Arsenic Adsorption from Aqueous Solution by Waste Tea:Kinetic and Thermodynamics Studies

This study is to assess the uptake of tervalent arsenic from aqueous solutions onto waste tea; The variables (pH, contact time and temperature) affecting process was investigated in order to found optimum biosorption conditions. The results showed that the maximum adsorption was noted at pH 7.0 and attained at 150 min; the maximum efficiency increased from 33.2% to 37.8% with an increase in temperature from 20 to 40℃ at 0.2 mg / L of initial As3+ ion concentration. The adsorption of As3+ ions increased with increasing temperature indicating endothermic of the adsorption process. The adsorption data follow the Langmuir model and the Freundlich model; Kinetic parameters were evaluated and found that Pseudo-second-order rate kinetic model showed the better correlation at different temperature; Various thermodynamic parameters, such as △G°, △H° and △S°have been calculated at different temperature. It indicated that the adsorption process was spontaneous and endothermic.