Removal of As(3+), As(5+), Sb(3+), and Hg(2+) 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 As(5+), As(3+), Sb(3+) and Hg(2+) 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 As(3+), As(5+), Sb(3+) and Hg(2+) in aqueous solutions was evaluated using the nonlinear kinetics models of Langmuir, Lagergren, Ho–McKay, Bangham, Elovich and simplified Elovich. In addition, transmission (57)Fe Mössbauer 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 Sb(3+) and Hg(2+) were the fastest and slowest pollutants respectively adsorbed on all akaganeites. The kinetics models that best described the experimental data for As(3+), As(5+) and Sb(3+) were those of Elovich and simplified Elovich. For Hg(2+), the kinetic model that best described the experimental data was that of Bangham. The 300 K and 77 K Mössbauer spectrometry showed only slight variations in some of the hyperfine parameters for the akaganeites after adsorption.