Weak Base Anion Exchange Resin Research Articles

Adsorption of Re and 99Tc by means of radiation-grafted weak basic anion exchange resin

To avoid using toxic solvents, weak basic anion exchange resin with aromatic amine groups was prepared by grafting 4-vinyl pyridine onto polystyrene microspheres through simultaneous radiation grafting method. In batch adsorption experiments toward Re(VII) which was selected to simulate 99Tc, the adsorption efficiency maximized when the concentration of HNO3 was set at 0.02 M. Using reductive eluents SnCl2 it was found a method to efficiently regenerated resin at low acidity. For adsorption toward 99Tc, the results matched well with Re, which indicates that the prepared exchangers will have wide applications in the future to remove 99Tc from spent nuclear fuel.

Evaluation of Weak and Strong Basic Anion Exchange Resins for NOM Removal

The feasibility of using ion exchange resins in stirred (suspended) mode operation for the removal of natural organic matter (NOM) from surface water was investigated. Resins were compared in terms of their NOM removal capacity, kinetics, and regeneration efficiency under batch and consecutive batch loading conditions. The dominant mechanism for NOM removal with the strong basic A860 resin was ion exchange whereas a combination of ion exchange and surface adsorption governed the removal with the weak basic A847. The estimated limiting capacity (qm) and the equilibrium constant (α) for A860 were higher than the ones for A847, showing greater affinity of A860 for natural organic matter. Also, under consecutive batch loadings, the strong basic resin showed greater removal (∼10% higher) compared to A847. Different regeneration scenarios were also examined and A860 resin showed a superior regeneration efficiency (∼20%) compared to A847. Overall, findings indicated the strong basic resin as a better candidate for the removal of NOM from surface water. This paper proposes an evaluation scheme for the selection of appropriate ion exchange resins aiming to reduce NOM in surface waters.

Chromium Removal From Strong Base Anion Exchange Waste Brines

Regeneration of strong base anion (SBA) exchange resin produces concentrated and hazardous brine. In this research, one alternative regenerant and two brine treatment options were investigated to reduce the hazardous characteristics of the brine. These options included replacing sodium chloride with sodium bicarbonate as the regenerant, using ferrous sulfate (FeSO4) to reduce/coagulate hexavalent chromium (CrVI) in the brine, and applying weak base anion (WBA) exchange resin and chemical reductive media (CRM) to adsorb/reduce CrVI. It was found that bicarbonate was as effective as chloride in regenerating chromium‐saturated resins, and the affinity of the bicarbonate‐form resin for chromium was similar to that of the chloride‐form resin. It was observed that FeSO4 applied at doses close to the stoichiometric ratio achieved almost complete removal of total chromium from the SBA brine. In column tests, two CRM exhibited more than 20 times greater removal capacity for total chromium than did the WBA exchange resins.

Performance and modeling of continuous ion exchange processes for phenols recovery from olive mill wastewater

A continuous-flow ion exchange (IE) process for phenols recovery from olive mill wastewaters was examined through both strong-base and weak-base anion exchange resins. The effect of initial pH showed that phenols removal efficiency increased with an increase in the pH value up 7 and efficiency remains constant at higher pH values for Amberlyst A26. On the other hand, phenols removal efficiency for Amberlite IRA-67 also increased with an increase in the pH value up 7, reaching phenols removal efficiencies close to 57%. In addition, Thomas, Yoon–Nelson and Clark models were applied to the experimental data to predict the breakthrough curves. The simulation of the best-performing operational condition was used to evaluate the process performances for different inlet phenols concentrations (5, 25 and 100mgL−1). The results showed an increase in initial phenols concentration improved the adsorption capacity. In both cases, the Thomas model was found to give best fit to experiment data for the three initial phenols concentrations, followed by the Yoon–Nelson and Clark models. Finally, column regeneration studies showed almost 100% phenols recovery efficiencies were obtained. IE process led to a phenols solution susceptible to be concentrated and used in food, cosmetic or pharmaceutical sectors.

