PHOTOCATALYTIC DEGRADATION OF CASSAVA WASTEWATER USING ACIDACTIVATED CLAY-TIO₂ COMPOSITES UNDER UV-IRRADIATION

The cassava processing industry produces large quantities of wastewater that is highly contaminating, marked by a severe organic load and the presence of toxic cyanide. This wastewater represents considerable threats to public health and the environment. Conventional treatment methods often lack efficiency or are too costly, particularly for small-scale processors. This study explored the creation and effectiveness of an economical, sustainable photocatalytic system based on acid-activated clay-TiO₂ composites for breaking down cassava wastewater when exposed to UV light.Kaolin and bentonite clays from Auchi, Nigeria were sourced locally and their surface properties were enhanced through acid activation using 2M H₂SO₄. Using a direct impregnation method, composites were synthesized with TiO₂ (Degussa P25). Characterization of the materials with SEM, XRD, FTIR, and XRF confirmed successful acid activation, as demonstrated by increased porosity and surface area, along with the effective formation of the clay-TiO₂ composite. With a pH of 4.1, a COD of 32,000 mg/L, a BOD₅ of 18,500 mg/L, and a cyanide concentration of 50 mg/L, the raw cassava wastewater demonstrated significant pollution strength.The photocatalytic degradation experiments assessed the influence of catalyst dosage, irradiation time, pH, and initial cyanide concentration. Under optimal conditions (catalyst dosage: 1.5 g/L,pH: 3.0, irradiation time: 180 min), the acid-activated Bentonite-TiO₂ composite achieved a maximum cyanide removal efficiency of 94.7%,surpassing that of the Kaolin-TiO₂composite(88.9%).The kinetic analysis indicated that the degradation process adhered to a pseudo-firstorder model, with the Bentonite-TiO₂ composite showing a higher apparent rate constant (0.0154min⁻¹)than that of Kaolin-TiO₂(0.0116 min⁻¹).The bentonite-based composite performsbetter due to its enhanced porosity, increased surface area, and improved TiO₂ dispersion, which together improve adsorption and photocatalytic degradation.This research effectively shows that acid-activated clay-TiO₂ composites, especially those made with bentonite, serve as highly effective, economical, and environmentally friendly catalysts for cassava wastewater treatment, presenting a promising sustainable approach to pollution reduction in the agro-processing sector