Magnetic Anion Exchange Resin Research Articles

Synthesis of a Novel Porous Self‐Settling Magnetic Anion Exchange Resin and its Removal Mechanism for Tannic Acid

AbstractA new porous self‐precipitating magnetic anion exchange resin (CMIET) doped with γ‐Fe2O3 was prepared by suspension polymerisation and characterized by FT‐IR, TGA, SEM, BET, and VSM. An adsorbent with a rough surface porous structure, enriched with a mesoporous strong magnetic self‐absorbent was obtained. A specific surface area of 19.10 m2/g, a pore volume of 0.2045 cm3/g, a pore size of 36.71 nm exchange capacity of 7.81 mmol/g, and an equilibrium adsorption capacity of up to 46.28 mg/g were measured. The effects of contact time, initial concentration, and solution pH were investigated by batch adsorption experiments. In the removal process, the removal rate of TA was up to 95 % at pH=4–7, saturation adsorption was achieved in 30 min, and regeneration time of 120 min could restore the resin activity. The adsorption isotherm of TA on the resin was by the Langmuir model, the adsorption kinetics was by the Pseudo Secondary Kinetic model, and the adsorption process was spontaneous heat absorption. The regeneration experiments showed good reusability of CMIET, a highly efficient and fast magnetic ion exchange resin with a wide range of applications in the aqueous environment.

Irreversible membrane fouling caused by free TEP: Mitigation performance and mechanism of the integrated MIEX/UF process

Free transparent exopolymer particles (TEP) are an important type of TEP. Researchers have recognized the significant contribution of free TEP to irreversible membrane fouling when treating algae-laden water. Constructing a reasonable process to effectively decelerate membrane fouling caused by free TEP is necessary for the ultrafiltration of algae-laden water. Our experiments indicate that the integrated process of magnetic anion exchange resin (MIEX)/ultrafiltration (UF) can effectively impede the irreversible membrane fouling caused by free TEP. Compared with independent UF, after multi-cycle filtration, the growth rate of hydraulically and chemically irreversible fouling decreased by 40 % and 21 %, respectively, during the MIEX/UF process. The interfacial forces between free TEP and polyvinylidene fluoride (PVDF)/MIEX were determined using atomic force microscopy, and the results showed that the interfacial force of MIEX–free TEP was 4.3-fold higher than that of PVDF–free TEP. Although the adsorption of free TEP by MIEX partly reduced membrane fouling during the MIEX/UF process, the MIEX dynamic layer contributed the most to the alleviation of irreversible membrane fouling during MIEX/UF. Our experimental results provide a more feasible process design for effectively controlling the TEP-induced irreversible membrane fouling.

Release regularity and cleaning measures of magnetic anion exchange resin during application

Anion exchange resin is responsible for removing harmful anionic contaminants in drinking water treatment, but it may become a significant source of precursors for disinfection byproducts (DBPs) by shedding material during application without proper pretreatment. Batch contact experiments were performed to investigate the dissolution of magnetic anion exchange resins and their contribution to organics and DBPs. Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) released from the resin were highly correlated with the dissolution conditions (contact time and pH), in which 0.7 mg/L DOC and 0.18 mg/L DON were distributed at exposure time of 2 h and pH 7. The formation potential of four DBPs in the shedding fraction was also revealed that trichloromethane (TCM), dichloroacetonitrile (DCAN), nitrosodimethylamine (NDMA), and dichloroacetamide (DCAcAm) concentrations could reach 21.4, 5.1, 12.1 μg/L, and 69.6 ng/L, respectively. Furthermore, the hydrophobic DOC that preferred to detach from the resin mainly originated from the residues of crosslinkers (divinylbenzene) and porogenic agents (straight-chain alkanes) detected by LC-OCD and GC-MS. Nevertheless, pre-cleaning inhibited the leaching of the resin, among which acid-base and ethanol treatments significantly lowered the concentration of leached organics, and formation potential of DBPs (TCM, DCAN, and DCAcAm) below 5 μg/L and NDMA dropped to 10 ng/L.