Phenols removal from industrial effluents through novel polymeric resins: Kinetics and equilibrium studies

Abstract The efficient removal of phenols from wastewaters has increasingly become a significant environmental concern due to its high toxicity even at low concentrations. In this research work, phenols removal from aqueous solution was evaluated by using Amberlyst A26, a strong-base anion exchange resin, and Amberlite IRA-67, a weak-base anion exchange resin. The influence of phenols concentration in the feedstream was investigated as well as the effect of recirculation time. Equilibrium data fitted to the Langmuir, Freundlich and Temkin isotherms revealed Langmuir isotherm provided the best correlation for both resins ( R 2 = 0.99). Kinetic studies performed based on pseudo-first order, pseudo-second order and intraparticle diffusion models showed that although the correlation coefficients of the second-order model were the highest ( R 2 = 1) and also the SSE values were the lowest ( G ° = −1.55 kJ mol −1 ), whereas it is not spontaneous for Amberlite IRA-67 (Δ G ° = 3.06 kJ mol −1 ). Finally, Amberlyst A26 was confirmed to be considerably more efficient than Amberlite IRA-67 for the potential removal of phenols from industrial effluents.

Sorptive recovery of rhodium (III) from multicomponent chloride solutions in presence of tin (II) chloride

The paper studies the effect of tin (II) chloride additive agents on the sorption of rhodium (III) on ion-exchange resin Purolite S920 with isothiouronium functional groups, weak base anion-exchange resin Purolite S985, and a strong-base anion-exchange resin Purolite A500. It is found that introduction of SnCl2 leads to a substantial improving of selectivity of all tested ion-exchange resins to Rh(III), and increases sorption rate on ion-exchange resins S985 and S920. The paper determines the optimum dosage of SnCl2 (0,01 mol/l), at which partition coefficients of Rh(III) during adsorption on all tested ion-exchange resins reach maximum values. It is shown that quantitative recovery of Rh(III) is achieved in practice during flowing of the multicomponent chloride solution composed of, g/l: 0,2 Rh(III); 72,9 HCl; 53,5 NH4Cl; 2,7 Al(III); 1,23 Fe(III); 5,9 Sn(IV) with addition of SnCl2, through the ion-exchange resin Purolite S920 with isothiouronium functional groups. Desorption of Rh(III) from the saturated ion-exchange resin Purolite S920 with the use of an acidified thiourea solution is not full, no more than 60 %.

Comparison between different ion exchange resins combinations for final treatment of olive mill effluent

Abstract Industrial wastewater is subjected to strict environmental legislation, thus making its adequate management a key issue. In this research work, the final purification of two-phase olive mill wastewater (OMW-2) was investigated through four ion exchange resins (a weak-acid cation exchange resin, a strong-acid cation exchange resin, a weak-base anion exchange resin and a strong-base anion exchange resin). Central composite design was used for the optimization of the IE processes. Results revealed that the only final treated OMW-2ST effluent fulfilling the legislated requirements for drinking water was the one from the combination of the strong-acid cation exchange resin and the weak-base anion exchange resin. The proposed IE process yielded up to 88% removal of these pollutants when the initial pH, operating temperature and flow rate were set to 5.1, 26.8 °C and 12.1 L h−1, respectively. Under these conditions, the achieved concentrations for all contaminants in the final stream were maintained below the maximum established limits. Finally, high treated effluent volume recovery (28 L) could be achieved in continuous mode under the optimal operating conditions found, complying with standards for reuse in the production process.

Phosphate removal from aqueous solutions using a hybrid fibrous exchanger containing hydrated ferric oxide nanoparticles

This study presents the evaluation of a fibrous ion exchanger impregnated with nanoparticles of hydrated ferric oxide (HFO) as a selective sorbent for phosphate. The hybrid impregnated anion exchanger (FIBAN-As) combines the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. The phosphate loading capacity at the common pH of waste waters treatment plant secondary effluents was 162±12mg PO43−/g sorbent. Dynamic experiments were carried out and data obtained was fitted to fixed-bed sorption models. The theoretical sorption capacities reported by the Thomas model were in good agreement to the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased in multicomponent system due to the faster ion exchange of competing anions compared to phosphate ions. The loaded FIBAN-As was efficiently regenerated by using a sodium hydroxide solution, reporting up to 90% of recovery. Finally, reuse of FIBAN-As was evaluated in three successively sorption–desorption cycles by using two regeneration solutions. A sorption capacity reduction of 23% and 30% was observed for acid and alkaline solutions, respectively after the third cycle.

