Detoxification of Real Pulp and Paper Industry Wastewater via Sunlight-Assisted Dual Technology Employing Waste Driven Composite: A Parametric Optimization and Statistical Analysis

Using industrial waste-driven Fe-TiO₂ composite, this study focuses on the removal of color remaining in secondary treated effluent from the pulp and paper industry. This composite facilitated a hybrid system of photocatalysis and photo-Fenton for the treatment of real industry wastewater. The catalyst performance was evaluated in terms of durability, quantum yield, and several other factors. The hybrid, photocatalysis, and photo-Fenton process have a quantum yield of 0.184 \(\times\) $\times$ 10⁻¹⁵, 0.00071 \(\times\) $\times$ 10⁻¹⁵, and 0.00044 \(\times\) $\times$ 10⁻¹⁵, respectively. With more quantum yield, the first-order rate constant (k) of the hybrid process was 16–24 times higher than the individual processes. The optimized values for this system came out to be pH = 4.3, H₂O₂ dose = 587 mg L⁻¹, % surface area covered = 91.4%, and time = 60 min. A significant color and COD reduction of 89% and 60%, i.e., it got reduced from 400 to 160 mg/L, respectively, was observed for these optimized parameters. The Fe-TiO₂ composite showed its efficacy to retain its hybrid nature even after 50 recycles as only a 5–10% reduction in efficiency (in terms of color and COD reduction) was observed. The results of the present study show the potential of composite fabricated from waste for effective color and COD removal in very less time, implying that the technique with reactor modifications can opt as a tertiary treatment in real-life applications.