Search

A thin-film composite ultrafiltration (UF) membrane grafted with amine-functionalized MCM-41 was prepared and used for removing heavy metals from aqueous solution. The porous NH 2 -MCM-41 nano-particles formed a uniform hydrophilic and adsorptive layer on the thin-film which endowed the composite membrane with affinity to heavy metals and better anti-fouling performance. The adsorption capacity of Cr (VI) and Cu (II) on membrane were 2.8 mg Cr/g and 3.7 mg Cu/g, respectively, and their adsorption processes reached equilibrium around 5 min. The continuous UF experiments demonstrated that the membrane can be used as an effective filter medium to purify the water containing trace heavy metals. The metals concentration in filtrates was maintained below initial concentration of 1 mg/L (Cu) and 0.5 mg/L (Cr) during the 7-hour filtration. The membrane’s adsorption capacity could be regenerated by being immersed in 0.5 M HNO 3 . Besides, to examine its anti-fouling performance, the model NOM (natural organic matter) water was used as a feed solution. The composite membrane showed not only slower irreversible fouling evolution but also higher rejection of NOM compared with that without grafting NH 2 -MCM-41. The method reported in this study was efficient to enhance the rejection and anti-fouling performance of UF membrane, what’s more, endowed the membrane with affinity to heavy metals.

Nanoscale zero-valent iron (nZVI) technology is promising for treating the oxidizing pollutants. Understanding the potential risk of nZVI in solution is important for in situ remediation. In this work, the impacts of nZVI on the chemical properties of solution and microorganism were investigated to assess the risk of environmental exposure of nZVI. The effects of salinity (NaCl), pH and humic acid on the chemical stability of nZVI were studied, the concentrations of released toxic ions within 36 days were examined, and the toxicity of solution was evaluated based on the luminous bacteria-based toxicity test. The results indicated that nZVI was chemically stable as the total chromium concentration was below 0.05 mg/L all along and the maximum concentration of released total iron ion was 0.22 mg/L. The results of the toxicity test showed that the reaction products were non-toxic to microorganism even if they existed in solution for a long-term time.

In this study, the Fe 3 O 4 magnetic nanoparticles (MNPs) were synthesized as heterogeneous catalysts to effectively degrade bisphenol A (BPA). The properties of the synthesized catalysts were characterized by Brunnaer–Emmett–Teller (BET), X-ray powder diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The results indicated that the Fe 3 O 4 MNPs appeared to be roughly spherical shapes and their average size was 10–20 nm. The catalytic capacity of MNPs in US + Fe 3 O 4 + H 2 O 2 system with different pH conditions, H 2 O 2 concentrations and MNPs doses was investigated. It was found that the OH radicals were promptly generated due to the catalysis of the Fe 3 O 4 MNPs. BPA could be degraded within a wide pH range from 3 to 9, and the degradation efficiencies were remarkably enhanced by ultrasound. The apparent rate constants were 8.31 × 10 −3 , 7.96 × 10 −3 and 5.64 × 10 −3 min −1 , respectively, when the pH values were 3, 7 and 9, respectively. The removal efficiencies of BPA were all over 95%. About half total organic carbon (TOC) in solution was eliminated under neutral condition by sono-Fenton process. Furthermore, the results of stability and reusability demonstrated that the Fe 3 O 4 MNPS were promising in the treatment of wastewater with refractory organics.

The remediation effectiveness and negative effect on ecotoxicity are needed to be considered in a suitable emergency remedial action for polluted river. In this work, the stabilized nanoscale zero-valent iron (nZVI) was applied in the remediation of a simulated Cr(VI)-polluted river, and a mathematical model was developed based on a reaction network to describe the process. The results showed that the remediation effectiveness was improved with the increasing nZVI dose, decreasing initial concentration of pollution source and water flow rate. Water analysis was conducted to investigate the effects of the nZVI to the process. Toxicity evaluation indicated that almost no toxicity was detected in 36 days’ exposure of reaction products in the water. Model parameters including mass-loss coefficient (K1) and reaction coefficient (K2) were obtained in laboratorial experiment, and a statistical comparison method was employed to assess the simulated results. Thus, the obtained mathematical modeling and physical modeling could be exploratory researches for practical remediation of polluted river.