Improvement of Fe(Ⅲ)/percarbonate system by molybdenum powder and tripolyphosphate: Co-catalytic performance, low oxidant consumption, pH-dependent mechanism

Zhengwei Zhou; Guojie Ye; Yang Zong; Zhenyu Zhao; Deli Wu

doi:10.1016/j.jhazmat.2023.132924

Improvement of Fe(Ⅲ)/percarbonate system by molybdenum powder and tripolyphosphate: Co-catalytic performance, low oxidant consumption, pH-dependent mechanism

J Hazard Mater. 2024 Feb 15:464:132924. doi: 10.1016/j.jhazmat.2023.132924. Epub 2023 Nov 4.

Authors

Zhengwei Zhou¹, Guojie Ye¹, Yang Zong¹, Zhenyu Zhao¹, Deli Wu²

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China.
² State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China. Electronic address: wudeli@tongji.edu.cn.

PMID: 37984133
DOI: 10.1016/j.jhazmat.2023.132924

Abstract

The homogeneous sodium percarbonate (SPC) systems are limited by narrow pH range, ineffective consumption of oxidant, and weak reusability of catalyst. Herein, molybdenum (Mo) powder and sodium tripolyphosphate (STPP) were selected to overcome these challenges. Sulfamethoxazole (SMX), as a model contaminant, was almost completely degraded in 60 min with higher removal rate (0.1367 min^-1) than the Mo or STPP-absent system. In addition, Mo/STPP-Fe(Ⅲ)/SPC system was cost-effective in terms of oxidant consumption, requiring only 0.2 mM SPC. About activation mechanism, the main active species for SMX degradation was pH-dependent, with hydroxyl radical (·OH) as the dominant active species at pH_i = 7 and ·OH, carbonate radical (CO₃·^-), and superoxide radical (O₂·^-) derived from a series of chain reaction at pH_i = 10, respectively. Due to the generation of various electrophilic free radical, the system exhibited excellent performance towards electron-rich pollutants under a wide pH range. Furthermore, Mo exhibited excellent stability and reusability. SMX was degraded through hydroxylation, N-S cleavage, amino and sulfanilamide oxidation into intermediates whose toxicities were evaluated by Toxicity Estimation Software Tool (T.E.S.T.) software. This work provided new insights to Fe/SPC system towards high-efficiency and low consumption treatment of practical application.

Keywords: Molybdenum powder; PH-dependent active species; Sodium percarbonate; Sulfamethoxazole degradation; Tripolyphosphate.