Magnetic Cation Exchange Resin Research Articles

Selective adsorption performance and mechanism of magnetic cationic resin for emerging contaminants

The presence of emerging contaminants in the source water has become a critical issue to ensure the security of drinking water. In our study, a comprehensive investigation was carried out on the levels of three emerging contaminants (pesticides, antibiotics, and perfluorinated compounds) present in the source water from four water plants. Zero-valent iron modified cation exchange resin (ZVI-CER) and micron-sized magnetic cation exchange resin (m-MCER) were fabricated by in-situ and copolymerization methods and their removal performances for atrazine (ATZ), tetracycline (TC) and erythromycin (ETM) in water were also evaluated. The influencing parameters (pH, co-existing cations, and humic acid) of m-MCER resin were investigated in batch experiments. The removal rates of ATZ, TC, and ETM could be controlled within the ranges of 84.1–91.6 %, 65.4–91.1 %, and 82.2–99.5 % at different pH levels. Both ATZ and ETM exhibited higher resistance to different pH levels, coexisting ions (Na+, Ca2+) and humic acid during the removal process, suggesting prospective application potential for hardness removal. Whereas, TC was notably affected by the presence of NaCl, resulting in a decrease in the removal rate from 88.9 % to 61.1 %. Furthermore, the selectivity of the resin towards both emerging contaminants and coexisting cations was also examined and the sequence of selective exchange of ions in simulated water was Ca2+>Mg2+>ATZ/TC/ETM>K+>Na+. Finally, the selective adsorption mechanism of m-MCER resin for ATZ, TC, and ETM was established by analyzing various pathways, including ion exchange, hydrogen bonding and π-π stacking interactions.

Highly selective adsorption performance and mechanism of basic amino acids by modified cation resin: Batch experiments and DFT calculation

Basic amino acids have been a major concern due to poor removal and high generation potential for nitrogenous disinfection by-products in drinking water treatment. Conventional cation exchange resins struggle to effectively eliminate basic amino acids owing to their inferior selectivity. In this work, a novel magnetic cation exchange resin (noted as MCER resin) was designed for the selective adsorption of basic amino acids. Batch experiments were conducted to investigate the removal efficiency for basic amino acids (histidine, arginine) and influencing factors (pH, ionic strength). Notably, MCER resin was superior in the removal of histidine (68.5%) and arginine (90%), which significantly reduced the generation of disinfection by-products (DBPs). It exhibited higher resistance to the interference of cations (Na+, Ca2+) at different levels and displayed a promising application potential for simultaneous removal of hardness. The adsorption for histidine and arginine reached equilibrium within 140 min and was well defined by pseudo-first order and intra-particle diffusion kinetic models. Furthermore, the reusability of MCER resin was elucidated after five consecutive adsorption-desorption cycles and the selective adsorption mechanism was determined through various pathways such as electrostatic attraction, hydrogen bonding and ion exchange, as evidenced by XPS and DFT calculations.

Determination of Heterocyclic Aromatic Amines in Various Fried Food by HPLC–MS/MS Based on Magnetic Cation-Exchange Resins

Determination of Heterocyclic Aromatic Amines in Various Fried Food by HPLC–MS/MS Based on Magnetic Cation-Exchange Resins

Efficient co-removal of copper and tetracycline from aqueous solution by using permanent magnetic cation exchange resin

This work aimed to examine a permanent magnetic cation-exchange resin (MCER) for synergistic co-removal of Cu(II) and tetracycline (TC) from their mixed solutions. Batch adsorption experiments and characterizations were performed to elucidate the adsorption mechanisms. The adsorption of Cu(II) followed the Langmuir isotherm model in most cases, while Freundlich isotherm model was more suitable for fitting TC adsorption, which was due to the surface coordination between adsorbed Cu(II) and TC and the formation of multilayer MCER-Cu-TC complexes. The equilibrium TC adsorption amount in binary Cu/TC system was about 5.5–13.5 times of that in sole system, whereas Cu(II) uptake was nearly unchanged. Decomplexing-bridging was ascribed as the primary mechanism, which involved the [Cu-TC] decomplexing and [resin-Cu] bridging for TC uptake. Moreover, these MCER microbeads could be reused with negligible loss in adsorption capacity during five adsorption-desorption cycles, indicative of great potential in synergistic co-removal of organics-Cu complexes from aqueous solutions.

