Sorption and destruction of veterinary antibiotics on natural minerals

Abstract

Excessive use of antibiotics induces accumulation of them in the environment and due to their adverse effects antibiotics are classified as an emergent pollutant. Considering the importance of antibiotic pollution control, the adsorption of a widely used tetracycline group antibiotic, oxytetracycline (OTC) onto perlite, sepiolite, and bentonite as natural adsorbents was investigated. The effects of initial antibiotic concentration, contact time, and pH on the adsorption of OTC were studied. Batch adsorption experiments indicate that the extent of sorption is strongly dependent on the pH of solution. The adsorption capacity of perlite, sepiolite, and bentonite for OTC at pH 6.5 was found 5.87, 5.57, and 10.93 mg g-1, respectively. Pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion kinetic models were applied to the experimental data to describe the adsorption process. It was found that OTC adsorption on each adsorbent could be described more favorably by the pseudo-second order kinetic model. Standard adsorption isotherms were used to fit the equilibrium data and isotherms of each adsorbent were adequately described by Freundlich and Temkin models. Among the investigated adsorbents bentonite exhibited the highest adsorption performance. The treatment of spent bentonite was also performed by Fenton and ozonation processes which efficiently degraded OTC. While the extraction pretreatment enhanced the OTC degradation efficiency of ozonation process, it didn’t affect the performance of Fenton process.|Keywords: Oxytetracycline, Perlite, Sepiolite, Bentonite, Advance Oxidation