Strong Base Anion Resin Research Articles

Ion exchange resin selection for concentration and purification of uranium leached by sulphuric acid solution

Ion exchange is one of the most popular techniques for recovery and purification of uranium from sulfuric acid leaching solution, especially for recovery of uranium from a low uranium containing solutions. Resins commonly used are strong base or weak base anion resins with amine functional group. The anionic form of resins may be NO3-, Cl- , SO­42- or OH-. The selection of a resin depends on the uranium total exchange capacity, selectivity and the cost. The previous studies often use Amberlite IRA-420 for concentration and purification of uranium solution from Pa Lua sandstone ores. This is a good and suitable resin but high price. To diversify the resins and reduce the costs, instead of IRA-420, the authors tested two commercial resins Indion GS300 (India) and Purolite A400 (UK) in the processing of uranium solution from sandstone ores. The results showed that the uranium total exchange capacity of these resins is only about 80 - 85% over Amberlite IRA-420, but these resins should be able to be used instead of Amberlite IRA-420 due to their low cost and availability in Vietnam.

REMOVAL OF FLUORIDE IONS BY ION EXCHANGE RESIN: KINETIC AND EQUILIBRIUM STUDIES

The extent of the problem of the excessive fluoride in drinking water remains an important health issue. In the present work, strong-base anion resins were investigated to assess their sorptive removal capacity of fluoride from water. It was found that the removal of fluoride was high at natural pH (7) and was improved for increasing contact time and adsorbent dosage. The maximum sorption of the resin was 13.7 mg/g according to the Langmuir model, namely higher than the values reported in the literature for other sorbents and in the range of maximum capacities of some geo-materials, showing the efficiency of strong-base anion resins for fluoride removal. Among the Langmuir, Freundlich and Temkin isotherm models tested, it was found that the Freundlich model was the most appropriate to describe fluoride sorption at equilibrium (r2>0.99); while among the pseudo-first order, pseudo-second order and modified pseudo-first order models, the pseudo-first order model was found to match experimental kinetic data. It was also shown that the rate-limiting step was the film diffusion rather than the intra-particle diffusion. A simple and efficient statistical method, based on factorial design analysis using linear regression model, was applied for the determination of the optimal removal conditions deduced from 3D plots and contour plots. To approach real conditions, the effect of co-existing ions showed slightly reverse effect of hardness and chloride ions while a higher reverse effect for nitrate. Contrarily, sulfate had no significant effect on fluoride removal.

Chromium (VI) removal from aqueous solutions by purolite base anion-exchange resins with gel structure

The removal of Cr (VI) from aqueous solution using two strong base anionic resins with gel structure, Purolite A-400 (styrene-divinylbenzene matrix) and Purolite A-850 (acrylic matrix) was investigated in batch technique. The sorption efficiency was determined as a function of phases contact time, solution pH, resin dose, temperature and initial Cr (VI) concentration. The percentage of Cr (VI) removed reaches maximum values (up to 99 %) in the pH range 4 - 5.3 under a resin dose of 6 g/L and of Cr (VI) concentration up to 100 mg/L. An increase in temperature has a positive effect on the Cr (VI) sorption process. The equilibrium sorption data were fitted with the Freundlich, Langmuir and Dubinin-Radushkevich isotherm models, using both linear and nonlinear regression method. The Langmuir model very well verifies the experimental data and gives the maximum sorption capacity of 120.55 mg Cr (VI)/g and 95.82 mg Cr (VI)/g for A-400 and A-850 resins, respectively. The thermodynamic study and mean free energy of sorption values calculated using Dubinin-Radushkevich equation indicated the sorption is a chemical endothermic process. The kinetic data were well described by pseudo-second order kinetic equation and the sorption process is controlled by external (film) diffusion and intraparticle diffusion.

Separation of phenylalanine and tyrosine by ion-exchange using a strong-base anionic resin. I. Breakthrough curves analysis

Dynamics of separations of the amino acids phenylalanine and tyrosine in fixed-bed ion-exchange column using the strongly basic resin PA 316 was investigated for different operating conditions. The flow rate, feed amino acid concentration and pH solution affect significantly the breakthrough time of the saturations curves. A mathematical model which takes into account axial dispersed plug flow, external and intraparticle mass transfer resistances, as well as non-constant selectivity coefficient data, enabled successfully to simulate the experimental breakthrough curves. The model was satisfactorily extended to prediction of the experimental dynamic behaviour of phenylalanine (Phe) and tyrosine (Tyr) mixtures where the ratio of the feed concentrations of both amino acids was changed. A most effective separation of the amino acids was achieved when the concentration of Phe in the feed solution is higher than that of Tyr.

