Effective degradation of 2,4-dihydroxybenzophenone by zero-valent iron powder (Fe0)-activated persulfate in aqueous solution: Kinetic study, product identification and theoretical calculations

Mengting Zou; Yumeng Qi; Ruijuan Qu; Gadah Al-Basher; Xiaoxue Pan; Zunyao Wang; Zongli Huo; Feng Zhu

doi:10.1016/j.scitotenv.2020.144743

Effective degradation of 2,4-dihydroxybenzophenone by zero-valent iron powder (Fe⁰)-activated persulfate in aqueous solution: Kinetic study, product identification and theoretical calculations

Sci Total Environ. 2021 Jun 1:771:144743. doi: 10.1016/j.scitotenv.2020.144743. Epub 2021 Jan 23.

Authors

Mengting Zou¹, Yumeng Qi¹, Ruijuan Qu¹, Gadah Al-Basher², Xiaoxue Pan¹, Zunyao Wang³, Zongli Huo⁴, Feng Zhu⁵

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
² King Saud University, College of Science, Zoology Department, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
³ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China. Electronic address: wangzy@nju.edu.cn.
⁴ Jiangsu Provincial Center for Disease Control and Prevention, No. 172 Jiangsu Road, Nanjing 210009, Jiangsu, PR China.
⁵ Jiangsu Provincial Center for Disease Control and Prevention, No. 172 Jiangsu Road, Nanjing 210009, Jiangsu, PR China. Electronic address: zf850824@163.com.

PMID: 33540164
DOI: 10.1016/j.scitotenv.2020.144743

Abstract

2,4-Dihydroxybenzophenone (BP-1), a typically known derivative of the benzophenone-type UV filter, has been frequently detected in aqueous environments and poses a potential risk to human health and the entire ecosystem. In this study, an effective advanced oxidation technique using zero-valent iron powder (Fe⁰)-activated persulfate (PS) was used for the degradation of BP-1. The effects of several experimental parameters, including Fe⁰ dosages, PS dosages, pH, and common natural water constituents, were systematically investigated. The BP-1 degradation efficiency was enhanced by increasing the Fe⁰ and PS dosages and decreasing the solution pH. The presence of different concentrations of humic acid (HA) could inhibit BP-1 removal, while the addition of various cations and anions had different effects on the degradation. Moreover, the degradation of BP-1 in five water matrices was also compared, and the removal rates followed the order of ultrapure water > tap water > secondary clarifier effluent > river water > synthetic water. Thirteen oxidation products were identified by liquid chromatography-time-of-flight-mass spectrometry (LC-TOF-MS) analysis, and five possible degradation pathways were proposed. The addition reactions initiated by HO and SO₄^-, as well as single-electron coupling reactions and ring-closing reactions, were further supported by density functional theory (DFT) calculations. Assessment of toxicity of intermediates of the oxidation of BP-1 suggested decreased toxicity from the parent contaminant. The present work illustrates that BP-1 could be efficiently degraded in the Fe⁰/PS system, which may provide new insights into the removal of benzophenones in water and wastewater.

Keywords: 2,4-Dihydroxybenzophenone; Fe(0)-activated persulfate; Kinetics; Reaction pathways.