Mechanism and equilibrium modeling of Re and Mo adsorption on a gel type strong base anion resin

A static-batch technique was used to demonstrate the adsorption behavior of Re (VII) and Mo ions onto Dowex 21K at equilibrium in single and binary component systems. The single equilibrium adsorption data were modeled through a linear form of four widely used equilibrium isotherm equations. The results indicated that Freundlich and D-R models for Re, and Temkin and D–R isotherms for Mo fitted the obtained data satisfactorily. Binary adsorptions of Re and Mo ions onto Dowex 21K were also analyzed using Extended Langmuir, Modified Langmuir, Extended Freundlich and Langmuir–Freundlich models. The competitive Extended Freundlich model fitted the binary adsorption equilibrium data adequately. Studies on mutual interference effects of Mo ions on Re adsorption capacity indicated that the adsorption of perrhenate ions is always suppressed. In this perspective, the results from EDX studies confirmed the rhenium atom decrease in the simulated Re–Mo adsorption. However, under the studied conditions the affinity of the Dowex 21K for rhenium ions is marginally greater than that of molybdenum ions.     

Empirical Multicomponent Equilibrium and Film-Pore Model for the Sorption of Copper,Cadmium and Zinc onto Bone Char

The adsorption of three metal ions onto bone char has been studied in both equilibrium and kinetic systems. An empirical Langmuir-type equation has been proposed to correlate the experimental equilibrium data for multicomponent systems. The sorption equilibrium of three metal ions, namely, cadmium (II) ion, zinc (II) ion and copper (II) ion in the three binary and one ternary systems is well correlated by the Langmuir-type equation. For the batch kinetic studies, a multicomponent film-pore diffusion model was developed by incorporating this empirical Langmuir-type equation into a single component film-pore diffusion model and was used to correlate the multicomponent batch kinetic data. The multicomponent film-pore diffusion model shows some deviation from the experimental data for the sorption of cadmium ions in Cd-Cu, Cd-Zn and Cd-Cu-Zn systems. However, overall this model gives a good correlation of the experimental data for three binary and one ternary systems.     

A NOVEL METAL CHELATE AFFINITY ADSORBENT FOR PROTEIN UPTAKE

1. INTRODUCTION Chitosan is a hydrolyzed derivative of chitin and belongs to a family of linear unbranched polysaccharides which contain large amounts of 1,4-linked-2-amino-2-deoxy-β-D-glucan residues. The presence of free amine groups in chitosan enhances the solubility and reactivity of this polymer. Interest in modifying chitosan by using glutaraldehyde has recently increased. The derivatized polymers have been employed for many applications [1~2], including protein immobilization…     

Propane–Propylene Binary Adsorption on Zeolite 4A

In this work we report new experimental data of pure and binary adsorption equilibrium of propane and propylene on zeolite 4A at 423 and 473 K. The pressure range studied was 0–500 kPa, which is the entire pressure range used in PSA–VSA (Pressure–Vacuum Swing Adsorption) units. The amount adsorbed of propane is much higher than that reported in previous literature. Propane diffusivity was estimated from uptake curves in the linear isotherm region. Adsorption of propane was extremely slow and equilibrium was established only after three days of adsorbate–adsorbent contact. The IAST (Ideal Adsorbed Solution Theory) using the Generalized Dubinin model to describe the pure propylene equilibrium and the Langmuir model for propane predicted with acceptable accuracy the binary adsorption data. Alternatively, the multisite model of Nitta was used to fit pure component isotherms and used in the IAST. Predictions were worse than those with the other strategy.     

A NOVEL METAL CHELATE AFFINITY ADSORBENT FOR PROTEIN UPTAKE

In this article,a spherical chitosan gel crosslinked by epichlorohydrin was prepared.It was then loaded with copper ions to produce a metal chelate affinity adsorbent for protein.The uptake of bovine serum albumin(BSA)by the affinity adsorbent was investigated.and the adsorption capacity for BSA as high as 40mg/g-wet beads was observed.The adsorption equilibrium data was well correlated by the Langmuir equation.The adsorption was considerably affected by pH.In additio.The amount of BSA adsorbed onto the beads decreased with the increasing of aqueous phase ionic strength,so adsorbed BAS can be desorbed by adjusting pH orionic strength of the solution.     

