Ion Exchange Operation Research Articles

Hybrid exchange methods regulate Cu+ location on Cu-Y zeolites and improve CO adsorption capacity and selectivity

This work systematically examines the influence of preparation methods on the active Cu+ anchoring sites over FAU zeolites and their CO storage capacity and selectivity. The involved preparation methods here include individual liquid ion exchange method with CuCl2 solution, individual solid ion exchange method with CuCl powder and the hybrid exchange method. For the obtained Cu-Y samples, XRD, Ar adsorption/desorption at 87 K, TEM and NMR were used to characterize their skeleton structure, meanwhile, XPS and H2-TPR were utilized to identify the Cu+, Cu2+ and CuCl distribution. The CO storage capacity was implemented through CO adsorption–desorption isotherms. The correlation between various Cu species and CO storage capacity was analyzed and DFT calculation was employed to further elucidate the optimal Cu+ location induced by preparation methods. Finally, it is found that the isolated Cu+ is the dominating CO adsorption sites and Cu+ on site III present higher bonding energy with CO molecules. The hybrid preparation method seems the optimal choice for Cu-Y synthesis since the initial liquid ion exchange operation could prevent the framework corrosion from the subsequent solid ion exchange process, which benefits the optimal CO storage capacity and CO/N2 selectivity.

The fractal pack: New equipment for ion exchange operations in the sugar industry

The fractal pack is a new patented ion exchange configuration that is conceptually similar to a plate and frame filter press and contains a number of ion exchange plates held within a frame. With bed depths as shallow as 3 to 24 inches, this ion exchange system design results in a substantial reduction in capital cost by delivering the following benefits: compact equipment, modularity (by easy addition or removal of resin chambers from the existing frame), inexpensive capacity expansion / reduction and reduced installation costs. Furthermore, the capital and operating costs benefit from reductions in cycle times (and hence reduced resin fouling), regenerant use (and hence reduced chemical consumption and waste production), pressure drop, water consumption and product dilution. Increased resin loadings and longer life may also be possible. The plates are manufactured from corrosion resistant materials, making it possible to use aggressive resin regeneration chemicals if necessary. Testing has been carried out on both a small pilot / bench scale as well as a large pilot scale for several potential applications across a range of industries. In the sugar industry, successful performance has been demonstrated in the decolorization and softening of juice and syrups. Experimental work at various scales has confirmed that performance is maintained on scale-up to fractal pack plates of full industrial size.

Removal of natural organic matter by ion exchange: Comparing regenerated and non-regenerated columns

Dissolved organic matter (DOM) in water has adverse impacts on the water treatment process and is effectively removed by ion exchange (IEX). Some researchers have proposed the term biological ion exchange (BIEX) for the process of continuous DOM removal by ion exchange without the need for chemical regeneration that results in brine waste. Surface water with moderate dissolved organic carbon (DOC) concentrations (4–6 mg/L) and high sulfate concentrations (80 – 120 mg/L) was fed to two regenerated and two non-regenerated columns for 12,500 bed volumes (9 months) with the goal of investigating the effects of chemical and possibly biological regeneration on long-term IEX operation. Chemically regenerated columns achieved between 60 and 80% DOC removal for the entirety of the experiment, while non-regenerated columns achieved steady DOC removal of ~50%. Inorganic ion analysis showed that biological activity had minimal impact on DOC removal, and the main mechanism of removal was secondary IEX between sulfate (SO42−) and fractions of DOC with high affinities for ion exchange. Fluorescence and specific UV absorbance at 254 nm (SUVA 254) data showed that fractions of DOC with higher SUVA 254 values (terrestrial-like fractions) were better removed by secondary IEX than those with lower SUVA 254 values (aquatic/microbial-like fractions). Scanning electron microscopy showed that biofilms on non-regenerated resins covered 5–15% of the resin surface and are composed of numerous species of bacteria with varying functions, with some protozoa present.

Prediction of multicomponent ION exchange equilibria by using the e-NRTL model for computing the activity coefficients in solution

The e-NRTL model for computing the activity coefficients in solution of electrolytes was used for the first time, as the best of our knowledge, together with the Wilson's equation for evaluating the non-ideal behavior of the resin phase, in the prediction of multicomponent ion exchange equilibria. For this purpose, experimental data for the binary systems Ni2+/Na+ and Zn2+/Na+ and the ternary system Ni2+/Zn2+/Na+ using Amberlite IR-120 reported by Franco et al. [1] were considered. The results obtained showed that the major impact over the equilibrium modelling was caused by the inclusion of the Wilson's equation demonstrating the predominant effect of the non-ideality of the resin phase. No significant differences in the results (for the systems and ionic concentrations explored here) were observed when Bromley, Pitzer and e-NRTL equations were used to predict the activity coefficients in solution. Regarding the prediction of the multicomponent equilibria, it can be said that the most complex models: Pitzer's and e-NRTL ones, yield the best results. Again, the major impact in the improvement of the prediction was the inclusion of the Wilson's parameters. Finally, since the e-NRTL model allows to indistinctly work with both electrolytes and non-electrolytes, it could be possible to design modules for simulating the ion exchange operation in process simulations software like Aspen Plus®.

