Removal of As3+, As5+, Sb3+, and Hg2+ ions from aqueous solutions by pure and co-precipitated akaganeite nanoparticles: adsorption kinetics studies

Adsorption kinetics models have been used to evaluate the adsorption behaviour of pollutants on different materials but there are no reports for the adsorption of As5+, As3+, Sb3+ and Hg2+ on co-precipitated akaganeite nanoparticles which were previously formed in the presence of these ions. In this research, the performance of pure and co-precipitated akaganeite nanoparticles as adsorbents of As3+, As5+, Sb3+ and Hg2+ in aqueous solutions was evaluated using the nonlinear kinetics models of Langmuir, Lagergren, Ho-McKay, Bangham, Elovich and simplified Elovich. In addition, transmission Fe-57 Mossbauer spectrometry was used for the first time to compare the physico-chemical properties of akaganeite before and after the adsorption processes. The results showed that co-precipitated akaganeites had much better adsorption capacities than pure akaganeites. On the other hand, the Sb3+ and Hg2+ were the fastest and slowest pollutants respectively adsorbed on all akaganeites. The kinetics models that best described the experimental data for As3+, As5+ and Sb3+ were those of Elovich and simplified Elovich. For Hg2+, the kinetic model that best described the experimental data was that of Bangham. The 300 K and 77 K Mossbauer spectrometry showed only slight variations in some of the hyperfine parameters for the akaganeites after adsorption.