Optimization of ciprofloxacin adsorption from synthetic wastewaters using γ-Al2O3 nanoparticles: An experimental design based on response surface methodology

Pollution of water resources and the environment by antibiotics is one of the most concerning environmental issues. So, this study investigates adsorption of ciprofloxacin, as a common antibiotic and an emerging pollutant, onto gamma-Al2O3 nanoparticles (NPs) and evaluates the effect of the operational parameters and their interactions using central composite design. Furthermore, the adsorption process is optimized by the response surface methodology. The removal efficiencies predicted by the resultant model demonstrate a good correlation (R-2 > 0.96) with the experimental data. Increase of NPs from 0.33 g/L to 0.78 g/L increased removal efficiency from 29.15% to 43.78%. However, increasing the initial concentration of ciprofloxacin from 20 to 40 mg/L decreased the efficiency from 36.68 to 20.52%. The maximum experimental efficiency of 53% can be achieved at the optimum conditions, which include pH 7.5, 20 mg/L initial ciprofloxacin concentration, 0.775 adsorbent dose and 46.25 min contact time. The Temkin isotherm and the pseudo-second-order kinetics model were the most appropriate models for describing the experimental data. The findings of this study confirm that the proposed model is suitable for predicting the performance of adsorptive ciprofloxacin removal by the gamma-Al2O3 nanoparticles.