Polystyrene Anion Exchange Resin Research Articles

Efficient Removal of Ciprofloxacin from Contaminated Water via Polystyrene Anion Exchange Resin with Nanoconfined Zero-Valent Iron.

Ciprofloxacin (CIP), an important emerging contaminant, has been frequently detected in water, and its efficient removal has become an issue of great concern. In this study, a nanocomposite material nZVI/PA was synthesized by impregnating nanoscale zero-valent iron (nZVI) inside a millimeter-sized porous host (polystyrene-based anion exchange resin (PA)) for CIP removal. The nZVI/PA composite was characterized by field emission scanning electron microscopy coupled with energy-dispersive X-ray, transmission electron microscopy, X-ray diffraction, as well as X-ray photoelectron spectroscopy, and it was confirmed that nZVI was uniformly dispersed in PA with a small particle size. Furthermore, several key factors were investigated including initial solution pH, initial CIP concentration, co-existing ions, organic ligands, and dissolved oxygen. The experimental results indicated that the nZVI/PA composites exhibited a high removal efficiency for CIP under the conditions of initial pH 5.0, and initial CIP concentration 50 mg L-1 at 25 °C, with the maximum removal rate of CIP reaching 98.5%. Moreover, the nZVI/PA composites exhibited high efficiency even after five cycles. Furthermore, quenching tests and electron spin resonance (ESR) confirmed that CIP degradation was attributed to hydroxyl (·OH) and superoxide radicals (⋅O2-). Finally, the main degradation products of CIP were analyzed, and degradation pathways including the hydroxylation of the quinolone ring, the cleavage of the piperazine ring, and defluorination were proposed. These results are valuable for evaluating the practical application of nZVI/PA composites for the removal of CIP and other fluoroquinolone antibiotics.

Efficient Removal of Azlocillin Sodium from Water by Polystyrene Anion Exchange Resin Supported MIL-53

Due to the widespread use of antibiotics in medical treatment, animal husbandry and aquaculture, a large number of antibiotics are discharged into the environment as metabolites or in their original state, causing pollution to water bodies, which is a serious issue. In this study, a novel nanocomposite adsorbent MIL-53/D201 was successfully prepared by hydrothermal synthesis. This approach overcomes the disadvantage of easy dissociation of MOF material in the water phase and realizes the efficient removal of antibiotic azlocillin sodium in water. The crystal morphology and basic structure of the composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy scattering spectroscopy (EDS), and specific surface area and porosity analyzer (BET). The results showed that MIL-53 was successfully synthesized in situ in D201. The results of adsorption experiments show that the maximum saturated adsorption capacity of the composite is 122.3 mg/g when the dosage of the composite is 1.0 g/L. Compared with pure MIL-53 material, the composite material exhibits greater stability and efficient adsorption performance for target pollutants at different pH values. The adsorption process accords with the quasi-second-order kinetic adsorption model and Langmuir adsorption isothermal model. After five cycles of adsorption and desorption, the removal rate of MIL-53/D201 to azlocillin sodium was still above 87%.

Bidentate and Monodentate Binding of Chromium (VI) on the Acid Scavenger Exchange Resin, MP-Carbonate, as a Function of pH

Hexavalent chromium or Cr (VI) is a serious health risk that has been identified in drinking water and generally originates as industrial by-products and hazardous waste sites, although natural sources have been reported. Common methods to remove Cr (VI) employ adsorption, filtration, ion exchange technologies, and redox reactions. We report on a macro porous polystyrene anion exchange resin, a solid-supported equivalent of tetra-alkyl ammonium carbonate (Biotage® MP-Carbonate), to effectively remove Cr (VI) from synthetic wastewater with bidentate or monodentate binding modes of chromate, depending on the pH environment. Sorption capacity is pH dependent with 332, 161, and 163 mg CrO42− per gram of MP-Carbonate adsorbed at pH 2, 6.8, and 10, respectively. Experimental data indicate an exergonic and endothermic adsorption process. Static vs. dynamic reaction conditions are discussed. Density functional theory calculations parallel the Gibbs free energy results of the bidentate binding of the large chromate ion compared to carbonate with the ammonium ions. These studies identify the potential uses of MP-Carbonate in the remediation of Cr (VI) wastewater unrelated to the pH of the water source.

