Highly efficient degradation of dimethyl phthalate from Cu(II) and dimethyl phthalate wastewater by EDTA enhanced ozonation: Performance, intermediates and mechanism

Ying Liu; Yong Feng; Yunfei Zhang; Shun Mao; Deli Wu; Huaqiang Chu

doi:10.1016/j.jhazmat.2018.12.003

Highly efficient degradation of dimethyl phthalate from Cu(II) and dimethyl phthalate wastewater by EDTA enhanced ozonation: Performance, intermediates and mechanism

J Hazard Mater. 2019 Mar 15:366:378-385. doi: 10.1016/j.jhazmat.2018.12.003. Epub 2018 Dec 3.

Authors

Ying Liu¹, Yong Feng², Yunfei Zhang³, Shun Mao¹, Deli Wu⁴, Huaqiang Chu¹

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, 200092, Shanghai, PR China.
² Department of Civil Engineering, The University of Hong Kong, 999077, Hong Kong, PR China.
³ Research Center for Eco-Enviornmental Engineering, Dongguan University of Technology, Guangdong, 523808, PR China.
⁴ State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, 200092, Shanghai, PR China. Electronic address: wudeli@tongji.edu.cn.

PMID: 30544039
DOI: 10.1016/j.jhazmat.2018.12.003

Abstract

In this study, the presence of Cu(II) ions was found for the first time to severely inhibit +-dimethyl phthalate (DMP) degradation by ozone due to the formation of the stable complex Cu(II)-DMP. However, 100% DMP removal was rapidly reached when ethylenediamine tetraacetic acid (EDTA) was added with a Cu(II)/EDTA molar ratio of 3:1. Subsequent studies indicated that Cu(II)-DMP is sequestrated by EDTA, then DMP was degraded and Cu(II) was removed by precipitation. The freshly formed Cu-EDTA^2- and organic nitrogen intermediates further decomposed O₃ into OH, which induced to the rapid degradation of DMP. The k_obs of Cu-EDTA/O₃ were 9-10 times greater than the k_obs of DMP removed by ozonation alone within 10 min. The reaction mechanism involved a OH generation was proposed. The OH and O₂- are generated from the rapid reaction between ozone and EDTA. Acting as a more strongly negative species, the specific Cu(II) in Cu-EDTA complexes is more inclined to react with O₂- to give Cu(I), accelerating the forward reaction to produce more OH. The synergistic removal of DMP and Cu(II) can be achieved after reaction. Therefore, this study provides an effective method to dispose metal ion and organic pollutant wastewater.

Keywords: Cu(II); DMP; EDTA; Hydroxyl radical; Ozonation; Superoxide radicals.