Evaluation of the efficacy of Fe2O3 magnetised kaolin: simultaneous removal of ceftriaxone and cefixime from aqueous media

Abstract

ABSTRACT Traces of antibiotics in domestic and industrial effluents have toxic effects on human health and the surrounding plants and animals, besides their potential to increase antibiotic resistance of microorganisms. Therefore, this study aims to develop a new adsorbent made from kaolin magnetised with Fe2O3 (Kaolin- Fe2O3) composite and apply it to remove ceftriaxone and cefixime from aqueous solutions. The efficiency of the new adsorbent in removing ceftriaxone and cefixime from solutions was studied under different adsorbent doses, antibiotic concentrations, solution pH values, and contact times. The results indicated the best ceftriaxone and Cefixime removal was attained at pH of 5 and 3, respectively, while the best antibiotic concentration, contact time, and adsorbent dose were 20 mg/L, 60 min, and 0.4 g/250 cc, respectively. It was noticed the adsorption was improved at low temperatures (25 for ceftriaxone and 35 for cefixime). Five types of isotherms matched the equilibrium data, including Langmuir, Freundlich, Temkin, Redlich-Peterson, and Sips. Equilibrium data were also matched with pseudo-first and second-order kinetics, Elovich, and intraparticle diffusion. Freundlich and Sips isotherm models were more consistent with equilibrium data. The positive results of Gibbs free energy and the negative enthalpy obtained from thermodynamic parameters indicate that the adsorption process is spontaneous and the adsorption process is exothermic. In light of the obtained results, the Kaolin-Fe2O3 nanocomposites could be considered an effective and inexpensive adsorbent for removing antibiotics from aqueous solutions.