Özet:

In this research, the adsorption capacity of fly ash, which was obtained from Hopa Thermal Power Plant using fuel-oil, was studied with the use of Crystal Violet (CV) dyestuff. For that purpose, the effects of pH, initial CV dyestuff concentration, the dosage of fly ash (FA), and its particle size, and of temperature on the adsorption process were investigated in order to determine the optimum conditions for the adsorption. It was obtained that the highest adsorption capacity of FA with CV dyestuff, a cationic compound, was obtained at the original pH of the dye solution (5.48), and that fly ash with a size of more than 75 μm was found to be optimal for the process. While it was noticed that increasing temperature enhanced adsorption efficiency, adsorption equilibrium also fitted very well to Freundlich isotherm, and the highest adsorption capacity was calculated as 0.541 mg/g at 40 oC. The results of kinetic studies suggested that the adsorption fitted into Pseudo-Second-Order Kinetic model, and the rate constant (k2) were calculated as 0.283, 0.158 and 0.141 min-1 at specific temperature values of 20, 30 and 40 oC respectively. Intraparticle Diffusion Model was also analyzed and found that it was efficient on the adsorption kinetics but not on rate-controlling step. According to the thermodynamic studies, the Gibbs free energies (ΔGo) were calculated as -390.902, -514.042, and -637.182 kJ/mol at 20, 30 and 40 oC, respectively. This indicated a chemical adsorption process occurred spontaneously.

Anahtar Kelimeler: