Removal of methylene blue by African hazelnut shell modified by zero valent iron and silver bimetallic nanoparticles

This work focuses on MB sorption by hazelnut shell (HN) modified by zero valent iron and silver bimetallic nanoparticles. The purpose of this study is to understand the mechanisms that govern the elimination of MB and to find a suitable kinetics model of removal. Spectroscopic studies including FTIR, (TG-DSC), Methylene blue, Iodine number and effet of pHZPC were used for its characterization. Equilibrium data was examined using a comparison of linear Langmuir, Freundlich and Temkin isotherm models. The Freundlich and Langmuir isotherm provided the best fit to the experimental data for MB as indicated by the values of the regression coefficient. The kinetic rates were modeled by using the Lagergren-first-order, pseudo-second-order, Elovich and Intraparticle diffusion model. The pseudo-second-order model was found to explain the adsorption kinetics most effectively. The presence of intra-particle diffusion mechanism was prominent, although it was not the sole rate-determining step. The results showed that HN, HN-Fe0 and HN-Fe0/Ag0, can be effective for removing MB from solution