Efficient removal of recalcitrant naphthenic acids with electro-cocatalytic activation of peroxymonosulfate by Fe(III)-nitrilotriacetic acid complex under neutral initial pH condition

Yu Chen; Yajing Li; Yongjian Wang; Igor Ying Zhang; Rongfu Huang

doi:10.1016/j.jhazmat.2023.131524

Efficient removal of recalcitrant naphthenic acids with electro-cocatalytic activation of peroxymonosulfate by Fe(III)-nitrilotriacetic acid complex under neutral initial pH condition

J Hazard Mater. 2023 Aug 5:455:131524. doi: 10.1016/j.jhazmat.2023.131524. Epub 2023 May 15.

Authors

Yu Chen¹, Yajing Li², Yongjian Wang¹, Igor Ying Zhang², Rongfu Huang³

Affiliations

¹ Sichuan Provincial Key Laboratory of Universities on Environmental Science and Engineering, MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
² Shanghai Key Laboratory of Molecular Catalysis and Innovation Materials, Collaborative Innovation Centre of Chemistry for Energy Materials, MOE Laboratory for Computational Physical Science, Shanghai Key Laboratory of Bioactive Small Molecules, Department of Chemistry, Fudan University, Shanghai 200433, China.
³ Sichuan Provincial Key Laboratory of Universities on Environmental Science and Engineering, MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. Electronic address: rongfu@scu.edu.cn.

PMID: 37196437
DOI: 10.1016/j.jhazmat.2023.131524

Abstract

This work investigated the activation of peroxymonosulfate by electrochemical (EC) system assisted with Fe(III)-nitrilotriacetic acid (NTA) complex for degradation of persistent naphthenic acids (NAs) under neutral initial pH conditions. As NAs are a complicated mixture, 1-adamantanecarboxylic acid (ACA) was selected as the model NA compound for degradation experiment. The addition of NTA is to chelate with Fe(III), gaining stability under neutral pH condition to facilitate the circulation of Fe(II)/Fe(III) by the electrochemical process to activate PMS. The EC/Fe(III)-NTA/PMS system was explored with applicable pH range of 3-9 and an optimized molar ratio 1: 2 for Fe: NTA. Results of quenching and chemical probe experiment together with results of electron paramagnetic resonance (EPR) analysis revealed the main reactive species of the system, including ^•OH, SO₄^•-, ¹O₂ and possibly Fe(IV). With the addition of NTA, the yields of ^•OH, SO₄^•-, ¹O₂ were enhanced. Results of mass spectrometry analysis and DFT calculations indicated the formation of 9 degradation byproducts of ACA via three primary degradation pathways such as hydroxyl substitution, carbonyl substitution, and decarboxylation. Furthermore, the EC/Fe(III)-NTA/PMS system could achieve excellent removal efficiency of ACA with different anions such as Cl^-, HCO₃^-, NO₃^- and H₂PO₄^- in the background. The practical applicability of the system was also verified with the high removal of commercial NAs mixture standard. Overall results have indicated the EC/Fe(III)-NTA/PMS system could be utilized for efficient reclamation of authentic oil and gas industrial wastewater under natural pH conditions.

Keywords: Electrocatalytic oxidation; Naphthenic acids; Neutral pH; Nitrilotriacetic acid.