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Adsorption: Journal of the International Adsorption Society (v.8, #4)
Experimental Determination and Analysis of High Pressure Adsorption Data of Pure Gases and Gas Mixtures by S. Beutekamp; P. Harting (pp. 255-269).
Adsorption data of the pure gases ethane, methane and their mixtures on zeolite 13X and the pure gases carbon dioxide, nitrogen and their mixtures on activated carbon Norit R1 were measured gravimetrically at a temperature of 298 K and pressures up to 15 MPa. From the total loads the partial loads were calculated by the modified van Ness approach. The calculated loads show a good agreement with the experimental data.
Keywords: adsorption; gas mixtures; high pressure; gravimetric measurements
Adsorption of Nitrogen, Oxygen and Argon on Na-CeX Zeolites by Ambalavanan Jayaraman; Ralph T. Yang; Soon-Haeng Cho; Thirumaleshwara S.G. Bhat; Venkateshwarlu N. Choudary (pp. 271-278).
Commercial type X zeolites (Linde 13X) are nitrogen selective. Oxygen is the less abundant component in air; hence oxygen selective sorbents are desired for air separation. Mixed Na-Ce type X zeolites containing different ratios of Ce3+/Na+ ions are prepared by partial ion exchange of commercial X zeolite. The adsorption isotherms of nitrogen, oxygen and argon are measured and the pure-component selectivity ratios are compared and analyzed against commercial zeolites (13X) for air separation. Oxygen selectivity over nitrogen (∼1.5) and argon (∼4.0) are seen for mixed Na-Ce type X zeolite (Si/Al = 1.25; Ce3+/Na+ < 4.0) from Henry's constant determined from low pressure adsorption measurements. The oxygen and nitrogen isotherms cross over for mixed Na-Ce type X zeolite (Si/Al = 1.25; Ce3+/Na+ < 4.0), and the pressure at which cross they over increases as Ce3+/Na+ approaches 1. The oxygen selectivity as claimed in the patent by N.V. Choudary, R.V. Jasra, and S.G.T. Bhat (US Patent no. 6,087,289, 2000) is seen only at very low pressures in the volumetric adsorption measurement and the hydrogen treatment of the Ce-exchanged samples have no effect on the adsorption characteristics.
Keywords: Ce-X zeolite; nitrogen sorbent; sorbent for air separation; Ce-ion exchange
Adsorption of Sulfur Dioxide from Pseudo Binary Mixtures on Hydrophobic Zeolites: Modeling of the Breakthrough Curves by Marcus Mello; Mladen Eić (pp. 279-289).
The adsorption of SO2 from pseudo binary mixtures with water and CO2 on hydrophobic zeolites (MFI and MOR type) was investigated using the breakthrough curve method. The SO2 and water breakthrough curves were compared with theoretical ones based on an axially dispersed plug flow through the column and the linear driving force rate equation. In addition, different semi-predictive multi-component equilibrium equations were used for the breakthrough modeling: Langmuir 1, Langmuir 2 and Langmuir-Freundlich extended models. The overall mass transfer coefficients were derived by matching theoretical with experimental breakthrough curves for single component systems, i.e., water vapor or SO2 in a carrier gas. They were also predicted from a simplified bi-porous adsorbent model and compared with experimentally derived values. The presence of CO2 species in ternary mixtures with water vapor and SO2, even at relatively high concentrations of 9 vol%, had no significant effect on the breakthrough behavior of the other two species. For that reason the CO2 species was ignored in the analysis of the resulting pseudo binary mixtures. The breakthrough model was solved by finite element orthogonal collocation method using the commercial software gPROMS. Both extended Langmuir 1 and Langmuir 2 based models gave reasonable predictions of the water and SO2 breakthrough curves for pseudo binary mixtures involving a mordenite sample for all water concentration levels used in this study (up to 3.5 vol%). However, the same models were successfully used to predict SO2 breakthrough curves for a MFI sample only at low water concentrations, i.e., 1.5 vol%. At the higher water levels both models failed to describe equilibrium behavior in the MFI sample due to the introduction of multi-layer adsorption in the interstices between small MFI-26 crystals.
Keywords: adsorption; modeling; breakthrough curves; SO2 ; roll-up effect
Determination of a Solid Phase Mass Transfer Coefficient for Modeling an Adsorption Bed System Using Ammonium Molybdophosphate-Polyacrylonitrile (AMP-PAN) as a Sorbent for the Removal of 137Cs from Acidic Nuclear Waste Solutions by T.J. Tranter; R.S. Herbst; T.A. Todd (pp. 291-299).
Ammonium molybdophosphate (AMP) immobilized on a polyacrylonitrile (PAN) support is an engineered form of cesium selective sorbent material developed at the Czech Technical University in Prague. This material is being investigated as a sorbent for removing 137Cs from Idaho National Engineering and Environmental Laboratory (INEEL) acidic sodium bearing waste (SBW) solution. As part of this study, a computer program to solve the partial differential equations (PDE's) for continuity and rate of exchange in a fixed bed system has been developed using numerical finite difference algorithms. These equations are solved iteratively in order to derive a mass transfer coefficient that agrees with the results of bench scale column experiments. This mass transfer coefficient is then applied in the PDE solutions to predict breakthrough behavior in a semi-scale column experiment. The model provided excellent agreement with the semi-scale data with a mass transfer coefficient of 0.0126 min−1.
