Magnetic hollow Fe 3 O 4 -based Mg/Al layered double hydroxide (Fe 3 O 4 @SiO 2 @LDH) was successfully synthesized and subsequently the laboratory scale tests were conducted to systematically investigate the sequestration of roxarsone (ROX) and arsenate (As(V)). Owing to its abundant surface metal hydroxyl (M-OH) groups and exchangeable CO 3 2− groups in the interlayer of MgAl-LDH nanosheets , the obtained Fe 3 O 4 @SiO 2 @LDH exhibited remarkable behavior for As(V) and ROX removal. Both As(V) and ROX could be effectively immobilized at a relatively wide pH range (3–8), and the maximum adsorption capacities of As(V) and ROX were 96.47 and 71.67 mg/g, respectively. Meanwhile, the negligible mutual effect demonstrated the Fe 3 O 4 @SiO 2 @LDH can simultaneously remove inorganic and organic arsenic compounds . The competitive cations/anions (except for PO 4 3− ions) and ionic strength were negligible on As(V) and ROX removal, whereas the inhibitory effect stem from humic acid (HA) seemed to be more seriously for As(V) than that of ROX. Adsorption mechanism of As(V)/ROX were attributed to electrostatic attraction and ion/ligand exchange process, whereas hydrogen bonding and π-π interaction may also involve in the ROX removal. Furthermore, the excellent performance in fix-bed column tests and prominent reusability indicated this magnetic Fe 3 O 4 @SiO 2 @LDH was a promising candidate adsorbent and of great potential application in organic/inorganic As-contamination wastewater treatment .
To realize potential efficient and scalable application of pyrite-based oxidation system for roxarsone (ROX) degradation in livestock wastewater, sulfur vacancies (SVs) was introduced in pyrite through a facile one-step mechanical ball-milling treatment. Comprehensive characterization demonstrated that the introduction of SVs reduced particle aggregation, enriched low-valence Fe and S species, and enhanced electron transfer capability. SVs preferred to be the adsorption sites and Fe as the electron donation sites during O 2 activation process. The specific contribution rate of different O 2 sources for ROX degradation was calculated via well-designed control experiments and the increased dissolved oxygen (DO) in water was proved to enhance the contribution of •OH, cooperating with 1 O 2 and beneficial for complete ROX mineralization. 97.13% of total arsenic derived from ROX can be effectively immobilized and surface coprecipitation played the major role. Speciation analysis revealed that ROX underwent initial oxidative degradation to inorganic arsenic, followed by rapid adsorption on the pyrite surface. FeS 2 -600 showed the high adaptability to complex environment and made effluent As of real livestock wastewater stably below the emission standard of China. This work further provides a universal strategy for potential scalable application of pyrite in water purification with zero-oxidant.
To enhance the special selectivity and recognizability of two kinds of typical phenylarsonic compounds ( p -arsanilic acid ( p -ASA) and roxarsone (ROX)) in complicated water bodies, novel double-template molecularly imprinted polymers (DMIPs) were successfully synthesized via the suspension polymerization method. Subsequently, laboratory scale tests were carried out to systematically investigate the adsorption behavior and performance of p -ASA and ROX by using polymers. The result indicated that DMIPs exhibited super p -ASA/ROX sequestration and immobilization compared with non-imprinted polymers (DNIPs), which was associated with imprinting effect of polymers. The better removal efficiency of p -ASA/ROX by DMIPs were occurred in a broad pH region (3.0–9.0), whereas solution pH severely affected the uptake of DNIPs for organic arsenic compounds. According to the remarkable binding selectivity and special recognizability of DMIPs, common inorganic ions and natural organic matters (NOM) were negligible influence on targeted pollutants removal, and excellent adsorption capacity could still maintain even in the presence of interfering substances that displayed similar chemical structure with templates to a certain extent. Finally, the remarkable reusability and stable performance in continuous flow studies demonstrated the obtained DMIPs were promising candidates for simultaneously and effectively eliminating these multiple organic arsenic pollutants in harsh and complicated aquatic environment.
危险品化学品经营许可证（带存储）