Rapid purification of As(III) in water using iron–manganese composite oxide coupled with sulfite: Importance of the SO5− radicals. (15th August 2022)

• Record Type: Journal Article
• Authors: Cai, Guiyuan; Li, Lipin; Li, Daikun; Wang, Qinyu; Zhang, Luyu; Zhang, Jun; Zuo, Wei; Tian, Yu
• Is Part Of: Water research. Volume 222(2022)
• Publication Date: 2022-08-15
• Subjects: Arsenite -- Iron–manganese composite oxide -- Sulfite -- Oxidation -- Adsorption; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118839
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: The FeMnOx /S(IV) system has faster removal speed and higher adsorption capacity for As(III) compared to FeMnOx alone. The As(III) (1079 µg/L) could be decreased to less than 10 µg/L within 10 min. The SO5 − radicals generated by S(IV) acting as the driving force for the redox cycle between As(III) and Mn(II/III/IV). The possible mechanism of As(III) oxidation and removal for the FeMnOx /S(IV) system was proposed. The FeMnOx nanocellulose aerogel broadened the scope of FeMnOx /S(IV) system in engineering applications. Abstract: Manganese (Mn)-containing composite metal adsorbents are very effective at removing arsenite (As(III)) from contaminated water, however, the low removal speed and oxidation efficiency have limited their further application. In this study, a nonhomogeneous catalytic oxidation–adsorption system was constructed by coupling iron–manganese composite oxide (FeMnOx ) with sulfite (S(IV)) to enhance the recovery of oxidative capacity and accelerate the removal of As(III). Experimental results showed that the FeMnOx /S(IV) system decreased the As(III) concentration from 1079 to <10 µg/L within 10 min and almost completely oxidized As(III) to As(V). In contrast, FeMnOx alone removed only 82.4% of As(III) within 30 min, and 60.0% of the adsorbed As(III) was not oxidized. Meanwhile, the adsorption capacity of FeMnOx /S(IV) system for As(III) was considerably higher than that of the only-FeMnOx system (76.5 > 46.3 mg/g). The efficient and fast As(III) removal was attributed to the SO5 − radical generated by S(IV) acting as the driving force for the redox cycle between As(III) and Mn(II/III/IV). Several environmental factors (e.g., solution pH and inorganic anions) and the reusability and practicality of FeMnOx were systematically investigated, and the results further confirmed the superiority of the FeMnOx /S(IV) system in As(III) removal. In particular, the proposed FeMnOx nanocellulose aerogel effectively purified arsenic-contaminated groundwater using a fixed-bed column. Thus, FeMnOx –S(IV) coupling is very promising for the purification of arsenic-contaminated water bodies. Graphical abstract: Image, graphical abstract