Keywords: ammonium molybdophosphate; polyacrylonitrile; cesium-137; nuclear waste; adsorption; fixed bed
Adsorption of Acid Dyes from Aqueous Solutions by Calcined Alunite and Granular Activated Carbon by Mahmut Özacar; İ. Ayhan Şengil (pp. 301-308).
Dyestuff production units and dyeing units have always had a pressing need for techniques that allow economical pretreatment for color in the effluent. The effectiveness of adsorption for dye removal from wastewaters had made it an ideal alternative to other expensive treatment options. This paper deals with an investigation on alunite, existing wide reserves in Türkiye and in the world, for dye removal. Calcined alunite was utilized for this study and its performance evaluated against that of granular activated carbon (GAC). The use of calcined alunite for the removal of Acid Blue 40 and Acid Yellow 17 (AB 40 and AY 17) from aqueous solution at different calcination temperature and time, particle size, pH, agitation time and dye concentration has been investigated. The adsorption followed by Langmuir and Freundlich isotherms. The process follows first order adsorption rate expression and the rate constant was found to be 7.65 × 10−2 and 5.74 × 10−2 min−1 for adsorption of AB 40 and AY 17 on calcined alunite, and 8.41 × 10−2 and 10.04 × 10−2 min−1 for adsorption of AB 40 and AY 17 on GAC, respectively. The equilibrium saturation adsorption capacities were 212.8 mg dye/g calcined alunite and 151.5 mg dye/g calcined alunite for AB 40 and AY 17, respectively. The adsorption capacities were found to be 57.47 mg and 133.3 mg dye per g of GAC for AB 40 and AY 17, respectively. The results indicate that, for the removal of acid dye, calcined alunite was most effective adsorbent, although comparable dye removals were exhibited by GAC.
Keywords: acid dye; calcined alunite; adsorption dynamics; isotherm; color removal
Analysis of Adsorption Data of Graphitized Thermal Carbon Black with a DFT-Lattice Gas Theory by D.D. Do; H.D. Do (pp. 309-324).
In this paper we analyzed the adsorption of gases and vapors on graphitised thermal carbon black by using a modified DFT-lattice theory, in which we assume that the behavior of the first layer in the adsorption film is different from those of second and higher layers. The effects of various parameters on the topology of the adsorption isotherm were first investigated, and the model was then applied in the analysis of adsorption data of numerous substances on carbon black. We have found that the first layer in the adsorption film behaves differently from the second and higher layers in such a way that the adsorbate-adsorbate interaction energy in the first layer is less than that of second and higher layers, and the same is observed for the partition function. Furthermore, the adsorbate-adsorbate and adsorbate-adsorbent interaction energies obtained from the fitting are consistently lower than the corresponding values obtained from the viscosity data and calculated from the Lorentz-Berthelot rule, respectively.
Keywords: carbon black; lattice gas theory; multi-layering adsorption; adsorbate-adsorbate interaction
Adsorption Kinetic Characteristics of H2S on Activated Carbon by Hung-Lung Chiang; Jiun-Horng Tsai; Gen-Mu Chang; Yi-Chun Hsu (pp. 325-340).
This study compared H2S adsorption kinetic parameters in both grain adsorption and column adsorption systems. Results indicated that when the nondimensional mass transfer parameter for adsorption column design was included, the axial dispersion (Pe > 1, δ < 1) and external film resistance (B ≫ 1) could be neglected, the fluid viscosity effect was small (Sc = 0.76), and the adsorbate affinity was fine (ψ). Surface and pore diffusion controlled the adsorbent and fluid mass transfer. In addition, spent activated carbon could be treated by a thermal process and then impregnated with NaOH. After the pretreatment, the spent activated carbon could be used for H2S adsorption. Furthermore, we also propose that the H2S adsorption reaction on the carbon is due to the formation of sulfur crystals.
The Removal of Victoria Blue from Aqueous Solution by Adsorption on a Low-Cost Material by Ozkan Demirbaş; Mahir Alkan; Mehmet Doğan (pp. 341-349).
The use of perlite for the removal of victoria blue from aqueous solution at different concentration, ionic strength, pH and temperature has been investigated. Adsorption process is attained to the equilibrium within 1 h. It is found that the adsorption capacity of perlite samples for the removal of victoria blue increased by increasing pH and temperature, and decreased by expansion and ionic strength. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (Q m and K) have been calculated for perlite samples as well. It is concluded that victoria blue is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless seperation factor (R) have shown that perlite can be used for removal of victoria blue from aqueous solutions, but unexpanded perlite is more effective.
Keywords: adsorption; adsorption isotherms; victoria blue; perlite; dye
Diffusion and Immobilization Mechanisms in Zeolites Studied by ZLC Chromatography
by M. Eic; A. Micke; M. Kocirík; M. Jama; A. Zikánová (pp. 353-353).