Mesoporous Magnetic Carbon Adsorbents Prepared from Sugarcane Bagasse and Fe2+ and Fe3+ via Simultaneous Magnetization and Activation for Tetracycline Adsorption

Abstract

Tetracycline (TC) is one of the pharmaceutical antibiotics most employed for human and veterinary use in Thailand. The release of TC is considered a threat to the aquatic environment; hence, it urgently needs to be efficiently removed from the water streams. One of the popular and effective methods of removal of TC is adsorption. Magnetic carbon composites derived from biomass-based materials have attracted attention as novel adsorbents for removal of toxic substances from aqueous solution. However, their preparation involves multi-step procedures, which is time and energy consuming. In this work, we have prepared novel magnetic carbon composites using sugarcane bagasse, abundantly wasted biomass from sugar industries, a mixture of Fe2+ and Fe3+, and NaOH, as a carbon precursor, source of magnetite particles (Fe3O4), and precipitating/activating agent, respectively. The facile preparation has been performed via a simultaneous magnetization and activation process in a single step. The effects of preparation conditions on physicochemical properties of the resulting materials were studied, discussed and optimized. A selected sample showed satisfactory magnetic stability due to the presence of Fe3O4 particles (confirmed by XRD) and high porosity, with a BET surface of 566 m2/g and mesopore fraction (pore size > 2 nm) of more than 84%, suitable to adsorb the large TC molecules. The adsorption performance towards TC was determined using batch adsorption experiments. The maximum TC adsorption on the selected sample was as high as 48.40 mg/g, outperforming many literature sorbents, while the magnetic stability can even be retained after complete adsorption.