Kinetic modeling and error analysis for zinc removal on a weak base anion exchange resin

The efficiency of Purolite A103S resin for zinc removal (as zinc chloride complexes) has been studied using different resin quantities and temperatures in a batch adsorption system. The experimental data were analyzed using pseudo-first-order, pseudo-second-order forms, Elovich, and intra-particle diffusion models. Kinetic studies showed that the adsorption followed type 1 pseudo-second-order reaction model. The results obtained from the kinetics models were examined by the most common error functions (e.g. ERRSQ/SSE, HYBRID, ARE, EABS, MPSD,rs, sRE, S.E., RMSE, APE, and ∆q). Thermodynamic parameters, enthalpy, entropy, and Gibbs free energy were calculated in order to determine the adsorption behavior. The enthalpy value indicated an exothermic reaction. The activation energy value suggested that the process that rules over the zinc sorption on the Purolite A103S resin is physical.

Batch and fixed bed column studies on removal of Orange G acid dye by a weak base functionalized polymer

The performance of a weak base anion-exchange resin in removing Orange G dye from aqueous solutions in batch and column system was investigated. The adsorption capacity was found to depend on: pH, dye concentration, contact time, adsorbent dosage, electrolyte presence and temperature. The adsorption equilibrium is best described by the non-linear Langmuir isotherm model. At the optimum pH of 2, the maximum adsorption capacity was 1,076 and 1,218 mg g−1, at 20 and 50°C, respectively. The adsorption kinetics could be described by the pseudo-second-order reaction model. The thermodynamic parameters indicated that adsorption is a spontaneous and endothermic process. FT-IR and SEM analyses provided additional information on adsorption mechanism and on morphological changes of the adsorbent. The breakthrough experimental results were processed by means of Thomas, Yoon–Nelson and Wolborska models. The reusability of the column was examined by conducting several cycles of adsorption and desorption (with 0.05M NaOH).

Preparation of thiacalix[4]arenetetrasulfonate-modified D201 resin and its adsorption of heavy metal ions

A thiacalix[4]arenetetrasulfonate-modified resin has been prepared by loading thiacalix[4]arenetetrasulfonate onto resins for the adsorption of heavy metal ions. Various factors affecting the adsorption capacities such as different resins, resin size, pH, contact time, and temperature were investigated by batch adsorption experiments, and the adsorption isotherms, thermodynamics, kinetics, selectivity, and regeneration were also studied. It was found that the loading capacity of the D201 resin (macroporous strong basic anion exchange resin) for thiacalix[4]arenetetrasulfonate was substantially higher than those of the D301 (macroreticular weak basic styrene anion exchange resin) and the 717 (strong base styrene anion exchange resin) resins and increased with decreasing particle size of the D201 resin. The adsorption kinetics followed the pseudo-second-order rate law for heavy metal ions, indicating that chemical sorption is the rate-limiting step of the adsorption mechanism. The adsorption of heavy metal ions onto the thiacalix[4]arenetetrasulfonate-modified resin was analyzed and was found to fit better to the Langmuir isotherm than to the Freundlich isotherm, and the maximum adsorption capacities were 78.1, 65.8, 54.3, and 49.8 mg/g for Cu2+, Zn2+, Cd2+, and Pb2+ ions, respectively. The prepared modified resin has high adsorption selectivity for heavy metal ions under the co-occurrence of alkali metal and alkaline earth metal ions. The regeneration efficiencies still exceed 90% after five cycles, indicating that the thiacalix[4]arenetetrasulfonate-modified resin could be favorably recycled.

GALLIUM SORPTION FROM ALKALINE SOLUTIONS OVER ANIONITES

Gallium sorption from alkaline solutions over various weak- and strong-basic anion-exchange resins under the dynamic conditions has been studied. The values of dynamic exchange capacity before breakthrough and full dynamic exchange capacity have been calculated. D-403 selective anion exchange resin has been selected. The gallate-ion sorption isotherm over D-403 weak-basic anion-exchange resin is described by Langmuir equation modified for ion-exchange equilibrium and the thermo-dynamic sorption parameters are determined. A method for determining gallium forms in alkaline solution is proposed. A series of anion sorption ability on the solid phase surface of D-403 anion exchange resin is presented.

