Adsorption of tetracycline using CuCoFe2O4@Chitosan as a new and green magnetic nanohybrid adsorbent from aqueous solutions: Isotherm, kinetic and thermodynamic study

Abstract

Utilizing a new microwave-assisted method, CuCoFe 2 O 4 @Chitosan (Ch) was synthesized as a very strong, magnetically separable nano-adsorbent. The magnetic nanohybrid adsorbent was characterized by FESEM (Field emission scanning electron microscopy ) , EDS (energy dispersive X-ray), Mapping & Linescan, BET (Brunauer-Emmett-Teller), FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction analysis), TGA (Thermogravimetric analysis), and VSM (Vibrating Sample Magnetometer) techniques. Then, the adsorption process of Tetracycline (TC) was investigated. The highest percentage of pollutant adsorption on the synthetic and real samples was recorded at an initial concentration of 5 mg/L, pH 3.5, contact time of 20 min, the dose of 0.4 g/L, and temperature of 25 °C, 93.07 %, and 67%, respectively. The TC adsorption process via the synthesized magnetic nanocomposite was consistent with the Freundlich isotherm model (R 2 = 0.992) and pseudo -second-order kinetic (K 2 = 0.267). The outcomes of thermodynamic analyses, which included entropy changes (ΔS = 10.122 J/mol.k), enthalpy changes (ΔH = −1.975 kJ/mol), and the Gibbs negative free energy (ΔG = −4.992 kJ/mol), revealed that the adsorption process was spontaneous, favorable, and exothermic. The good magnetic properties allow easy separation after the adsorption operation. Finally, the efficiency of the nano-adsorbent in the removal process was 82.16% after four adsorption–desorption cycles. Some advantages of this research are a fast and green method for synthesis of adsorbent, fast kinetic, and magnetic properties to easy separation.