MIEX Resin Research Articles

Synthesis and characterization of a novel magnetic resin (m-MAR resin) and its removal performance for alkaline amino acids

Alkaline amino acids as dissolved organic nitrogen (DON) have raised much concern in drinking water treatment due to poor removal in conventional treatment process and high potential for nitrogenous disinfection by-products (N-DBPs). This work was intended to devise a new magnetic adsorption resin (noted as m-MAR resin) for the efficient reduction of alkaline amino acids and explore the application potential of combined MIEX and m-MAR resins. The distribution and composition of DON and amino acids was clarified for different water sources in Lake Taihu basin, in which alkaline amino acids accounted for a higher proportion. The removal of different nitrogenous organics by MIEX resin was also examined, where the resin was effective in removing phycocyanin (65.6%) and glutamic acid (74.2%), reducing the generation of disinfection by-products (DBPs). The m-MAR resin was manufactured and characterized to cope with alkaline amino acids, and batch experiments were undertaken to investigate its adsorption behaviors on histidine and arginine under different operating conditions. The maximal adsorption capacities of arginine and histidine onto m-MAR resin were 2.84 mg/g and 1.62 mg/g, respectively, which was better than MIEX resin. The removal mechanism of the two basic amino acids by m-MAR resin was mainly due to the hydrogen bonding and the acid-base reaction. Moreover, the reusability of the m-MAR resin was elucidated after six successive adsorption-desorption cycles. Finally, the effectiveness of combined MIEX and m-MAR resin in treating DON derived from Microcystis aeruginosa reached 35.2% and the DON concentration in Lake Taihu could be reduced from 0.56 to 0.16 mg/L, which simultaneously decreased the generation potential of N-DBPs. The enhancement of coagulation by the combined process of m-MIER and m-MAR as pretreatment was estimated.

Response surface methodology directed adsorption of chlorate and chlorite onto MIEX resin and study of chemical properties

For the first time, response surface methodology has been used to optimize the adsorption process of chlorite and chlorate by MIEX.

Fluorescence spectroscopy for assessing trihalomethane precursors removal by MIEX resin.

This study investigated the applicability of fluorescence excitation-emission matrix spectroscopy (EEMS) to assess total trihalomethane formation potentials (TTHMFPs) and the ability of magnetic ion exchange (MIEX®) resin to reduce TTHMFP. We treated a surface water and secondary wastewater effluent with MIEX mimicking full-scale operation by repeatedly exposing the same resin batch to additional feed water, with batches ranging from 500 to 5,000 resin bed volumes. Results showed that MIEX was more effective at removing or reducing ultraviolet absorbance (UVA254), dissolved organic carbon (DOC), and TTHMFP in surface water than in secondary effluent. The greater UVA254, DOC and TTHMFP removal for surface waters was explained by the stronger affinity of MIEX for terrestrial dissolved organic matter (DOM) compared to microbial DOM. Fluorescence EEMS results showed that the ratio between terrestrial and microbial fluorescent signals of DOM was significantly greater in surface water than in secondary effluent. Fluorescence surrogate parameters were strongly correlated with TTHMFP, namely, fluorescence intensity of humic-like peak C (R2 = 0.98, p < 0.01), protein-like peak T (R2 = 0.96, p < 0.01), and fulvic-like peak A (R2 = 0.87, p < 0.01). Correlations between fluorescence surrogate parameters and TTHMFP were substantially stronger than correlations between DOC and TTHMFP. Overall, the results indicate that fluorescent parameters extracted from EEMS data can be used as quick surrogate parameters to monitor TTHMFP for a diverse group of raw and MIEX-treated waters.

Effects of humic acids with different molecular weights on the adsorption behavior of bromide on MIEX resin

Effects of humic acids with different molecular weights on the adsorption behavior of bromide on MIEX resin

Parameters Optimizing of Removal of Hexavalent Chromium from the Emergently Polluted Raw Water Using MIEX Resin

Parameters Optimizing of Removal of Hexavalent Chromium from the Emergently Polluted Raw Water Using MIEX Resin

Removal Characteristics of Tanic Acid Adsorbed on MIEX Resin

Removal Characteristics of Tanic Acid Adsorbed on MIEX Resin

Removal of chlorite from aqueous solution by MIEX resin

Removal of chlorite from aqueous solution by MIEX resin

Removal of dissolved organic carbon and bromide by a hybrid MIEX-ultrafiltration system: Insight into the behaviour of organic fractions

