Ion‐exchange kinetics based on film theory

The ion‐exchange kinetics in polymer complexes was theoretically formulated. The regeneration of metal species from an ion‐exchange or chelate resin was described as a competitive reaction between metal ions and protons. We considered the ion‐exchange terms and the Langmuir terms to describe the rate of reaction, and film diffusion was also taken into account to describe the profile of the kinetics. In contrast to early methods, the surface concentrations were determined so that the rates of the chemical reactions and diffusion were self‐consistent. Although in the initial stage ion exchange was controlled by diffusion, in the last stage ion exchange was controlled by chemical reactions, particularly under excess acid. The kinetics were supported by experimental data for an iminodiacetic acid chelate resin and amidinourea resins. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39358.     

Novel Bifunctional Resins in Metal Ion Separations: Ion Exchange/Coordination Resins and Ion Exchange/Precipitation Resins

Abstract

Dual mechanism bifunctional polymers (DMBP's) as metal ion extractants are described within the context of two new examples. The carboxylic acid/pseudocrown resin is a new example of the DMBP class of resins described as ion exchange/ coordination resins. The polyethylene glycol ligand within the resin functions as a coordinating site for metal ions which are brought into the resin via ion exchange with the acid ligand. Initial studies with alkali metal ions are presented. The third general class of DMBP's is also presented. In this case, precipitation is the reaction occurring along with ion exchange thus yielding the ion exchange/precipitation resins. Barium recovery from aqueous solution via barium sulfate precipitation is described.     

Porosimetrie gequollener makroretikularer Ionenaustauscher

The relative micro and macro pore volumes and the macro pore size distribution were used to characterize the pore structure of ion exchangers. The evaluation of these from density measurements and mercury penetration measurements was described for a sulphonated macro reticular ion exchange resin in the swollen state with different contents of swelling agent. On taking up water the dry volume of the exchange resin increased (swelling) until a water content of about 33 wt.-% was reached. Additional water filled up the macro pores to a final content of 58 wt.-%. With the specific volume of the exchange resin in the swollen state in addition to the specific volume of the gel phase, the relative macro pore volume of the fully swollen state was evaluated. The results of the mercury penetration method agreed with those of the density measurements taking into account the compressibility of the mercury itself and those of the swelling agent and the matrix. Corresponding correction factors could be evaluated from measurements on micro reticular ion exchange resins. The mercury penetration measurements provided additional information on the macro pore size distribution of the swollen state. For the examined ion exchange resins a logarithmic standard distribution with an arithmetically weighed mean pore radius of about 1 100 Å was evaluated. The relative over-all pore volume of 0,65 was not identical with the value of 0,61 for the partition coefficient of ethylene glycol from dilute aqueous solutions, as only that part of the water, which is bound to the sulphonic groups (hydrated water), could be exchanged by ethylene glycol. Pure ethylene glycol substituted the hydrated water completely. The specific volume of the exchange resin thereby decreased in comparison to that of the water-swollen state.     

树脂离子交换提取拜耳法流程中钒的动力学

采用201′7树脂对拜耳法生产Al2O3流程中种分母液沉钒后再浸出,对制得的Na2VO4溶液进行了静态吸附动力学研究,分析了吸附机理. 采用批式离子交换法,考察了树脂粒径、温度、搅拌速率、溶液浓度对离子交换过程的影响,并用动边界模型对树脂吸附钒的离子交换过程进行了描述. 结果表明,离子交换过程由颗粒内扩散控制,搅拌速率和反应温度对交换速率影响较小,吸附速率随Na2VO4溶液中钒初始浓度的增加而升高;交换过程的反应速率常数为10.052 cm4/(mol×s),反应级数n为0.5507,表观活化能为39.67 kJ/mol. 吸附机理分析结果表明,在动力学实验过程中201′7树脂主要吸附的钒阴离子为V10O286-.     

Kinetics of metal ion exchange in iminodiacetic resins at low concentrations

The kinetics of metal exchange processes with iminodiacetic chelating resin, which occurs with metal concentration change, has been studied. Mechanisms of rate control were analyzed, and diffusivities determined from experiments in batch solutions with decreasing metal concentrations, following the unreacted core model. Metal exchange in binary and ternary systems are analyzed and diffusivity variations of these systems discussed in terms of reaction fronts. The influence of temperature was also studied and energies of activation determined.     

