Deep removal of arsenic from regenerated products of spent V2O5-WO3/TiO2 SCR catalysts and its concurrent activation by bioleaching through a novel mechanism

Autor: Baoping Xin, Tianqi Niu, Can Qian, Geoffrey M. Gadd, Jia Wang, Wen Shi, Huichao Chu, Ning Duan
Rok vydání: 2021
Předmět:
Zdroj: Chemical Engineering Journal. 420:127722
ISSN: 1385-8947
DOI: 10.1016/j.cej.2020.127722
Popis: Selective catalytic reaction (SCR) is widely used in flue gas denitrification to convert NOx air pollutants into N2 and H2O in the presence of SCR catalyst, but arsenic poisoning causes serious deactivation of SCR catalyst and produces a huge amount of spent SCR catalyst worldwide. Therefore, the regeneration and recycling of spent SCR catalysts are of great necessity for the sustainable flue gas denitrification due to the very high cost of replacing commercial catalysts. Nowadays, a combination of alkali treatment and acid washing is usually used to regenerate spent SCR catalysts. However, high residue of As strongly inhibits the catalytic activity of the regenerated products. In this study, an active bioleaching liquor produced by Acidithiobacillus thiooxidans as indirect bioleaching was attempted to deeply remove As from the regenerated product for the first time. The results showed that bioleaching resulted in maximal As removal of 53.1% even at a high pulp density of 10% to harvest a minimum As residue of 174 mg/kg below the limiting value of 200 mg/kg; whereas H2SO4 leaching attained 6.7% As removal and as high as 345 mg/kg of As residue. A stronger activation of the regenerated products simultaneously occurred with the bioleaching. A great amount of cysteine in the bioleaching liquor secreted by the microbe accounts for both the enhancement of As removal and strong activation of the product. A novel mechanism is proposed to explain the excellent As removal by the indirect bioleaching based on nucleophilic attack of the sulfhydryl groups in cysteine.
Databáze: OpenAIRE
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