Tin dioxide decorated on Ni-encapsulated nitrogen-doped carbon nanotubes for anodic electrolysis and persulfate activation to degrade cephalexin: Mineralization and degradation pathway

Pingzhou Duan; Dadi Chen; Xiang Hu

doi:10.1016/j.chemosphere.2020.128740

Tin dioxide decorated on Ni-encapsulated nitrogen-doped carbon nanotubes for anodic electrolysis and persulfate activation to degrade cephalexin: Mineralization and degradation pathway

Chemosphere. 2021 Apr:269:128740. doi: 10.1016/j.chemosphere.2020.128740. Epub 2020 Oct 26.

Authors

Pingzhou Duan¹, Dadi Chen², Xiang Hu³

Affiliations

¹ College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, PR China; Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China.
² Beijing Municipal Research Institute of Environmental Protection, Beijing, 100037, PR China.
³ College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, PR China. Electronic address: huxiang@mail.buct.edu.cn.

PMID: 33139044
DOI: 10.1016/j.chemosphere.2020.128740

Abstract

In this study, bamboo-shaped carbon nanotubes exhibiting high nitrogen content and Ni encapsulation (Ni@NCNT) were effectively synthesized by a simple pyrolysis method. The catalytic peroxydisulfate activation for cephalexin (CPX) degradation was investigated using the prepared material. SnO₂ was further decorated and fabricated on the anode material (SnO₂/Ni@NCNT) for electrochemical degradation of CPX in an aqueous solution. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that the SnO₂ nanoparticles were uniformly distributed on the surface of Ni@NCNT. Electrochemical characterization employing cyclic voltammetry and linear sweep voltammetry demonstrated that SnO₂/Ni@NCNT displayed higher oxygen evolution potential and electrocatalytic activity than Ni@NCNT. Mineralization of CPX in wastewater was performed using electrolysis coupled with persulfate oxidation. The analysis revealed a synergistic strengthening effect. The electropersulfate oxidation resulted in higher total organic carbon (TOC) removal (70.3%) than the sum of electrooxidation (48.1%) and persulfate oxidation (9.2%) toward CPX. This phenomenon might result from the regeneration of sulfate radicals (SO₄^•-) on the anode and complementary oxidation by SO₄^•- and OH. Persulfate oxidation alone was shown to result in low TOC removal, although CPX was mostly degraded. Additionally, the CPX degradation pathway involving electropersulfate oxidation was proposed and it is indicated that CPX molecules were completed decomposed by the examination of short chain acids, mineralized ions, and ecotoxicity evolution indicated that the antibiotic was completely degraded. This study provides a new approach for the design and preparation of novel electrode materials and electrochemical degradation facilities for the removal of pollutants via persulfate activation.

Keywords: Cephalexin; Degradation intermediates; Ecotoxicity; Electropersulfate oxidation; SnO(2)/Ni@NCNT.

MeSH terms

Cephalexin
Electrodes
Electrolysis
Nanotubes, Carbon*
Nitrogen
Oxidation-Reduction
Tin Compounds
Water Pollutants, Chemical*

Substances

Nanotubes, Carbon
Tin Compounds
Water Pollutants, Chemical
stannic oxide
Nitrogen
Cephalexin