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Adsorption: Journal of the International Adsorption Society (v.7, #2)
Adsorption Equilibrium and Dynamics of Methyl Iodide in a Silver Ion-Exchanged Zeolite Column at High Temperatures by Byung Seon Choi; Geun Il Park; Joon Hyung Kim; Jae Wook Lee; Seung Kon Ryu (pp. 91-103).
An extensive evaluation was carried out to determine the optimal silver ion-exchanged level for the removal of methyl iodide at high temperatures up to 400°C. Based on the degree of silver utilization, the optimal silver loading and temperature were about 10 wt% and 175°C, respectively. The physical and chemical properties of silver ion-exchanged zeolite were characterized by instrumental analysis such as BET, TG/DTA and SEM-EDS. Adsorption dynamics was also studied at different temperatures, and methyl iodide concentrations. A simple dynamic model was formulated by employing the linear driving force (LDF) approximation inside adsorbent particles, and the nonisothermal Langmuir-Freundlich equation. The model equations were solved numerically by an orthogonal collocation method. The proposed dynamic model satisfactorily simulated the experimental breakthrough results.
Keywords: high temperature; methyl iodide; silver ion-exchanged zeolite; adsorption equilibrium; dynamic model
Adsorption/Desorption Behavior of Bovine Serum Albumin and Porcine Insulin on Chemically Patterned Porous Gel Networks by Herman S. Mansur; Rodrigo L. Oréfice; Zélia P. Lobato; Wander L. Vasconcelos; Eliane S. Mansur; Lucas J. C. Machado (pp. 105-116).
Adsorption/desorption of proteins onto a biomaterial surface plays a major role on the biocompatibility of the implanted material. By modifying the biomaterial surface with specially designed functional groups one may achieve the most specific behavior of the developed material used in a biological system. Based on that, porous gel matrixes with functionalized surfaces offer unlimited possibilities to control the protein-substrate interaction behavior. In the present work, we have functionalized the surface of porous glass with several chemical groups during the synthesis of the silica matrix. The porous glass matrixes were obtained using tetraethoxysilane (TEOS)/ethanol and functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltriethoxysilane (APTES). In vitro tests of the kinetics of protein adsorption and desorption from the gel matrix were monitored by UV-visible spectroscopy. The bioactivity of the incorporated protein was verified by in vivo experiments with adult male rats, where they presented an acute hypoglycemic peak.
Keywords: protein adsorption; adsorption kinetics; sol-gel process; porous glass; surface engineering
Preparation and Characterization of Adsorption-Selective Carbon Membranes for Gas Separation by Antonio B. Fuertes (pp. 117-129).
The preparation and characterisation of adsorption-selective carbon membranes (ASCMs) is described. ASCMs can separate the components of a gas mixture depending on their adsorption strength. These membranes allow the separation of non-adsorbable or weakly adsorbable components (e.g. N2, H2, O2, etc) from the more strongly adsorbable components (e.g. hydrocarbons) in a gas mixture. They are prepared from the deposition of a thin film of a phenolic resin on the inner face of an alumina tube. Air oxidative treatment at temperatures in the range of 300–400°C, prior to carbonisation (pre-oxidation) or after carbonisation (under vacuum at 700°C) (post-oxidation) gives rise to an adsorption-selective carbon membrane. This membrane shows a high permeability and selectivity towards the separation of gas mixtures formed by hydrocarbons and N2. Taking into account the permeation and separation properties of the membranes, post-oxidation treatment is shown to be more effective than pre-oxidation. The separation characteristics of the carbon membranes are dependent on the composition of the gas mixture (i.e. proportion of more strongly adsorbable components) and temperature.
Keywords: gas separation; carbon membrane; adsorption selectivity; hydrocarbon; phenolic resin
Application of Ion Exchange Techniques to Industrial Process of Metal Ions Removal From Wine by V.M. Palacios; I. Caro; L. Pérez (pp. 131-138).
In this article, the application of selective ion exchange resins to the industrial metals removal of wine has been studied as an alternative to the "blue clarification" technique. In this sense, under the perspective of using this technology in the metals removal of sherry wines, a set of experiments at laboratory and pilot plant scale have been carried out. The study shows the behavior of several alkaline ions, metal ions and other parameters (pH, colour, protein index, etc.) during the process. Moreover, using the general theoretical model for continuous multistage processes, this study contemplates also the engineering design and the economic balance of the industrial process based on ion exchange columns. The experimental results demonstrates that ion exchange techniques are more effective and economic than "blue clarification" for metals removal of sherry wines. The proposed practice does not produce alterations in the qualities of the products; it achieves stability enough and also permits an important decrease of the contents of heavy metals.
Keywords: ion exchange; metal removal; iminodiacetic resin; wine oxidative stabilisation
Sorption Studies of Acid Dye by Mixed Sorbents by Y.S. Ho; C.C. Chiang (pp. 139-147).
The sorption of Acid Blue 9 onto the mixture of activated clay and activated carbon has been studied in terms of pseudo-first order and pseudo-second order chemical sorption processes. The batch sorption model, based on the assumption of a pseudo-second order mechanism, has been developed to predict the rate constant of sorption and the equilibrium capacity with the effect of initial dye concentration, mass of mixed sorbent, temperature and initial solution pH. The rates of sorption were found to conform to pseudo-second order kinetics with good correlation. Batch isotherm studies showed that the sorption of Acid Blue 9 by the mixed sorbent from aqueous solution was described by the Langmuir isotherm equation. A comparison of the evaluated equilibrium capacity of sorption has been made by the pseudo-second order rate equation as well as by the Langmuir isotherm and operating line method. In addition, an activation energy of sorption has also been determined based on the pseudo-second order rate constants.
Keywords: sorption; kinetics; acid dye; mixed sorbent
Solar-Gas Solid Sorption Refrigerator by L.L. Vasiliev; D.A. Mishkinis; A.A. Antukh; L.L. Vasiliev Jr. (pp. 149-161).
The general goal of this paper is to present the results of an investigation of a new environmentally friendly refrigerator. In this design a physical adsorption and chemical reactions are used simultaneously for a heat and cold generation. A solar refrigerator is made of a solar collector, adsorbed natural gas vessel (ANG), and compact, portable refrigeration system, which consists of two small adsorbers with heat pipe heat recovery system. An active carbon fiber “Busofit” saturated with different salts (CaCl2, BaCl2, NiCl2) is used as a sorbent bed and ammonia is used as a working fluid. The main particularity of this refrigerator is consumption of solar energy with methane gas burner as a back-up. The system management consists only in actuating the special type valves to change the direction of the heating circuit and water valves to change the water cooling circuit. The goal of this work is the experimental determination of the main refrigerator parameters using solar/gas high temperature source of energy and air/water as a low temperature source of energy to cool and heat air/water.
Keywords: solar/gas refrigerator; adsorption; chemical reactions; heat recovery; heat pipes