Green Synthesis of a Biochar-Based Iron Oxide Catalyst for Efficient Degradation of Pesticides: Kinetics and Photoactivity

Photocatalysis is considered as promising methodology for the removal of pesticides from wastewater given its cost-effective and environmental benignity. Pesticide toxicity and bioaccumulation have brought up environmental issues, underlining the necessity for efficient removal techniques based on novel nanomaterials. Herein, biochar (BC) synthesized by using waste peels of citrus limetta embedded with green synthesized Fe2O3 nanoparticle by using green tea extract. By using PXRD analysis, the alpha phase of Fe2O3 confirmed. Endosulfan (ES) and Ethion (ET) pesticides are degraded photocatalytically using a sequential, BC@ Fe2O3 nanohybrid. At the pollutant concentration (50 mg L-1), with catalytic dose (25 mg) in acidic condition under natural sunlight, BC@ Fe2O3 showed to be extremely effective in the breakdown of pesticides. The higher removal of pesticides by BC@ Fe2O3 supported by higher value of zeta potential (-22.5 mV), enhanced surface area (74 m(2) g(-1)) and lower value of band gap (1.8 eV) as an effect of interactive characteristic and semiconducting behaviour. The fast decline in pesticide concentration followed by a gradual decrease demonstrated I-st order kinetics triggered by Langmuir adsorption. The availability of active species such as oxygen(,) hydroxyl radicals and holes, which are liable for pesticide breakdown, proved by scavenger analysis. Formation of safer metabolites during the photocatalytic studies confirmed by the LC-MS studies. Finally, modified BC@ Fe2O3 nanohybrid may prove to be a viable alternative catalyst for industrial applications due to their reusability (n=7), charge separation, stability and high surface activity.