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.     

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.     

Spherical Resorcinol‐Formaldehyde Resin Testing for Cesium Removal from Hanford Tank Waste Simulant

Abstract

A new spherical form of resorcinol‐formaldehyde (RF) resin was tested for efficacy of cesium removal from Hanford tank waste. Two spherical RF formulations, prepared by varying curing temperature, were tested. Both resins had a tight particle size distribution and a high degree of sphericity. Small‐scale column testing (on ～20‐mL resin beds) was conducted evaluating the cesium load profile with AZ‐102 simulated tank waste and the cesium elution profile using 0.5 M HNO₃ eluant. The load and elution profiles were compared in side‐by‐side testing with ground‐gel RF resin and SuperLig® 644, the Waste Treatment Plant baseline ion exchanger. Although breakthrough capacity was not as high as the other resins tested, the spherical RF resin met plant cesium loading requirements with the AZ‐102 simulant matrix. Excellent reproducibility of cesium load and elution was demonstrated over three process cycles with no evidence of degraded performance. Residual cesium on the resin beds after elution was nearly a factor of 10 lower than that of the ground‐gel RF and SuperLig^® 644.     

D296树脂分离锆、铪洗脱的效果

介绍了在离子交换固定床上用D296强碱性阴离子交换树脂分离锆、铪的洗脱实验研究。吸附与洗脱实验的温度均控制在2~5℃,洗脱实验在饱和吸附的离子交换柱、过漏的离子交换柱、未过漏的离子交换柱中进行。研究结果表明:离子交换柱吸附状态以及洗脱剂酸度对分离效果有显著的影响。当离子交换柱存在交换区时,用任何酸度的硫酸作为洗脱剂,铪均被先洗脱出来,但高酸度的洗脱剂对分离锆、铪更有利;当离子交换柱为饱和状态时,低酸度和高酸度的洗脱剂洗脱,锆、铪不能得到分离。实验证明了单一的固定床分离锆、铪的效率低,要成功实现锆、铪的分离,需采用连续分离的离子交换移动床。     

Multiple Ion Exchange Column Tests for Cesium (CS+) Removal from Hanford Site Tank 241‐AW‐101 with SuperLig® 644 Resin

Abstract

Six cycles of loading, elution, and regeneration were performed to remove cesium (Cs⁺) from a Hanford Site tank waste sample using SuperLig^® 644 resin. The sample, which was retrieved from Tank 241‐AW‐101, was diluted to 5.09 M Na⁺ and processed through dual ion exchange columns to remove ¹³⁷Cs. Each column had an inside diameter of 1.45 cm and a height of 30 cm; and contained 15 mL of wet resin in the sodium form. The columns, designated as primary (lead) and polishing (lag), were connected in series during loading, but they were separated during elution and regeneration. The cesium loading on the primary column during the six cycles ranged from 160 to 225 bed volumes (BV) at <50% breakthrough. A gradual decline of the resin loading performances was observed as a function of number of loading cycles. For all cycles, the percent removal of cesium (¹³⁷Cs) was greater than 99.99% and the decontamination factors (DFs) achieved were higher than 1.0 × 10⁴. Elution of the resin with 0.5 M nitric acid at 25 ± 2°C was effective. Approximately 99% of the ¹³⁷Cs bound on the resin was eluted with less than 15 BV of the eluent (0.5 M nitric acid). The cumulative dose absorbed by the resin in the primary column was 1.99 × 10⁷ rad with a 20% loss of ion exchange capacity was at 50% breakthrough after completing six loading cycles.     

The effects of amine additives and flow rate on the performance of mixed-bed ion exchange at ultralow concentrations

Experimental data were obtained to evaluate the effects of amine additives for pH control of solution and the volumetric flow rate of feed solution on the performance of mixed-bed ion exchange for the removal of ionic impurities in solution. The experiments were performed under various temperatures and cation resin ratios by using a continuous column system with NaCl solution. The breakthrough curves of ions, plotted as the ratio of the effluent to influent concentration versus run time or treated solution volume, give detailed results about the effects of the existence of the pH controller, such as ammonia and morpholine, and the variable flow rate on the fate of each ion in the units. The experimental results show that the morpholine breakthrough occurs earlier than the ammonia breakthrough and that the effect of ammonia on both sodium and chloride exchange rates is more significant than that of morpholine. The addition of ammonia in solution results in the decrease of cation resin capacity for the sodium removal much more than the addition of morpholine. The step changes in the flow rate affect significantly the shapes of sodium and chloride breakthrough curves. The effluent concentrations of sodium and chloride change according to the flow rate. However, the effect increases with decreasing operation capacity of cation resin, while it becomes serious around the breakthrough time of chloride and negligible after the time.     

Kinetics and optimization of L-tryptophan separation with ion-exchange chromatography

Adsorption and desorption of L-tryptophan (L-trp) on strong acid cation exchange resin were investigated in a fixed-bed column. L-trp was effectively adsorbed onto the resin HZ-001, with the loading capacity and breakthrough time determined. Four kinetic models, including Adams-Bohard, Wolborska, Thomas, and Yoon-Nelson models, were adopted to determine the kinetic parameters of adsorption and to predict the breakthrough curves. The results showedthat the models used described the breakthrough well. Desorption of L-trp from the column bed was performed usingaqueous ammonia as the eluant. Optimum procedure was obtained with 2.0 M aqueous ammonia at the elution velocityof 6 BV/h. Five cycles of adsorption-elution-regeneration were conducted to evaluate the column reutilization.     

