New breakthrough in dye removal: Ultrafast removal of high concentration MB with biochar-based organic photocatalysts under indoor light (30W/m2) drive

Abstract

At the present stage, the light sources used in the photocatalytic degradation of organic pollutants are generally UV and simulated sunlight, which invariably increase the extra energy loss. Therefore, it is important to find an effective strategy for the rapid removal of high concentrations of organic pollutants in a cleaner and low-light environment with lower energy consumption. Here we prepare three biochar-based organic photocatalytic materials PM6:TPIC/BC, PM6:TPIC-2Cl/BC, PM6:TPIC-4Cl/BC by impregnation method. Among the three photocatalysts, PM6:TPIC-4Cl/BC exhibits the highest apparent rate constant (0.105 min−1), which is 3 times and 1.5 times higher than PM6:TPIC/BC (0.034 min−1) and PM6:TPIC-2Cl/BC (0.071 min−1) respectively. Due to a wider range of light absorption, the best material is able to completely degrade high concentrations of MB in 3 min. Moreover, photoluminescence (PL), time-resolved photoluminescence (TRPL), electrochemical impedance (EIS), and photocurrent (PCR) measurements confirm its exceptional photogenerated electron-hole separation. Free radical trapping identifies h+, ·OH, and ·O2− as key reaction species. DFT analysis reveal atoms with higher Fukui index (f0) as prime free radical targets. LC-MS detects intermediates, suggesting possible degradation pathways. The reduced toxicity of the degradation products after photocatalysis indicates an environmentally friendly approach. This work demonstrates the valuable of PM6:TPIC-4Cl/BC organic photocatalysts for treating organic wastewater.