour 5 COV et 8 carbones activés à 293, 313, 333 et 353 K (complètement 120 expériences d'isotherme) et les utiliser ensuite dans le modèle de simulation; développer une simulation pose pour le processus de régénération et l'adsorption; concevoir et optimiser l' expérimentale de TSA qui a été établi dans Ecole des les Mines de Nantes; concevoir et optimiser l'expérimentale de VTSA qui a été établi dans GRL ARKEMA; la validation de simulation de résultats expérimentaux de le processus TSA et VTSA. Une fois après l'achèvement de tous les objectifs, le but est de se développer et le lancement un utile de simulation complet pour l'adsorption et les pas de régénération de COV avec la coopération de la Société PROSIM. / Organic vapors emitted from solvents used in chemical / food / pharmaceutical processes, or from hydrocarbon fuel storage stations at oil terminals, can be efficiently captured by adsorption onto activated carbon beds. The overall objective of the research program is the experimental and simulation studies of the adsorption and regeneration steps in the case of VOC removal which accounts into industrial emissions by Temperature Swing Adsorption (TSA) and Vacuum Temperature Swing Adsorption (VTSA) processes. This is achieved by the following steps : to establish the isotherm equilibrium data for 5 VOCs and 8 activated carbons at 293, 313, 333, and 353 K (totally 120 isotherm experiments) and then use them in the simulation model; to develop a simulation model for adsorption and regeneration process; to design and optimize the experimental setup of Thermal Swing Adsorption (TSA) which has been established in Ecole des Mines de Nantes; to design and optimize the experimental setup of Vacuum Temperature Swing Adsorption processes (VTSA) which has been established in GRL ARKEMA unit ; simulation validation of experimental results of TSA and VTSA process. Once after the completion of all the objectives, the goal is to develop and launch a complete simulation package for adsorption and regeneration steps of VOCs with the co-operation from PROSIM Corporation.

Hydrophilic interaction chromatography is well known as a powerful technique separation of polar and ionizable compound nowadays. However the retention mechanism of the technique is still under debate. Understanding retention mechanism would facilitate the method development using the technique and its future improvement. This was inspiring and became the goal of this thesis. This work involves the characterization of the water enriched layer regarding to water and buffer salt accumulation. Twelve HILIC stationary phase with a diverse surface chemistry regarding to function groups and modification type were studied. Effect of water and salt on regarding to the retention mechanism was investigated by correlating the adsorption data to the retention of selected solutes This also involved the characterization of interactions involve in the separation of 21 HILIC columns. Interactions was probe by retention ratio of pair solutes which are characteristic for each specific interaction. The data was evaluate using principle component analysis – a multivariable data analysis method. The model was comprehensive and its outcomes were confirmed by the studies on adsorptions of water and salts.

This study investigated the adsorptive capacity and isotherm of HgCl2 onto spherical activated carbons (SAC) via thermogravimetric analysis (TGA). Activated carbon injection (ACI) is thought as the best available control technology (BACT) for mercury removal from flue gas. There are two major forms of vapor-phase mercury, Hgo and Hg2+, of which HgCl2 accounts for 60-95% of total mercury. Mercury emitted from the incineration of municipal solid wastes (MSW) could cause severely adverse effects on human health and ecosystem since it exists mainly in vapor phase due to high vapor pressure. Although the adsorptive capacity of HgCl2 onto activated carbon has been studied in previous adsorption column tests, only a few studies have thoroughly investigated the adsorption isotherms of HgCl2 onto SAC. Equilibrium and kinetic studies are important towards obtaining a better understanding of mercury adsorption. Many investigations have addressed the relationship between sorption kinetics and equilibrium for different adsorbent/adsorbate combinations. For the removal of vapor-phase mercury, several bench-pilot, and full-scale tests have be proceeded to examine the influence of carbon types, carbon structures, carbon surface characteristics, injection methods (dry or wet), amount of carbon injected, and flue gas temperature on mercury removal. In addition, the dynamics of spherical activated carbons (SAC) adsorbers for the uptake of gas-phase mercury was evaluated as a function of temperature, influent concentration of mercury, and empty-bed residence time. However, only a few studies investigated the adsorption isotherms of HgCl2 onto activated carbons. In this study, TGA was applied to obtain the adsorptive capacity of HgCl2 onto SAC with adsorption temperature (30~150oC) and influent HgCl2 concentration (50~1,000£gg/m3). Experimental results indicated that the adsorptive capacity of HgCl2 onto SAC was 0.67and 0.20 mg/gC at 30¡B70 and 150oC, respectively. This study investigated the adsorptive capacity of HgCl2 vapor onto SAC via TGA analysis. Experimental results indicated that the adsorptive capacity of SAC decreased with the increase of the adsorption temperature. Furthermore, the results suggested that that the adsorption of SAC on HgCl2 vapor was favorable equilibrium at 30 and 70¢J and unfavorable equilibrium at 150¢J. In comparison of the experimental data with isotherm equations, Freundlich isotherm fitted the experimental results better than Langmuir isotherm. The model simulations were found to fit very well to the high concentration experimental kinetic data for both adsorption and desorptionusing two adjust parameter, effective diffusivity, and the Freundlich isothermexponent.¡@The extracted model parameter, effective diffusivity and n, were then used to predict the experimental kinetic data for the same combination at other concentrations.

