Removal of Acid Red 151 from water by adsorption onto nano-composite MnFe 2 O 4 /kaolin

Abstract

The adsorption of Acid Red 151 (AR151) from water was determined for kaolin, MnFe₂O₄ and MnFe₂O₄/kaolin magnetic nano-composite. MnFe₂O₄ and MnFe₂O₄/kaolin were prepared using a simple chemical co-precipitation procedure. The MnFe₂O₄/kaolin composite was prepared with Mn : Fe : kaolin mass ratios of 1 : 1 : 10, 1 : 1.5 : 10 and 1 : 2 : 10. The adsorption capacity increased in 1 : 2 : 10 Mn : Fe : kaolin. Powder XRD and SEM were used to characterize the sorbents. The spinel magnetic phase is present in the MnFe₂O₄. The AR151 adsorption is strongly dependent on pH and increases with increasing acidity with a maximum at pH 2. The adsorption capacity of the composite is greater than that of natural kaolin and MnFe₂O₄. The adsorption was not affected by the presence of chloride, but was significantly affected by sulfate. The adsorption kinetics of AR151 on kaolin and ferrite powder are similar, but the adsorption of AR151 on the MnFe₂O₄/kaolin composite is much more rapid and occurs within 2–5 min of contact. The adsorption process follows pseudo-second order kinetics. The solid magnetic composite could be conveniently recovered after adsorption.