Pilot‐Scale Evaluation of Bicarbonate‐Form Anion Exchange for DOC Removal in Small Systems

This article highlights results from an ion exchange (IX) pilot‐plant study that evaluated bicarbonate‐form anion exchange resin (AER) with sodium bicarbonate (NaHCO3) regeneration for dissolved organic carbon (DOC) removal. Sodium chloride (NaCl) is the conventional regeneration salt; however, NaHCO3 could be used as an alternative to reduce the environmental impacts associated with NaCl brine disposal. In a comparison of chloride‐form AER and bicarbonate‐form AER, results indicated that chloride‐form AER and bicarbonate‐form AER have a similar affinity for DOC; chloride‐form AER treats more bed volumes before breakthrough than bicarbonate‐form AER; chloride‐form AER is regenerated 10–48% more efficiently with NaCl compared with bicarbonate‐form AER regenerated with NaHCO3; polyacrylic AER is regenerated more efficiently than polystyrene AER using both NaCl and NaHCO3; and the total cost of using NaCl and NaHCO3 is comparable when brine disposal is considered. Results from this study provide guidance for small water systems considering IX treatment.

Effect of polymeric matrix on the adsorption of reactive dye by anion-exchange resins

Two ion-exchange resins with similar properties, namely, polystyrene anion-exchange resin SAER and polyacrylic anion-exchange resin AAER, were applied for orange G removal to investigate the effect of polymeric structure on adsorption. Despite having similar adsorption capacities, AAER exhibited an initial reaction rate that was 2.0–4.4 times greater than that of SAER. Moreover, the adsorption isotherm on AAER followed the Langmuir equation, whereas the adsorption on SAER was better described by the Freundlich equation. AAER adsorption was dominated by ion exchange, as indicated by the ratio of released Cl− to adsorbed orange G, which was 1.10. By contrast, this ratio was 0.754 in SAER, indicating that other interactions aside from ion exchange were involved in the adsorption of SAER, such as hydrophobic and π–π interactions. AAER showed higher regeneration efficiency than SAER using NaCl solution as the desorption agent. These results demonstrated that AAER was a more suitable adsorbent for orange G removal.

Photocatalysis of chloroform decomposition by tetrachlorocuprate (II) on Dowex 2-X8.

Heterogenized on a polystyrene anion exchange resin and in the presence of oxygen, CuCl4(2-) catalyzes the photodecomposition of chloroform at wavelengths above 345 nm with greater efficiency than an equivalent amount in homogeneous solution. The reaction is proposed to proceed in two stages, the first stage yielding CCl4 and HO2(-) as products, the second consisting of a chain reaction resulting from the CuCl4(2-)-catalyzed photodissociation of CCl4, yielding phosgene with CCl3 radicals as chain carriers. Photodecomposition is retarded by added Cl(-), CH3CN, C6H12 or C2H5OH, which is ascribed to the displacement of CHCl3 molecules from the vicinity of the copper by attraction to the polystyrene matrix or to the alkylammonium cation sites.

Understanding and Modeling Removal of Anionic Organic Contaminants (AOCs) by Anion Exchange Resins

Ionic organic contaminants (OCs) are a growing concern for water treatment and the environment and are removed inefficiently by many existing technologies. This study examined removal of anionic OCs by anion exchange resins (AXRs) as a promising alternative. Results indicate that two polystyrene AXRs (IRA910 and IRA96) have higher sorption capacities and selectivity than a polyacrylate resin (A860). For the polystyrene resins, selectivity follows: phenolates ≥ aromatic dicarboxylates > aromatic monocarboxylates > benzenesulfonate > aliphatic carboxylates. This trend can be explained based on hydration energy, the number of exchange groups, and aromaticity and hydrophobicity of the nonpolar moiety (NPM) of the anions. For A860, selectivity only varies within a narrow range (0.13-1.64). Despite the importance of the NPM of the anions, neutral solutes were sorbed much less, indicating synergistic combinations of electrostatic and nonelectrostatic interactions in the overall sorption. By conducting multiple linear regression between Abraham's descriptors and nature log of selectivity, induced dipole-related interactions and electrostatic interactions were found to be the most important interaction forces for sorption of the anions, while solute H-bond basicity has a negative effect. A predictive model was then developed for carboxylates and phenolates based on the poly parameter linear free energy relationships established for a diverse range of 16 anions and 5 neutral solutes, and was validated by accurate prediction of sorption of five test solutes within a wide range of equilibrium concentrations and that of benzoate at different pH.

