Comparison of nano-TiO2 immobilization approaches onto biochar: Superiorities of click chemistry strategy and self-acceleration of pollutant degradation. Issue 3 (June 2022)

• Record Type: Journal Article
• Authors: Sha, Jianhua; Sun, Yunkai; Yu, Haiyan; Yang, Zitong; Chu, Hongwei; Wang, Yan; Yue, Qinyan; Yin, Weiyan; Xu, Shiping
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 3(2022)
• Publication Date: 2022-06
• Subjects: Click chemistry -- Nano-TiO2 immobilization -- Biochar -- Degradation acceleration; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.107544
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: To overcome the recovery challenge of nanoscale photocatalysts, great endeavor has been paid to explore effective nano-TiO2 immobilization approaches, but comprehensive comparison between these methods is still lacking. Herein, four approaches, namely impregnation-calcination, sol-gel, solvothermal route and click chemistry strategy were fully compared to immobilize nano-TiO2 onto biochar from the viewpoint of properties characterization, photocatalytic activity, structure stability and pollutant degradation pathway. It was found that, compared to other three methods, product obtained by click chemistry (CC-P25/BC) showed superior adsorption-photocatalysis synergy and persistent long-term stability. These superiorities were not attributed to pore structure, crystallinity or light absorption, but predominated by the robust chemical bonds between TiO2 and biochar, which served as an effective internal channel for electrons transportation. Besides, with CC-P25/BC as photocatalyst, a unique self-acceleration period was observed during methylene orange (MO) degradation. Via investigating MO degradation pathway and solution environment, we found that it was the strong photocatalytic activity of CC-P25/BC that selectively accelerated MO demethylation, thus leading to solution pH drop and subsequent MO adsorption enhancement and then degradation acceleration. Thus, this study confirmed the superiority of click chemistry in nanoscale photocatalyst immobilization, and affirmed the importance of pollutant degradation process in governing its degradation rate. Graphical Abstract: ga1 Highlights: Click chemistry was superior to traditional nano-TiO2 immobilization methods. Click chemistry provided robust chemical connection between TiO2 and biochar. Robust connection created great adsorption-photocatalysis synergy and stability. Strong photoactivity can selectively accelerate demethylation of methylene orange. Acceleration of demethylation induced pH drop and promoted faster degradation.