Nitrogen-doped carbonized polyaniline (N-CPANI) for peroxydisulfate (PDS) activation towards efficient degradation of doxycycline (DOX) via the non-radical pathway dominated by electron transfer

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-02, Vol.453, p.139810, Article 139810
• Main Authors: Cheng, Minxian, Ma, Rui, Chai, Guodong, Chen, Yongjun, Bai, Linqin, Wang, Dongqi, Qian, Jin, Chen, Guang-Hao
• Format: Article
• Language: English
• Subjects: Degradation pathways and mechanism; Electron transfer; Nitrogen-doped carbonized polyaniline (N-CPANI); Non-radical pathways; Peroxydisulfate (PDS) activation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.139810

[Display omitted] •Synthesis of N-doped CPANI for PDS activation towards DOX degradation.•High mineralization of DOX in the N-CPANI-900/PDS with TOC removal efficiency of 83.77%.•High robustness to environmental variations and good recyclability of N-CPANI-900.•The graphitic N and ketonic group(CO) were the main catalytic reactive sites.•N-CPANI-900/PDS complexes mediated electron transfer accounts for the major DOX degradation. In this study, nitrogen-doped carbonized polyaniline (N-CPANI-T, T is the carbonized temperature) was firstly synthesized to activate peroxydisulfate (PDS) towards the sustainable degradation of doxycycline (DOX). Compared to other carbon-based catalysts reported in the previous studies, N-CPANI-900 had better DOX decomposition rate (91.66 %) and higher TOC elimination efficiency (83.77 %) within 120 min with the initial DOX concentration as high as 20 mg/L, which could be attributed to the accelerated electron transfer and the large adsorption capacity of N-CPANI-900. The active sites for PDS activation driven by N-CPANI-900 mainly include graphitic N, ketonic group (CO) and defect sites in the carbon matrix. The results of both quenching experiments and electron paramagnetic resonance (EPR) test illustrated that non-radical pathway was dominated in the N-CPANI-900/PDS/DOX system. Moreover, metastable N-CPANI-900/PDS complexes mediated electron transfer made a remarkable contribution to DOX degradation compared with singlet oxygen. The effects of pH, inorganic anions, NOM and different water matrices on DOX degradation were almost negligible in the N-CPANI-900/PDS system. This research provides a new strategy into the preparation of metal-free PDS activators towards efficient removal of emerging contaminants in real wastewater.