Diclofenac removal in urine using strong-base anion exchange polymer resins

One of the major sources of pharmaceuticals in the environment is wastewater effluent of which human urine contributes the majority of pharmaceuticals. Urine source separation has the potential to isolate pharmaceuticals at a higher concentration for efficient removal as well as produce a nutrient byproduct. This research investigated the efficacy of using strong-base anion exchange polymer resins to remove the widely detected and abundant pharmaceutical, diclofenac, from synthetic human urine under fresh and ureolyzed conditions. The majority of experiments were conducted using a strong-base, macroporous, polystyrene resin (Purolite A520E). Ion-exchange followed a two-step removal rate with rapid removal in 1 h and equilibrium removal in 24 h. Diclofenac removal was >90% at a resin dose of 8 mL/L in both fresh and ureolyzed urine. Sorption of diclofenac onto A520E resin was concurrent with desorption of an equivalent amount of chloride, which indicates the ion-exchange mechanism is occurring. The presence of competing ions such as phosphate and citrate did not significantly impact diclofenac removal. Comparisons of three polystyrene resins (A520E, Dowex 22, Dowex Marathon 11) as well as one polyacrylic resin (IRA958) were conducted to determine the major interactions between anion exchange resin and diclofenac. The results showed that polystyrene resins provide the highest level of diclofenac removal due to electrostatic interactions between quaternary ammonium functional groups of resin and carboxylic acid of diclofenac and non-electrostatic interactions between resin matrix and benzene rings of diclofenac. Diclofenac was effectively desorbed from A520E resin using a regeneration solution that contained 4.5% (m/m) NaCl in an equal-volume mixture of methanol and water. The greater regeneration efficiency of the NaCl/methanol–water mixture over the aqueous NaCl solution supports the importance of non-electrostatic interactions between resin matrix and benzene rings of diclofenac. Experiments with ketoprofen, in addition to diclofenac, suggest that polystyrene anion exchange resins can be used to selectively remove other acidic pharmaceuticals from urine.

Removal of Cr(VI) and As(V) ions from aqueous solutions by polyacrylate and polystyrene anion exchange resins

The sorption of Cr(VI) and As(V) from the aqueous solutions with the polyacrylate anion exchangers of the strong base functional groups Amberlite IRA 458 and Amberlite IRA 958 was studied. The studies were carried out by the static-batch method. The concentration of Cr(VI) and As(V) ions in the aqueous solution was determined by the UV–VIS spectrophotometer. The influence of several parameters was studied with respect to sorption equilibrium. The phase contact time and the concentration affect the sorption process. The equilibrium state was established already after 15 min of phase contact time. Maximum uptake of Cr(VI) and As(V) occurred at pH 5 and 10, respectively. The determined kinetic parameters imply that the sorption process proceeds according to the equation type of pseudo second-order. Sorption equilibrium data were correlated with the Langmuir and Freundlich isotherms. Removal of As(V) ions on macroporous Amberlite IRA 900 decreased about 12 % in presence of other anions (Cl−, NO3−, SO42−) in the solution. The sorption was temperature dependent.

Catalysis of the Photodecomposition of Chloroform by a Polystyrene Anion Exchange Resin

Irradiation at wavelengths above 360 nm of a suspension of Dowex 2-X8 anion exchange resin (Cl¯ form) in chloroform causes the decomposition of chloroform with formation of COCl2 and HCl. The presence of CCl4 as the most important secondary product, along with the lack of any photodecomposition in CDCl3, the absence of photodecomposition when O2 is excluded, and the lack of any secondary products related to CHCl2 radicals rule out a mechanism based on sensitized C–Cl dissociation, as occurs in the direct UV photolysis of chloroform. A mechanism is proposed in which an initial photoreaction produces COCl2 and HCl at a slow rate, along with CCl4. A second photoreaction causes Cl dissociation from CCl4, greatly increasing the net rate of COCl2 and HCl formation after a sufficient concentration of CCl4 is attained.

Dependence of Photocatalytic Reaction Yields on Catalyst Mass in Solid-Liquid Suspensions

When the yield of a heterogeneously photocatalyzed reaction is seen to pass through maximum as the mass of catalyst is increased in a suspension, this behavior may be attributable to a regime in which back-reflection most often occurs after a single photon-particle encounter, while absorption requires multiple internal reflections. This was modeled with a double exponential equation, which predicts that the yield will pass through a maximum with increasing catalyst mass when the catalyst has low absorptivity, but approach an asymptotic limit when the absorptivity is high. The rate of photodecomposition of chloroform, catalyzed by the chloride form of a polystyrene anion exchange resin (low absorptivity), was found to pass through a maximum as the amount of resin was increased, while catalysis by the CuCl4 2- form of the resin (higher absorptivity) caused an increase in the rate of decomposition with catalyst mass to an asymptotic value. Keywords: Heterogeneous photocatalysis, suspensions, chloroform photodegradation, reflectance, catalyst mass

Evaluation of polystyrene anion exchange resin for removal of reactive dyes from aqueous solutions

The Amberlite IRA-900 resin was tested to remove C.I. Reactive Black 5, C.I. Reactive Red 2 and C.I. Reactive Red 120 dyes from solutions. Batch adsorption studies concerning effects of the phase contact time, pH, temperature, the presence of salts and surfactants were run. A pseudo second-order kinetic model was used to evaluate the rate constants. The Langmuir equation provided good fit for the experimental data of the equilibrium adsorption. The studies of dyes uptake using the dynamic method were run. The treatment efficiency of Amberlite IRA-900 to model wastewaters was tested. Desorption experiments by the batch method were performed.

