Removal of methylene blue from synthetic wastewater by the selected metallic oxides nanoparticles adsorbent: equilibrium, kinetic and thermodynamic studies

Abstract

A batch equilibrium system was utilized to examine methylene blue (MB) adsorption on prepared NiO and CuO nanoparticles (NPs). Different factors affecting the adsorption performance of NiO and CuO NPs with respect to MB were studied. Isotherm data were analyzed using the models of Langmuir and Freundlich at different temperatures, with that of Langmuir providing the best results. Higher MB adsorption capacities (166.67 mg/g, 156.25 mg/g, and 111.11 mg/g) were found for NiO NPs than for CuO NPs (28.66 mg/g, 34.47 mg/g, and 50.25 mg/g) at 30 °C, 45 °C, and 60 °C, respectively. Kinetic data were examined using models of the pseudo-first-order, pseudo-second-order, and intraparticle diffusion, and were best described by the pseudo-second-order model. The observed adsorption rates of MB on CuO NPs were higher, while the total adsorption capacity of NiO NPs was higher, and the adsorption thermodynamic values were exothermic for NiO NPs and endothermic for CuO NPs.