Performance and mechanism in degradation of typical antibiotics and antibiotic resistance genes by magnetic resin-mediated UV-Fenton process

Incomplete removal of antibiotics and antibiotic resistance genes (ARGs) has often been reported in wastewater treatment plants. More efficient treatment processes are needed to reduce their risks to the environment. Herein, we evaluated the degradation of antibiotics and ARGs by using magnetic anion exchange resin (MAER) as UV-Fenton catalyst. Sulfamethoxazole (SMZ), ofloxacin (OFX), and amoxicillin (AMX) were selected as the target compounds. The three antibiotics were almost completely degraded (> 99%) following the MAER UV-Fenton reaction for 30 min. From the degradation mechanism study, it was found that Fe3+/Fe2+ could be cyclically transferred from the catalyst at permeable interface, and the photo-generated electrons could be effectively separated. The dominant reactive radicals for antibiotics degradation were hydroxide during the MAER UV-Fenton reaction. The degradation pathway for sulfamethoxazole was proposed. In addition, wastewater samples from a wastewater treatment plant were applied to investigate the removal efficiency of antibiotics and their ARGs by the MAER UV-Fenton system. A rapid decrease in antibiotics and ARGs level was observed with this reaction system. The results from this study suggest that the MAER-mediated UV-Fenton reaction could be applied for the effective removal of antibiotics and ARGs in wastewater.

Enhanced Photo–Fenton Removal Efficiency with Core-Shell Magnetic Resin Catalyst for Textile Dyeing Wastewater Treatment

Heterogeneous photo–Fenton reactions have been regarded as important technologies for the treatment of textile dyeing wastewaters. In this work, an efficient core-shell magnetic anion exchange resin (MAER) was prepared through in situ polymerization and used to remove reactive brilliant red (X-3B) in a UV–Fenton system. The MAER exhibited satisfactory removal efficiency for X-3B because of its highly effective catalytic activity. More than 99% of the X-3B (50 mg/L) was removed within 20 min in the UV–Fenton reaction. This is because the uniformly dispersed core-shell magnetic microsphere resin could suppress the aggregation of Fe3O4 nanoparticles and, thus, enhance the exposure of Fe reaction sites for catalytic reaction with H2O2. The good adsorption capacity of MAER also played an important role in promoting contact between X-3B and reactive radicals during the reaction. Mechanism research showed that hydroxyl radical (•OH) was the main reactive radicals for the removal of X-3B in the MAER UV–Fenton system. The MAER can be easily separated by a magnet after catalytic reactions. Moreover, the matrix effects of different substrates (Cl−, NO3−, SO42−, and humic acid) were investigated. The results showed that SO42− could be beneficial to improve the removal of X-3B but that the others decrease the removal. The MAER UV–Fenton also removed significant amounts of total organic carbon (TOC) for the X-3B solution and an actual textile dyeing industrial wastewater. The heterogeneous oxidation system established in this work may suggest prospects for practical applications in the treatment of textile dyeing wastewater.

The effect of incorporating inorganic materials into quaternized polyacrylic polymer on its mechanical strength and adsorption behaviour for ibuprofen removal

Quaternized polyacrylic polymer has many applications in water treatment because of its ion exchange effects, but its further industrial applications are largely restricted because of its poor mechanical strength. In this work, a magnetic anion exchange resin with a polyacrylic matrix (MAP) was prepared by incorporation of Fe3O4 and subsequent modification with tetraethyl orthosilicate (TEOS) to improve the mechanical strength and adsorption performance. The incorporation of Fe3O4 significantly enhanced the mechanical strength of the polymer and improved the sphericity rate after ball milling of the polyacrylic resin from 80.1% to 97.2% as a result of hydrogen bonding between the -OH groups on Fe3O4 and the -NH- groups on the resin matrix. Further TEOS modification could effectively prevent Fe3O4 particles from dislodging from the resins. The adsorption performance was evaluated by using ibuprofen as a model compound. The adsorption kinetics showed that adsorption equilibrium was reached in 150 min. XPS analysis indicated that hydrogen bonding greatly contributed to the adsorption of ibuprofen onto the MAP. Adsorption isotherm analysis indicated that the adsorption was endothermic.

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.

