Malachite green adsorption onto Fe 3 O 4 @SiO 2 -NH 2 : isotherms, kinetic and process optimization

Higher environmental standards have made the removal of dye from water an important problem for many industrialized countries. Among the removal methods, magnetic adsorbents have received much attention for adsorption of dyes. In this paper, a novel magnetic adsorbent with an amino-modified SiO 2 -coated Fe 3 O 4 magnetite was prepared. The analysis of Fe 3 O 4 @SiO 2 -NH 2 proved that the nanoparticles were uniform with a diameter of 90 nm. The difference between Fe 3 O 4 @SiO 2 -NH 2 and Fe 3 O 4 @SiO 2 on the adsorption behaviour of malachite green was studied. Fe 3 O 4 @SiO 2 -NH 2 showed a good capacity for the adsorption of malachite green compared with Fe 3 O 4 @SiO 2 , which was shown to be influenced by the initial concentration and pH. Under the optimal conditions, the removal efficiency of malachite green was over 90% by Fe 3 O 4 @SiO 2 -NH 2 , while using Fe 3 O 4 @SiO 2 efficiency was below 60%. The experimental data fit well with the Freundlich isotherm and the pseudo-second-order kinetic model. In further applications, real samples were treated with Fe 3 O 4 @SiO 2 -NH 2 nanoparticles. All the results demonstrated that the Fe 3 O 4 @SiO 2 -NH 2 nanoparticles could be promising and effective adsorbents.