Unexpected discovery of superoxide radical generation by oxygen vacancies containing biomass derived granular activated carbon. (15th February 2021)

• Record Type: Journal Article
• Authors: Choong, Choe Earn; Wong, Kien Tiek; Kim, Hyeseong; Jang, Seok Byum; Yoon, So Yeon; Nah, In Wook; Kim, Wooyul; Kim, Sang-Hyoun; Jeon, Byong-Hun; Yoon, Yeomin; Jang, Min
• Is Part Of: Water research. Volume 190(2021)
• Publication Date: 2021-02-15
• Subjects: Granular palm shell activated carbon -- Oxygen vacancies -- Superoxide radical -- Adsorption -- Photocatalyst; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.116757
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: PSAC under UVC365 irradiation exhibits higher production of O2 due to slower e − /h + recombination than other light sources. The O2 generation from oxygen vacancies associated Si 1+ is detected by using EPR spin trapping. A strong correlation between the content of oxygen vacancies and Si 1+ in PSAC and photocatalysis was obtained. The continuous-flow column of PSAC under UVA365 irradiation had a > 16-fold longer life than that of the adsorption column. Abstract: Herein, we discovered and reported oxygen vacancies in silicon oxycarbide containing granular palm shell activated carbon (Si-PSAC) as a photocatalyst under UV irradiation. A strong correlation between the atomic content of Si 1+, oxygen vacancies and photocatalytic performance of Si-PSAC was obtained. Based on the electron paramagnetic resonance and photoluminescence analyses, Si-PSAC under UVA365 irradiation exhibited a higher donor density, better charge transfer and lower electron-hole recombination than that under the other light sources, leading to a higher O2 · production efficiency. Si-PSAC exhibited effective removal performance for various anionic dyes and endocrine-disrupting chemicals under UVA365 irradiation. Continuous-flow column tests revealed the life span of Si-PSAC under UVA365 irradiation was extended by more than 16-fold compared to adsorption column. Since the oxygen vacancies can be created from the naturally present Si in the biomass derived Si-PSAC during the activation, this unexpected discovery of O2 · production can extend commercially-available Si-PSAC into the full-scale photocatalysis. Graphical abstract: Image, graphical abstract