The adsorption in a batch system for methylene blue (MB) and methyl orange (MO) on waste ash were evaluated. The adsorption isotherms showed adsorptive maximum capacities for waste ash of MB and MO 40.983 mg g-1 35.614 mg g-1 respectively. The equilibrium adsorption data were fitted by Dubinin-Radushkevic (D-R) adsorption isotherm model. The estimated values of adsorption energy, Ea, calculated from the D-R isotherm, for both MB and MO and waste ash systems were found to be 0.015 kJ mol-1 , 0.091 kJ mol-1 at room temperature respectively which implies that adsorption of both MB and MO on waste ash (0.3 g) is by physical adsorption. Waste ash and the dyes loaded waste ash were characterized by SEM. We studied reusability and it was found that the waste ash is stable and regenerable by 5 M HNO3 without losing their activity. This research suggests that the waste ash can be an effective adsorbent for the removal of such acidic and basic dyes from aquatic solution.
Waste ash, Isotherm; Desorption