Phosphate removal from aqueous solution using a hybrid impregnated polymeric sorbent containing hydrated ferric oxide (HFO)

AbstractBACKGROUNDThis study evaluated a polymeric ion exchanger impregnated with nanoparticles of hydrated ferric oxide as a selective sorbent for anionic P(V) species. The hybrid impregnated anion exchanger (HAIX) employed as sorbent combines the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of hydrated ferric oxide towards P(V) species.RESULTSThe P(V) loading capacity of the sorbent at a pH simulating the expected conditions in treated wastewaters was 92 ± 3 mg P‐PO4 g−1 in single component solutions. The sorption of P(V) is affected slightly by the common ions typically present in these effluents such as Cl−, SO42− and NO3−, and a reduction of only 5% was observed (89 ± 2 mg P‐PO4 g−1) in multicomponent solutions. The sorbent can be regenerated (95 ± 3%) using 4% (w/w) sodium hydroxide solution.CONCLUSIONSHAIX displays high selectivity for phosphate and small affinity for SO42−, NO3− and Cl− ions, which provides excellent conditions for its application at pH values typical of secondary wastewater effluents. HAIX exhibits higher and competitive phosphate removal capacity compared with data reported in the literature for materials based on HFO and for adsorbents prepared by impregnation of HFO onto polymeric supports. © 2015 Society of Chemical Industry

Impacts of integrated strong-acid cation exchange and weak-base anion exchange process for successful removal of saline toxicity from model olive mill wastewater

In the present work, the performance of a fixed-bed ion exchange (IE) process comprising novel strong-acid cation exchange and weak-base anion exchange resins was examined for the removal of the ionic species, that is, sodium and chloride ions, responsible for the high salinity of olive mill wastewater from an olive mill working with the two-phase decanting technology exiting a primary–secondary treatment (OMW-2ST). Sodium IE efficiency was found to increase with an increment in the pH value up 5, whereas the optimum pH for chloride IE was equal to 1. Equilibrium behaviour of both species was accurately predicted by Langmuir isotherm, showing sodium uptake is 53.9% higher than for chloride. Sodium and chloride removal efficiencies decreased (from 97.0 to 74.0% and from 95.0 to 77.0%, respectively) when their initial concentration increased from 250 to 1000mgL−1. Finally, the integrated IE system in continuous mode ensured 80–90% average removal efficiencies for both ionic species and conductivity. IE efficiency loss below 5% after several regeneration cycles is a technical-economical key fact. The final treated effluent complied with the standards established by the Food and Agricultural Association (FAO) with the goal of reusing the regenerated water for irrigation purposes.

Adsorption behavior of α-tocopheryl succinate and α-tocopheryl polyethylene glycol succinate onto weakly basic anion exchange resins

Polyethylene glycol (PEG) esters are important, nontoxic and biodegradable non-ionic surfactants. A key procedure in producing PEG esters is their separation from unreacted or excess acids. We propose an adsorption method using the weakly basic anion exchange resins for the separation of organic acids and PEG esters for the first time. With α-tocopheryl polyethylene glycol succinate (TPGS) and α-tocopheryl succinate (α-TS) as the examples of PEG ester and organic acid, respectively, single-component equilibrium experiments revealed the great potential of this method. Studies on the adsorption equilibrium, thermodynamics and kinetics of α-TS onto a weakly basic anion exchange resin were also carried out. This research is not only important for the production of TPGS, but also instructive for the separation of other PEG-esters from the reaction mixtures.

Selection of Ion Exchange Resins for Tungsten and Molybdenum Separation

A solution containing tungsten and molybdenum was acidified using hydrochloric acid, and the ability of several commercial ion exchange resins to separate tungsten and molybdenum was evaluated. The results from the acidification test indicate that when the pH of the solution is adjusted to 7.0, WO42- is polymerized into HW6O215-, while MoO42- is not. The test results of resins selection show that the D213 resin and the D308 resin are superior to other resins in separating low concentrations of tungsten and molybdenum, whereas the D201 resin and the D309 resin are suitable for separating high concentrations of tungsten and molybdenum. The results from the column test indicate that weak-base anion exchange resins are better than strong-base anion exchange resins for both low and high concentrations of tungsten and molybdenum.

