Photocatalytic and antibacterial characteristics of biochar-supported ZnO and TiO2 nanocomposites

Coexistence of organic dyes and pathogenic bacteria in wastewater demands integrated treatment, yet affordable, reusable photocatalysts that target both remain limited. In this study, biochar-supported TiO₂ (TiO₂/BC) and ZnO (ZnO/BC) nanocomposites were synthesized via a hydrothermal method to address this dual challenge. The incorporation of biochar enhanced dye adsorption and improved charge separation, leading to high photocatalytic degradation efficiency of methyl orange (up to 92% and 97%) under light irradiation. The nanocomposites retained over 80% and 90% of their activity after three reuse cycles, respectively for TiO₂/BC and ZnO/BC, demonstrating good stability. Additionally, the materials showed strong antibacterial activity against Escherichia coli , with inhibition rates reaching 90%. These results confirm the potential of the TiO₂/BC and ZnO/BC nanocomposites as sustainable, multifunctional materials for simultaneous pollutant degradation and water disinfection applications.