Isotherm and kinetics modeling of Pb(II) and Cd(II) adsorptive uptake from aqueous solution by chemically modified green algal biomass

Abstract

In this study, the adsorption efficiency of epichlorohydrin modified fresh water green algal biomass was assessed for Pb(II) and Cd(II) uptake from aqueous solution. The process parameters such as contact time, dose, initial metal concentration, solution pH and temperature were optimized. The Langmuir, Freundlich, Temkin and Dubnin–Redushkevich isotherm model was applied to the equilibrium data, which best fitted the Langmuir isotherm indicating homogenous distribution of adsorption sites. The monolayer adsorption capacity was 100.00 for Pb(II) and 72.46 mg/g for Cd(II) adsorption. The kinetic data was best described by pseudo-second order model, with intraparticle and liquid film diffusion controlled mechanism. The negative values of Gibbs free energy change (ΔGº) and positive enthalpy change (ΔHº) showed that adsorption process was spontaneous and endothermic. The functional groups, surface morphology and elemental composition of adsorbent, before and after adsorption, was evaluated using FTIR spectra, SEM and EDS studies. The study revealed that the modified algal biomass can effectively and efficiently remove the title metal ions from aqueous solution.