Isothermal and Batch Adsorption Studies of Malachite Green Oxalate Dye onto Activated Carbon from Snail Shell

Adsorption efficiency, kinetic and thermodynamic studies of the adsorption of Malachite green oxalate onto activated carbon from snail shell was carried out. The cleaned Snail shell was carbonized at 400oC, crushed and sieved before it was activated with 0.1m HCl at 800oC in a furnace. Batch adsorption experiment was carried out at variable concentration, time and temperature while other factors are kept constant. The adsorption isotherms used show that the correlation coefficient of Freundlich isotherm is closer to unity compare to that of Langmuir isotherm. The adsorption follows the Pseudo second order kinetic with adsorption capacity of 1.7544 (mg/g) and rate constant of 0.471(g/mg.min). The thermodynamic parameters: change in enthalpy, ∆H = 15.90 KJ/mol, change in entropy ∆S = 60.16J/mol. K and the change in Gibbs free energy ∆G = -1.69, -2.98, -3.64, -3.24, -3.43 and -3.51 KJ/mol at 303, 308, 313, 318, 323 and 328K respectively. These results show that activated carbon from snail shell has the potential of a good low cost adsorbent for the removal of this hazardous dye from wastewater.