阳离子交换树脂对虫草素的静态吸附动力学研究

研究了732阳离子交换树脂对虫草素的静态吸附行为。首先对阳离子交换树脂吸附虫草素的pH条件进行了优化,随后在最佳pH条件下考察了温度、浓度及树脂粒径对虫草素在阳离子交换树脂上静态交换过程的影响,并用动边界模型描述了虫草素交换过程的动力学。确定虫草素交换行为的速度控制步骤为颗粒扩散,并推算出交换过程的表观活化能为36.66 kJ/mol,反应级数为1.60,表观频率因子为5.49×103m in-1。     

阴离子交换树脂吸附辣椒碱的动力学研究

以辣椒树脂为原料,采用静态吸附法确定了201×7型阴离子交换树脂吸附辣椒碱的最优工艺和提取机理。通过可见分光光度法测定了辣椒碱的质量浓度,并绘制出了不同pH的吸附等温线,建立了离子交换吸附辣椒碱的动力学模型。实验结果表明:该树脂吸附辣椒碱的最优pH值为5.5,当pH5.0或pH6.0时,Langmuir方程能够更好地拟合该吸附过程;而当pH=5.0~6.0时,辣椒碱的吸附等温线更符合Freundlich方程。在pH=5.5、308.15K下,较高的辣椒树脂的质量浓度能显著提高离子交换速率,且初期(t30 min)800~1200r/min的搅拌速率有利于吸附过程。通过计算得出,树脂吸附辣椒碱模型的速率常数k0=2.11×10-3s-1、活化能Ea=12.6 k J/mol、反应级数为0.268,并利用Freundlich模型解析获得了最优pH值(5.5)下阴离子交换树脂吸附辣椒碱的动力学方程。     

Synthesis and cation exchange properties of a new porous cation exchange resin having an open-celled monolith structure

We succeeded in introducing cation exchange groups quantitatively into a porous resin having an open-celled monolith structure. The resulting new cation exchange resin had the following advantages compared with conventional ion exchange resins having a bead structure. First, it was easier to pack it in a column. Second, the ion exchange rate of the new cation exchange resin was much higher than that of the conventional ion exchange resins, and the ion exchange band length of the new resin was smaller than that of the conventional ones. In addition, the electric conductivity was about five times higher than that of the conventional ones, although they had similar ion exchange capacities. These unique properties of the new cation exchange resin were caused by the quantitative introduction of ion exchange groups into the resin having the open-celled monolith structure.     

Liquid-side diffusion controlled cation exchange kinetics. Comparison between macroporous and gelular resins

The rates of H⁺Mg²⁺ exchange at low solution concentration on several styrene sulfonic acid resins with either a macroporous or gelular matrix have been measured by the shallow-bed technique. The kinetics of Mg²⁺ uptake on macroporous and gelular resins were compared. The location of the liquid-solid interphase in the resin bead, where the ion diffusion rate controls the overall exchange rate, was estimated.     

PROTON / NICKEL(II) INTERD1FFUSION COEFFICIENTS ON STRONG ACID RESINS

ABSTRACT

Ion exchange kinetics between proton and nickel(II) ions on sulfonic acid cation resins, with polystyrene-divinylbenzene matrix, type gel and macroporous, in high concentration of the external solution was studied at 298 K using a potentiometric method. The ratio between the amount of ions in the resin and in the solution phase was kept smaller than 0.1. The integral interdiffusion coefficients were determined using the quasi-homogeneous resin phase kinetic models at infinite and finite solution volume. The results were compared and discussed in terms of their range of validity. The influence of the ionic composition of the ion exchanger and matrix nature (gel or macroporous) on the integral interdiffusion coefficients was investigated and discussed. The simpler infinite solution volume kinetic model gives higher values for the integral interdiffusion coefficients than the Paterson's finite solution volume model. The numerical values of the integral interdiffusion coefficients are greater for gel than for macroporous type resin up to     

A Comparative Study of Gel-Type and Macroreticular Cation Exchange Resins for the Separation of Rare Earth Elements

Abstract

Owing to the macro- and micro- pores in the matrix, macroreticular resins have larger micro-void volume ratio in the ion exchange column chromatography. It is advantageous in the ion exchange kinetics resulting from the quicker mass transfer. By means of EDTA displacement column chromatography for the Pr-Nd separation study, we have found that macroreticular cation exchange resins have higher separation efficiency in HETP, single stage time, and the pure Pr production rate, e. g. for AG 50W-X8, 200～400 mesh resin (gel-type) and AG MP-50, 200～400 mesh resin (macroreticular), the HETP values are 0.40 cm and 0.24 cm; the single stage times are 3.11 min and 1.30 min; the pure Pr production rates are 0.19 and 0.68 m mole/hr, respectively. Because both types of resins contain the same functional group, the single stage separation factors for Pr-Nd separation have the same value of 2.0±0.1 at 92°C. The cation exchange resins which were prepared in our laboratory with higher micro-void volume ratio could improve the separation efficiency as well as reduce the pressure drop in the ion exchange column. It is suggested that new macroreticular cation exchange resins with high micro-void volume ratio and high degree of crosslinking can improve the rare earth separation efficiency which is an important design factor in the large-scale separation process for rare earth elements.     

