Valorizationof Lignocellulosic Biomass for PhotocatalyticApplications: Development of Activated Carbon-TiO₂ Composites

This study investigates the utilization of lignocellulosic biomass residues to prepare activated carbon (AC) with high porosity for use as a support for TiO₂ photocatalysts aimed at degrading organic contaminants. Residues like coffee husk, sugarcane bagasse, and coffee grounds were converted into porous AC supports via chemical activation with zinc chloride. TiO₂ was synthesized using the peroxide gel method to be supported on these ACs, which were extensively characterized. The ACs exhibited high specific surface areas (up to 1600 m² g^–1) and pore volumes that were suitable for supporting TiO₂. TiO₂ maintained its anatase phase after synthesis and dispersion on the ACs, with 10 ± 2 nm crystallite sizes. SEM and TEM analyses revealed good dispersion of TiO₂ nanoparticles on the AC surface. Photocatalytic assays showed that the AC-TiO₂ composites efficiently degraded N-acetyl-para-aminophenol (APAP) under ultraviolet (UV) light, surpassing pure TiO₂. Composites with higher TiO₂ content (85%) exhibited the best performance on the photodegradation, degrading 74% to 82% of APAP over 5 h. Pseudo-first-order kinetics indicated enhanced degradation rates for the composites compared to TiO₂. Furthermore, the AC-TiO₂ materials showed sustained photocatalytic activity over multiple cycles, confirming their stability and practical potential. XRD analysis verified the stability of the composites after six reuse cycles. This study demonstrates the feasibility of producing high-performance AC-TiO₂ composites from lignocellulosic residues, offering an economical and sustainable approach to environmental remediation technologies. The properties of ACs as TiO₂ supports enhance photocatalytic efficiency, promising significant applications in environmental cleanup and sustainable development.