Efficient removal of Cu(II) and citrate complexes by combined permanent magnetic resin and its mechanistic insights

Owing to the enormous threat from anthropogenic contamination in water resources, the effective control of heavy-metal pollution has become increasingly important. In this study, the combination of permanent magnetic anion exchange resin (MAER) and magnetic cation exchange resin (MCER) was employed to efficient removal of Cu(II) and citrate acid (CA). The removal mechanisms were systematically investigated by batch adsorption experiments, and also certificated by species distribution calculation, kinetic tests and solid-phase characterizations. The presence of CA markedly inhibited the adsorption of Cu(II) onto MCER, while the co-existing Cu(II) was beneficial for CA uptake onto MAER. With the increase of Cu(II) concentrations, the adsorption amount of CA onto MAER gradually increased and reached a plateau, with promotion rates ranging of 24.4%–47.9%. For combined magnetic resins treatment, as the MAER dosage increased from 0 to 1.50 g/L, the removal efficiencies of CA and Cu(II) were enhanced from 1.1% and 33.2% to 98.8% and 99.1%, respectively. The anionic [Cu-CA] complexes (mainly CuL− and a small fraction of Cu2L22−) in bi-solutes system possessed higher affinity than free-CA species towards MAER, resulting in a mutual enhancement of Cu(II) and CA uptake. Both decomplexing-adsorption of Cu(II) from neutral Cu species (CuHL0) by MCER and direct complex-adsorption of anionic complex species (CuL− and Cu2L22−) by MAER were proposed as the mechanisms for synergetic removal of CA and Cu(II) in combined processes. Furthermore, nanoscale Cu powders were recovered from the desorption liquid by chemical reduction. The combined magnetic resins exhibited superior reusability over five repeated cycles, indicating their great potential in treatment of complexing heavy metal-organic acid wastewaters.

Synthesis of a magnetic polystyrene-based cation-exchange resin and its utilization for the efficient removal of cadmium (II).

A magnetic cation-exchange resin (MCER) was prepared by copolymerization of oleic acid-grafted magnetite with styrene, divinylbenzene (DVB), and triallylisocyanurate (TAIC) for removing Cd(II) from wastewater. A non-magnetic cation-exchange polystyrene resin (CEPR) was also prepared as a reference. Structural and morphological analyses revealed that the MCER and CEPR were mesoporous microspheres; the MCER contained about 25% Fe3O4. The influence of temperature, pH, contact time, and the initial concentration of Cd(II) on the adsorption of Cd(II) was investigated. The maximum adsorption capacity of the MCER reached 88.56 mg/g, which was achieved at 343 K using a Cd(II) initial concentration of 200 mg/L. The adsorption processes attained equilibrium within 120 min for the MCER and 300 min for the CEPR, and were well described by a pseudo-second-order kinetic model. Furthermore, the equilibrium adsorption data fitted the Freundlich isotherm model better than the Langmuir model. The superior magnetic response and regeneration of the MCER make it a good candidate as an adsorbent for removing Cd(II) from wastewater.