Modified polystyrene anion exchange resins with long chain alkyl groups to enhance the aldolization reaction selectivity

The aldolization of formaldehyde and acetone to form 4-hydroxy-2-butanone over anion exchange resins with and without modifications is investigated in this work. Attempts such as surfactants addition and Soxhlet extraction are taken aiming to improve the aldolization selectivity thus the product yield. Subsequently, resins grafted long alkyl chains intrigue us for its steric hindrance effect and the synergic effect of weak and strong basic sites. Two types of modifications are carried out (1) one long alkyl chain on the copolymer tertiary amine via Menshutkin N-alkylation reaction; (2) two long alkyl chains: one on polystyrene aromatic ring through Friedel–Crafts alkylation under the circumstances of tertiary amine and the other on the copolymer tertiary amine using the Menshutkin N-alkylation reaction. The reaction results indicate that the yield for 4-hydroxy-2-butanone can be increased from 44.3% to around 50% for the resin with one long alkyl chain (the first case), while this can achieve up to 71.3% for the resin with two long alkyl chains.

Degradation and Removal of Sulfadiazine from Waters by a Novel Polymer-supported Hydrous Manganese Dioxide(HMO)

A new polymer-supported hydrous manganese dioxide(HMO-201) was prepared by impregnating HMO onto a porous polystyrene anion exchange resin(D201) through ion exchange,oxidation and reduction.The removal of sulfadiazine(SD) by HMO-201 was evaluated as a function of solution pH,background electrolyte NaCl and dissolved organic matter(DOM).HPLC-MS results showed that the removal of SD by HMO-201 was due to degradation rather than adsorption.The results indicated that the removal of 0.01 mmol/L SD reached 99.9% at pH=1.0 within 120 min.The SD degradation followed the pseudo-first-order kinetics.SD removal efficiency was little affected by ionic strength and DOM.With simulated SD wastewater containing NaCl and DOM,SD removal efficiency remained above 99% within 240 min for up to ten batches of continuous operation.Fixed-bed column experiment results of HMO-201 showed that SD remained undetected after 2000 bed volume simulated SD wastewater was passed through the column.HMO-201 was effective for the removal of sulfonamide antibiotics commonly found in the environment.It could be reused without a significant loss of capacity and thus has a great potential of real-world applications.

Removal of tartrazine from aqueous solutions by strongly basic polystyrene anion exchange resins

The removal of tartrazine from aqueous solutions onto the strongly basic polystyrene anion exchangers of type 1 (Amberlite IRA-900) and type 2 (Amberlite IRA-910) was investigated. The experimental data obtained at 100, 200, 300 and 500 mg/dm 3 initial concentrations at 20 °C were applied to the pseudo-first order, pseudo-second order and Weber–Morris kinetic models. The calculated sorption capacities ( q e,cal) and the rate constant of the first order adsorption ( k 1) were determined. The pseudo-second order kinetic constants ( k 2) and capacities were calculated from the plots of t/q t vs. t, 1 /q t vs. 1 /t, 1 /t vs. 1/q t and q t /t vs. q t for type 1, type 2, type 3 and type 4 of the pseudo-second order expression, respectively. The influence of phase contact time, solution pH and temperature on tartrazine removal was also discussed. The FTIR spectra of pure anion exchangers and those loaded with tartrazine were recorded, too.

The immobilization of d-hydantoinase and characterization under classic condition and microwave irradiation

d-Hydantoinase was covalently immobilized onto polystyrene anion exchange resin via glutaraldehyde. Immobilization conditions were optimized: the carrier as D-92 type polystyrene anion exchange resin, temperature as 25 °C, immobilization time as 12 h, and initial concentration of protein as 6 mg/ml. Under the optimized reaction conditions the activity of the free and immobilized d-hydantoinase was determined. The free and immobilized d-hydantoinase samples were characterized with their kinetic parameters, thermal, and storage stability. The K m and V max values were 14.985 mM and 0.6 mM/min for the free, and 27.030 mM and 1.187 mM/min for the immobilized, respectively. Operational stability of the immobilized d-hydantoinase was also detected in a circulating packed-bed reactor. The half-time of the immobilized d-hydantoinase was 11 days. Nearly 90% of activity of the immobilized d-hydantoinase was reserved for 100 days stored at 4 °C. The free and immobilized d-hydantoinases were also characterized under microwave irradiation. Results shown that the reactions catalyzed by both free and immobilized d-hydantoinase were accelerated under microwave irradiation. The half-time of the immobilized d-hydantoinase reduced to 16 min under microwave irradiation.

