Removal of malachite green dye from aqueous solutions by a magnetic adsorbent

A magnetic adsorbent was prepared through chemical precipitation using a solution of iron salts and halloysite clay. The obtained material was then characterized and subsequently applied in the removal of malachite green (MG) dye. The pseudo-second-order model was found to explain the adsorption kinetics most effectively, while the equilibrium was well fitted with the Freundlich isotherm model. The data also suggest that MG dye adsorption was spontaneous and exothermic, involving physisorption. Moreover, the adsorbent can be easily separated from the aqueous medium by applying an external magnetic field and reused without significant loss of properties after its regeneration.