Removal of heavy metal-cyanide complexes by ion exchange

Simultaneous removal of heavy metal and cyanide ions in an ion exchange column is studied on the basis of formation of metal-cyanide complexes at high pH range. Strong base anion exchange resin beads were contacted with water containing heavy metal (Cu, Cd, Zn) and cyanide ions in semi-fluidized and fluidized beds. Compositions of the heavy metal-cyanide complexes formed for different heavy metal and cyanide concentrations are used to explain the ion exchange behavior. Ion exchange equilibrium data of this study were fitted well with the Langmuir isotherm. The ion exchange capacity of CNas metal complexes increased to about three times that of free cyanide due to higher selectivity of metal complexes on the anion exchange resin. The ion exchange efficiency of the three heavy metalcyanide systems decreases as the concentration ratio of cyanide and heavy metal increases. The regeneration rates of the regenerants used was in the order of NaSCN>NaCN>NaOH, and the regeneration rate of NaOH was substantially lower than other two. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

High Aspect Ratio Ion Exchange Resin Bed – Hydraulic Results for Spherical Resin Beads

Abstract

A principal role of the DOE Savannah River Site is to safely dispose of a large volume of liquid nuclear waste held in many storage tanks. An in-tank ion exchange unit is being considered for cesium removal to accelerate waste processing. This unit is planned to have a relatively high bed height to diameter ratio (10:1). Complicating the design is the need to cool the ion exchange media; therefore, the ion exchange column will have a central cooling core making the flow path annular. To separate cesium from waste the media being considered is made of resorcinol formaldehyde resin deposited on spherical plastic beads and is a substitute for a previously tested resin made of crystalline silicotitanate. This spherical media not only has an advantage of being mechanically robust, but, unlike its predecessor, it is also reusable, that is, loaded cesium can be removed through elution and regeneration. Resin regeneration leads to more efficient operation and less spent resin waste, but its hydraulic performance in the planned ion exchange column was unknown. Moreover, the recycling process of this spherical resorcinol formaldehyde causes its volume to significantly shrink and swell. To determine the spherical media's hydraulic demand a linearly scaled column was designed and tested. The waste simulant used was prototypic of the wastes' viscosity and density. This paper discusses the hydraulic performance of the media that will be used to assist in the design of a full-scale unit.     

Cyanide Recovery from Gold Extraction Process Waste Effluents by Ion Exchange II. Modelling of the Fixed Bed Operation

Abstract

An ion exchange operation in a fixed bed column is tested as a method to recover copper cyanide complexes from gold extraction process waste effluents. With this aim in mind, load and elution breakthrough curves are obtained using the anionic resin Lewatit MP500. A good performance of the resin in the load stage can be deduced from the breakthrough curves obtained in all the assays at two different pHs (12, 8.5). After load step operation, column elution was carried out using NaSCN 1.25 M as eluent. A good elution peak is obtained in all cases, indicating a good performance of the resin and the eluent in this stage. With the aim of testing the design of the industrial operation, a phenomenological model is tested by fitting experimental data to theoretical equations. The model used for the simulation of both steps incorporates axial dispersion, ion exchange equilibrium, and diffusion inside particles described by the linear driving force approximation, as well as taking into account the fact that the resistance to mass transfer controls the kinetics of the ion exchange process. The models are able to simulate the experimental load and elution results reasonably well.     

Kinetics of the neutralisation of weak acid ion exchange resins with different solutions

If a weak acid ion exchange resin, in the H⁺-form comes into contact with NaOH-, NaHCO₃-or Na₂CO₃ solutions an exchange process occurs in which non dissociated fixed groups are ionized by a neutralisation reaction with coions from the solution. The exchange kinetics of such systems has been studied by means of a photographical technique and by batch experiments. The conceptual model of a non steady state diffusion process accompanied by a fast chemical reaction was applied to this exchange problem, by comparison of theoretical and experimental results interdiffusion coefficients in the resin phase have been determined and their dependence on system parameters is shown.     