New processes for amine regeneration

Two different procedures for amines regeneration, after carbon dioxide capture by chemical absorption, have been performed in present work. Both procedures are based on the removal of the main reaction product (bicarbonate ion) and amine deprotonation. The first method is a treatment of the carbon dioxide-rich amine with calcium hydroxide, and the second one is based on an ion exchange operation. Both methods have been tested with different amines (mainly tertiary amines) and the experimental results show suitable regeneration degrees. These data indicates that these new methods can be used instead of the commercial procedures achieving a high reduction of the energy consumed in the regeneration step.

Sulfamethazine Retention from Water Solutions by Ion Exchange with a Strong Anionic Resin in Fixed Bed

Veterinary antibiotics such as sulfonamides were detected in the environment from animal excreta in soils, contaminating soil surface and then groundwaters by percolation. The contaminated waters can enter in this way into drinking water treatment plants (DWTPs). On the other hand, direct wastewaters from humans or animals or pharmaceutical industries disposals are discharged in wastewater treatment plants (WWTPs). These water and wastewater treatment plants are not designed to remove highly polar micropollutants like antibiotics. Removal of pharmaceuticals by adsorption and ion exchange constitutes a promising technique for its low cost, easy regeneration, and selective removal of pollutants. This work studies the removal of sulfamethazine (SMZ). The SMZ retention capacity of an anionic ion exchange resin, Lewatit MP500, was determined. Equilibrium and kinetics were studied and equilibrium constants and diffusivity values were obtained using different models. Load and elution breakthrough curves were plotted to evaluate ion exchange operation in a fixed bed column. In the elution step, 100% SMZ was recovered in all cycles and could be concentrated up to twelve times, thus facilitating its final treatment or removal. Load and elution breakthrough curves were simulated using a fixed bed model in which axial dispersion was considered the parameter model fit.

Sulfamethoxazole Removal from Synthetic Solutions by Ion Exchange using a Strong Anionic Resin in Fixed Bed

Numerous antibiotics like sulfonamides have been found in effluents from drug manufacturers due to the fact that these pollutants cannot be removed completely in STPs. Removal of pharmaceuticals by adsorption and ion exchange comprise some of the most promising techniques due to their low cost, easy regeneration, and selective removal of pollutants. This article studies the removal of sulfamethoxazole (SMX), a common antibiotic that prevents the formation of dihydrofolic acid and which is the most frequently detected as sulfonamide in municipal sewage. The SMX retention capacity of an anionic ion exchange resin, Lewatit MP-500 (Lanxess Chemical), was initially determined. Equilibrium and kinetics were studied and equilibrium constants and diffusivity values were obtained using different models. Load and elution breakthrough curves were plotted to evaluate ion exchange operation in a fixed bed column. In the elution step, 100% SMX was recovered in all cycles and could be concentrated up to nine times, thus facilitating the treatment of this compound. Load and elution breakthrough curves were simulated using a fixed bed model in which axial dispersion was considered the parameter model fit. A good correlation between experimental results and the numerical solution of the fixed bed model demonstrates the validity of the model.

Selective separation of Cr(III) and Fe(III) from liquid effluents using a chelating resin

This study aimed to assess the selective separation of Cr(III) from Fe(III) from liquid solutions by using a chelating ion exchange resin, Diaion CR 11, from Mitsubishi Chemical Corporation, in the H(+) form. Equilibrium experiments with synthetic solutions of iron and chromium were carried out in batch mode. For both metals favorable adsorption isotherms were obtained, and the experimental data were well described by the Langmuir model. However, the resin exhibited higher affinity for iron than for chromium. The regeneration experiments revealed that, for both metals, HCl provided higher removal efficiencies than H(2)SO(4) and HNO(3). Moreover, precipitation with NaOH allows selectively separate chromium and iron to be stripped from the resin. Experiments in fixed bed operation were carried out to assess the dynamic behavior of the sorption of Cr(III) and Fe(III) into the tested resin by using synthetic and industrial solutions. The experiments with industrial effluent showed that the resin can remove low levels of contaminant transition metal ions, and thus the effluent can be purified for reuse of chromium during periods of 20-25 min. The resin regeneration was achieved with a sequential treatment with HCl and NaOH/H(2)O(2). High efficiencies were observed for both monocomponent and multicomponent systems. A global strategy for separating and recovering Cr(III) from an effluent that also contains Fe(III) is presented, involving the integration of ion exchange (saturation and regeneration phases) and precipitation processes. In conclusion, our approach demonstrates that efficient separation of chromium and iron is possible if ion exchange operation in a fixed bed configuration is optimized and combined with conventional processes such as precipitation.

