Valorization of agro-industrial waste into nanoparticle-modified biochar for sustainable wastewater treatment

This study presents the synthesis of a TiO₂/Fe₃O₄-modified biochar derived from agro-industrial residues for multifunctional wastewater treatment. The objective was to develop a low-cost, sustainable material integrating adsorption, photocatalysis, and magnetic separation. Biomass was pyrolyzed under controlled conditions and chemically activated using KOH and ZnCl₂ to enhance porosity and surface functionality. TiO₂ was deposited via the sol–gel method, followed by co-precipitation of Fe₃O₄ nanoparticles to impart photocatalytic and magnetic properties. The composite was characterized using XRD, FTIR, SEM-EDS, BET, and VSM techniques.
The synthesized material exhibited a high specific surface area of 312 m²·g⁻¹ and demonstrated strong Pb²⁺ adsorption capacity of 168 mg·g⁻¹ at pH 5.0. Photocatalytic experiments using methylene blue (20 mg·L⁻¹) showed 94% degradation within 90 minutes under UV irradiation (λ = 365 nm). Adsorption kinetics followed a pseudo-second-order model, while equilibrium data were best described by the Langmuir isotherm. The composite retained 86% of its efficiency after five regeneration cycles, indicating good stability and reusability.
In conclusion, the developed TiO₂/Fe₃O₄-biochar composite offers an effective and sustainable solution for wastewater remediation, combining multiple treatment mechanisms in a single material.