Kinetics and competitive modeling of cesium biosorption onto iron(III) hexacyanoferrate modified pine cone powder

Abstract

This study looked at incorporation of iron(III) hexacyanoferrate onto chemically treated pine cone via iron(III) surface loading and its application for cesium (Cs) adsorption in the presence of alkali/alkali earth metals. The optimum iron(III) loading concentration was 2.50 mol l−1 at pH 7, while optimum hexacyanoferrate (HCF) loading was achieved at a hexacyanoferrate concentration of 0.26 mol l−1. The best-fitting kinetic model was confirmed using the closeness of the predicted equilibrium capacities to the experimentally determined capacity, three error determination methods, and the comparative plots of predictive and experimental uptake of Cs with time. The adsorption rate constants were reduced by alkali/alkali metal addition and the reduction was higher in the HCF-modified pine. The mechanism of Cs adsorption onto raw pine followed the pseudo-second-order model and involved stripping of the hydration water from the metal ion. The presence of Na+ did not alter the adsorption mechanism but Ca2+ addition changed the best-fitting model to pseudo-first-order. The diffusion-chemisorption model best fitted Cs adsorption onto HCF-modified pine and involved adsorption of Cs in its hydrated form, which migrated easily through the zeolite-like lattice of hexacyanoferrate. Addition of Na+ and Ca2+ changed the best-fitting model to a pseudo-first-order model.