Adsorptive removal of malachite green using novel GO@ZnO-NiFe2O4-αAl2O3 nanocomposites

The performance of a newly prepared nanocomposite adsorbent containing nickel ferrite, zinc oxide and alpha alumina nanoparticles onto graphene oxide substrate was investigated for the adsorptive removal of malachite green. The composites were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM) and BET techniques. The results confirmed the presence of particles in the composites and structure of constituent particles in the composite was better preserved in COM4. The effect of pH (from 3 to 9), initial dye concentration (100 to 1500 mg/L), adsorbent mass, temperature (5 to 45 °C) and contact time on adsorption efficiency was examinaed using linear and non-linear adsorption models. Maximum adsorption was observed for linear Langmuir model (607.66 mg/g) at pH 7 under ambient temperature. The contact time showed 73 % of dye adsorption within the first 15 min. Experimental data fitting showed good agreement with Freundlich adsorption isotherm in the pseudo-first-order linear kinetic model as well as the pseudo-second-order nonlinear kinetic model with a correlation coefficient of 0.97. Also, adsorption mechanism was proposed by surface functional groups, electrostatic interactions, H-bonding, π-π interactions, and permeation of MG dye molecules into the pores of the adsorbent. The adsorbent showed good performances up to three cycles after washing with ethanol when compared to acetone and water.