Competitive removal of cadmium and lead ions from synthetic wastewater using Kappaphycus striatum

Abstract

Abstract The main aim of this study was focused on modeling of simultaneous biosorption of Cd2+ and Pb2+ ions from aqueous solution using Kappaphycus striatum. The effect of process parameters (pH, biosorbent dosage, temperature, initial metal ion concentration, and time) on biosorptive efficiency was examined. The greatest removal efficiency of Pb2+ ions (97.82 %) and Cd2+ ions (86.73 %) was observed at pH 4 and 5, respectively. For simultaneous removal of Pb2+ and Cd2+ ions, the optimum values of process parameters were chosen as biosorbent dosage (1 g/L), pH (5.0), and temperature (30 °C). The equilibrium has been achieved at 60 min. The total removal percent was 45.77 % for total 350 mg/L Pb2+ and Cd2+ ions mixture. The single metal ion biosorption study was done to obtain the parameters which were required for multicomponent biosorption isotherms. For single metal ion system six isotherm models were fitted to experimental data. The best fitted isotherm model for Cd2+ and Pb2+ ions was Fritz and Radke-Prausnitz, respectively. Six multicomponent isotherm models were analyzed to determine the best fitted isotherm model for multicomponent system by minimizing Average Relative Error function. For multicomponent biosorption system, extended Freundlich was found to be the best fitted model. In this study, the mutual effect of both metal ions on Kappaphycus striatum was antagonistic. The biosorption of both metal ions followed pseudo-second order kinetics which shows the chemisorption mechanism. Thermodynamic study confirmed the spontaneous, feasible, and endothermic nature of Cd2+ and Pb2+ ions biosorption on Kappaphycus striatum.