Effect of a pH-controlled co-precipitation process on rhodamine B adsorption of MnFe2O4 nanoparticles

Abstract

We investigated the effect of a pH-controlled co-precipitation process on the adsorption behavior of manganese ferrite (MnFe₂O₄) nanoparticles as well as their structural and magnetic properties. The pH of prepared MnFe₂O₄ nanoparticles is typically an important factor affecting the adsorption capacity of an adsorbent. In this study, MnFe₂O₄ nanoparticles were prepared using a co-precipitation method at four different pH values of 9.0, 9.5, 10.0, and 10.5. The adsorption behaviors on rhodamine B (RhB) by MnFe₂O₄ nanoparticles prepared at different pH values were investigated. It was found that, via a pH-controlled process, MnFe₂O₄ nanoparticles prepared at pH 10.5 showed the highest RhB removal efficiency. The results indicated that the large pore size and surface charge of MnFe₂O₄ nanoparticles improved the adsorption capacities for RhB. Kinetic data were fitted to a pseudo-second order kinetic model and revealed that equilibrium was reached within 60 min. The isotherm data showed that the Langmuir maximum adsorption capacity of the MnFe₂O₄ nanoparticles prepared at pH 10.5 for RhB was 9.30 mg g⁻¹.