Transforming palm oil fuel ash into functional Cu/KCC-1 nanostructures: A sustainable route toward high-performing photocatalytic dye degradation

A waste-to-wealth strategy is reported for the fabrication of a copper-functionalized fibrous nanosilica (Cu/KCC-1) photocatalyst derived from palm oil fuel ash (POFA), an abundant silica-rich agricultural residue. The Cu/KCC-1 nanocomposite retains the characteristic dendritic fibrous architecture and high surface area of KCC-1, while incorporating catalytically active Cu species within the amorphous silica framework, as confirmed by FESEM, XRD, BET, FTIR, and UV–Vis DRS analyses. The resulting catalyst exhibits outstanding photocatalytic activity toward methylene blue degradation, achieving 94.30% efficiency under UV irradiation at pH 8 with a catalyst dosage of 3 g/L and an initial dye concentration of 10 mg/L. Reaction temperature strongly influenced performance, with optimal degradation at 50°C, beyond which charge-carrier recombination and partial deactivation limited the catalytic efficiency. The superior activity is attributed to enhanced light absorption, increased density of accessible active sites, and improved charge separation induced by Cu incorporation within the fibrous silica matrix. Alkaline conditions further promoted degradation by facilitating reactive oxygen species generation. A mechanism involving surface adsorption followed by •OH− and O2•− driven oxidative mineralization is proposed. This study demonstrates the viability of POFA-derived Cu/KCC-1 as a high-performance, low-cost, and sustainable photocatalyst for advanced wastewater remediation.