Adsorption and regeneration characteristics of phosphorus from sludge dewatering filtrate by magnetic anion exchange resin

Removal and recovery of phosphorus (P) from sewage are essential for sustainable development of P resource. Based on the water quality determination of sludge dewatering filtrate from a wastewater treatment plant in Beijing, this study investigated the adsorption and regeneration characteristics of P by magnetic anion exchange resin (MAEX). The experiments showed that the P adsorption capacity of MAEX could reach a maximum of 2.74mg/mL when initial P concentration was 25mg/L and dosage of MAEX was 8mL/L. The P adsorption on MAEX resin was suitable for large temperature range (283-323K). However, the adsorption capacity was reduced in various degrees due to the interference of different anions (Br-, SO42-, Cl-, NO3-, HCO3-, CO32-) and organic compounds (bovine serum albumin, humic acid). Kinetics studies indicated that the P adsorption process followed the pseudo-second-order model. The MAEX resin had a rapid P adsorption rate and the P adsorption capacity at 30min could reach 97.7-99.3% of qe. Increase of temperature was favorable to P adsorption on MAEX, and the adsorption isotherm data fitted to Langmuir model more than Freundlich model. Meanwhile, the thermodynamics parameters were calculated; it was shown that the adsorption process was an endothermic reaction. Desorption and regeneration experiments showed that NaHCO3 was a suitable regenerant, and the P adsorption capacity could reach 90.51% of the original capacity after 10 times of adsorption-desorption cycles; this indicated that MAEX resin has an excellent regeneration performance and thus has a very good application prospect of P removal and recovery. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that ion exchange, charge attraction, and hydrogen bonding affected the removal of P by the MAEX resin. The vibrating sample magnetometer (VSM) analysis revealed that MAEX resin was a kind of soft magnetic materials with good magnetism.

Preparation of Permanent Magnetic Resin Crosslinking by Diallyl Itaconate and Its Adsorptive and Anti-fouling Behaviors for Humic Acid Removal

In this research, a series of permanent magnetic anion exchange resins (MAERs) were prepared by polymerizing glycidyl methacrylate monomer and crosslinking diallyl itaconate (DAI) and divinylbenzene. The properties and performances of these novel MAERs were systematically characterized and evaluated for humic acid (HA) adsorption by batch experiments. With the increase of DAI content from 0 to 15%, the moisture of MAERs was elevated from 50.23% to 68.53%, along with the adsorption capacity increasing from 2.57 to 3.14 mmol g−1. As the concentrations of co-existing cation (Ca2+ and Mg2+) increased, the adsorption amounts of HA dropped drastically at first and increased a little at high cation concentrations. Although ion exchange was the primary mechanism for HA adsorption, other physical interactions and electrostatic attraction between HA molecules and newly formed oxonium group also played significant roles for HA adsorption. The MAERs could be efficiently regenerated by a mixture of NaCl/NaOH solution (10%/1%), and notably, the MAER-3 with the highest DAI content displayed unapparent loss of adsorption capacity during twenty-one successive adsorption-desorption cycles. These results suggested a novel resin adsorbent for its excellent performances on adsorption, regeneration, and sedimentation in water treatment for natural organic matter removal.

Effect of pore structure on the removal of clofibric acid by magnetic anion exchange resin

The effect of pore structure of resin on clofibric acid (CA) adsorption behavior was investigated by using magnetic anion exchange resins (ND-1, ND-2, ND-3) with increasing pore diameter by 11.68, 15.37, 24.94 nm. Resin with larger pores showed faster adsorption rates and a higher adsorption capacity because the more opened tunnels provided by larger pores benefit the CA diffusion into the resin matrix. The ion exchange by the electrostatic interactions between Cl-type resin and CA resulted in chloride releasing to the solution, and the ratio of released chloride to CA adsorption amount decreased from 0.90 to 0.65 for ND-1, ND-2 and ND-3, indicating that non-electrostatic interactions obtain a larger proportional part of the adsorption into the pores. Co-existing inorganic anions and organic acids reduced the CA adsorption amounts by the competition effect of electrostatic interaction, whereas resins with more opened pore structures weakened the negative influence on CA adsorption because of the existence of non-electrostatic interactions. 85.2% and 65.1% adsorption amounts decrease are calculated for resin ND-1 and ND-3 by the negative influence of 1 mmol L−1 NaCl. This weaken effect of organic acid is generally depends on its hydrophobicity (Log Kow) for carboxylic acid and its ionization degree (pKb) for sulfonic acid. The resins could be reused with the slightly decreases by 1.9%, 3.2% and 5.4% after 7 cycles of regeneration, respectively for ND-1, ND-2 and ND-3, suggesting the ion exchange resin with larger pores are against its reuse by the brine solution regeneration.