Separation of phenylalanine and tyrosine by ion-exchange using a strong-base anionic resin. II. Cyclic adsorption/desorption studies

Cyclic adsorption and desorption dynamics of phenylalanine (Phe) and tyrosine (Tyr) was investigated in a column packed with a strong anionic resin, Diaion PA316, under different pH conditions. Experiments were performed in order to study the effect of the pH in two sequential bed saturations keeping constant the feed concentration. A adsorption step at isoelectric pH (≈6) followed by a desorption step at high pH (12–13) causes an overshoot in the breakthrough curves due to lower affinity resin by amino acid under alkaline conditions. Contrarily to this behaviour, the solution that leaves the column reaches a zero concentration of amino acid during a certain time in two consecutive saturations at high pH and isoelectric pH. The regeneration bed with 0.14M NaOH is almost effective for conditions less favourable of sorption of amino acid by the resin. Satisfactory agreement was achieved between experimental and simulated results using a mathematical model that considers axial dispersed plug flow and intraparticle mass transfer described by the linear driving force model. Preliminary pH parametric pumping experiments, in semi-continuous mode, enabled to achieve a concentration factor of the top product of ≈2.3 and 2.0 for Phe and Tyr during 10 cycles of operation.

Process study on adsorption of glycerin from saline wastewater by strong base anion resin

A physicochemical method was used to adsorb glycerin in saline wastewater by strong base anion resin (D201). Boric acid, a kind of weak acid, can combine with glycerin, and a specific complex can be produced, which possess bigger molecule than glycerin. Then, this specific complex could be adsorbed by strong base anion resin. Via the experiment, the equation of adsorption isotherm with D201 at 20°C can be shown by lgx/m = 1.74lgCe - 5.72; for column test with simulative glycerin wastewater, the treatment capability was more than nine bed volumes, and 39.77 mg glycerin could be removed by per gram resin. When the NaCl concentration was 10 g/L, five bed volumes of simulative wastewater could be treated, and the adsorb mass was 29.09 mg/g. When the NaCl concentration was 30 g/L, only three bed volumes of simulative wastewater could be treated, and the adsorb mass was 14.83 mg/g.

Transesterification of Glycerides Using a Heterogeneous Resin Catalyst Combined with a Homogeneous Catalyst

Biodiesel, produced by the transesterification of vegetable oils or animal fats with methanol, is a promising alternative diesel fuel. In this study, a series of strong base anion resins with different basicity, pore structure, degree of cross-linking, and particle size were investigated as heterogeneous catalysts for the transesterification of soybean oil with methanol. A trace amount of CH3ONa, functioning as a homogeneous catalyst, was found to exhibit synergetic effects with the resin catalysts. By using this combined method, the transesterification reaction approached completion after 6 h at 328 K. The reason for this synergetic effect can be attributed to the regeneration of active catalytic sites in a basic environment.

Influence of anionic species on uranium separation from acid mine water using strong base resins

The presence of uranium and other elements in high concentrations in acid mine drainage at Poços de Caldas Uranium Mine (Brazil) is a matter of concern. The acid water pH is around 2.7, the uranium concentration is in the range of 6–14 mg L −1, sulfate concentration near 1400 mg L −1, fluoride 140 mg L −1 and iron 180 mg L −1. In this solution, where sulfate is present in elevated concentrations, uranium is basically in the form of UO 2(SO 4) 3 4−. This study investigated the separation of uranium from the other anions present in the acid water under batch and column mode using ion exchange technique. The pH studied was 2.7 and 3.9. Two strong base anionic resins were tested. The influence of ions, commonly found in acid waters like sulfate and fluoride, on ion exchange process was also assessed. Equilibrium studies were carried out to determine the maximum adsorption capacities of the resins. The resins showed a significant capacity for uranium uptake which varied from 66 to 108 mg g −1 for IRA 910U and 53 to 79 mg g −1 for Dowex A. The results also showed that SO 4 2− is the most interfering ion and it had a deleterious effect on the recovery in the pH range studied. Fluoride did not affect uranium removal.