Synthesis and characterization of a novel magnetic cation exchange resin and its application for efficient removal of Cu2+ and Ni2+ from aqueous solutions

In this study, a novel magnetic cation exchange resin (MCER) was developed for highly efficient removal of heavy metal ions (HMIs). The MCER was systematically characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Batch experiments were conducted for investigating the HMIs (Cu2+ and Ni2+) removal performance by MCER under different conditions. The HMIs removal and potential ecological risk of real electroplating wastewater were also evaluated. As revealed, the self-prepared MCER was about 80–150 μm in size with uniform grain diameter. The superior magnetic characteristics of MCER made it easily agglomerated with others and sunk quickly in aqueous solution. For both Cu2+ and Ni2+ adsorption, the adsorption processes were equilibrated within 30 min and well described by pseudo-second order kinetic model and intra-particle diffusion kinetic model. Furthermore, the equilibrium adsorption data fitted the Langmuir isotherm model better than Freundlich model. Compared with MCER-1, the twice polymerized MCER-2 possessed obviously enhanced acid resistance in acidic conditions. The removal efficiencies of Cu2+ and Ni2+ onto MCER-2 increased gradually with the pH increasing from 2.0 to 4.0, and reached a plateau at pH 4.0–6.0. The MCER-2 could be efficiently regenerated by diluted HCl solution without noticeable loss of adsorption capacity after continuous adsorption/desorption cycles. For real electroplating wastewater treatment by MCER-2, the concentrations of target pollutants (Ni2+ and Cu2+) were decreased sharply and satisfied the requirements of emission standard of pollutants for electroplating, while the final wastewater was non-toxic (TUa <0.3). All these results indicated that the MCER-2 had great potential for the removal of HMIs from wastewater.

Competition and enhancement effect in coremoval of atenolol and copper by an easily regenerative magnetic cation exchange resin

This paper aimed to investigate the removal of combined Cu2+ and atenolol (ATL) in aqueous solution by using a newly synthesized magnetic cation exchange resin (MCER) as the adsorbent. The MCER exhibited efficient removal performance in sole, binary, pre-loading and saline systems. The adsorption kinetics of Cu2+ and ATL fitted both pseudo-first-order and pseudo-second order model, while better described by pseudo-second order model in binary system. In mixed Cu2+ and ATL solution, the adsorption of ATL was suppressed due to direct competition of carboxylic groups, while Cu2+ adsorption was enhanced because of the formation of surface complexes. This increasing in heterogeneity was demonstrated by adsorption isotherms, which were more suitable for Freundlich model in binary system, while better described by Langmuir model in sole system. As proved by FTIR and XPS spectra, both amino and hydroxyl groups of ATL could form complexes with Cu2+. Decomplexing-bridging interaction was elucidated as the leading mechanism in coremoval of Cu2+ and ATL, which involved [Cu-ATL] decomplexing and newly created Cu- or ATL sites for additional bridging. For saline system, the resulting competition and enhancement effects in mixed solution were amplified with the addition of co-existing cations. Moreover, the MCER could be effectively regenerated by 0.01 M HCl solution and maintain high stability over 5 adsorption-desorption cycles, which render it great potential for practical applications.

Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins

Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC–MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL−1. The LOD and LOQ ranged from 2 to 6ngmL−1 and 5 to 19ngmL−1 respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%.

PRELIMINARY STUDIES OF AN 18-CROWN-6 ETHER MODIFIED MAGNETIC CATION EXCHANGE POLYMER IN RAPID 90SR BIOASSAY

A cation exchange polymer resin embedded with magnetic nanoparticles and modified with crown ether was developed for urinalysis to rapidly monitor levels of (90)Sr exposure in humans who have been involved in a nuclear event. Invention of the resin matrix of 2-acrylamido-2-methyl-1-propanesulfonic acid cross-linked with divinylbenzene incorporated a Sr(2+) chelating agent, di-tert-butyl-cyclohexano-18-crown-6 through surface immobilization using a molecular modifier 1-octanol. The performance of these magnetic cation exchange resin particles was investigated by separating (90)Sr in the presence of (90)Y progeny. Masking agents and precipitants were examined to ascertain that sodium hydroxide at pH 7.5 was capable of selectively removing 89 ± 2% (90)Y before subsequent (90)Sr uptake. Preliminary investigations in rapid urinalysis were successful in isolating 83 ± 2% (90)Sr when pH was optimized to 9, with a sample turnover time <2 h, which is promising for radiological emergencies.