Preparation of nitrate-selective porous magnetic resin and assessment of its performance in removing nitrate from groundwater

ABSTRACT Nitrate-selective, porous magnetic anion-exchange resin (NS-PMAER) with enhanced affinity and higher selectivity for nitrate was synthesized, characterized and its performance in nitrate removal was investigated. The results show that NS-PMAER consists of spherical particles with an average size of 200 μm. It has mean pore diameter, total pore volume, and BET specific surface area of 21.38 nm, 0.3605 cm3/g, and 67.455 m2/g, respectively. The specific saturation magnetization of NS-PMAER was about 10.79 emu/g. Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS) results indicate that NS-PMAER has selectivity for nitrate higher than that of MIEX® resin; its coefficients of selectivity toward nitrate for nitrate and sulfate are 20.978 and 6.769, respectively, higher than those of MIEX® resin (1.256 and 4.342, respectively). Its working exchange capacity was 72.41 mg/mL. Column-exchange experiments’ results suggest that it could be easily regenerated using 1.5 mol/L sodium chloride solution for a contact time of 30 min. Its recovery rate stayed at > 95% even after five rounds of recycling. Results of the pilot test indicate that NS-PMAER could effectively remove nitrate in groundwater, and ensure that nitrate concentrations of effluent to meet the guideline limit for drinking water by the World Health Organization.

Performance evaluation of magnetic anion exchange resin removing fluoride

AbstractBACKGROUNDFluoride above a permissible level in drinking water has serious health effects on human beings. In this study, magnetic anion exchange resin, NDMP, was used to remove fluoride under different conditions and its defluoridation performance was compared with that of commercial D201 resin.RESULTSNDMP had favourable adsorption capacity for fluoride at pH 5.0 to 9.0. Coexisting anions generated competition adsorption towards fluoride and the different competition influence ordering followed the sequence SO42− > Cl− > NO3− > HCO3−. The existence of HA did not have a negative effect on fluoride adsorption under 40 mg L−1 of HA solution. The pseudo‐first‐order kinetic model fitted better for fluoride adsorption by both resins. The adsorption process was fitted better by the Langmuir model with a maximum fluoride adsorption capacity (13.5 mg g−1), indicating that the interaction between fluoride and NDMP resin was a homogeneous process. The negative values of ΔG° and ΔH° revealed that the adsorption was a spontaneous and exothermic reaction. Regenerated NDMP recovers adsorption performance without any loss.CONCLUSIONSHigh adsorption and regeneration performance suggest that NDMP can be used as an effective and reusable defluoridation adsorbent. © 2015 Society of Chemical Industry

Evaluation of nitrate removal properties of magnetic anion-exchange resins in water

BACKGROUND High concentrations of nitrates in drinking water can lead to various types of cancers and to risks of contracting diseases. Two magnetic anion-exchange resins (MD217 and MD218) were synthesized to remove nitrate quickly from aqueous solution. RESULTS Results show that nitrate adsorption onto the resins fitted both pseudo-first-order and pseudo-second-order kinetic models. The equilibrium adsorption time for both resins was ∼10 min with the adsorption behaviour following the Freundlich adsorption isotherm model. MD218 showed high adsorption capacity and higher selectivity for nitrate in the presence of dissolved organic matter (DOM). MD217 showed higher selectivity in the presence of competing anions such as SO42− in aqueous solution. Among the DOMs examined, humic acid affected nitrate removal the most, which can be explained well by a mechanism based on electrostatic interaction. CONCLUSIONS Utilization of the resins in purification of water samples showed that both could be used for the treatment of ion-containing polluted ground and surface waters. © 2015 Society of Chemical Industry

Effect of pore structure on adsorption behavior of ibuprofen by magnetic anion exchange resins