Treatment of Condensates of Gas Coke by Anionic Exchange Resins: Thiocyanate and Phenol Retention

In coke production plants one of the most important wastewaters generated comes from the condensates of the gas coke pipelines which contains important quantities of toxic components such as phenols or thiocyanates. These contaminants can be treated by ion exchange. In this work, thiocyanate and phenol has been retained on strong anionic resins: Lewatit MP500 and Lewatit M610. Equilibrium and kinetics were studied and equilibrium constants and diffusivity values determined using different models. Breakthrough curves from the load and elution steps were carried out in order to evaluate the ion exchange operation in fixed bed. In the elution step the contaminants could be concentrated four times permitting their treatment. The results allow the determinination of the feasibility of ion exchange operations to diminish the thiocyanate and phenol concentration producing a final wastewater that can be used as treatment in the biological depuration of plants without poisoning the active sludges.

Recent Patents Review on Electrodeionization

The recent patents and progress of electrodeionization (EDI) in fields of water deionization and wastewater treatment are reviewed in the present paper. The discussion focuses on such major aspects: applied ion exchange media, inner configuration and operation manner of the EDI, integrated membrane processes based on EDI and new applications of the technology. As the newest outstanding technology for water deep desalting, EDI has been widely used for ultrapure water production in many industries and laboratories together with important improvements in recent years. Durative advancements have been achieved by inventors such as more even current distribution, higher contact efficiency between water and ion exchanger, more effective precipitation preventing and lower energy consumption. Besides, some improvements also have been achieved in other new fields in addition to pure water production. The application in water softening, seawater desalination and wastewater treatment were introduced for example. It is believed that the electromembrane process of EDI will play an important role in water desalting, wastewater reclamation and cleaner production of chemical engineering near future. Keywords: Electrodeionization, continuous deionization, ultrapure water, ion exchange resins, electroregeneration

General applications of modified Stokes expression for modeling and scale-up of expanded beds

The modeling of the behavior of expanded beds using Richardson-Zaki correlation in combination with the modified Stokes expression developed by Chae et al. [1] was successfully applied to the cases of small expanded beds (1 cm in column diameter) containing two different polydisperse particles used for ion-exchange operations, Chelating excellose (70-210 μm in diameter, 1.21 g/cm3 in density) and Streamline DEAE (100-300 μm in diameter, 1.20 g/cm3 in density). Empirical parameters determined for the modeling of the expansion of these small-beds (1 cm diameter) were found to have values similar to those for the case of larger expanded beds (2.5 cm in diameter) containing the same particles. This indicates that the modeling method can be utilized for the scale-up purposes of the expanded beds with various feed solutions.

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

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.

Hydrofluoric Acid Recovery from Waste Semiconductor Acid Solution by Ion Exchange

Recovery of hydrofluoric acid (HF) from waste semiconductor acid solution by ion exchange was investigated. Strong base anionic and strong acid cationic ion exchange resins were involved in the recovery process. The former was used to capture the fluoride in the waste acid solution while the latter was employed for exchanging hydrogen ion for sodium in the NaF solution resulting from regeneration of the anion exchanger with NaOH. The ion exchange process consisted of two ion exchange steps and two regeneration steps. Batch experiments were conducted to determine the equilibrium ion exchange capacities and to develop ion exchange isotherms. Column tests were made to examine the performances of continuous ion exchange operations under conditions of different feed flow rates and inlet acid concentrations. A simplified model based on the general logistic function was adopted and tested for describing the solute breakthrough behaviors of the exit aqueous solution. Regeneration of exhausted ion exchange resins was also examined to test their effectiveness for repeated use. The hydrofluoric acid recovered by the ion exchange process would be available for reuse. It could also be converted by calcium chloride to high-purity calcium fluoride.

