Valorization of Lignocellulosic Biomass for Photocatalytic Applications: 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.