Synthesis of a Novel Magnetic Resin and the Study of Equilibrium in Cation Exchange with Amino Acids

Magnetic cation-exchange resins usually consist of small polymeric particles with a magnetic material dispersed within their structure. Because the mass-transfer kinetics through these solid particles depends on their size, very small diameter particles are desirable. Nevertheless, faster kinetics can also be obtained by using particles consisting of spherical magnetic cores covered with a thin layer of polymeric adsorbent material. In the present work, we describe the synthesis of a novel type of ion-exchange resin, in which the magnetic core was a single spherical stainless steel particle and the covering layer was poly(styrene-co-divinylbenzene). To check their ion-exchange characteristics, the equilibrium adsorption of the amino acids methionine, phenylalanine, and tryptophan on magnetic and nonmagnetic resins was investigated. The experimental results are explained in terms of a model that considers that the surface of the ion exchangers is heterogeneous, with two different types of adsorption sites ...

Preparation of magnetic ion‐exchange resins by the suspension polymerization of styrene with magnetite

AbstractMagnetic polymer microspheres composed of magnetite, styrene, and divinylbenzene were prepared by suspension polymerization to produce magnetic ion‐exchange resins (MIEXs). The magnetite was grafted with oleic acid to improve the magnetic properties of the MIEXs and to prevent the magnetite from flushing out of the MIEXs. The shape and magnetic properties of the magnetic microspheres were investigated with scanning electron microscopy and vibrating‐sample magnetometry. The average diameter of the prepared magnetic polymer microspheres was about 219 μm. The two types of MIEXs were prepared, magnetic cation‐exchange resins (MCEXs) and magnetic anion‐exchange resins (MAEXs). MCEX was prepared by sulfonation of magnetic polymer microspheres, and MAEX was made by a quaternization reaction with triethylamine of chloromethylated magnetic polymer microspheres. With diffuse‐reflectance Fourier transform infrared spectroscopy, elemental analysis, and acid–base titration, the degree of substitution and ion‐exchange capacity of the MIEXs were assessed. The efficiency of each MCEX and MAEX for the purification of contaminated water was examined with Co2+ and NO solutions, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2058–2067, 2003

Stainless steel microbeads coated with sulfonated polystyrene-co-divinylbenzene

A new kind of gel-type magnetic cation-exchange resin based on stainless steel microspheres coated with sulfonated polystyrene-co-divinylbenzene has been synthesized in a two-step process. First, magnetic polymeric beads were prepared by radical suspension polymerization, after which these particles were functionalized by a post-polymerization sulfonation process. The effects of slight modifications in the synthesis process (metal surface modification, initial contact between metal and catalyst, and the use of double polymerization) on the thickness of the polymeric layer were evaluated. Both the precursor magnetic polymeric beads and the final cation exchange resins were studied by scanning electron microscopy and X-ray energy dispersive (EDX) analysis. Finally, the cation exchange capacity of the resins was determined.

Colour and turbidity removal with reusable magnetic particles—I. Use of magnetic cation exchange resins to introduce aluminium ions

Clarification of hard, turbid surface water by Al 3+ ions introduced on a sulphonic acid ion exchanger is described. If the resin beads are sufficiently fine, they act as nuclei for floc formation and accelerate the subsequent settling of the flocs. Incorporation of magnetic iron oxide in the resin beads enables them to be conveniently separated from the clarified water. Acidification of the resin-containing sludge then results in partial reloading of the resin with Al 3+ ions. However, the regenerated resin proved ineffective as a coagulant, a result attributed chiefly to hydrolysis of Al 3+ ions within the resin. The findings of this work are significant for the theory of coagulation and also suggested the possibility of enhancing clarification by adding fine particles with an absorbing surface.