Performance evaluation of agro-waste (sugarcane bagasse ash) for MB dye effluents removal under UV and dark environmental conditions: A cost-effective approach

The current work presents a relatively simple, cost-effective, and environmentally friendly solution for the removal of dye effluents from wastewater. The work demonstrated the treatment of MB dye effluents using varying contents of SBA. The performance of SBA contents in MB dye solution was evaluated via absorbance values of the supernatant measured under dark and UV environments at different time intervals varying from 0.5 to 120 h. The obtained result shows that after 6 h of contact between the MB dye (5 ppm) and SBA (20 mg), the removal efficiency of SBA in a dark environment was found to be 44.6% in comparison to 55.2% under a UV environment. The data suggests the greater removal efficiency of UV-irradiated dye samples in comparison to the samples kept in dark. Further, the concentration of dye decreased to 2.7 mg/L from the initial concentration (5 mg/L) after 6 h of addition of 20 mg of SBA, while it decreased to 2 mg/L after exposure to the UV environment. Adsorption kinetic models such as pseudo-first and pseudo-second-order were applied to find the rate of adsorption on SBA. The practical feasibility of SBA as a dye removal agent was checked using an unknown yellowish-green colored dye. The results confirmed the removal of dye from the wastewater to a significant extent in about 15 min, which proves its importance for industrial applications. The experiments for the desorption of dye molecules from SBA were performed in an acidic medium (0.1 M HNO₃) of pH = 1. This provision resulted in the desorption of the MB dye from the SBA into the solution through electrostatic forces of repulsion. The desorption results confirmed the recovery of SBA. The obtained SBA at the end of the process can be reused again for the removal of dye molecules and hence provides an additional advantage in large-scale industrial applications in terms of the cost-effectiveness of the approach.