Response surface optimized removal of cefixime from wastewater samples using magnetic ferric oxide nanoparticles

Cefixime is a broad-spectrum cephalosporin antibiotic that is orally administrated to treat bacterial infections diagnosed from mild to moderate ones. Since cefixime is considered a widely used antibiotic in many countries, it was important to develop a method for its removal from water as a part of water purification using an adsorption technique with different nanoparticles. In order to optimize its removal conditions, a fractional factorial design was applied to screen experimental factors including pH, contact time, and amounts of nanoparticles. A three-factor, two-level I-optimal design was designed using Derringer's desirability algorithm, in which the optimal removal conditions of cefixime were found to be Fe₃O₂ dose (13 mg/L), pH (5.9), and contact time (180 min) at room temperature. An HPLC method was developed for monitoring the adsorption process using a Kinetex C₁₈ stationary phase (100 mm L × 4.6 mm i.d., particle size 5 μm, USA), and a mobile phase consisting of phosphate buffer (adjusted to pH 6.8) and methanol in the ratio of 75: 25 which was pumped at a flow rate of 1 mL/min at room temperature with UV detection at 288 nm. The proposed HPLC method was validated according to ICH guidelines and was assessed using the greenness tools Analytical Eco-scale (AES), GAPI, and AGREE. The removal and analysis procedures were successfully applied to simulated wastewater samples containing cefixime with a bias of 1.9%. The method can be easily applied for large-scale water treatment.