Use of Activated and Modified Pumice Stone for Removal of Mercury (II) and Arsenic (III) Ions From Aqueous Solution

Removal of Hg (II) and As (III) ions from aqueous solutions using activated and modified pumice stone were investigated. The pH, temperature, initial metal ion concentration which are very important for removal studies, were investigated by batch method. The experiments demonstrated that the equilibrium adsorption data fit the Freundlich isotherm model well for Hg (II) and As (III) ions. The negative value of ΔH° = -199.92 kJ mol-1 and -78,15 kJ mol-1 for mercury (II) and arsenic (III) ions indicates that the adsorption process is exothermic. ΔS° were calculated as -267.85 J K-1 mol-1 for As (III) ions and the positive value of ΔS° = 0.69 kJ K-1 mol-1 for Hg (II) ions. The negative value of ΔG°=-405.14 kJ mol-1 for Hg (II) ions and -1.67 kJ mol-1 for As (III) ions indicates that adsorption is voluntary. EDTA has been found to be a good desorbent in desorption studies to recover arsenic and Hg ions. The experiments show that pumice stone can be used for Hg (II) and As (III) removal in aqueous solution.