A novel method for extraction and separation of total flavones and total astragalosides from Radix astragali

In this paper a novel method for extraction and separation of total flavones and total astragalosides from Radix astragali using a resin method is suggested. Ethanol is used as the extractant, the macroporous absorption resin modeled H-107 is used to enrich the astragalus extract, and the macroporous strong base anion resin D-280 is used to separate the total flavones and the total astragalosides. This method allows a good yield of total flavones of 600 mg/100 g Radix astragali, a purity of 94.2%, and a yield of total astragalosides of 28 mg/100 g Radix astragali.

Breakthrough curves for adsorption and elution of rhenium in a column ion exchange system

Impure rhenium and molybdenum bearing solution was passed through a column of Varian strong base anionic resin for selective adsorption of rhenium and molybdenum ions from the solution. Elution of molybdenum and rhenium was carried out using 2 N NaOH and 0.2 N NH 4SCN, respectively. The effect of resin bed height on breakthrough time was investigated. Experimental and theoretical curves were compared with good agreement. The results showed that the behavior pattern of these curves was repeatable and almost constant.

Examination of styrene-divinylbenzene ion-exchange resins, used in contact with food, for potential migrants

The nature of extractable substances from five types of styrene-divinylbenzene ion-exchange resins used in the preparation of foodstuffs was investigated. Strong acid cation resins, strong and weak base anion resins, and an active carbon replacement resin were examined. These resins are used for a variety of purposes including water softening, decalcification of sugar syrups, demineralization, removal of nitrate ions from water and decolourization. Analysis was carried out using electrospray LC-MS- and GC-MS-based methodologies. Extractable substances from new resins were identified as mainly being by-products of the resin manufacturing process. Levels of extractable substances decreased with washing.

Selective removal of arsenate from drinking water using a polymeric ligand exchanger

The new maximum contaminant level (MCL) of 10 μg/L for arsenic in the US drinking water will take effect on January 22, 2006. The compliance cost is estimated to be ∼$ 600 million per year using current treatment technologies. This research aims to develop an innovative ion exchange process that may help water utilities comply with the new MCL in a more cost-effective manner. A polymeric ligand exchanger (PLE) was prepared by loading Cu 2+ to a commercially available chelating ion exchange resin. Results from batch and column experiments indicated that the PLE offered unusually high selectivity for arsenate over other ubiquitous anions such as sulfate, bicarbonate and chloride. The average binary arsenate/sulfate separation factor for the PLE was determined to be 12, which were over two orders of magnitude greater than that (0.1–0.2) for commercial strong-base anion (SBA) exchangers. Because of the enhanced arsenate selectivity, the PLE was able to treat ∼10 times more bed volumes (BVs) of water than commonly used SBA resins. The PLE can operate optimally in the neutral pH range (6.0–8.0). The exhausted PLE can be regenerated highly efficiently. More than 95% arsenate capacity can be recovered using ∼22 BVs of 4% (w/w) NaCl at pH 9.1, and the regenerated PLE can be reused without any capacity drop. Upon treatment using FeCl 3, the spent brine was recovered and reused for regeneration, which may cut down the regenerant need and reduces the volume of process waste residuals. The PLE can be used as a highly selective and reusable sorbent for removal of arsenate from drinking water.

Improved and selective platinum recovery from spent α-alumina supported catalysts using pretreated anionic ion exchange resin

Improved and selective recovery of platinum from a spent dehydrogenation platinum α-alumina supported catalyst using a strong basic ion exchange resin is reported. Platinum and other precious metal group (PMG) complexes are leached using concentrated hydrochloric acid along with about 0.20 vol.% nitric acid as an oxidizing agent from de-coked and crushed spent catalyst. Effects of hydrochloric acid concentration, time, and temperature in leaching stage are investigated. The strong basic anionic resin is treated by sodium hydroxide solution to replace chloride anion by hydroxyl group ion. The supernatant of the leaching process is passed through a fixed column of hydroxylated strong base anionic resin. The treated resin on which the platinum complex is adsorbed is dried and burned in an oxidizing atmosphere at 750–800 °C. The recovered gray metallic powder is mainly platinum. Results compared with those obtained from untreated anionic resin show that adsorption of platinum complexes onto the treated anionic resin is more selective and the yield of separation is considerably improved. The breakthrough curves of the pretreated anion exchanger and that of untreated exchange resin reveals that the capacity of the hyroxilated resin is decreased by about 14%. These breakthrough curves can be used for calculation of height of a practical exchange plate (HPEP) for design purposes.