Shale Oil Denitrogenation with Ion Exchange

Abstract

The nitrogen-containing aromatics normally found in crude retorted shale oils have been shown to be involved in reactions leading to the deposition of insoluble gums and sediments. These nitrogen-containing compounds must be removed in order to permit the effective utilization of the shale oil product.

A process is proposed in which the nitrogen-containing compounds found in raw shale oil are removed by mild hydrodenitrogenation followed by resin ion exchange. Ion exchange data from experimentation involving six jet fuel (15M-271°C) and diesel fuel (271–343°C) boiling point cuts are presented. Amberlyst A-15, a macroreticular, strongly acidic, cation exchange resin is used in this study. Three types of experiments were performed: batch sorption equilibrium experiments, batch sorption kinetics experiments, and dynamic ion-exchange column performance tests. The Langmuir isotherm was found to describe the equilibrium sorption behavior of the shale oil/ion-exchange resin system fairly Well. The sorption kinetics are described using a quadratic-driving force model.     

Effect of ion exchange resin on increased surface area crystallization process for purification of vancomycin

We investigated the effects of ion exchange resins on the efficiency of crystallization with an increased surface area for the purification of vancomycin. As surface area-increasing materials, diverse types of ion exchange resin were used to increase the surface area per working volume (S/V). When the S/V was increased, in cation exchange resin Amberlite 200, Amberlite IR 120 (Na), and Amberlite IRC 50 and in anion exchange resin Amberlite IRA 400 (Cl) and Amberlite IRA 910 (Cl), vancomycin crystals were successfully generated. The yield of vancomycin increased (>97%), and the time necessary for crystallization was reduced dramatically (reduced from 24 hr to 12 hr). On the other hand, the purity of the vancomycin was approximately 95% and was not affected by increasing S/V. Use of an ion exchange resin also resulted in the production of smaller vancomycin crystals than in the absence of ion exchange resin.     

Reaction kinetics for the heterogeneously resin-catalyzed and homogeneously self-catalyzed esterification of thioglycolic acid with 2-ethyl-1-hexanol

Producing 2-ethyl-1-hexyl thioglycolate (ETE) via esterification reaction with thioglycolic acid (TGA)aqueous solution as raw material by reactive-separation coupling technology is a promising process inten-sification method.To choose suitable reactive-separation coupling strategy,the kinetic studies of the esterification of TGA with 2-ethyl-1-hexanol (EHL) were carried out in a batch system.The commercial ion exchange resin was employed as an eco-friendly catalyst.The effects of temperature,catalyst concen-tration and molar ratio were determined.It was interesting to observe that the equilibrium conversion of TGA increased with the increase of catalyst mass fraction due to the adsorption of product water onto resin surface.The activity-based pseudo-homogeneous (PH),Eley-Rideal (ER) and Langmuir-Hinshelwood-Ho ugen-Watson (LHHW) models were used to fit the kinetics data of the resin-catalyzed reaction.The models of ER and LHHW performed better than the PH model.The kinetics of the TGA-self-catalyzed reaction was also determined.An activity-based homogeneous kinetics model could well describe this self-catalyzed reaction.These results would be meaningful to the selection and design of an appropriate reaction-separation strategy for the production of ETE,to realize the process intensification.     

Lead removal from aqueous solutions by 732 cation‐exchange resin

Kinetics and thermodynamics of the removal of Pb²⁺ from an aqueous solution by 732 cation‐exchange resin in hydrogen type (732‐CR) were studied in the temperature range of 298–328 K and Pb²⁺ concentration range of 5–50 mol/m³. The effects of ion exchange temperature and initial lead ion concentration on the time evolution of the experimental concentration for the metal ion were investigated. Ion exchange kinetics of Pb²⁺ onto 732‐CR follow the Nernst‐Planck equation and unreacted‐core model (UCM). The diffusion coefficients of counter ions and the efficient diffusion coefficient of lead ions within the resin were calculated. The results show that the ion exchange process is favoured under the particle diffusion control mechanism. The ion exchange isotherm data agreed closely with the Langmuir isotherm. The maximum monolayer exchange capacity for Pb²⁺ was found to be 484.0 mg/g at 308 K. Thermodynamic studies show that Pb²⁺ onto 732‐CR is spontaneous and exothermic in nature. The ion exchange processes were verified by Energy Disperse Spectroscopy (EDS).