An activity model for multi-component ion exchange

Ion exchange resin is used extensively in the mineral processing industry to recover dissolved species form solution. These processes are usually modeled using a dual resistance model incorporating both external film diffusion and some form of intraparticle diffusivity. Although this type of model is tested and proven in many systems, certain assumptions relating to the model makes it impractical to apply to certain ion exchange operations, especially those involving multi-component ion exchange. This study addresses these short-comings by using a dual kinetic rate model which does not rely on accurately predicting equilibrium conditions. The model assumes that ion exchange takes place from a liquid layer surrounding the particle and that a single rate constant can be used to explain ion exchange kinetics from this ‘proximity’ layer. Furthermore, the concentration of a species in the bulk solution is influenced by the rate at which it is transported into the ‘proximity’ liquid layer. The model has been applied to various systems and proved to be extremely effective. Also, the model was able to describe reversible ion exchange.

On the Thomas Equation for the Ion-Exchange Operations

The Thomas equation is an interesting subject in physical sciences. In this paper, we analytically solve the Thomas equation. The transformation obtained hereby is more general than the Thomas-Rosales transformation.

Recovery of Lysine from Corn Steepwater

ABSTRACTOne approach to increasing the utilization of agricultural products is fractionation of low‐value materials to yield high‐value products. In this study, lysine recovery from corn steepwater, an internal processing stream generated in the wet‐milling of corn, was investigated. A weakly acidic cation exchange resin was employed to selectively recover lysine from corn steepwater at pH 7.0. In column studies, the product from the ion exchange operation had a lysine content of 4–6% (db). The only other amino acid in the product was arginine. The presence of sodium, potassium, and magnesium ions at significant concentrations in the steepwater limited the lysine content of the product because of competitive adsorption on the resin. The lysine‐enriched product reported here is 4–10 times higher in lysine content than other corn milling coproducts and could potentially be useful as a lysine supplement in animal feeds.

Biological treatment of saline wastewater in a rotating biodisc contactor by using halophilic organisms

Biological treatment of saline wastewater presents unique difficulties as a result of plasmolysis of microorganisms in the presence of salt. Removal of salt from wastewater before biological treatment by reverse osmosis or ion exchange operations are rather expensive. Inclusion of halophilic organisms in activated sludge culture seems to be a more practical approach in biological treatment of saline wastewater.

Mathematical Model for Adsorption of Boric Acid on a Boron-Specific Ion Exchanger

Abstract The present study was undertaken to investigate boron removal from the waste waters of borax and boric acid producing plants. A boron-specific resin, Amberlite XE 243, was selected for the present work. Experimental results show that the ion-exchange operations are effective in removing boron from the waste waters. The variation of boron concentrations in the effluents has been observed to depend, for various initial boron concentrations, C0, on the ratio of the filtrate volume to the volume occupied by resin. An empirical equation has been developed relating boron concentration, C, to filtrate and resin volumes V1 and V, respectively, as C = 2.34 × 10−6·C0(V)−0.043(V1)2.80

Simplified Predictions of Breakthrough Fronts for Constant-Pattern Adsorption and Ion Exchange

The loading cycle of many (perhaps most) commercial adsorption and ion exchange operations involves a favorable isotherm. Concentration fronts for favorable isotherms approach a constant pattern for long bed lengths, and most industrial adsorption and ion exchange operations use sufficiently deep beds that the constant-pattern conditions are approached. Once a constant pattern is established, the region around the front can be analyzed using conventional methods developed for continuous absorption/stripping operations, but the location of the feed and withdrawal points must be assumed to move down the bed at the same rate at which the front moves. Using this approach, the constant-pattern front can be calculated for any shape of constant-pattern isotherm. The dimensionless distance in the bed is expressed in terms of transfer units, and the shape of the front can be evaluated graphically even when the relations can not be integrated analytically. This procedure is illustrated for binary ion exchange isotherms. In the simplest cases, exchange of ions like charge, the integration can be performed analytically. For other cases, numerical and graphical solutions are illustrated

Production of high fructo-oligosaccharide syrup with two enzyme system of fructosyltransferase and glucose oxidase

A novel two enzyme system of fructosyltransferase and glucose oxidase to enhance the content of the net fructo—oligosaccharide (FOS) fractions in the industrial production of FOS syrup from sucrose was devised. The net FOS content in the commercial FOS syrup has been limited only to 55–60 % due to the accumulation of glucose which acts as a feedback inhibitor of the fructosyltransferase. By supplementing glucose oxidase to the conventional FOS reaction system, we could convert the glucose to gluconic acid readily separable from neutral sugars by simple ion exchange operation in the next step. The simultaneous removal of glucose was proved effective in proceeding the reaction by fructosyltransferase further by relieving the product inhibition caused by glucose. By this way, we could raise the net FOS content as high as 90 %.