Activation of Peroxydisulfate on Carbon Nanotubes: Electron Transfer Mechanism.

By Wei Ren, Liangliang Xiong, Xuehong Yuan, Ziwei Yu, Hui Zhang, Xiaoguang Duan, Shaobin Wang. Environmental Science and Technology, 2019

701 citations recorded by the source corpus.

This study proposed an electrochemical technique for investigating the nonradical oxidation pathway of organics in carbon nanotubes (CNTs)-catalyzed peroxydisulfate (PDS) activation. The half-wave potentials of twelve phenolic compounds (PCs) were evaluated and correlated to their kinetic rate constants in the PDS/CNTs system. Integrated with quantitative structure-activity relationships (QSARs), electron paramagnetic resonance (EPR) and radical scavenging tests, the nature of nonradical pathway was unveiled to be an electron-transfer regime without singlet oxygenation process. The QSARs accurately predicted the oxidation process of PCs according to their standard electrode potentials, reactive pH and temperature. A novel electrochemical analysis method (transient open circuit potential combined with chronoamperometry) was employed to probe the mechanism, suggesting that PDS was firstly catalyzed by CNTs to form a surface-confined CNTs-PDS* complex with a high redox potential. Then, the CNTs-PDS* selectively abstracted electrons from the co-adsorbed PCs to initiate the oxidation. Finally, a comparison of PDS/CNTs and graphite anodic oxidation under constant potentials was comprehensively analyzed to unveil the relative activity of the nonradical CNTs-PDS complexes toward different PCs, which was determined by the oxidative potentials of the CNTs-PDS* complex and the adsorbed organics.

Subfields: Electrical and Electronic Engineering, Electrochemistry, Water Science and Technology

View Paper: https://www.semanticscholar.org/paper/a881051f079b80ecc96298ec7e4bba8bca1609cd