Engineering phytogenic groundnut shell biochar supported MgFe2O4 nanoarchitecture for sunlight driven detoxification of organic contaminants

The development of efficient nanocatalysts for eliminating chemically distinct organic pollutants under natural sunlight is of significant interest to current research. To address this gap, a biomass-derived groundnut shell biochar-supported MgFe 2 O 4 nanocomposite (GNS@MgFe 2 O 4 ) was synthesized via a green route using Murraya koenigii leaf extract. Comprehensive structural and physicochemical characterization confirmed the successful formation of a mesoporous GNS@MgFe 2 O 4 nanocomposite possessing a specific surface area of 30.44 m 2 g −1 and a reduced optical band gap of 2.01 eV, facilitating efficient sunlight harvesting, enhanced adsorption and photocatalytic activity. Under optimized conditions (pH 7), the GNS@MgFe 2 O 4 exhibited superior photocatalytic performance, achieving 93.1% removal of benzyl butyl phthalate (BBP; 20 mg L −1 , 20 mg catalyst) and 96.2% removal of indigo carmine (IC; 11 mg L −1 , 15 mg catalyst) within 120 and 80 min, respectively, significantly outperforming pristine MgFe 2 O 4 nanoparticles. Adsorption equilibrium was best described by the Langmuir isotherm, while the degradation process followed first-order kinetics. Scavenging experiments revealed that hydroxyl ( OH) radicals predominantly governed BBP degradation, whereas superoxide ( O 2 − ) radicals primarily contributed to IC degradation. GC–MS and TOC analyses confirmed the proposed degradation pathways and substantial mineralization. The GNS@MgFe 2 O 4 composite showed promising results with excellent activity over nine reuse cycles with no significant structural changes, demonstrating remarkable stability. Overall, this study demonstrates the fabrication of a novel biomass-derived GNS@MgFe 2 O 4 nanocomposite that integrates waste feedstock and green synthesis to enable efficient, sunlight-driven removal of two chemically distinct organic contaminants (BBP and IC) via a reusable photocatalyst for environmental remediation.