Removal of amoxicillin and ampicillin using manganese dioxide/montmorillonite composite

Abstract

BACKGROUND Clay-based materials represent great potential for the development of efficient and environmentally friendly sorbents. The study focuses on a laboratory-obtained manganese dioxide/montmorillonite (MnO2/MMT) composite for removal of two types of antibiotics - amoxicillin (AMX) and ampicillin (AMP) - from aqueous solution.

RESULTS The composite was successfully prepared using a reduction procedure involving the reaction between potassium permanganate (KMnO4) and hydrochloric acid (HCl) to form MnO2 followed by the addition of MMT. X-ray analysis, scanning electron microscopy, X-ray fluorescence and Fourier transform infrared spectroscopy were performed for characterization of physicochemical and structural properties, simultaneous thermogravimetry and differential scanning calorimetry for estimation of thermal stability and high-performance liquid chromatography for determination of antibiotic equilibrium concentrations in aqueous solution. The precipitated MnO2 component, manifested by long fibers, corresponded to the tunnel structure of cryptomelane. In the case of MnO2/MMT it is evident that MnO2 developed short fibers with the participation of the MMT matrix. The thermal data suggested that the MnO2 phase upon contact with the clay support showed better thermal stability. The final decomposition of Mn2O3 was shifted to higher temperature of 985 degrees C. Adsorption procedure in a batch regimen showed sufficient sorption ability for both antibiotics with over 90% efficiency. For AMP the value of q(max) was about 45 mg g(-1) and for AMX it was only 21 mg g(-1).

CONCLUSIONS The results provided valuable information for the design of a potentially inexpensive clay-based adsorbent and demonstrated the removal of two types of broad-spectrum beta-lactam antibiotics from aqueous solution to a sufficient degree.