A rapid and effective method based on a novel permanent magnetic hypercrosslinked resin W150 was proposed for the removal of organic micropollutants in drinking water. W150 was prepared by suspension and post-crosslinking reaction and found to possess a high specific surface area of 1149.7 m2·g−1, a small particle size of 50 μm to 100 μm, and a saturation magnetization as high as 8 emu·g−1. W150 was used to eliminate nitrofurazone (NFZ) and oxytetracycline (OTC) from drinking water compared with commercial adsorbents XAD-4 and F400D. The adsorption kinetics of NFZ and OTC onto the three adsorbents well fitted the pseudo-second-order equation (r>0.972), and the adsorption isotherms were all well described by the Freundlich equation (r>0.851). Results showed that the reduction in adsorbent size and the enlargement in sorbent pores both accelerated adsorption. Moreover, the effect of particle size on adsorption was more significant than that of pore width. Given that the smallest particle size and the highest specific surface area were possessed by W150, it had the fastest adsorption kinetics and largest adsorption capacity for NFZ (180 mg·g−1) and OTC (200 mg·g−1). For the adsorbents with dominant micropores, the sorption of large-sized adsorbates decreased because of the inaccessible micropores. The solution pH and ionic strength also influenced adsorption.

A novel magnetic weak acid resin (MWA06) was successfully synthesized and characterized. To enhance the acid resistance and lipophilicity of the γ-Fe2O3 particles, a titanate coupling agent (TCA) was employed to modify the particle surface. Afterward, the resultant resin was obtained through copolymerization and hydrolysis reactions, with a specific saturation magnetization of 10.9 emu/g and weak acid cation exchange capacity of 8.44 mmol/g. Leaching tests in acid showed that the magnetic resin was stable at pH 2. The presence of Ca2+ in the solution had an obviously negative impact on the adsorption of Ni2+, whereas Na+ did not influence the adsorption process. The adsorption of Ni2+ was pH-dependent as the uptake capacity increased from 0.06 to 2.81 mmol/g with the pH rising from 2 to 6. The desorption efficiency was nearly 100% by using 0.01 M HCl solution as desorption agent. Moreover, MWA06 could maintain high adsorption capacities for at least 10 regeneration cycles, indicative of a good reusability.

•Larger average pore sizes lead to faster adsorption dynamics.•The surface area and pore volume of the resins have positive effects on adsorption.•The fouling caused by humic acid to the resins is weak.•Tannic acid could seriously foul resins by site competition and pore blockage.•Q100-3 was proved to be anti-fouling by its unobstructed internal pore structure.Pore structures are very important factors that influence the adsorption and fouling-resistance properties of adsorbents. This study prepared three magnetic porous resins using different amounts of porogen. The pore volume, average pore size, and specific surface area of the resin improved with increased usage of the solvating porogen toluene. Q100-3, which was obtained at a porogen ratio of 3:1, showed the largest surface area (1322 m2/g) and pore volume (2.8 cm3/g). The increase in average pore diameter improved the adsorption equilibrium of the resins, and the increase in total pore volume and specific surface area enhanced the number of adsorption sites of the adsorbents. Q100-3 showed a larger adsorption capacity for tetracycline (TC) than Q100-1 and Q100-2. Two model compounds of natural organic matter, humic acid (HA) and tannic acid (TA), were chosen to evaluate the fouling-resistance of the resins during TC removal. The resins adsorbed very low amounts of HA (3–13 mg/g); thus, competition between HA and TC was weak. HA molecules, because of their large size, were prevented from transportation into the pores by size exclusion effects, leading to negligible pore blocking. By contrast, because of its small molecular size, TA could be well adsorbed by all three resins. The competitive adsorption experiment demonstrated that the presence of TA had a very important effect on both Q100-1 and Q100-2 in terms of TC adsorption. In particular, the amount of TC adsorbed onto Q100-1 with 200 mg/L TA dropped to only 7.88% of the adsorbed amount of TC on Q100-1 without TA because of serious pore blockage. Adsorbed TA could not cause pore blockage in the magnetic resin Q100-3, which featured an unobstructed internal pore structure. Thus, the decrease in adsorbed amount of TC was controlled to within 3% in this resin.

