Design of lignin-based TiO2 composite for enhanced photocatalytic activity and its applications

Lignin with TiO2 necessitates careful consideration of the organic-to-inorganic ratio in order to achieve the desired functional characteristics. This study synthesized a Lignin-TiO2 hybrid material through a single-step process utilizing the Taguchi design, which significantly enhanced photocatalytic efficiency under visible light. The Lignin-TiO2 composite demonstrated improved dispersion, negative surface charge, lower bandgap energy, and reduced charge carrier recombination compared to the controls, resulting in a 2.2-fold increase in photocatalytic efficiency for the removal of methylene blue (MB) dye relative to pure TiO2. Additionally, lignin was found to be an effective inhibitor of photo-corrosion, significantly enhancing the stability of Lignin-TiO2 during 690 min of irradiation. The role of OH radicals in MB photodegradation was confirmed by the degradation of coumarin to 7-hydroxycoumarin (7-OHC). Moreover, Lignin-TiO2 displayed antimicrobial activity against S. aureus and showed potential as a filler in polyvinyl alcohol (PVA), extending the shelf life of cherry tomatoes by up to 7 days. This study presents a promising approach to enhancing visible light-active photocatalysts using renewable materials while highlighting the practical applications of the composite in environmental remediation and the preservation of agricultural products.