The biosorptive effect of untreated and chemically modified fir cone powder on Pb(II) removal

In this work, the main aim was to investigate the adsorption potential of untreated and chemically modified (sodium hydroxide and hydrogen peroxide treatment) fir cone powder (Abies alba) for the removal of Pb(II) from aqueous solutions. The effect of contact time, initial concentration of Pb(II), initial pH and temperature was studied in a batch process mode. Adsorption isotherm models (Langmuir, Freundlich, Dubinin–Radushkevich (D–R) and Temkin) and kinetics (pseudo-first-order and pseudo-second-order) models for both processes (treated and untreated) were used to analyse the equilibrium data. The kinetic data were found to fit better the pseudo-second-order. Maximum adsorption capacities calculated using the Langmuir model are 4.8 and 2.9 mg/g for NaOH and H2O2 treated fir cone powder, respectively, and 3.7 mg/g for untreated fir cone powder. The results indicate that the NaOH treatment increases the fir cone powder adsorption capacity, while the H2O2 treated biomass showed a slight decrease in its adsorption capacity in comparison to the untreated one.