Preparation and evaluation of a magnetite-doped activated carbon for enhanced cefotaxime antibiotic removal: equilibrium, thermodynamic, kinetics, mechanism and process design

Abstract: The presence of Cefotaxime, a widely used antibiotic, has been documented in sewage treatment plant effluents. Unfortunately, applying conventional methods for wastewater treatment did not show a significant performance to remove these compounds, so these can enter to aquatic environments [1]. Non- biodegradability, high toxicity, and carcinogenic effects, increasing allergic reactions in humans and expanding resistant bacteria to antibiotics will lead to health and environmental hazards if they are not removed from wastewater [2, 3]. Therefore, its removal from water sources as emerging contaminant is greatly desired. In the current work Response Surface Methodology (RSM) was applied to optimize and evaluate the effect of operating factors on the removal efficiency. The effect of various variables including: initial cefotaxime concentration (10-100 mg.L-1), pH solution (3-11), adsorbent dosage (0.1-0.5 mg.L-1), temperature (5-50 °C), and reaction time (10-100 min) were investigated. Adsorption process was applied successfully with removal efficiency of 96.5% under optimal operating conditions of initial cefotaxime concentration of 73.6 mg.L-1, pH of 5.2, adsorbent dosage of 0.35 mg.L-1, temperature of 35 °C, and reaction time of 20 min. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R2) value of 0.9832, adjust correlation coefficient (Adj.R2) value of 0.9640 and predicted correlation coefficient (pred. R2) value of 0.9237. The kinetics of the process followed the second-order model (R2=0.9685) and the isotherm of the process best fitted by the Langmuir adsorption model (R2=0.9892). According to the obtained results, adsorption process using magnetic activated carbon was found to be an efficient technique for or treatment of hospital wastewater.