Decomplexation of heterogeneous catalytic ozonation assisted with heavy metal chelation for advanced treatment of coordination complexes of Ni

Zhijie Guan; Yanping Guo; Shoupeng Li; Shaoqing Feng; Yanghong Deng; Xuelian Ou; Jie Ren; Shuiyu Sun; Jialin Liang

doi:10.1016/j.scitotenv.2020.139223

Decomplexation of heterogeneous catalytic ozonation assisted with heavy metal chelation for advanced treatment of coordination complexes of Ni

Sci Total Environ. 2020 Aug 25:732:139223. doi: 10.1016/j.scitotenv.2020.139223. Epub 2020 May 8.

Authors

Zhijie Guan¹, Yanping Guo², Shoupeng Li¹, Shaoqing Feng¹, Yanghong Deng¹, Xuelian Ou², Jie Ren², Shuiyu Sun³, Jialin Liang¹

Affiliations

¹ Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
² Guangdong Province Solid Waste Recycling and Heavy Metal Pollution Control Engineering Technology Research Center, Guangdong Polytechnic of Environmental Protection Engineering, Foshan 528216, China.
³ Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangdong Province Solid Waste Recycling and Heavy Metal Pollution Control Engineering Technology Research Center, Guangdong Polytechnic of Environmental Protection Engineering, Foshan 528216, China. Electronic address: sysun@gdut.edu.cn.

PMID: 32438144
DOI: 10.1016/j.scitotenv.2020.139223

Abstract

Following the conventional physicochemical treatment of electroless nickel (Ni) plating wastewater (ENPW) in electroplating wastewater treatment plants, highly stable and recalcitrant coordination complexes of Ni (CCN) still remain. This results in various technical problems, leading to the treatment difficulty, poor wastewater biochemistry, and failure to meet effluent standards. Therefore, an efficient decomplexation system involving heterogeneous catalytic ozonation assisted with heavy metal chelation (O₃/SAO3II-MDCR) was proposed in this study for the advanced treatment of CCN. The catalyst SAO3II was characterized by various methods, which revealed the mechanism of catalytic ozonation. Hydroxyl radicals (OH) and other reactive oxygen species (ROS) groups were detected, proving that catalytic ozonation was a complicated reaction process and also a foundation process of the entire system. These ROS are vital for decomplexation via heterogeneous catalytic ozonation of the system. During the catalytic decomplexation process via ozonation, CCN first underwent gradual decomposition from a highly stable macromolecular state to a volatile micromolecular state (or even completely mineralized state). Then Ni was chelated to form an insoluble and stable chelate via competitive coordination. The optimum conditions for the O₃/SAO3II-MDCR system were determined by single factor static experiments. After treatment with the O₃/SAO3II-MDCR system, the effluent concentration of total Ni was found to be <0.1 mg L^-1, exhibiting a removal rate of up to 95.6% and achieving effective removal of total Ni from ENPW and stably meeting the discharge standard. O₃/SAO3II-MDCR system can easily and hopefully be extended to practical engineering applications.

Keywords: Competitive coordination; Coordination complexes of nickel; Decomplexation; Electroless nickel plating wastewater; Hydroxyl radicals.