Sorption of Pb(II) from aqueous solution by konjac glucomannan beads

Abstract

Konjac glucomannan beads have been investigated as metal biosorbent for Pb(II) from aqueous solutions. The effect of contact time, solution pH, initial metal concentration, and desorption were studied in batch experiments at 20°C±2°C. Maximum mental sorption was found to occur at initial pH 4.0–5.5. Kinetic studies revealed that the initial uptake was rapid and equilibrium was established in 3 h and that the data followed the prseudo-second order reaction. The equilibrium sorption data at initial pH 4.0 were described by the Langmuir and Freundlich isotherm models; however, Langmuir isotherm model has been found to provide the best correlation. The highest value of Langmuir maximum uptake (q max) was found to be 105.71 mg·g−1. Similar Freundlich empirical constant (K F) was obtained to be 1.98 for lead. Adsorption-complexation may be involved in the sorption process of lead. Desorption experiments showed evidence that after two contacts neither HCl nor EDTA solutions were able to desorb lead from the konjac glucomannan beads, but the desorbtion efficacy of HCl solution was higher than EDTA solution. The results obtained show that konjac glucomannan beads may be used for the treatment of wastewater contaminated with lead.