A series of magnetic anion exchange resins (ND-1, ND-2 and ND-3) with different pore structure were prepared for ibuprofen (IBU) adsorption by using different amount of cyclohexanol as porogen in this work. For adsorption kinetics, resins with larger pore structure showed faster adsorption rates and higher equilibrium adsorption capacities because the internal diffusion process was facilitated by the increase of pore diameter and pore volume. As for adsorption isotherms, the experimental data was better fitted by Freundlich model especially for the resins with broader pores, suggesting that heterogeneous interactions took place in pores. The counter ion released by resin was measured, and ratios of equilibrium adsorption capacity to the counter ion were between 1.22 and 1.56, which confirmed that adsorption process was predominantly attributed to ion exchange while other interactions also existed. Hence, the co-existent anion reduced the adsorption amount of IBU onto resin by competing adsorption in ion exchange process, and the optimal pH ranged from 6 to 8. Resins with more open structure showed better regeneration abilities, of which the adsorption amounts witnessed no significant decrease during 7 circles of use, indicating the advantages of larger pore canal in the adsorption and regeneration behavior.

Advanced treatment of textile dyeing secondary effluent using magnetic anion exchange resin and its effect on organic fouling in subsequent RO membrane

Strict regulations are forcing dyeing factory to upgrade existing waste treatment system. In this study, advanced treatment of dyeing secondary effluent by magnetic anion exchange resin (NDMP) was investigated and compared with ultrafiltration (UF); NDMP as a pre-treatment of reverse osmosis (RO) was also studied. NDMP resin (20mL/L) gave higher removal of dissolved organic carbon (DOC) (83.9%) and colority (94.9%) than UF with a cut-off of 10kDa (only 48.6% and 44.1%, respectively), showing that NDMP treatment was effective to meet the stringent discharge limit of DOC and colority. Besides, NDMP resin (20mL/L) as a pretreatment of RO increased the permeate flux by 12.5% and reduced irreversible membrane fouling by 6.6%, but UF pretreatment did not mitigate RO membrane fouling. The results of excitation-emission matrix fluorescence spectra and resin fractions showed that NDMP had more efficient removal than UF for transphilic acid and hydrophilic fraction, such as protein-like organic matters and soluble microbial products, which contributed to a significant proportion of RO membrane fouling. In sum, NDMP resin treatment not only gave effective removal of DOC and colority of dyeing secondary effluent, but exhibited some improvement for RO membrane flux and irreversible fouling.

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

AbstractThe 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 254 nm (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...

Dissolved organic matter removal using magnetic anion exchange resin treatment on biological effluent of textile dyeing wastewater

This study investigated the removal of dissolved organic matter (DOM) from real dyeing bio-treatment effluents (DBEs) with the use of a novel magnetic anion exchange resin (NDMP). DOMs in two typical DBEs were fractionized using DAX-8/XAD-4 resin and ultrafiltration membranes. The hydrophilic fractions and the low molecular weight (MW) (<3kDa) DOM fractions constituted a major portion (>50%) of DOMs for the two effluents. The hydrophilic and low MW fractions of both effluents were the greatest contributors of specific UV254 absorbance (SUVA254), and the SUVA254 of DOM fractions decreased with hydrophobicity and MW. Two DBEs exhibited acute and chronic biotoxicities. Both acute and chronic toxicities of DOM fractions increased linearly with the increase of SUVA254 value. Kinetics of dissolved organic carbon (DOC) removal via NDMP treatment was performed by comparing it with that of particle active carbon (PAC). Results indicated that the removal of DOC from DBEs via NDMP was 60%, whereas DOC removals by PAC were lower than 15%. Acidic organics could be significantly removed with the use of NDMP. DOM with large MW in DBE could be removed significantly by using the same means. Removal efficiency of NDMP for DOM decreased with the decrease of MW. Compared with PAC, NDMP could significantly reduce the acute and chronic bio-toxicities of DBEs. NaCl/NaOH mixture regenerants, with selected concentrations of 10% NaCl (m/m)/1% NaOH (m/m), could improve desorption efficiency.