Adsorption equilibria of binary gas mixtures on graphitized carbon black

Adsorption equilibria for binary gas mixtures (methane-carbon dioxide, methane-ethane, and carbon dioxide-ethane) on the graphitized carbon black STH-2 were measured by the open flow method at 293.2 K. The experimental pressure range was (0 to 1.6) MPa. The extended Langmuir (EL) model and the ideal adsorption solution theory (IAST) have been adopted to predict the equilibria of binary gas mixtures. The results indicate that gas mixtures adsorbed on the homogeneous surface of STH-2 exhibit the nonideal behavior, which is mainly induced by adsorbate-adsorbate interactions. The real adsorption solution theory (RAST) has been used to analyze the property of the adsorbed mixtures. The activity coefficients have been correlated with the Wilson equation. The investigation demonstrates that the nonideality of adsorbed phase is completely dissimilar with the bulk liquid phase. The adsorption of the heavier component would benefit the adsorption of the lighter component.     

Single and multicomponent equilibrium studies for the adsorption of acidic dyes on carbon from effluents

The ability of activated carbon to adsorb three acidic dyes, namely, Acid Blue 80 (AB80), Acid Red 114 (AR114), and Acid Yellow (AY117), from wastewater has been studied at 20 degrees C. The three single-component systems and the three binary equilibrium systems have been measured experimentally. The three single-component isotherms were analyzed using the Langmuir, Freundlich, Redlich-Peterson, and Sips equations. The Redlich-Peterson equation gave the lowest errors using the sum of the squares of the errors closely followed by the Sips and Langmuir equations; the Freundlich fits were significantly worse. The three bisolute experimental equilibrium sets of data were analyzed by incorporating the previous four single-component isotherm equations into the ideal adsorbed solution theory (IAST). The solution methods for each of the four isotherm equations are presented in the paper, and the predicted results for the three bisolute systems, using the four isotherm equations, are compared. For the three bisolute systems (AB80 + AR114, AB80 + AY117, and AR114 + AY117), the Redlich-Peterson isotherm gives the best correlation with the experimental isotherm data.     

Isolation and partial characterization of a biosurfactant mixture produced by Sphingobacterium sp. isolated from soil

The concentration decay curves for the adsorption of phenol on organobentonite were obtained in an agitated tank batch adsorber. The experimental adsorption rate data were interpreted with diffusional models as well as first-order, second-order and Langmuir kinetic models. The surface diffusion model adjusted the data quite well, revealing that the overall rate of adsorption was controlled by surface diffusion. Furthermore, the surface diffusion coefficient increased raising the mass of phenol adsorbed at equilibrium and was independent of the particle diameter in the range 0.042-0.0126 cm. It was demonstrated that the overall rate of adsorption was essentially not affected by the external mass transfer. The second-order and the Langmuir kinetic models fitted the experimental data quite well; however, the kinetic constants of both models varied without any physical meaning while increasing the particle size and the mass of phenol adsorbed at equilibrium.     

Binary Adsorption of Phenol and m-Cresol Mixtures onto a Polymeric Adsorbent

Adsorption processes are gaining interest as methods of purifying industrial effluents. Most industries discharge effluents containing several components. The adsorption of phenol and m-cresol mixtures from aqueous solutions onto a macroporous polymeric adsorbent, Duolite ES-861, was investigated experimentally in a fixed-bed adsorber for different flowrates, feed concentrations and bed initial conditions (clean or pre-saturated).The experimental results are presented in this work, where the major objective is placed on the modelling of these fixed bed adsorption experiments using an extended Langmuir isotherm equation for two components, based on single component equilibrium data obtained for phenol and m-cresol.The model presented in this paper takes into account axial dispersion of the liquid phase, film diffusion and intraparticle mass transfer and successfully simulates the adsorption behaviour of the phenol and m-cresol mixtures.     

Competitive Adsorption of Chloroform and Iron Ion onto Activated Carbon Fiber

Chloroform in tap water has been a significant problem because it may be a carcinogenic substituent. Iron ion exists in tap water because of dissolution from iron water pipes. Iron ions in tap water cause discoloration and a bad odor. The isotherms of chloroform and iron ion adsorption onto activated carbon fibers in a single solution (chloroform or iron ion) and in a binary mixture solution (chloroform and iron ion) were investigated to estimate the competitiveness between chloroform and iron ions. The amount of adsorbed iron ions increased with increasing pore volume of the activated carbon fibers, while that of chloroform decreased. The amount of chloroform adsorbed onto the activated carbon fibers in the binary mixture solution was greater than that in the single solution. These results indicate that the adsorption of chloroform and iron ion onto activated carbon fibers could be competitive.     

