Effect of adsorption parameters on biosorption of Zn++ ions from aqueous solution by graft copolymer of locust bean gum and polyacrylamide

Abstract

Graft copolymers of locust bean gum (LBG) and polyacrylamide have been synthesized using ammonium persulphate (APS) as initiator for removal of Zn⁺⁺ ions from water systems. The effect of reaction variables including the concentration of acrylamide 10 to 30 g/L, APS 0.1×10^-3 to 10×10^-3 mol/L, LBG 10 to 25 g/L, time duration 30-180 min and temperature 40-80^oC have been studied. Grafted copolymer has been characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). To optimize the adsorption conditions several experimental parameters were varied. The sorption data obeyed Langmuir and Freundlich sorption isotherms. The Langmuir sorption capacity (Q_max) is found to be 30.30 mg/g. Freundlich constants, K_F and n, are found to be 9.04 and 3.73, respectively. The adsorption of Zn⁺⁺ ions by graft copolymer has been assessed by FTIR and SEM analysis. A metal capped structure is observed by SEM analysis after Zn⁺⁺ biosorption. The results of the study indicate that the synthesized graft copolymer is an efficient adsorbent for removal of Zn⁺⁺ ions from water systems.