The transformation of dissolved organic matter and formation of halogenated by-products during electrochemical advanced oxidation pretreatment for shale gas produced water

Hualiang Feng; Zhaoji Zhang; Qiyue Kuang; Shaohua Chen; Da Huang; Xuewen Zhou

doi:10.1016/j.jhazmat.2023.131614

The transformation of dissolved organic matter and formation of halogenated by-products during electrochemical advanced oxidation pretreatment for shale gas produced water

J Hazard Mater. 2023 Aug 5:455:131614. doi: 10.1016/j.jhazmat.2023.131614. Epub 2023 May 10.

Authors

Hualiang Feng¹, Zhaoji Zhang², Qiyue Kuang³, Shaohua Chen⁴, Da Huang⁵, Xuewen Zhou⁶

Affiliations

¹ Key Laboratory of Urban Environment and Health, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China.
² Key Laboratory of Urban Environment and Health, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China. Electronic address: zjzhang@iue.ac.cn.
³ Key Laboratory of Urban Environment and Health, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China; Fujian Agriculture & Forestry University, Coll Resources & Environment, Fuzhou 350002, China.
⁴ Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
⁵ Shenzhen Branch, China Design Group Co., Ltd., Shenzhen 518019, China.
⁶ Hubei Jiangxiao Environmental Protection Technology Co., Ltd., Wuhan 430048, China.

PMID: 37201277
DOI: 10.1016/j.jhazmat.2023.131614

Abstract

Electrochemical advanced oxidation processes (EAOPs) have shown great potential for the treatment of shale gas produced water (SGPW). In this study, we investigated the transformation of dissolved organic matter (DOM) during EAOPs of SGPW and the formation of toxic halogenated by-products at various current densities, using fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. We found that the priority of DOM removal was terrestrial humic-like > microbial humic-like > protein-like substances. Non-Halogenated organic compounds (non-HOCs) and HOCs were predominantly CHO, and CHOCl/CHOBr compounds in EAOP-treated SGPW, respectively. As applied current density and treatment time increased, the production of oxyhalides increased, with chlorate > bromate > perchlorate. Meanwhile, most DOM was mineralized, resulting in residual products with higher modified aromaticity index (AI_mod) and nominal oxidation state of carbon (NOSC). The resistants had lower mass-to-charge ratio (m/z), AI_mod, NOSC, and double bond equivalent minus oxygen per carbon ((DBE-O)/C). The dominant reactions were the addition of tri-oxygen and deallyl. Bromine addition dominated the reactions of halogenating addition, while chlorine addition took second place. Furthermore, the acute toxicity of SGPW was positively correlated with inorganic halogenated by-products. This study contributes to the understanding and improvement of EAOPs for the treatment of SGPW.

Keywords: Electrochemical advanced oxidation process; FT-ICR MS; Halogenated by-products; Shale gas produced water.