Removal of metals and anions from drinking water by ion exchange

Five organic and two inorganic ion exchangers were evaluated for the removal of metals and anions from water of two drilled wells. Sodium titanate (CoTreat) and a chelating aminophosphonate resin were the most efficient exchangers in removing transition metals from the total of 1800 bed volumes processed. CoTreat was the best for almost all of the transition metals. The breakthrough level of manganese was below 1% with CoTreat even when its concentration in the feed water was high (1 mg/l). The weak acid cation resin took up transition metals relatively efficiently. Somewhat unexpectedly, the cation exchangers also removed arsenic from water. Arsenic may have been sorbed on iron species, which again was adsorbed and filtered by the exchanger beds. Most of the cation exchangers took up calcium and magnesium at low processing capacities (<400 BV), and the strong base anion resin took up nitrate, bromide and sulphate very efficiently below 700 bed volumes. Neither chloride nor fluoride was taken up by the exchangers tested.

As removal using ion exchange with Spent Brine Recycling

A conventional sulfate‐selective Type‐2 polystyrene strong base anion resin was studied for arsenic (As) removal from Albuquerque, N.M., drinking water. Attention was focused on the regeneration aspects of ion exchange and the potential for reusing the spent brine directly without removing As. The major finding was that As‐laden spent brine with makeup salt addition to 1 M chloride could be reused up to 20 times with no effect on As leakage and minimal effect on run length. The authors also found that As could be removed from the spent recycle brine using ferric hydroxide coagulation in such a way that the resulting sludge passed the toxicity characteristic leaching procedure test as a nonhazardous waste.

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.

Catalytic denitrification: direct and indirect removal of nitrates from potable water

A nitrate removal process that drastically reduces salt consumption and waste discharge has been developed on a bench scale. Nitrate is removed by chloride ion exchange, and the strong-base anion resin is completely regenerated at mild reaction conditions (i.e., ambient temperature, atmospheric pressure) in a closed circuit containing a single-flow fixed-bed reactor packed with a Pd–Cu/γ-Al 2O 3 catalyst. The combined treatment system avoids direct contact between the denitrification reactor and the water to be treated, and minimizes operational problems associated with each separate technique. No dissolution of Pd and Cu metallic-phases was observed at the given operating conditions.

Integrated ion exchange/catalytic process for efficient removal of nitrates from drinking water

A nitrate removal process that drastically reduces salt consumption and waste discharge has been developed on a bench scale. Nitrate is removed by chloride ion-exchange, and the strong-base anion resin is completely regenerated at mild reaction conditions (i.e., ambient temperature, atmospheric pressure) in a closed circuit containing a single-flow fixed-bed reactor packed with a Pd–Cu/ γ–Al 2O 3 catalyst. The combined treatment system avoids direct contact between the denitrification reactor and the water to be treated, and minimizes operational problems associated with each separate technique. No dissolution of Pd and Cu metallic phases was observed at the given operating conditions.

Removal of Uranium from Finnish Groundwaters in Domestic Use with a Strong Base Anion Resin

The removal of uranium from Finnish groundwaters with a strong base anion resin (SBA) has been tested in domestic use with different types of ion exchange filter and water. SBA resin was considered to be the best type of resin for testing due to its high capacity, simplicity and cost effectiveness, and due to the well owners acute need for removal equipment. The removal of uranium using SBA resin achieved over 95% effectiveness at all six test places independently, with different water qualities and competing ions. Attention was also paid to the quality of the treated water, especially the hygienic quality. The water quality has been monitored regularly for two years and improved rather than deteriorated during the treatment.

Adsorption characteristics of carbon on ion exchange resin in nuclear power plant

The adsorption characteristics of carbon on a strong base anion and cation exchange mixed resin, Amberlite IRN-150 in OH+ and H− (1∶1) used in nuclear power plant, were investigated at 6, 30 and 50 °C at a concentration of carbon up to 0.02M. The expression for the adsorption of carbon was well fitted to the Freundlich equation and the constants,k andn in the equation were deduced. Furthermore, we could explain that the adsorption capacity on the mixed resin increases with temperature.