Effective Removal of Tetracycline Antibiotics from Water by Magnetic Functionalized Biochar Derived from Rice Waste

Abstract

The effective removal of tetracyclines (TCs) from water is of great significance and remains a big challenge. In this work, a novel magnetized biochar (magnetic functionalized carbon microsphere, MF-CMS) was prepared by the coupling hydrothermal carbonization and pyrolysis activation of starch-rich rice waste using ZnCl2 and FeCl3 as activators. As the MF-CMS dosage was 2.0 g/L, the removal rates of typical four tetracycline antibiotics were from 83.50% to 99.52%. The analysis on the physico-chemical properties of the obtained biochar and the adsorption kinetics, isotherms, and intraparticle diffusion model suggested that both chemisorption and physisorption occurred in all removal processes, in which chemisorption dominated. TCs were efficiently adsorbed through the combined effects of ion exchange, electrostatic attraction, π-π interactions, and complexation reactions of surface functional groups (such as γ-Fe2O3 and FeOOH). The cycling and metal ion release experiments of MF-CMS indicated the MF-CMS had good reusability, stability, and safety. The magnetic biochar derived from starch-rich rice waste is promising and effective as an adsorbent for the removal of tetracycline antibiotic from water.

Keywords: Magnetic biochar, Tetracycline antibiotics, Water remediation, Adsorption