WITHDRAWN: A new Fe3O4/CuO/AC Nanocomposite for Imidacloprid Removal: Characterization, Optimization, and Adsorption Modeling

Abstract

A new magnetic adsorbent (Fe3O4/CuO/AC) composed of magnetite (Fe3O4) and copper oxide (CuO) nanoparticles Impregnated with activated carbon (AC) has been fabricated and used for the first time to remove imidacloprid (IMCP) insecticide from the aqueous solutions. This composite was characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, energy dispersive x-ray diffraction, and vibrating sample magnetometer. The main influential factors such as the solution pH, the adsorbent amount, temperature, agitating time, and initial pesticide concentration were also tested to evaluate the optimized condition. Based on the results obtained from isotherm and kinetic modeling, the adsorption mechanism of IMCP on Fe3O4/CuO/AC is a combination of physisorption and chemisorption phenomena. The experimental data fitted best to the Freundlich isotherm model revealing the presence of heterogeneous sites for IMCP adsorption. Besides, the kinetics results revealed that the adsorption process well fitted with pseudo-second-order model, implying that the chemisorption was determining step in adsorption process. Thermodynamic results showed the spontaneous and exothermic nature of the adsorption process. Under optimal conditions (pH 7; contact time, 10 min; initial pesticide concentration, 10 mg L-1), IMCP removal efficiency was 99.6%, indicating the excellent ability of Fe3O4/CuO/AC nanocomposite for the adsorption of this pesticide from water solutions.