Green biochar-supported ZnFe2O4 composite photocatalyst derived from waste banana peel: a sustainable approach for highly efficient visible Light-driven degradation of organic pollutants in wastewater

Ferrite-based photocatalysts have raised as potent agents for breaking down organic pollutants in wastewater treatment. However, the challenge of developing an environmentally sustainable and economically viable photocatalyst with heightened efficacy persists. In this study, we prepared a green biochar-supported ZnFe2O4 (BC-ZnFe2O4) composite catalyst through a simple calcination method using waste banana peel (Macho plantain). The physicochemical properties of the prepared catalysts were thoroughly characterized, encompassing phase structure, surface morphology, purity, size, optical features, and charge separation efficiency. The characterization results confirmed that the ZnFe2O4 had a specific crystal structure in the composite. Microscopic analysis showed that the BC-ZnFe2O4 composite had a consistent cubic-like shape, with grains sized between 60-80 nm. Importantly, these BC-ZnFe2O4 composite had a direct band gap of about 2.29 eV, making them suitable for photocatalytic reactions. The photocatalytic methylene blue (MB) degradation experiments revealed that BC-ZnFe2O4 (91.08%; k = 0.3938 min(-1)) exhibits a superior photocatalytic activity compared to its pure BC-ZnO (75.26; k = 0.2129 min(-1)) counterparts within 100 min visible light irradiation. The excellent photocatalytic performance of the BC-ZnFe2O4 composite was due to the combined effect of the biochar and ZnFe2O4, which generated reactive oxygen species during the degradation process. In addition, the as-prepared BC-ZnFe2O4 composite demonstrated remarkable catalytic stability throughout multiple reaction cycles, making it suitable for sustained degradation of dye pollutants. Considering the outstanding performance of BC-ZnFe2O4 composite for the photocatalytic reaction, we believe that BC-ZnFe2O4 holds significant potential for purifying pollutants in various applications.