Dissolved organic carbon (DOC) and bromide (Br−) are principal precursors in the formation of halogenated disinfection by-products resulting from chlorination of drinking water. Their effective removal from water represents, thus, one of the main challenges faced by drinking water treatment plants worldwide. The objective of this study was to evaluate the performance of a pilot-scale hybrid system based on the patented magnetic ion-exchange resin (MIEX) combined with ultrafiltration (UF) in the removal of DOC and Br− from water. Two different doses of MIEX (1mL/L and 3mL/L) were applied and compared. Samples of feed water, UF permeate and tank solution were regularly collected to assess the system performance in terms of removal of DOC and Br−. DOC was characterised by high-performance size-exclusion chromatography (HPSEC) and 3D-fluorescence excitation-emission matrix (FEEM) to identify which organic fractions were preferentially removed by the MIEX/UF process. Results demonstrated that the hybrid MIEX/UF system was able to remove DOC and Br− from water. The evolution and extent of these removals depended on the MIEX dose applied, with percentage removals clearly increasing when the MIEX dose was increased from 1mL/L to 3mL/L. MIEX exhibited higher affinity toward DOC than toward Br−. Saturation of MIEX toward Br− was achieved short after the start of the experiment, while removal of DOC persisted until the end of the experiment. Fractionation of DOC by HPSEC indicated that the highest molecular weight fraction was mainly removed by size-exclusion by the UF membrane, while lower molecular weight fractions seemed to be better removed by ion-exchange on the MIEX resin. FEEM analysis revealed a poor affinity of MIEX toward microbial by-products, whereas fulvic and humic acid-like material were the most retained by MIEX.

Adsorption and removal of clofibric acid and diclofenac from water with MIEX resin

This study demonstrates the use of MIEX resin as an efficient adsorbent for the removal of clofibric acid (CA) and diclofenac (DCF). The adsorption performance of CA and DCF are investigated by a batch mode in single-component or bi-component adsorption system. Various factors influencing the adsorption of CA and DCF, including initial concentration, contact time, adsorbent dosage, initial solution pH, agitation speed, natural organic matter and coexistent anions are studied. The Langmuir model can well describe CA adsorption in single-component system, while the Freundlich model gives better fitting in bi-component system. The DCF adsorption can be well fitted by the Freundlich model in both systems. Thermodynamic analyses show that the adsorption of CA and DCF is an endothermic (ΔHo > 0), entropy driven (ΔSo > 0) process and more randomness exists in the DCF adsorption process. The values of Gibbs free energy (ΔGo < 0) indicate the adsorption of DCF is spontaneous but nonspontaneous (ΔGo > 0) for CA adsorption. The kinetic data suggest the adsorption of CA and DCF follow the pseudo-first-order model in both systems and the intra-particle is not the unique rate-limiting step. The adsorption process is controlled simultaneously by external mass transfer and surface diffusion according to the surface diffusion modified Biot number (Bis) ranging from 1.06 to 26.15. Moreover, the possible removal mechanism for CA and DCF is respectively proposed based on the ion exchange stoichiometry.

A preliminary batch study of sorption kinetics of Cr(VI) ions from aqueous solutions by a magnetic ion exchange (MIEX®) resin and determination of film/pore diffusivity

A magnetic ion exchange resin was tested for the removal of Cr(VI) ions from aqueous solutions in a batch reactor at different resin dosages (0.5–1.5gL−1), pH values (2−10), temperatures (25°C–55°C) and initial concentrations of Cr(VI) (0.11–2.12mmolL−1 or 5.7–110mgL−1). The experimental data were evaluated using kinetic models based on the rate controlling steps relevant to pseudo-first order or pseudo-second order reactions or diffusion through fluid film or pores of the MIEX resin beads. Fast uptake of Cr(VI) ions by MIEX resin facilitates the attainment of equilibrium within 60min. The sorption process is strongly dependent on the initial pH of the solution with maximum occurring at pH4–6. The sorption of Cr(VI) at equilibrium increases with the increase in initial concentration according to the Langmuir isotherm, with a maximum sorption capacity of 93mgg−1 on MIEX resin. Relatively low activation energy of 43kJmol−1 at a high initial concentration of 1mmolL−1 Cr(VI) suggests a mixed chemical-diffusion controlled process, supported by the agreement of the sorption results with the homogeneous particle diffusion model with a film diffusivity of Df=1×10−9m2s−1 and a pore diffusivity of Dp=8×10−13m2s−1.

Control of disinfection by-product derived from humic acid using MIEX process: optimization through response surface methodology

Response surface methodology (RSM) was used to optimize humic acid (HA) removal by MIEX resin for controlling the disinfection by-product (DBP) formation.

Enhanced DOC removal using anion and cation ion exchange resins

Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes.