This study investigated the production of powdered activated carbon derived from carbon black of pyrolyzed waste tires, and their adsorptive capacity on vapor-phase mercury chloride (HgCl2) using both adsorption column and thermogravimetric adsorption systems. The adsorption isotherms and kinetic models were further simulated in the study. In addition, an innovative compositive impregnation process was developed to increase the sulfur content of powdered activated carbon derived from waste tires. The activation of carbon black to form powdered activated carbon was performed in a tubular oven. The operating parameters including activation temperatures, activation time, and water feed rates were investigated in this study. Experimental results indicated that the yield of carbon-black derived powdered activated carbon (CBPAC) decreased with the increase of activation temperature, activation time, and water feed rate, while the BET surface area and pore volume decreased. In the comparison of activation time and water feed rate in the activation process, activation time had an important impact on the production of specific surface area than water feed rate. The optimal operating parameters included activation temperature of 900¢J, activation time of 180min, water feed rate of 0.5 mLH2O/gC-sec, and water injection behind activation process of 17.5 min. From the analysis of carbon surface, the carbon contents of powdered carbon black (PCB), CBPAC, commercial powdered activated carbon (CPAC) were 89.5%, 87.6%, and 88%, respectively. The C (1s) peak region of PCB consisted of 49.8% C-C, 38.9% C-O, 10.5% C=O or O-C-O. Similar analysis results showed that the total area of the C (1s) peak region of CBPAC consisted of 57.5% C-C, 26.8% C-O, 8.1% C=O or O-C-O, and 7.6% O-C=O. Similar to CPAC, the C (1s) peak region consisted of 42.6% C-C, 41.8% C-O, and 15.6% O-C=O. Furthermore, the sulfur contents of PCB and CBPAC were both 0.5%. The S (2p) peak region of PCB consisted of 58.9% ZnS (zinc sulfide) and 41.1% S=C=S. For CBPAC, the S (2p) peak region solely contained S=C=S. The comparison of two sulfur impregnation processes revealed that the innovative compositive impregnation process could simultaneously increased the sulfur content and the BET surface area of powdered activated carbon (PAC), however, the direct impregnation process increased the sulfur content while the BET surface area of PAC decreased linearly. Without the disadvantages of time and energy consumption associated with direct impregnation, the compositive impregnation is an efficient and energy-saving process for producing sulfurized PAC with a high BET surface area and high sulfur content. Experimental results obtained from the adsorption column tests indicated that the influence of the adsorption depth on the adsorptive capacity of CBPAC did not vary much, while the adsorptive capacity of CBPAC increased with HgCl2 concentration. Furthermore, the adsorptive capacity of CBPAC on vapor-phase HgCl2 was less than that of CPAC at the adsorption temperatures of 25~150¢J and high humidity of 12.3 wt %. The difference of adsorptive capacity for CBPAC and CPAC correlated closely with BET surface area and sulfur content. Results form the thermogravimetric adsorption analysis indicated that the adsorptive capacity of CBPAC and initial adsorption rate on vapor-phase HgCl2 increased with HgCl2 concentration and decreased with adsorption temperature. In the kinetic modeling, the deviation of experimental and simulated values simulated by the pseudo-first-order model was lower than those of pseudo-second-order models. Furthermore, the r (correlation coefficient) of pseudo-first-order and pseudo-second-order models were 0.9745~0.9977 and 0.9217~0.9780, respectively. It suggested that the pseudo-first-order model could simulate the adsorption of HgCl2 onto CBPAC better than pseudo-second-order model.