•A novel magnetic resin NAND-1 was prepared by membrane emulsification.•NAND-1 had a uniform particle size and a high surface area.•NAND-1 exhibited good extraction efficiency toward 8 organic micropollutants.•The magnetic solid-phase extraction (MSPE) method by NAND-1 was efficient and rapid.•The MSPE method could increase enrichment factor and improve detection limit.A magnetic solid-phase extraction (MSPE) method based on a novel magnetic sorbent was proposed for the extraction of target compounds from large-volume water samples. First, magnetic hypercrosslinked microspheres (NAND-1) were prepared via membrane emulsification–suspension polymerization and post crosslinking reaction. To ensure that the Fe3O4 nanoparticles could completely pass through the membrane without blocking the pores, oleic acid was used to modify the Fe3O4 nanoparticles, which enhanced lipophilicity and monodispersity of the magnetite nanoparticles. The obtained NAND-1 microspheres exhibited super paramagnetic characteristics and excellent magnetic responsiveness with a saturation magnetization of 2.53 emu/g. In addition, a uniform particle size (∼8 μm) and a large average surface area (1303.59 m2/g) were also observed, which were both beneficial for the extraction of the target compounds. Thus, NAND-1 has the potential to simultaneously exhibit good extraction efficiencies toward different types of organic micropollutants (OMPs), including triazines, carbamazepine and diethyl phthalate. The conditions of the MSPE based on NAND-1 were optimized by single factor and orthogonal design experiments. This MSPE method needed only a small amount of sorbent (50 mg/L) for the extraction of OMPs from a large-volume aquatic sample (5 L) and reached equilibrium in a short amount of time (30 min). Moreover, the solution volume, the pH, and the salinity had insignificant influences on the extraction of the eight target OMPs. Under the optimum conditions, the recoveries of the eight OMPs calculated by analyzing the spiked samples were from 91.7% to 99.4%. The NAND-1 could be recycled ten times and still achieve recoveries of the eight OMPs higher than 86%. The limits of detection of the eight OMPs ranged from 1.76 to 27.56 ng/L, and the limits of quantification were from 5.71 to 92.05 ng/L. These results indicated that the proposed method, based on the use of NAND-1 as a magnetic sorbent, has the advantages of convenience and high efficiency and can be successfully applied to analyze the OMPs in real water samples.

A novel, bifunctional, hypercrosslinked, magnetic resin W2 was prepared using divinylbenzene (DVB) and glycidyl methacrylate (GMA) as comonomers in three steps (i.e., suspension polymerization, amination and post-crosslinking reactions). To evaluate the adsorption of natural organic matter (NOM) and organic micropollutants (OMPs) on the obtained resin W2, two magnetic resins W1 (the precursor of W2 before post-crosslinking) and W0 (the precursor of W1 before amination) were chosen for comparison. The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.A novel, bifunctional, hypercrosslinked, magnetic resin W2 that possessed high specific surface area (325 m2/g) and functional groups was prepared in this work for the first time. The resin can be used for effective removal of both natural organic matter (NOM) and organic micropollutants (OMPs).

•UPLC/ESI-tqMS parameters were optimized for better detection of the 13 new DBPs.•Disinfectant, contact time, and pH all affected the formation of the 13 new DBPs.•Gallic acid was confirmed to be the precursor of the 13 new DBPs.•Formation pathways of the 13 new DBPs from gallic acid were elucidated.•Occurrence of the 13 new DBPs in 16 Chinese tap water samples was investigated.Recently, 13 new polar phenolic chlorinated and brominated disinfection byproducts (Cl- and Br-DBPs) were identified and quantified in simulated chlorinated drinking water by adopting product ion scan, precursor ion scan, and multiple reaction monitoring (MRM) analyses using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry (UPLC/ESI-tqMS). The 13 new DBPs have been drawing increasing concern not only because they possess significantly higher growth inhibition, developmental toxicity, and chronic cytotoxicity than commonly known aliphatic DBPs, but also because they act as intermediate DBPs that can decompose to form the U.S. EPA regulated DBPs. In this study, through MS parameter optimization of the UPLC/ESI-tqMS MRM analysis, the instrument detection and quantitation limits of the 13 new DBPs were substantially lowered to 0.42–6.44 and 1.35–16.51 μg/L, respectively. The total levels of the 13 new DBPs formed in chlorination were much higher than those formed in chloramination within a contact time of 3 d. In chlorination, the 13 new DBPs formed quickly and decomposed rapidly, and their total concentration kept on decreasing with contact time. In chloramination, the levels of the dominant species (i.e., trihalo-phenols) firstly increased and then decreased with contact time, whereas the levels of the other new DBPs were relatively low and kept on increasing with contact time. An increasing of pH from 6.0 to 9.0 decreased the formation of the 13 new DBPs by 57.8% and 62.3% in chlorination and chloramination, respectively. Gallic acid was found to be present in various simulated and real source water samples and was demonstrated to be a precursor of the 13 new DBPs with elucidated formation pathways. Furthermore, 12 of the 13 new DBPs were detected in 16 tap water samples obtained from major cities in East China, at total levels from 9.5 to 329.8 ng/L. The concentrations of the new DBPs were higher in samples with source waters containing higher bromide levels. Ozone-activated carbon treatment prior to disinfection might reduce the formation of the new DBPs since it was effective in precursor reduction.Download high-res image (344KB)Download full-size image