Phenolic resin derivatized TiO₂-walnut shell carbon hybrid materials for solar photocatalytic phenol removal

As a toxic organic pollutant in industrial wastewaters, phenol wastewater treatment is investigated extensively. TiO₂ based photocatalysts are widely used for such applications, due to its ecofriendly properties, ease of preparation, low toxicity and recycle stability. In this study, phenolic-resin-modified TiO₂ (PF/TiO₂), TiO₂/WSC (Walnut shell carbon) and PF/TiO₂/WSC hybrid composites were successfully synthesized by a sol-gel method. The obtained TiO₂-based composites were characterized by BET, XRD, SEM, FTIR and XPS techniques. The phase characterization results showed that the TiO₂ phase was anatase in the PF/TiO₂/WSC (300 °C, 2 h) composite. TiO₂ was uniformly loaded on the surface of the WSC, as revealed by a shift in the Ti binding energy. Ti–O–C bonds are formed in the prepared TiO₂/WSC and PF/TiO₂/WSC (300 °C, 2 h) photocatalyst. Using a catalyst dosage of 2.0 g/L and an initial phenol concentration of 80 mg/L, the 10%PF/30%TiO₂/WSC composite showed the best activity with 88% degradation obtained under sunlight for 150 min. The active species of PF/TiO₂/WSC photocatalytic degradation of phenol were ·OH and ·O₂⁻, and a photocatalytic degradation mechanism was proposed. The synergistic system of WSC adsorption and the superior photocatalytic performance of phenolic-resin-modified TiO₂ achieved high degradation efficiency of pollutants in water. This research provides an environmentally friendly method for utilizing agricultural wastes and applies a new idea for solar photocatalytic removal of pollutants.