Deactivation and regeneration of carbon nanotubes and nitrogen-doped carbon nanotubes in catalytic peroxymonosulfate activation for phenol degradation: variation of surface functionalities. Issue 2 (9th January 2019)

• Record Type: Journal Article
• Authors: Hou, Jifei; Xu, Lixia; Han, Yuxiang; Tang, Yuqiong; Wan, Haiqin; Xu, Zhaoyi; Zheng, Shourong
• Is Part Of: RSC advances. Volume 9:Issue 2(2019)
• Page Start: 974
• Page End: 983
• Publication Date: 2019-01-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8ra07696k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Both CNT and NCNT catalysts presented marked deactivation after activating PMS. Moreover, the initial activities of deactivated CNT and NCNT were restored by thermal treatment at different temperatures (T-350, T-550 and T-750) and chemical reduction (R–NaBH4 ). Abstract : The reuse, deactivation and regeneration of carbon nanotubes (CNT) and N-doped carbon nanotubes (NCNT) were studied in catalytic peroxymonosulfate (PMS) activation for phenol degradation. The results showed that for catalytic PMS activation, marked deactivation was observed on both CNT and NCNT, resulting in marked variation of the surface functionalities of the catalysts. Catalytic PMS activation led to markedly increased oxygen-containing functionalities and decreased points of zero charge (PZCs) of CNT and NCNT. The catalytic activity of CNT was strongly dependent on the initial PMS concentration but was independent of the initial phenol concentration. Furthermore, the dependency of the CNT activity on the initial PMS concentration closely followed the Langmuir–Hinshelwood model, indicating that the catalytic activation of adsorbed PMS was the rate controlling step. For the used CNT and NCNT, chemical reduction by NaBH4 or thermal treatment regeneration under inert atmosphere could effectively remove surface O-containing functionalities and enhance PZCs, restoring their catalytic activities; meanwhile, the N-containing functionalities of NCNT decreased with regeneration treatment, resulting in a negative impact on catalyst regeneration. The present findings indicate that surface functionalities are closely correlated with catalyst deactivation and regeneration, playing crucial roles in the catalytic activation of PMS.