混合气体中SAPO-34上单个物种的表面浓度简

运用Langmuir等温线方程和理想吸附溶液理论（IAST）两种方法计算了SAPO-34在混合气体中的单个物种表面浓度,并对比了计算值与实验值的吻合程度. 考察了两个二元混合体系,分别为80 ℃的甲醇和二甲醚以及25 ℃的二甲醚和乙烯混合气,发现IAST计算值在实验压力范围内均与实验结果吻合;但是Langmuir理论计算值仅在酸性位覆盖率低于1/3时与实验值吻合较好,随着压力增加严重偏离实验值,而且Langmuir理论不能描述随压力增加低饱和吸附量物种覆盖率降低的现象. 因此,针对包含不同饱和吸附量组分的混合气,Langmuir理论仅适用于描述表面浓度低时的反应动力学,当表面浓度高时应该采用IAST方法.     

Adsorption and desorption of binary mixtures of copper and mercury ions on natural and crosslinked chitosan membranes

Copper and mercury ion adsorption on chitosan membranes was investigated in batch systems (with both single and binary solutions). The Langmuir model and its extensions (extended Langmuir, Jain-Snoeyink, and Langmuir-Freundlich models) were tested for the modeling of experimental data. Chitosan membranes presented more affinity for Hg ions than for Cu ions. The decrease of the amount of metal adsorbed on natural chitosan in binary systems (compared to single-metal solutions) showed the competition effects between the two metal ions. For glutaraldehyde-crosslinked chitosan and epichlorohydrin-crosslinked chitosan, the mixture effect was present, producing unexpected result such as higher adsorption capacities, when compared to the monocomponent solution of each metal. The desorption of the metals was also investigated, and copper and mercury ions could be selectively recovered using a combined process by using NaCl and H₂SO₄ as eluant.     

高比表面活性碳微球分离H2中少量CO2

以实验数据为依据, 结合双Langmuir模型研究了用高比表面活性碳微球材料分离H2中少量CO2的行为. 在实验中, 用高精度的IGA-003重力吸附仪测定了温度为298、273 和268 K, 压力在0-1.8 MPa范围内CO2、H2及n(CO2):n(H2)=1:9混合物在活性碳微球中的吸附等温线. 比较不同吸附模型的计算结果与实验数据, 结果表明, 双Langmuir模型与实验结果拟合得较好; 而且通过结合理想吸附溶液理论, 该模型可以准确地计算不同的混合物体系(包括H2-CO2体系)的吸附量和吸附选择性. 利用该模型求解了不同温度下各组分的分吸附量, 得到了CO2的吸附选择性;在268 K和1.7 MPa下, CO2的吸附选择性可达到73.4, 表明活性碳微球是一种优秀的吸附H2中少量CO2的材料.     

苯酚和苯胺在超高交联吸附树脂上的共吸附行为

研究了水溶液中苯酚和苯胺在超高交联吸附树脂NDA103、NDA101、NDA100上的竞争吸附和协同吸附行为.实验结果表明,单组分苯酚或苯胺水溶液和双组分共存水溶液中吸附质分子在超高交联吸附树脂上的吸附等温线均符合Langmuir模型.当双组分摩尔比为1∶1时,在较低平衡浓度范围内苯酚和苯胺在树脂上呈现竞争吸附行为,其主导机制是两种吸附质分子对树脂内外表面上π-π作用吸附位点的直接竞争;而在较高平衡浓度范围内呈现协同吸附行为,其主导机制是两种吸附质分子之间的氢键作用.吸附温度由293K升至313K时,苯酚和苯胺在NDA103上的协同吸附作用加强,而在NDA101和NDA100上的协同吸附作用变化不明显.     

Removal of cadmium(II) and zinc(II) metal ions from binary aqueous solution by rice husk ash

The present study reports the competitive adsorptive removal of cadmium (Cd(II)) and zinc (Zn(II)) ions from binary systems using rice husk ash (RHA), a waste obtained from the rice husk-fired furnaces, as an adsorbent. The initial pH (pH₀) affects significantly the capacity of RHA for adsorbing the metallic ions in the aqueous solution. The pH₀ ≈ 6.0 is found to be the optimum for the removal of Cd(II) and Zn(II) ions by RHA. The single ion equilibrium adsorption from the binary solution is better represented by the non-competitive Redlich–Peterson (R–P) and the Freundlich models than by Langmuir model in the initial metal concentration range of 10–100 mg/l. The adsorption of Zn(II) ion is more than that of Cd(II) ion, and this trend is in agreement with the single-component adsorption data. The equilibrium metal removal decreases with increasing concentrations of the other metal ion and the combined effect of Cd(II) and Zn(II) ions on RHA is generally found to be antagonistic. Non-modified Langmuir, modified Langmuir, extended-Langmuir, extended-Freundlich, Sheindorf–Rebuhn–Sheintuch (SRS), non-modified R–P and modified R–P adsorption models were tested to find the most appropriate competitive adsorption isotherm for the binary adsorption of Cd(II) and Zn(II) ions onto RHA by minimizing the Marquardt's percent standard deviation (MPSD) error function. The extended-Freundlich model satisfactorily represents the adsorption equilibrium data of Cd(II) and Zn(II) ions onto RHA.     

