Enhanced removal efficiency of toluene over activated carbon under visible light

Shahid Saqlain; Shufang Zhao; Soong Yeon Kim; Young Dok Kim

doi:10.1016/j.jhazmat.2021.126317

Enhanced removal efficiency of toluene over activated carbon under visible light

J Hazard Mater. 2021 Sep 15:418:126317. doi: 10.1016/j.jhazmat.2021.126317. Epub 2021 Jun 4.

Authors

Shahid Saqlain¹, Shufang Zhao¹, Soong Yeon Kim¹, Young Dok Kim²

Affiliations

¹ Department of Chemistry, Sungkyunkwan University, Suwon 16419, South Korea.
² Department of Chemistry, Sungkyunkwan University, Suwon 16419, South Korea. Electronic address: ydkim91@skku.edu.

PMID: 34119970
DOI: 10.1016/j.jhazmat.2021.126317

Abstract

Toluene removal rates using activated carbon (AC) at various relative humidity (RH) levels (0%, 30%, 60%) were compared under dark and visible-light conditions. Light exposure significantly increased toluene-removal efficiency independent of RH. When AC was pre-treated with an optimal concentration of HNO₃, its toluene-removal efficiency was enhanced further with light, an effect that can be attributed to increased surface-area and porosity. Fourier-transform infrared analysis confirmed that exposure of HNO₃-modified AC to light induced partial oxidation of toluene. Within visible-light range (380-650 nm), shorter wavelengths were more effective for toluene-removal compared with longer wavelengths. This suggests that hydroxyl groups formed on AC-surface under light strongly interact with aromatic rings of toluene, allowing for greater uptake of toluene. Moreover, AC can sustain its photo-activity when mixed with cement and cured, suggesting its potential applications in air-purifying building materials. An efficient and practical method for regeneration of spent AC is also demonstrated.

Keywords: Activated carbon; Humidity dependence; Photo-induced oxidation; Volatile organic compounds; Wavelength dependence.