A simple and sensitive chromium speciation procedure by hyphenating flow injection on-line preconcentration with catalytic spectrophotometry

A high sensitive chromium speciation procedure based on spectrophotometric detection was developed by coupling flow injection on-line preconcentration with a catalytic indicator reaction. Chromium(VI) is retained on a mini-column packed with polystyrene anion exchange resin (strong basic 717 resin), which was afterwards eluted with a small volume of NaNO 3 solution. The eluted Cr(VI) is then directed to catalyze the decoloration of alizarin cyanine green (ACG) in the presence of bromate as oxidizing reagent, and the absorbance change is proportional to the concentration of Cr(VI). With a sampling volume of 12 ml and a loading time of 120 s, an enrichment factor of 26.5 was achieved for the preconcentration. The most distinct feature of this procedure is characterized by its overall detection limit, i.e., 50 ng l −1, which is much superior to those achieved by FAAS, and comparable to those obtained by inductively coupled plasma mass spectrometry (ICPMS) and electrothermal atomic absorption spectrometry (ETAAS). The procedure was validated with a certified reference material. It was also applied to the speciation of chromium in a series of surface water samples.

Fully automated synthesis module for preparation of S-(2-[ 18F]fluoroethyl)-L-methionine by direct nucleophilic exchange on a quaternary 4-aminopyridinium resin

A fully automated preparation of S-(2-[ 18F]fluoroethyl)-L-methionine (FEMET), an amino acid tracer for tumor imaging with positron emission tomography, is described. [ 18F]F - was produced via nuclear reaction 18O(p,n) [ 18F] at PETtrace Cyclotron. Direction nucleophilic fluorination reaction of [ 18F]fluoride with 1,2-di(4-methylphenylsulfonyloxy)ethane on a quaternary 4-(4-methylpiperidinyl)pyridinium functionalized polystyrene anion exchange resin gave 2-[ 18F]-1-(4-methylphenyl-sulfonyloxy)ethane, and then [ 18F]fluoroalkylation of L-homocysteine thiolactone with 2-[ 18F]-1-(4-methylphenylsulfonyloxy)ethane yielded FEMET. The overall radiochemical yield with no decay correction was about 10%, the whole synthesis time was about 52 min, and the radiochemical purity was above 95%.

Fully automated synthesis of O-(3-[ 18F]fluoropropyl)-L-tyrosine by direct nucleophilic exchange on a quaternary 4-aminopyridinium resin

A fully automated synthesis of O-(3-[ 18F]fluoropropyl)-L-tyrosine (FPT), an amino acid tracer for tumor imaging with positron emission tomography, is described. FPT was prepared by a two-step reaction sequence. Direct nucleophilic fluorination substitution of [ 18F]fluoride with 1,3-di(4-methylphenylsulfonyloxy)propane on a quaternary 4-(4-methylpiperidinyl)pyridinium functionalized polystyrene anion exchange resin, followed by [ 18F]fluoro-1-(4-methylphenylsulfonyloxy)propane yielded FPT. The overall radiochemical yield with no decay correction was about 12%; the whole synthesis time was about 52 min, and the radiochemical purity was above 95%.

Automated commercial synthesis system for preparation of O‐(2‐[18F]fluoroethyl)‐L‐tyrosine by direct nucleophilic displacement on a resin column

AbstractA slightly modified automated commercial synthesis system for preparation of O‐(2‐[18F]fluoroethyl)‐l‐tyrosine (FET), an amino acid tracer for tumor imaging with positron emission tomography, is described. Direct nucleophilic fluorination of [18F]fluoride with 1,2‐di(4‐methylphenylsulfonyloxy)ethane on a quaternary 4‐(4‐methylpiperidinyl)‐pyridinium functionalized polystyrene anion exchange resin gave 1‐[18F]‐2‐(4‐methylphenylsulfonyloxy)ethane, then [18F]fluoroalkylation of l‐tyrosine yielded FET. The overall radiochemical yield with no decay correction was about 8–10%, the whole synthesis time was about 52 min, and the radiochemical purity was above 95%. Copyright © 2003 John Wiley & Sons, Ltd.