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Zhou M, You T, Yan Z, Zhu X, Pi M, Zeng X, Wang S, Jia Y. Iodide and sulfite synergistically accelerate the photo-reduction and recovery of As(V) and As(III) in sulfite/iodide/UV process: Efficiency and mechanism. Water Res 2024; 252:121210. [PMID: 38324984 DOI: 10.1016/j.watres.2024.121210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/04/2024] [Accepted: 01/26/2024] [Indexed: 02/09/2024]
Abstract
Photo-reduction of arsenic (As) by hydrated electron (eaq-) and recovery of elemental arsenic (As(0)) is a promising pathway to treat As-bearing wastewater. However, previously reported sulfite/UV system needs large amounts of sulfite as the source of eaq-. This work suggests a sulfite/iodide/UV approach that is more efficient and consumes much less chemical reagents to remove As(III) and As(V) and recover valuable As(0) from wastewater, hence preventing the production of large amounts of As-containing hazardous wastes. Our results showed that more than 99.9% of As in the aqueous phase was reduced to highly pure solid As(0) (>99.5 wt%) by sulfite/iodide/UV process under alkaline conditions. Sulfite and iodide worked synergistically to enhance reductive removal of As. Compared with sulfite/UV, the addition of iodide had a substantially greater effect on As(III) (over 200 times) and As(V) (approximately 30 times) removals because of its higher absorptivity and quantum yield of eaq-. Furthermore, more than 90% of the sulfite consumption was decreased by adding a small amount of iodide while maintaining similar reduction efficiency. Hydrated electron (eaq-) was mainly responsible for As(III) and As(V) reductions and removals under alkaline conditions, while both SO3•- and reactive iodine species (e.g., I•, I2, I2•-, and I3-) may oxidize As(0) to As(III) or As(V). Acidic circumstances caused sulfite protonation and the scavenging of eaq- by competing processes. Dissolved oxygen (O2) and CO32- prevented As reduction by light blocking or eaq- scavenging actions, but Cl-, Ca2+, and Mg2+ showed negligible impacts. This study presented an efficient method for removing and recovering As from wastewater.
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Affiliation(s)
- Mengchao Zhou
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Tingting You
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Zelong Yan
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Xiayu Zhu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Minhan Pi
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Xiangfeng Zeng
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Shaofeng Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
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