Removal of Pb from Water by Adsorption on Apple Pomace: Equilibrium, Kinetics, and Thermodynamics Studies

The adsorption-influencing factors such as pH, dose, and time were optimized by batch adsorption study. A 0.8 g dose, 4.0 pH, and 80 min of contact time were optimized for maximum adsorption of Pb on AP. The adsorption isotherms (Langmuir and Freundlich) were well fitted to the data obtained with values of qmax (16.39 mg/g; r2=0.985) and K (16.14 mg/g; r2=0.998), respectively. The kinetics study showed that lead adsorption follows the pseudo-second-order kinetics with correlation coefficient (r2) of 0.999 for all of the concentration range. FTIR spectra also showed that the major functional groups like polyphenols (–OH) and carbonyl (–CO) were responsible for Pb binding on AP. The thermodynamic parameters as ΔG, ΔH (33.54 J/mol), and ΔS (1.08 J/mol/K) were also studied and indicate that the reaction is feasible, endothermic, and spontaneous in nature