<p>Arsenic (As) contamination in water supplies poses severe risks to human health and ecosystems, necessitating high-efficiency, regenerable, and cost-effective adsorbents. In this study, a bimetallic layered double hydroxide hybrid (MnFe-LDH/BC@H3BTC) was constructed using biochar (BC) and 1,3,5-benzenetricarboxylic acid (H3BTC) as a ligand-regulated structure for enhanced arsenite [As(III)] removal. MnFe-LDH/BC@H3BTC exhibited 99.4% As(III) removal at pH 7 within 2&#xa0;h equilibrium, showed superior adsorption capacity (2.99 mgg⁻¹) compared to MnFe-LDH (2.2 mgg⁻¹) and MnFe-LDH/BC (2.58 mgg⁻¹). Characterization (XRD, FTIR, 2D-COS, BET, and XPS) revealed synergistic contributions from redox-active Mn²⁺/Mn³⁺ and Fe²⁺/Fe³⁺, ligand exchange with -OH and -COOH groups, and a BET surface area enhancement from 4.15 to 122.17 m²g⁻¹. Kinetic and isotherm modelling followed pseudo-second-order (R²=0.99) and Langmuir monolayer adsorption, confirming a chemisorption mechanism. HPLC speciation demonstrated time-resolved As(III) to As(V) oxidation. Real water application tests confirmed 2.82 mg g⁻¹ As(III) removal, and regeneration studies confirmed high stability over five cycles with minimal metal leaching. This study provides a scalable, multifunctional strategy for As(III) remediation and contributes to understanding ligand-mediated redox-adsorption mechanisms in hybrid sorbents.</p> Graphical Abstract <p>The graphical abstract presents a visual summary of the synthesis, mechanistic pathways, and real-world performance of MnFe-LDH/BC@H3BTC for efficient arsenic removal from contaminated water. In the Preparation phase, manganese-iron layered double hydroxide (MnFe-LDH) is integrated with biochar and functionalized using trimesic acid (H3BTC), forming a porous and reactive hybrid structure. This composite material is engineered to provide abundant active sites for interaction with arsenic species. The Oxidation and Removal section details the mechanistic transformations involved in arsenic remediation. Arsenite (As(III)) undergoes oxidation to arsenate (As(V)) facilitated by redox-active Mn species, while multiple removal pathways electrostatic attraction, ligand exchange, complexation, and hydrogen bonding-contribute to the stable immobilization of arsenic on the material surface. This segment depicts the transformation and sorption processes, emphasizing the synergy between functional groups and structural components. In the Performance section, experimental data show that MnFe-LDH/BC@H3BTC achieves rapid removal of As(III), with a sorption efficiency of 99.4% within just 2&#xa0;h, outperforming the individual or partially modified components. The MnFe-LDH/BC@H3BTC composite demonstrates excellent potential as a practical and scalable solution for arsenic remediation in real water systems, offering a combination of rapid kinetics, high efficiency, and multifunctional removal mechani</p> <p></p>