Kinetics and thermodynamics studies of silver ions adsorption onto coconut shell activated carbon

The presence of silver in the natural water environment has been of great concern because of its toxicity, especially when it is in the free ion form (Ag+). This paper aims to study the adsorption kinetics of silver ions from an aqueous solution onto coconut shell activated carbon using batch methods. Batch kinetic data were fitted to the first-order model and the pseudo-second-order model, and this last equation fits correctly the experimental data. Equilibrium experiments were carried out at 30 degrees C, 40 degrees C, and 50 degrees C. The adsorption isotherms were reasonably fit using Langmuir model, and the adsorption process was slightly influenced by changes in temperature. Thermodynamic parameters (H degrees, G degrees, and S degrees) were determined. The adsorption process seems to be non-favorable, exothermic, and have an increase in the orderness.