Analytical Investigation of the Photocatalytic Decolourisation of Textile Dye Effluents Using Titanium Dioxide-Embedded Polymer Nanocomposite Films

Textile dye effluent decolourisation using photocatalytic treatment represents an emerging low-energy alternative to conventional biological treatment for highly coloured wastewater streams from dyeing operations in North West Nigeria. This study analytically investigates the photocatalytic decolourisation efficiency of titanium dioxide nanoparticles embedded in polyethylene and polypropylene polymer nanocomposite films, evaluating their effectiveness for treating simulated reactive and direct dye effluents. Titanium dioxide nanoparticles at 5, 10, and 15 percent weight loadings were compounded into polymer matrices and fabricated into films by compression moulding. Film surfaces were activated under simulated solar UV irradiation. Decolourisation of Reactive Blue 19 and Direct Red 81 dye solutions at initial concentrations of 50 and 100 mg/L was monitored by UV-visible spectrophotometry at 60-minute intervals over 6 hours. Mineralisation was tracked by total organic carbon analysis. The effect of dye concentration, pH, and initial titanium dioxide loading on decolourisation kinetics was analysed using pseudo-first-order kinetic modelling. Results demonstrate that 15 percent titanium dioxide in polyethylene film achieved 94 percent decolourisation of Reactive Blue 19 after 4 hours under simulated solar irradiation at pH 7. Mineralisation lagged decolourisation, reaching 68 percent total organic carbon removal after 6 hours. Decolourisation rate constants decreased with increasing initial dye concentration, consistent with competitive adsorption at photocatalyst surface sites. Polypropylene matrix films outperformed polyethylene films in repeated use cycles, retaining 88 percent activity after five reuse cycles due to superior UV durability. The study recommends solar-driven polymer-supported titanium dioxide photocatalysis as a sustainable and reusable treatment option for small-scale textile dyeing operations in North West Nigeria. Keywords: photocatalytic decolourisation, titanium dioxide, polymer nanocomposite, textile effluent, reactive dye