Adsorption of Ciprofloxacin and Tetracycline by Organically Modified Magnetic Bentonite

Abstract

In order to endow magnetic bentonite (MB) with better magnetic separation and magnetic stability, obtain stronger adsorption of antibiotics, carboxymethylcellulose-chitosan/magnetic bentonite composite (MB/CC) was prepared by modifying previously fabricated MB with carboxymethylcellulose (CMC) and chitosan (CS). The characterization of MB/CC and the adsorption properties towards ciprofloxacin (CIP) and tetracycline (TC) was investigated. The characterization results revealed that CC improves the Fe3O4 stability and removal capability of CIP and TC for the final product. Adsorption results indicated that MB/CC exhibited superior adsorption performance for CIP (182 mg·g−1) and TC (189 mg·g−1). Adsorptive removal of CIP and TC by MB/CC was more than 90% even after 5 cycles of adsorption-desorption process. The adsorption process fitted well with the Langmuir model and the pseudo-second order kinetic model. The main steps during the successful adsorption process of MB/CC for CIP and TC includes pore diffusion, ion exchange and electrostatic interaction. MB/CC has advantages of simplified synthesis, convenient operation and high-efficiency, which could be deemed as a promising alternative adsorbent for antibiotics removal from wastewater.