Equilibrium, Thermodynamic, and Kinetic Studies of the Adsorption of 2,4-Dichlorophenoxyacetic Acid from Aqueous Solution by MIEX Resin

The study investigated the performance of 2,4-D adsorption on MIEX resin. The different temperatures affecting the adsorption performance were specifically evaluated. Equilibrium data followed the Freundlich and Langmuir isotherm model for all investigated temperatures (283 K to 333 K). The Langmuir model was slightly better than the Freundlich model at a lower temperature (283 K); however, with the increase of temperature the Freundlich model could well describe the isotherm data. The solute coefficient of distribution (Kd) could be better used to estimate the thermodynamic parameters compared with the Langmuir equilibrium constant (KL). The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) showed that the adsorption of 2,4-D was feasible, endothermic, and spontaneous at 283 K to 313 K. The activation energy (Ea, 47.70 kJ·mol–1) determined by using the rate constant k2 of pseudo-second order model (the suitable kinetic model) and the mean free energy value (Efe, 6.0348 kJ·mol–1) evaluated by using the Dubinin–Radushkevich (D–R) model indicated that chemical ion-exchange was the predominant mechanism of 2,4-D adsorption. The calculated film diffusion coefficient value (Df) suggested film diffusion was the kinetic rate-limiting step. The adsorbent displayed excellent reusability with 0.1 mol·kg–1 NaCl as the regeneration agent.

Adsorption of perchlorate from aqueous solutions by anion exchange resins: Effects of resin properties and solution chemistry

In this study, the perchlorate sorption behaviors of three various representative anion resins were systematically investigated with respect to sorption kinetics, equilibrium capacity, perchlorate selectivity, thermodynamics and isotherms. Results showed that the equilibrium capacity of the three investigated resins followed the order of Purolite A530E≈magnetic ion exchange resin > Purolite A532E due to the effect of structure type, while magnetic ion exchange resin (MIEX) reached the equilibrium much faster than Purolite A530E and Purolite A532E, which can be attributed to its smaller particle size and larger surface area. Furthermore, the two Purolite resins showed superior perchlorate selectivity than MIEX resin because of matrix and functional groups. The adsorption kinetics for each of three selected resins fitted best with the pseudo-second-order model, indicating the adsorption process was controlled by chemical sorption. While the fitting of intra-particle model implied that intra-particle diffusion was not the only rate-limiting step of the whole process. The isotherm data can be best described by the Freundlich isotherm and the value of intensity of adsorption was larger than 1, suggesting the process was heterogenous and favorable adsorption. The negative ΔG° manifested that the adsorption of perchlorate by each of the three resins was a spontaneous process, and the positive indicated it was also an endothermic and entropy driven process. Besides, the effects of independent variables on the perchlorate sorption of the three resins were also evaluated completely. Results suggested that the removal of perchlorate increased with the increase of resin dosage and temperature for each of the three resins, and the sorption process was nearly independent of solution pH in a wide range of 4–10 for each of the resins.

Study on the removal of dissolved organic matters in the raw water by a new magnetic anion-exchange resin

The removal of dissolved organic matters (DOM) in the raw water of Tongyu River using a new magnetic anion-exchange resin (NDMP) was investigated. NDMP was more effective than a commercial magnetic ion-exchange resin (MIEX) for the purification of drinking water. NDMP can eliminate 49% of dissolved organic carbon (DOC) and 86% of UV absorbance at 254nm (UV254) in the raw water within 30 min. During multiple-loading jar tests, DOC of the effluent was 2.1 mg/L at 100 BV and increased to 3.0 mg/L after the loading of 1,200 BV by NDMP treatment. The saturated resin was renewed after regeneration with sodium chloride. NDMP displayed high removal ability for both hydrophobic acid (HPO) and transphilic acid (TPI) compared to MIEX resin, whereas the removal rate of hydrophilic (HPI) was relatively low. The removal rates of HPO, TPI, and HPI in the raw water at the NDMP amount of 10 mL/L were 62, 65, and 24%, respectively. Therefore, the NDMP resin can be used in the purification of drinking water at high DOC level.

