Removal of Pb (II) from an Aqueous Solution Using Modified Cuttlebone as a Biosorbent

Abstract

Biosorption is a promising method for removing heavy metals from wastewater, evidenced by several studies on the high efficiency and cost-effectiveness of its practical usage. In the present study, cuttlebone powder (CB-P) and cuttlebone modified via carbonization at 400°C (CB-M400) were used to remove Pb (II) from an aqueous solution. The adsorbents were characterized using a scanning electron microscope (SEM) and an X-ray diffractometer. An adsorption study was carried out at different initial pHs, biosorbent doses, and initial Pb (II) concentrations, in batch experiments in order to evaluate the optimum conditions for Pb (II) removal. The results showed that CB-P obtained a larger specific surface area (8.41 m2/g) than CB-M400 (2.69 m2/g); however, the calcite in CB-M400 displayed a remarkably higher sorption capacity for Pb (II) than the aragonite in CB-P. The carbonization of organic matter in CB-P resulted in a higher calcium carbonate content and the formation of fixed carbon, increasing the adsorption capacity of CB-M400. Optimum conditions for removal of Pb (II) occurred at pH 4.0 with 0.2 g/L of the biosorbent dose. In an equilibrium study, Langmuir’s isotherm was fixed at R2 > 0.9; the maximum capacities were calculated to be 869.57 mg/g for CB-P and 1,573.56 mg/g for CB-M400. In a kinetic study, a pseudo second-order model was fixed; the higher adsorption rate was found in CB-M400.

Keywords

• Pb (II) removal
• biosorption
• cuttlebone
• modification