Dissolved organic matter removal by magnetic anion exchange resin and released ion elimination by electrolysis

Abstract For the advanced treatment of municipal effluents, removal of dissolved organic matter (DOM) by a magnetic anion exchange resin and the released chloride ion were both investigated. A total of 78% of dissolved organic carbon was removed at an optimized dosage of 1.0 g resin in 300 mL effluent with a contact time of 60 min. DOM characterization by excitation–emission matrix spectroscopy revealed that humic acid-like substances, fulvic acid-like substances, and a significant portion of soluble microbial products can be efficiently removed by the resin. Ion exchange of humic acid- and fulvic acid-like substances onto resin resulted in an increase of chloride, which can be efficiently decreased by electrolysis. A disinfection effect caused by electrolysis was found as a result of the free chlorine generated from electrolysis. Results suggested that the combination of anion exchange and electrolysis is a feasible advanced treatment of municipal sewage for DOM removal and disinfection.

Reusable magnetic microspheres for efficient removal of atrazine in aqueous media

Abstract In this study, a magnetic hypercrosslinked microsphere (Q150) was prepared and used for organic micropollutants (OMPs) removal. Q150 has a high surface area (1103.6 m2/g) with a narrow particle size distribution (10–30 μm). The high saturation magnetization (9.6 emu/g) of Q150 demonstrates its excellent separation ability. The adsorption behaviors of a typical OMPs, atrazine, were studied and a commercial powdered activated carbon, 1240AC, was selected as comparison. Q150 and 1240AC both displayed fast adsorption kinetics, and the adsorption followed a pseudo-second-order equation (R2 > 0.99). Q150 exhibited a slightly larger adsorption capacity (107.1 mg/g) for atrazine than 1240AC (101.8 mg/g). The most cost-effective adsorbent dose was 0.06 g/L at an initial atrazine concentration of 20 μg/L, resulting in an atrazine removal efficiency that was higher than 99.5%. Q150 could treat 600 ml more of the atrazine solution than 1240AC in a single batch before reaching a breakthrough point (3 μg/L). In the presence of dissolved organic matter (DOM), the water treatment volume of Q150 decreased by 29.2%, which is less than that observed for 1240AC (47.6%). 1240AC completely lost its adsorption capability after 3 adsorption–desorption cycles, whereas Q150 maintained approximately 50% of the initial adsorption capacity after 6 repeated uses. NDMP (magnetic anion exchange resin) pretreatment removed 45.2% of DOM, which improved the atrazine treatment capability of Q150 by 20.8% and enhanced the reusability.

Combination of MIEX® resin and ozonation for reduction of dissolved organic matter during aquifer recharge using municipal effluent

Magnetic anion exchange resin treatment (MIEX®), as well as ozonation, was applied as pretreatment for soil aquifer treatment (SAT). The removal of dissolved organic matter (DOM) derived from municipal effluent was characterized during these treatments. The DOM removal ratio increased with the increasing of MIEX® resin dosage (5–20 mL/L), and a dosage of 5–10 mL/L was suggested for the SAT pretreatment. Under this dosage, 30 % DOC was removed from secondary effluent, which was much lower than those found with drinking water resources. The aromatic DOM with apparent molecular weight (AMW) ranging 2–5 kDa was preferentially removed by MIEX®, especially for aromatic proteins. Differently, ozonation preferentially destroyed larger AMW (>10 kDa) DOM, especially for fulvic and humic acid-like materials. Better purifucation was achieved by combining the two technologies. With pretreatments (MIEX®, ozonation, and combined MIEX®/ozonation), the DOM removals by SAT were significantly improved. The DOC and UV254 values were reduced by 40–77 % in SAT combined with pretreatments, compared with 20–30 % reduction by only SAT. Around 50% of the fluorescent DOM was reduced in SAT and MIEX/SAT systems, while higher reductions (76-84%) were achieved in ozonation/SAT and MIEX/Ozonation/SAT systems. Different modes were identified: ozonation improved SAT on removing DOM of 1.7–5.3 kDa, whereas MIEX® treatment attributed to the removal of small AMW (0.5–1.7 kDa) DOM responsible for the absorbance peak at 300 nm. Based on the results, DOM removed by MIEX® treatment is complementary with those removed by SAT and ozonation, and the best DOM purification was found in combined MIEX®/ozonation/SAT.