Hydraulic Testing of Ion Exchange Resins for Cesium Removal from Hanford Tank Waste

Abstract

The granular ion exchange resin SuperLig^® 644 is the ion exchange resin of choice for ¹³⁷Cs separation from Hanford tank wastes. Current testing activities are evaluating both ground gel and spherical resorcinol‐formaldehyde (RF) resins as alternatives to the sole‐source supplied SL‐644 while achieving comparable loading and elution performance. The purpose of this testing was then to compare the bed forces, resin particle breakage, and differential pressure across the resin bed during multiple load‐elute cycles. These tests were conducted in a small‐scale column with high flow rates to simulate the hydraulic conditions that would be experienced in a full‐scale column.     

The mixed-bed ion exchange performance at ultralow concentrations 1. Variable feed concentration and incomplete mixing of resins

Experimental data were obtained to evaluate the performance of mixed-bed ion exchange for the cases of variable feed concentration and incomplete mixing of anion and cation resins observed in large scale industrial units. For variable feed concentration, step changes in feed concentration were arbitrarily introduced into a test column. For incomplete mixing, only anion resin was loaded in the upper 20% of the column and more cation resin in the lower portion. Feed concentrations of 5.0× 10⁻⁵−2.0×10^-4 M NaCl were used for the experiments, with flow rates of 0.665-7.0 ml/sec. The effluent from the column was collected periodically and analyzed using on-line/off-line ion chromatography. The step changes in feed concentration affect the breakthrough times of sodium and chloride. Sodium breakthrough curve is more sensitive to the step changes than chloride breakthrough curve. With the same volumes of cation and anion resins, incomplete mixing of resins increases the cation exchange rate slightly and decreases the anion exchange rate slightly. As the cation resin volume increases, the effect of the incomplete mixing of resins decreases. The breakthrough curves of both ions, plotted as the ratio of effluent to the influent concentration versus run time in hour, give some detailed results about the effects of the conditions.     

REILLEX™-HPQ ANION EXCHANGE COLUMN CHROMATOGRAPHY: REMOVAL OF PERTECHNETATE FROM DSSF-5 SIMULANT AT VARIOUS FLOW RATES

ABSTRACT

The 1% breakthrough volumes (BTV) for TcO₄^on Reillex^?-HPQ anion exchange resin columns have been measured as a function of flow rate. The 1% BTV is defined as that point in the column loading when an aliquot of eluent contains 1% of the activity of an equivalent aliquot of column feed solution. The 2.54 × 50 cm     

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.     

Fixed‐Bed Adsorption Study for Fumaric Acid Removal from Aqueous Solutions by Amberlite IRA‐400 Resin

A fixed‐bed adsorption study was carried out by using a strong base anion‐exchange resin (Amberlite IRA‐400) for the removal of fumaric acid from aqueous solutions. The breakthrough curves were obtained as a function of flow rate, temperature, feed pH, and inlet fumaric acid concentration. The total adsorption capacity and the percent fumaric acid removal of the resin were calculated. The Yoon‐Nelson model was applied to the experimental data to predict the breakthrough curves and to determine the characteristic column parameters required for process design. The breakthrough curves fit the model predictions well.     

Evaluation of Elution Parameters for Cesium Ion Exchange Resins

Abstract

Cesium ion exchange is one of the planned processes for treating and disposing of waste at the U.S. Department of Energy Hanford Site. Radioactive supernatant liquids from the waste tanks will undergo ultrafiltration, followed by cesium ion exchange using a regenerable organic ion exchange resin. Two resins, SuperLig^®644 and a resorcinol‐formaldehyde resin, are being evaluated for cesium removal and cesium elution characteristics. The main purpose of this study is to optimize the cesium elution to provide a resin that, after undergoing elution, would meet the U.S. Department of Energy/Office of River Protection Project‐Waste Treatment Plant processing and resin disposal criteria. Columns of each resin type were loaded to greater or equal to 90% breakthrough with a Hanford waste stimulant and eluted with nitric acid. The temperature, flow rate, and nitric acid concentration were varied to determine the optimal elution conditions. Temperature and eluant flow rate were the most important elution parameters. As would be predicted based upon kinetic consideration alone, decreasing the eluant flow rate and increasing the temperature provided the optimal elution conditions. Varying the nitric acid concentration did not have a significant effect on the elution completion; however, elutions performed using both high acid concentration (1 M) and elevated temperature (45°C) resulted in resin degradation, causing gas generation and resin bed disruption.     