Simultaneous Removal of Azo and Phthalocyanine Dyes from Aqueous Solutions Using Weak Base Anion Exchange Resin

The performance of the Purolite A847 weak basic anion exchanger in the simultaneous removal of the azo dye Lanasyn Navy M-DNL (LNCr) and the phthalocyanine dye Acid Blue 249 (CuPc) from acidic aqueous solutions was studied under dynamic conditions. The comparison of FTIR spectra of unloaded and dye-loaded anion exchangers made it possible to consider suitable sorption mechanisms. The results of dynamic experiments revealed that anion exchanger had a greater dynamic sorption capacity with a longer breakthrough time and a shorter length of mass transfer zone when both dyes LNCr and CuPc were removed from the one-component solution as compared to those of their mixture. Models of Wolborska and Juang were found to be suitable to predict the character of breakthrough curves and to determine the characteristic parameters of the Purolite A847 column useful for process design: the mass transfer coefficient β (1/min) and time at the break point τ (minutes). The result would be useful in the design of wastewater treatment plants for removal of azo and phthalocyanine dyes from aqueous solutions and water recycling.

Development of a Modified Ion Exchange Resin Column for Removal of Gadolinium From the Moderator System of PHWRs

Gadolinium is used as neutron poison in Pressurized Heavy Water Reactors (PHWR) at 15 ppm concentration during emergency shut down and at 2 ppm during start up of the reactor. The pHa range of 5–5.5 is recommended based on the acidity requirement for maintaining gadolinium in the solution and to minimize corrosion of moderator system structural materials and radiolysis. Gadolinium has to be progressively removed as the reactor goes to power. It has been observed that gadolinium precipitates in the purification system consisting of ion exchange columns. Experimental investigations were carried out to understand the phenomenon of precipitation of gadolinium in the weak base ion exchange resin. Attempts were made to selectively cap the strong base groups in weak base resin with nitrate to prevent precipitation of gadolinium. Based on studies carried out on gadolinium pick-up and radiation decomposition of weak base anion exchange resins, a simple mixed resin column consisting of nitrate treated poly acrylic based macroporous weak base resin and a strong acid cation exchange resin has been recommended for the removal of gadolinium. It does not precipitate gadolinium and gives optimum chemistry parameters in the outlet.

Adsorption of zinc and cyanide from cyanide effluents on anionic ion-exchange resin

The adsorption of zinc and cyanide from cyanide effluents onto strong and weak basic anion exchange resins was studied in a batch adsorption system. Factors influencing the adsorption rates such as resin selection, resin amounts, contact time and temperature were studied and scanning electron microscopy-energy disperse spectroscopy( SEM-EDS) was used in the analysis. The present study shows that the adsorption capacity of resin 201×7 is better than that of resin 301. The adsorption process was relatively fast and came to equilibrium after 60 min. The kinetic data were analyzed with three models and the pseudo-second-order kinetic model was found to agree with the experimental data well. The equilibrium data could also be described well by Langmuir isotherm model. Thermodynamic parameters such as enthalpy change(ΔH0), free energy change(ΔG0) and entropy change(ΔS0) were calculated and the adsorption process was spontaneous and endothermic.

Comparative Study of Indion-AGR and Duolite A-638 Anion Exchange Resins by Application of <SUP>131</SUP>I and <SUP>82</SUP> Br as a Tracer Isotopes

The present study deals with modeling of ion-isotopic exchange reaction kinetics by application of radioactive tracer isotopes 82Br and 131I. The bromide and iodide ion-isotopic exchange reactions was carried out by using weak base anion exchange resins Indion-AGR and Duolite A-638. It was observed that for both the resins, reaction rate decreases with rise in temperature and increases with increase in ionic concentration. The study was extended further for characterization of these resins based on their performance under different operational parameters. It was observed that the percentage/amount of ions exchanged and distribution coefficient values calculated for Duolite A-638 was higher than Indion-AGR resins under identical operational parameters, indicating superior performance of Duolite A-638 over Indion-AGR resins.