Advantage of selective production of green rusts for Sb(V) removal in Fe(0) electrocoagulation

Inactivation of Escherichia Coli by mixed-valent nanoparticles in-situ generated during Fe electrocoagulation

Electrocoagulation (EC) is promising for the removal of chemical and microbial contaminants. Although the removal of pathogens from wastewater is efficient by conventional Fe-EC in the presence of dissolved oxygen (DO), the non-inactivated pathogens in the sediment still have a risk. Herein, the inactivation of Escherichia coli (E. coli) with the mixed-valent iron nanoparticles, magnetite and green rust (GR), in-situ generated from Fe-EC process in the absence of DO was investigated. The inactivation efficiency was significantly higher with magnetite (4.7 log cells) and GR (3.2 log cells) compared with FeOOH (0.7-1.7 log cells) generated at 50 mA in 10 min. The unstable in-situ generated magnetite with positive charges was prone to adsorb onto E. coli, damaging the cell membrane, inactivating the bacteria. The unstable in-situ generated GR was prone to coagulate with E. coli, delivering Fe2+ into the cell and inducing the generation of endogenous ROS, inactivating the bacteria. Fe-EC in the absence of DO was proved to be efficient for the inactivation of E. coli (4.2-4.3 log cells) in real wastewater. These findings identified the ignored inactivation effect and mechanism of E. coli with magnetite and GR generated in situ from Fe-EC process, which will provide theoretical support for real applications.

Detection of trace antimony by vanadium (IV) ion assisted photochemical vapor generation with inductively coupled plasma mass spectrometry measurement

In this work, a method for sensitive detection of trace antimony (Sb) was developed by inductively coupled plasma mass spectrometry (ICP MS) coupled with photochemical vapor generation (PVG). V(IV) ions were used as new "sensitizers" for improving the PVG efficiency of Sb. Factors influenced the PVG and the detection of Sb by ICP MS were investigated, including the type and concentration of low molecular weight organic acids, the UV irradiation time, the concentration of V(IV) ions, the air-liquid interface, the flow rate of Ar carrier gas, and interferences from co-existing ions. It was found that efficient reduction of Sb was obtained in the medium of 10% (v/v) formic acid (FA), 10% (v/v) acetic acid (AA), and 80 mg L^-1 of V(IV) with 100 s UV irradiation. Under the selected conditions, there was no significant difference in analytical sensitivity between Sb(III) and Sb(V). The limit of detection (LOD, 3σ) was 4.7 ng L^-1 for Sb with ICP MS measurement. Compared to traditional direct solution nebulization, the analytical sensitivity obtained in this work was enhanced about 19-fold. Relative standard deviations (RSDs, n = 7) were 1.9% and 2.3% for replicate measurement of 0.5 μg L^-1 Sb(III) and Sb(V) standard solutions, respectively. The proposed method was applied for the determination of trace Sb in water samples and two certified reference materials (CRMs) of sediments with satisfactory results. Moreover, the generated volatile species of Sb in this work was found to be (CH₃)₃Sb.

Antimony (Sb) pollution control by coagulation and membrane filtration in water/wastewater treatment: A comprehensive review

Antimony (Sb) pollution in the water environment caused by the large-scale mining of Sb ore and the wide use of Sb-containing products seriously endangers human health and poses a great threat to the ecological environment. Coagulation is one of the most cost-effective technologies for Sb pollution control in water/wastewater treatment and has been widely used. However, a comprehensive understanding of Sb pollution control by coagulation, from fundamental research to practical applications, is lacking. In this work, based on the current status of Sb pollution in the water environment, a critical review of the Sb removal performance and mechanism by coagulation and related combined processes was carried out. The influencing factors of Sb removal performance by coagulation are introduced in detail. The internal mechanisms and improvement strategies of Sb removal by oxidation/reduction-coagulation and coagulation-membrane filtration technologies are emphasized. Moreover, given the development of Sb-removing coagulants and the resource utilization of Sb-containing sludge, future perspectives of coagulation for Sb removal are discussed. As the first review in this field, this work will illuminate avenues of basic research and practical applications for Sb and Sb-like pollution control in water/wastewater treatment.

Antimony, a pollutant of emerging concern: A review on industrial sources and remediation technologies

Technologies for remediation of industrial effluents and natural sources contaminated with antimony - a pollutant of emerging concern - are just emerging. The complex speciation of antimony makes it challenging to devise effective remediation technologies. Antimony is used in several industrial applications and comes into the environment majorly through human induced activities such as antimony mining and other activities involving the use of various products containing antimony. Many researchers are working on the important task of developing methodologies to stop or limit the release of antimony into the environment through these activities. Antimony removal is an important requirement in nuclear industry as well due to the formation of its radioactive isotopes during power plant operations. Thus, better antimony remediation or removal techniques can have wider applications ranging from domestic water treatment and industrial effluent remediation to safe isolation of radioactive waste in the nuclear industry. Proper understanding of the problem is very important in designing the source appropriate remediation technique. Treatment methodologies needed for antimony effluents from antimony mining and smelting industries are different from antimony decontamination in nuclear reactors. The problem of antimony leaching from a polyethylene terephthalate bottle is very much different from the leaching of antimony from mining wastes. Each process necessitates custom-made treatment methodologies by taking into account various factors including the speciation and concentration. The current review is focused on this aspect. The review attempts to bring out a clear understanding on various industry specific sources of antimony pollution and the available antimony removal/remediation technologies.