Enhanced removal of cefixime from aqueous solutions using Fe3O4@GO nanocomposite with ultrasonic: Isotherm and kinetics study

Antibiotics, including cefixime (CEX), are widely used in medicine and veterinary medicine and enter aquatic environments through various pathways such as agricultural runoff, direct dis-charge from municipal wastewater treatment plants, human excreta, direct disposal of medical, veterinary, and industrial wastewaters. The aim of this study was to investigate the applicability of GO (graphene oxide)-Fe3O4 nanocomposite with ultrasonic (US) in the removal of CEX from aqueous solutions. To conduct the experiments of this experimental-lab scale study, application of the response surface methodology was considered. The effect of important operational param-eters such as solution pH, nanocomposite concentration, initial concentration of CEX, and reac-tion time was investigated at three levels (+1, 0, and -1) with a constant ultrasound intensity at 37 kHz. The optimization and analysis of the results were performed by Design-Expert 10 and Statgraphics software, and the residue of CEX was measured using a spectrophotometer at 288 nm. The results showed that the quadratic model was suitable for the data (P-value < 0.0001), and the proposed model (quadratic) was approved with a high correlation coefficient (R2 = 0.9824 and R2Adj. = 0.9670). Under the optimal conditions for the process (pH = 3, nanocomposite of 1 g/L, initial concentration of CEX of 10 mg/L, and reaction time of 90 min), the observed removal efficiency was about 100%. According to the results, the GO-Fe3O4/US process was approved to be effective in the degradation of the antibiotic CEX, and the Box-Behnken design was found to be a suitable tool to optimize the process conditions in the removal of CEX.