Browsing by Author "Tan, HKS"

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A continuous stirred tank reactor study on chromic acid removal by ion exchange
(1998)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
Dilute chromic acid removal by anion exchange was studied using a continuous stirred tank reactor (CSTR) system. A rate model based on film diffusion control was formulated for quantitative study on the chromate removal. For simplicity, the rate and mass balance equations were formulated for total Cr(VT) concentration. Equations were derived for the effluent concentration history as well as the time-dependent Cr(VI) concentration in the resin. The derived equations for solid and liquid phase Cr(VI) concentration variations were tested and verified by the experimental results obtained. Effects of various operating conditions, such as resin size, feed concentration, and flow rate, were also discussed.
Acid-salt separation by selective adsorption with ion-exchange resins
(1996)
Tan, HKS
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交大名義發表
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應用化學系
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National Chiao Tung University
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Department of Applied Chemistry
A separation technique based on the selective adsorption characteristics for an acid-salt mixture on an anion-exchange resin was used to separate acid and salt from solution. Its application can lead to the recovery and reuse of the waste acid solution in such metallurgical process as steel pickling and mineral extraction. Experimental studies were carried out in this work. Concentrated nitric acid and cuprous nitrate were treated with the strong anion-exchange resin Dowex 1. In column experiments the concentrated acid solution used was about 3 N and the cuprous nitrate concentration about 15 to 25 g/L. After the treatment, about one-fifth to one-third of the treated waste solution can be recovered and reused.
Chromic acid removal by anion exchange
(1999-02-01)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
The kinetics of dilute chromic acid removal by anion exchange was studied using a batch system. Rate model formulated for total Cr(VI) removal based on film diffusion control was applied. This rate model was shown to adequately fit the experimental rate data. In addition, column experimental runs were performed by using 20-50 mesh anion resin with feed solution containing 0.2 g/L CrO3. The bed heights of 15, 25 and 35 cm and flow rates ranging from 1.02 cm/s to 2.38 cm/s were employed in the experiments. Linear driving force rate expression based on film diffusion rate control was incorporated in the model equations for simulation of column performance. The kinetic parameter and equilibrium relation in the rate equation were obtained independently either by separate experiments or from data available in the literature. Satisfactory agreements between experimental and calculated breakthrough curves were obtained.
Effective isotherms and equilibrium characteristics of a weak acidic cation resin
(2001-07-01)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
The equilibrium properties of a weak acidic cation resin were studied theoretically and experimentally. Equations were derived for the effective isotherm of this type of resin. The derived equations are applicable to the exchange of hydrogen ions with any metallic ions with a valence of n. Based on equilibrium theory, theoretical breakthrough curves were derived from the effective isotherm expressions. Experiments were performed using IRC-50, a weak cationic resin. Column runs were conducted with 0.05 to 0.1 N of both NaCl and Ca(NO3)(2) solutions. The experimental breakthrougough curves obtained for both Na+ - H- and Ca+ + - H+ exchange show that the breakthrough occurs very early and that the operating capacity is only 2-3% of the ultimate capacity of the resin. Comparing the theoretical breakthrough curves with the experimental ones suggests that the value of the normalized dissociation constant is between 0.001 and 0.003, and that for both the Na+ - H+ and Ca+ + - H+ exchange systems, the normalized selectivity coefficient is between 0.2 and 0.5.
Ion exchange accompanied by neutralization in an anion bed
(2003-01-15)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
The performance of the anion bed in a two-bed deionization process was investigated. Experiments and simulation were carried out with a feed solution concentration of about 0.005N. The prepared solutions were dilute acid of HCl, H2SO4 and a mixture of the two. The bed height was about 40 cm and the flow rate in the range of 75-150 ml/min. Both the binary and ternary models were used to predict the column performance. In both models, it was found that the equilibrium parameters do not affect significantly the breakthrough behavior. This is due to the accompanied neutralization reaction which results in the irreversible form of the rate equation. The experimental and theoretical breakthrough curves show very good agreement especially for the early part of the data. Results of this study suggest that a pseudo-binary or pseudo-ternary model can be used to model the fixed bed deionization process by ion exchange. (C) 2002 Elsevier Science B.V. All rights reserved.
Ion exchange accompanied by neutralization reaction: Removal of dilute acids by anion exchange
(2000)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
The kinetics of exchange between an anion resin in the OH- form with dilute acids was studied in a batch system. The resin used was Dowex 1-X8 and the acids prepared for the experimental work were 0.005 to 0.01 N HCl and H2SO4. The results of study showed that a film diffusion model with a constant rate parameter fits all experimental data very well. The experimental results also showed that the rate is inversely proportional to the resin radius as predicted by the film diffusion model. It was found that the rate for Cl-OH- exchange is higher than that for the SO42--OH- exchange. This higher rate of exchange is attributed to the higher effective diffusivity for the HCl-OH- system as compared to that for the H2SO4-OH- system.
Ion exchange accompanied by neutralization reaction: Removal of dilute acids by anion exchange
(1999)
Tan, HKS
;
應用化學系
;
Department of Applied Chemistry
The kinetics of exchange between an anion resin in the OH- form with dilute acids was studied in a batch system. The resin used was Dowex 1-X8 and the acids prepared for the experimental work were 0.005 to 0.01 N HCl and H2SO4. The results of study showed that a film diffusion model with a constant rate parameter fits all experimental data very well. The experimental results also showed that the rate is inversely proportional to the resin radius as predicted by the film diffusion model. It was found that the rate for Cl-OH- exchange is higher than that for the SO42--OH- exchange. This higher rate of exchange is attributed to the higher effective diffusivity for the HCl-OH- system as compared to that for the H2SO4-OH- system.
New algorithms for the computation of column dynamics of multicomponent liquid phase adsorption
(1997-01-01)
Tan, HKS
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應用化學系
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Department of Applied Chemistry
New and efficient numerical algorithms were developed for simulating column dynamics of multicomponent liquid phase adsorption. Simple and realistic models are used for the simulation. Langmuir form of isotherm and linear driving force rate expressions are employed in the model equations. Algorithms were formulated for three different rate control mechanisms, namely, film diffusion control, particle diffusion control and combined film and particle diffusion control. The algorithms derived are explicit with the exception of the requirement of solving a nonlinear equation in one single variable which is the concentration of a reference species. Thus the tedious iterative calculation procedure for solving simultaneous nonlinear equations in a multicomponent fixed bed system is avoided. Example calculations indicated very good numerical accuracy as verified from an independent check by means of an overall mass balance.
New algorithms for the computation of column dynamics of multicomponent liquid phase adsorption
(1997-01-01)
Tan, HKS
;
應用化學系
;
Department of Applied Chemistry
New and efficient numerical algorithms were developed for simulating column dynamics of multicomponent liquid phase adsorption. Simple and realistic models are used for the simulation. Langmuir form of isotherm and linear driving force rate expressions are employed in the model equations. Algorithms were formulated for three different rate control mechanisms, namely, film diffusion control, particle diffusion control and combined film and particle diffusion control. The algorithms derived are explicit with the exception of the requirement of solving a nonlinear equation in one single variable which is the concentration of a reference species. Thus the tedious iterative calculation procedure for solving simultaneous nonlinear equations in a multicomponent fixed bed system is avoided. Example calculations indicated very good numerical accuracy as verified from an independent check by means of an overall mass balance.