介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Preparation of ion-exchange beads based on poly(methacrylic acid) brush grafted chitosan beads: Isolation of lysozyme from egg white in batch system

Poly(methacrylic acid) brush grafted crosslinked-chitosan (chitosan-g-poly(MAA)) beads were prepared in two sequential steps: in the first step, chitosan beads were prepared by phase-inversion technique and then were crosslinked with epichlorohydrin under alkaline condition; in the second step, the graft copolymerization of methacrylic acid onto the chitosan beads was initiated by ammonium persulfate (APS) under nitrogen atmosphere. The chitosan-g-poly(MAA) beads were first used as an ion exchange support for adsorption of lysozyme (LYZ) from aqueous solution. The influence of pH, equilibrium time, ionic strength and initial LYZ concentration on the adsorption capacity of the chitosan-g-poly(MAA) ion-exchange beads has been investigated in a batch system. Maximum LYZ adsorption onto chitosan-g-poly(MAA) beads was found to be 65.7 mg/g at pH 6.0. The experimental equilibrium data obtained LYZ adsorption onto chitosan-g-poly(MAA) ion-exchange beads fitted well to the Langmuir isotherm model. Kinetics parameters of this adsorption system were also analyzed by using the equilibrium experimental data. The result of kinetic analyzed for LYZ adsorption onto ion-exchange beads showed that the second order rate equation was favourable. Finally, the chitosan-g-poly(MAA) ion-exchange beads were used for the purification of LYZ from egg white in batch system and the purity of the eluted LYZ from ion-exchange chitosan-g-poly(MAA) beads was determined as 94% by HPLC from single step purification.     

Adsorption equilibrium of binary methane/ethane mixtures in BPL activated carbon: isotherms and calorimetric heats of adsorption

The adsorption of pure methane and ethane in BPL activated carbon has been measured at temperatures between 264 and 373 K and at pressures up to 3.3 MPa with a bench-scale high-pressure open-flow apparatus. The same apparatus was used to measure the adsorption of binary methane/ethane mixtures in BPL at 301.4 K and at pressures up to 2.6 MPa. Thermodynamic consistency tests demonstrate that the data are thermodynamically consistent. In contrast to two sets of data previously published, we found that the adsorption of binary methane/ethane in BPL behaves ideally (in the sense of obeying ideal adsorbed solution theory, IAST) throughout the pressure and gas-phase composition range studied. A Tian-Calvet type microcalorimeter was used to measure low-pressure isotherms, the isosteric heats of adsorption of pure methane and ethane in BPL activated carbon, and the individual heats of adsorption in binary mixtures, at 297 K and at pressures up to 100 kPa. The mixture heats of adsorption were consistent with IAST.     

Single, binary and multi-component adsorption of copper and cadmium from aqueous solutions on Kraft lignin--a biosorbent

A new biosorbent for removing toxic metal ions from water/industrial wastewater has been investigated using by-product lignin from paper production. Lignin was extracted from black liquor waste, characterized and utilized for the removal of copper and cadmium from aqueous solutions in single, binary and multi-component systems. Adsorption studies were conducted at different temperatures, lignin particle sizes, pHs and solid to liquid ratios. All the studies were conducted by a batch method to determine equilibrium and kinetic parameters. The Langmuir and Freundlich isotherm models were applied. The Langmuir model fits best the equilibrium isotherm data. The maximum lignin adsorption capacities at 25 degrees C were 87.05 mg/g (1.37 mmol/g) and 137.14 mg/g (1.22 mmol/g) for Cu(II) and Cd(II), respectively. Adsorption of Cu2+ (68.63 mg/g at 10 degrees C and 94.68 mg/g at 40 degrees C) and Cd2+ (59.58 mg/g at 10 degrees C and 175.36 mg/g at 40 degrees C) increased with an increase in temperature. Copper and cadmium adsorption followed pseudo-second order rate kinetics. From kinetic studies, various rate and thermodynamic parameters such as effective diffusion coefficients, activation energy, and activation entropy were evaluated. Adsorption occurs through a particle diffusion mechanism at temperatures 10 and 25 degrees C while at 40 degrees C it occurs through a film diffusion mechanism. The sorption capacity of black liquor lignin is higher than many other adsorbents/carbons/biosorbents utilized for the removal of Cu(II) and Cd(II) from water/wastewater in single and multi-component systems.