Adsorption of metronidazole in aqueous solution by Fe-modified sepiolite

Metronidazole (MET), a widely used antibiotic, has attracted more attention for its highly solubility, non-biodegradability, and suspected carcinogen. The original sepiolite and its modified counterparts were prepared by different methods and characterized by SEM, XRD, and BET. The specific surface area and pore volume of the Fe-modified sepiolite were 217.68 m2/g and 3.8743 cm3/g, respectively, with 19 and 215% increment compared with the original sepiolite. The samples were used to remove MET from aqueous solutions. The effects of pH, contact time, initial MET concentration, and temperature on the adsorption process were investigated. It was found that the Fe-modified sepiolite had higher adsorption capability (36.5%) for MET than that of others. The MET adsorption on the Fe-modified sepiolite was fast and the process conformed to the pseudo-second-order kinetic model, and the adsorption equilibrium data fitted well with the Freundlich isotherms.