Staged assessment for the involving mechanism of humic acid on enhancing water decontamination using H2O2-Fe(III) process

Bo Yang; Xin Cheng; Yongli Zhang; Wei Li; Jingquan Wang; Zixin Tian; Erdeng Du; Hongguang Guo

doi:10.1016/j.jhazmat.2020.124853

Staged assessment for the involving mechanism of humic acid on enhancing water decontamination using H₂O₂-Fe(III) process

J Hazard Mater. 2021 Apr 5:407:124853. doi: 10.1016/j.jhazmat.2020.124853. Epub 2020 Dec 14.

Authors

Bo Yang¹, Xin Cheng², Yongli Zhang³, Wei Li¹, Jingquan Wang¹, Zixin Tian¹, Erdeng Du⁴, Hongguang Guo⁵

Affiliations

¹ MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
² MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China; Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06511, United States.
³ MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. Electronic address: zylscu@126.com.
⁴ School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
⁵ MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. Electronic address: hgguo@scu.edu.cn.

PMID: 33348201
DOI: 10.1016/j.jhazmat.2020.124853

Abstract

Humic acid (HA) as a natural coordinating agent was employed to modify the Fenton-like process by promoting the redox cycle of Fe(III)/Fe(II) and enhancing the pH tolerance. However, the roles of coordinating stages of HA-Fe(III) and the dynamic changes of iron species remain unclear. In this study, HA was introduced into the H₂O₂-Fe(III) process to investigate the accelerating roles of coordinating stages and systematically reveal the mechanism via the reactive oxygen species (ROS) identification, HA-Fe(III)/Fe(II) redox cycles tracking, electrochemical and kinetic analysis. Results suggested that two reaction stages were separated concerning the enhancement for HA in H₂O₂-Fe(III) process, including coordinating stage (slow rate) and promoting the redox stage (fast rate). HA-Fe(III) was identified as the major contributor, along with hydroxyl radical (·OH) and superoxide radical (·O₂^-) as the dominant ROS with formation rates calculated as 7.0 × 10^-9 and 2.1 × 10^-3 M s^-1 via the steady-state model. Based on the density-functional theory (DFT) calculations and HPLC-MS/MS analysis, three degradation pathways of 2,4-Dichlorophenol were proposed with ten intermediate products identified, and the ecotoxicity was evaluated through Ecological Structure Activity Relationships (ECOSAR) program. This study unveiled the mechanism of HA on enhancing water decontamination via H₂O₂-Fe(III) process in stages.

Keywords: Coordination; DFT calculation; Ecotoxicity evaluation; Fenton-like reaction; Humic acid.

Publication types

Research Support, Non-U.S. Gov't