树脂环催化剂在乙酸甲酯催化水解精馏中的应用

用压制的离子交换树脂环催化剂在催化精馏塔中进行了乙酸甲酯水解的实验研究,获得了水解转化率及沿塔高浓度分布的稳态结果。采用基于传递理论的非平衡级模型对催化水解精馏过程进行模拟,得到了与实测数据吻合妨好的模拟结果。并与前期工作以均相阳离子交换膜为催化剂所得的测定结果进行了对比,考察了新型催化剂填料－树脂压制环的优越性。     

Parametric studies on the performance of cation exchange for the ammonium removal

Ion exchange performance to remove ammonium in drinking water was studied experimentally in batch and continuous operation systems under the various conditions. Data were collected using commercially available strongacid cationexchange resins of Na+ and H+ types. The performance was evaluated using equilibrium concentrations for the batch system or the effluent concentration histories for the continuous column system as a function of time or the solution volume passed through the experimental column until resins were exhausted. With high temperature or low initial feed concentration, ammonium removal characteristics of the batch system increase. At the solution concentrations of 0.5, 1.0, and 2.0 mg/L of NH4+-N and the temperatures of 15, 25, and 35 ‡C, the selectivity coefficients of resin were determined between 1.38 and 1.43 for Na+ type resin, and 3.22 and 3.47 for H+ type resin. The selectivity coefficient was correlated as a function of temperature using Kraus-Raridon equation. The breakthrough curves obtained from the continuous column operation give some results; i) with small column diameter or large column height, ii) with low initial feed concentration, iii) with low volumetric flow rate, or iv) with high solution temperature, the ammonium removal for the typical macroporous type resin increase. The results of this study could be scaled up and used as a design tool for the waterpurification systems of the drinking water treatment processes. This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

固定床不同床深下的米格列醇离子交换性研究

为考察米格列醇在固定床树脂不同堆积高度下的离子交换吸附行为,采用称量不同量的D001树脂装入离子交换柱中,通过固定床堆积高度的改变,在上样液流速和浓度固定前提下研究米格列醇溶液与树脂间的离子交换规律性,并结合床深服务时间(BDST)模型对此条件下固定床透过曲线进行分析评价。结果表明:固定床堆积高度的增加,提高了树脂与米格列醇溶液间的接触时间和树脂总的可交换离子数,有利于离子交换过程的进行,树脂的吸附质量和吸附率都得到了相应提高,堆积高度的增加使饱和点时间变长,吸附效率变小;对固定床透过曲线进行BDST模型拟合分析,结果表明:该模型与实验值间具有很高的相关系数,计算的相关参数间差异很小,对于该离子交换体系,表明BDST模型能很好地应用于该体系的离子交换吸附过程。     

SWELLING OF A CHELATING MACROPOROUS RESIN DURING METAL ION EXCHANGE

ABSTRACT

The kinetics of heavy metal ion exchange onto a commercial chelating resin was investigated from the standpoint of the swelling-shrinking experienced by the resin bead during the overall ion exchange process. Temporal measurements of the volume variations were carried out for every step of an operational cycle, metal load, elution and regeneration of the ion exchanger, using a microreactor mainly composed by a reaction cell, an optical microscope and an image treatment system. Experimental results were properly fitted to an empirical equation, whose parameters were used to characterize and compare different systems. A pseudosteady state kinetic model, which takes into account the volume variations of the resin bead during the ion exchange reaction, fits fairly well to experimental results, and was used to obtain the effective diffusion coefficients of the metals through the macroporous matrix. Finally, the study of the batch ion exchange kinetics of transition metal cations was completed with a potentiometric titration and other equilibrium determinations. These results were compared with those derived from swelling measurements.     

Adsorption Isotherms of Amino Acids and Kinetic Analysis of Ion-Exchange Chromatographs by the Moment Method

Abstract

Adsorption isotherms of three amino acids (aspartic acid, glutamic acid, and glycine) were measured in a single solute or multisolutes by the batchwise method. Kinetic parameters were determined in a column packed with ion-exchange resin by the moment method. The equilibrium constants obtained by both methods were in good agreement. Experimental elution curves agreed well with calculated one.     

PREDICTION OF BREAKTHROUGH CURVE OF METAL ION ON EXTRACTION CHROMATOGRAPHIC COLUMN

ABSTRACT

A mathematical model to predict the breakthrough curve of metal ion on an extraction chromatographic column was proposed. This model, which is the extension of that proposed in the previous paper (12), consists of the mass transfer equation of metal ion into a polymer gel impregnated with an extractant and the mass balance equation of chromatographic column. SDB (styrene-divinylbenzene copolymer) gels impregnated with CMP (dihexyl-N,N'-diethylcarbamoylmethylphosphonate), CMPO (octyl(phenyl)N,N'-diisobutylcarbamoylmethylphosphine oxide) and the equimolar mixture of CMP and CMPO were prepared. The column experiments for the extraction of Ce(III) from an aqueous solution containing nitrate ion were carried out. The predicted breakthrough curves of Ce(III) for the gels impregnated with CMP and the mixture of CMP and CMPO were in good agreement with the experimental ones. That for the gel impregnated with CMPO, however, overestimated the experimental data. This is due to adhesion among gel particles which is caused by the deliquescence of CMPO and not attributable to the mathematical model. These results suggest that the proposed model is applicable to the prediction of breakthrough curve and available as a design tool of extraction chromatographic column.