Inhibition of photosensitized degradation of organic contaminants by copper under conditions typical of estuarine and coastal waters

Yanheng Pan; Shikha Garg; Yiming Ouyang; Xin Yang; T David Waite

doi:10.1016/j.jhazmat.2023.131812

Inhibition of photosensitized degradation of organic contaminants by copper under conditions typical of estuarine and coastal waters

J Hazard Mater. 2023 Sep 15:458:131812. doi: 10.1016/j.jhazmat.2023.131812. Epub 2023 Jun 8.

Authors

Yanheng Pan¹, Shikha Garg², Yiming Ouyang³, Xin Yang³, T David Waite⁴

Affiliations

¹ School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China; School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
² School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
³ School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China.
⁴ School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia. Electronic address: d.waite@unsw.edu.au.

PMID: 37331060
DOI: 10.1016/j.jhazmat.2023.131812

Abstract

Dissolved organic matter (DOM) driven-photochemical processes play an important role in the redox cycling of trace metals and attenuation of organic contaminants in estuarine and coastal ecosystems. In this study, we evaluate the effect of Cu on 4-carboxybenzophenone (CBBP) and Suwannee River natural organic matter (SRNOM)-photosensitized degradation of seven target contaminants (TCs) including phenols and amines under pH conditions and salt concentrations typical of those encountered in estuarine and coastal waters. Our results show that trace amounts of Cu(II) (25 -500 nM) induce strong inhibition of the photosensitized degradation of all TCs in solutions containing CBBP. The influence of TCs on the photo-formation of Cu(I) and the decrease in the lifetime of transformation intermediates of contaminants (TC^•+/ TC^•_(-H)) in the presence of Cu(I) indicated that the inhibition effect of Cu was mainly due to the reduction of TC^•+/ TC^•_(-H) by the photo-produced Cu(I). The inhibitory effect of Cu on the photodegradation of TCs decreased with the increase in Cl^- concentration since less reactive Cu(I)-Cl complexes dominate at high Cl^- concentrations. The impact of Cu on the SRNOM-sensitized degradation of TCs is less pronounced compared to that observed in CBBP solution since the redox active moieties present in SRNOM competes with Cu(I) to reduce TC^•+/ TC^•_(-H). A detailed mathematical model is developed to describe the photodegradation of contaminants and Cu redox transformations in irradiated SRNOM and CBBP solutions.

Keywords: Marine photochemistry; Organic contaminants; Redox active metal; Triplet states of DOM.