A critical review on sulfur reduction of aqueous selenite: Mechanisms and applications

• Published in: Journal of hazardous materials 2022-01, Vol.422, p.126852, Article 126852
• Main Authors: Xiong, Jiaming, Wang, Hainan, Yao, Jinni, He, Qiang, Ma, Jun, Yang, Jingjing, Liu, Caihong, Chen, Yao, Huangfu, Xiaoliu, Liu, Hongxia
• Format: Article
• Language: English
• Subjects: Applications; Ecosystem; Humans; Oxidation-Reduction; Reaction mechanisms; Selenious Acid; Selenite; Selenium; Sodium Selenite; Species distribution; Sulfur; Sulfur reduction; Water
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126852

Selenite, which is extremely toxic at high concentrations, can easily be enriched in natural aquatic environments due to human activities, which causes great harm to ecosystems. Sulfur reduction can effectively reduce soluble selenite in large quantities to nontoxic solid elemental selenium, which plays a significant role in controlling the toxicity and cycle of selenium. In view of the bright prospects of the sulfur reduction reaction of selenite, this review comprehensively summarizes the continuous development in the sulfidation of selenite. First, the geochemical characteristics of aqueous selenium in different sulfur systems involving species distribution and various phase types at Eh-pH conditions were summarized. Second, sulfur reductions of selenite with chemical sulfide in natural water environments, sulfur reductase and extracellular polymer substances containing thiol groups in sulfate-reducing bacteria have been reviewed to further understand the corresponding mechanisms, rates and influencing factors. Furthermore, applications of sulfur reduction of selenium, including removal of selenium, enrichment of selenium, synthesis of selenoproteins and prevention of leakage of selenium, were also summarized. Finally, this review identified future research needs for the sulfidation of selenite for environmental applications. [Display omitted] •Overviewed the chemical properties of selenium in sulfur-systems.•Reviewed transformations and kinetics of selenite by sulfide compounds.•Elucidated mechanisms governing selenite reduction by sulfate-reducing bacteria.•Compared efficiency of various sulfur reduction technology on selenite removal.•Identified future research needs of sulfidation on selenite.