Synergistic adsorption and degradation of sulfamethazine by tobacco stalk-derived activated biochar: Preparation, mechanism insight and application

Green preparation of high value-added products from biomass waste for environmental remediation has received significant attention. In this work, activated biochars were developed through two-step thermal process using tobacco stalk as the precursor. Textural properties of biochar can be effectively tuned by adjusting carbonization and activation parameters. An optimized biochar (700TS-1000–5), carbonized at 700 ℃ and then thermally activated at 1000 ℃ for 5 h, showed higher specific surface area (905.61 m 2 g −1 ), rich porous structure, and abundant surface functional groups. 700TS-1000–5 showed excellent performance with a removal capacity of 99.37 mg g −1 for sulfamethazine (SMT) in 720 min, which was 4.3 times that of pristine biochar (700TS). And the SMT removal was high-efficient under normal environmental pH range. Adsorption and degradation simultaneously occurred during the whole process, which mainly relied on defects, functional groups, and·OH radicals. Moreover, this typical sample showed outstanding recycling ability and effectiveness of column experiment. Compared with KOH-assisted chemical activation, thermal activation had minor environmental impact and lower preparation cost through environmental and economic assessment. These findings not only propose a simple protocol for high-value reuse of agricultural waste but also shed new light on applications of tobacco stalk-derived biochar.