Lead biosorption using shrimp shell: Kinetics, isotherms and pH-dependent adsorption

This study examined the adsorption of lead (Pb) ions from aqueous solution onto shrimp shell. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, equilibrium time, and different initial concentration of Pb(II) ions were evaluated. The results indicated that the pseudo-second-order kinetic model could describe the kinetics of Pb adsorption by the adsorbent. With increasing Pb concentrations from 100 to 1000 mgL-1, the amount of Pb adsorbed by shrimp shell increased from 9 mg g-1 to 90.2 mg g-1. Increasing suspension pH from 4 to 7, enhanced adsorption of Pb. Further increase in pH from 7 to 10 resulted in decreasing of adsorption of the metal ion. The average adsorption of Pb by the adsorbent at pH 6 and 7 was more than 95 percent. The Sips and Freundlich models well described the adsorption of Pb isotherms data. Infrared spectrum analysis of adsorbent before and after adsorption of Pb showed that the N atoms of the amine functional groups played a major role in shrimp shell for adsorption of Pb.