Kinetic and Pseudo-Second-Order Modeling of Lead Biosorption onto Pine Cone Powder

The sorption of lead(II) onto pine cone powder (PCP) and 0.15 mol/L NaOH treated pine cone powder (PCP 0.15), an abundant agricultural waste from the wood industry, was studied to evaluate the effect of NaOH treatment on the kinetics of lead(II) uptake by performing batch kinetic sorption experiments. Batch biosorption kinetics was performed by varying biosorbent dose and initial lead(II) concentration and the kinetic data modeled using the pseudo-first, pseudo-second intraparticle, and Bangham diffusion models. The results revealed that NaOH treatment changed the pattern of the biosorption kinetics, the biosorption kinetic parameters, and influenced the rate-limiting step. The pseudo-second-order kinetic model gave a better fitting of the kinetic data for both PCP and PCP 0.15. The batch biosorption model, based on the pseudo-second-order mechanism, was applied to predict the rate constant of biosorption, the equilibrium capacity, the initial sorption rate, the effects of biosorbent dose, and initial lead(II) concentration. Equilibrium concentrations were evaluated with the equilibrium capacity obtained from the pseudo-second-order rate equation. In addition, pseudo-isotherms were obtained by changing initial lead(II) concentration using the equilibrium concentration and equilibrium capacity obtained based on the pseudo-second-order constants.