Abstract:
The use of low-cost, locally available, highly efficient, and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from waste water. This study investigates the potential use of activated carbon prepared from sugar-cane (bagasse), cassava peels, and groundnut shell for the removal of carmine dye from simulated waste-water. The effect of adsorbent dosage, initial dye concentration, temperature, contact time and pH were investigated and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbents increased, the percentage of dye removal increased accordingly. The maximum removal of carmine dye was obtained at pH 2 as 96.84% (bagasse), 95.96% (cassava peels), and 88.07% (groundnut shell) for maximum adsorbent dose of 0.25 g/50 ml at 25 mg L-1 initial dye concentration at room temperature. The adsorption kinetics of carmine dye was studied and the rate of adsorption was found to conform to pseudo-second order kinetics with a good correlation (R2 > 0.99) with intra-particle diffusion as one of the rate determining steps. The equilibrium data were analysed and fitted well to the Langmuir, and Freundlich isotherm. The adsorption thermodynamics of the adsorbents were also studied and the results revealed that ΔH0 had negative values, indicating chemisorptions and exothermic nature of the adsorption process, while positive values of ΔG0 indicated the non-spontaneity of the adsorption process. Activated carbon developed from non-woody product wastes (cassava peels, groundnut-shell and bagasse from sugar-cane) can be an attractive option for dye removal since test reaction made on simulated dyeing wastewater showed better dye removal.