Sorption of tetrabromobisphenol A from solution onto MIEX resin: Batch and column test

The sorption characteristics of tetrabromobisphenol A (TBBPA) onto MIEX resin were investigated using batch and column experiment. Effects of contact time, initial concentration, pH, temperature, coexisting anions and natural organic matter were determined. The kinetics data indicated that TBBPA sorption process reached equilibrium within 6h. TBBPA removal was high at the pH<8.0, and the removal sharply decreased with increasing the initial pH from 8.0 to 12.0. Major anions reduced TBBPA sorption in the order of HPO42−>SO42−>HCO3−>NO3−. The results were shown that the sorption equilibrium could be well fitted by Langmuir isotherm and the maximun sorption capacity was caculated as 49.19mg/g. The results demonstrated the sorption kinetics agreed with the pseudo second-order model, indicating that the sorption of TBBPA onto MIEX was chemical sorption. The negative ΔG0, ΔH0and ΔS0 values indicated that TBBPA sorption was a thermodynamically spontaneous and an exothermic process. The results of column test shown that the dynamic sorption capacity, 33.19mg/g, was less than the aforementioned sorption capacity. The simulation of the breakthrough curve was successful with Yoon–Nelson model and Thomas model. The present studies shown that MIEX had a good potential to be used as sorbent for TBBPA removal from water.

A Critical Analysis of MIEX Application in Water Treatment

A novel magnetic ion exchange resin called MIEX Resin is being utilized in potable water treatment, which indicates significant advantages. The objective of this article is to analyze characteristics and application of MIEX Resin in engineering projects, and hence provide critical review on merits and demerits of the resin. Furthermore, researches on combination of MIEX Resin with other water treatment technologies would be analyzed and discussed to prove potential that a MIEX Resin process integrated with other treatments can be employed in broader fields of wastewater treatment and reuse.

Adsorptive characteristics of perchlorate from aqueous solutions by MIEX resin

The adsorption characteristics of perchlorate on MIEX resin were investigated using batch experiments. Effects of contact time, agitation speed, pH, coexisting anions and organic matter were determined. The kinetics data indicated that the perchlorate adsorption process reached equilibrium within 30min. In an experimental pH of 4.0 to 9.0, perchlorate removal was above 98%. Major anions reduced perchlorate adsorption in the order of SO42− >PO43−>CO32−>NO3−. However, humic acid had not obvious effect on perchlorate removal. Langmuir, Freundlich, and Temkin isotherms were used to fit the perchlorate adsorption equilibrium at 298K. The results were shown that the adsorption equilibrium could be well fitted by Freundlich isotherm. The pseudo first-order and second-order kinetics models were used to fit the kinetics process of perchlorate adsorption on MIEX resin. The results demonstrated the adsorption kinetics agreed with the pseudo second-order model, indicating that the adsorption of perchlorate on MIEX was chemical sorption. The negative ΔG0 values indicated that the adsorption of perchlorate on MIEX resin was thermodynamically feasible and was a spontaneous process. The values of ΔH0and ΔS0 showed that the adsorption was an exothermic process in nature and the randomness degree at the solid/liquid interface increases after adsorption.

Adsorptive Removal of 2,4-Dichlorophenoxyacetic Acid (2,4-D) from Aqueous Solutions Using MIEX Resin

Batch experiments are carried out to evaluate the adsorption performances of 2,4-D from aqueous solutions by MIEX resin. The initial 2,4-D concentration, adsorption time, adsorbent dosage, inorganic ions, natural organic matter, and initial pH of solution have considerable effect on the removal of 2,4-D, but temperature has less effect. The isotherm experiments show the Redlich–Peterson and Sips models are the most appropriate models to simulate the equilibrium data at 293 K. The kinetic study demonstrates the pseudo-second-order model gives a best fitting to the adsorption of 2,4-D on the resin and the intraparticle diffusion is not the only rate-controlling step. The thermodynamic parameters are calculated. The results show that the adsorption of 2,4-D on the resin is a thermodynamically spontaneous and endothermic process. Accordingly, it can be concluded that MIEX resin can potentially be employed as an adsorbent for removing 2,4-D from raw water.

Adsorptive characteristics of phosphate from aqueous solutions by MIEX resin

This study investigated the potential of MIEX resin as the adsorbent for the removal of phosphate from aqueous solutions. In our batch experiments, we studied the effect of some parameters on the removal of phosphate. It was observed that uptake of phosphate was mainly affected by initial phosphate concentration, adsorbent dosage, initial pH of solution, and coexistent anions. The adsorption equilibrium data at 288K fitted well to Freundlich and Koble–Corrigan isotherm models. The kinetics studies displayed that the adsorption process followed the pseudo-second-order model. The diffusion studies showed that the intra-particle diffusion was not the only rate-controlling step and, the diffusion process of phosphate from solution to MIEX resin was controlled by film diffusion. The thermodynamics parameters were evaluated. The results showed that the adsorption process was spontaneous thermodynamically, endothermic, and entropy driven. These results have established a good potentiality for MIEX resin to be used as an adsorbent for the removal of phosphate from aqueous solutions. This work will deepen our understanding of the adsorptive characteristics of phosphate by MIEX resin and provide a better way to remove phosphate from wastewater.