Adsorption characteristics of ciprofloxacin onto g-MoS2 coated biochar nanocomposites

The g-MoS 2 coated biochar (g-MoS 2 -BC) composites were synthesized by coating original biochar with g-MoS 2 nanosheets at 300°C(BC300)/700°C (BC700). The adsorption properties of the g-MoS 2 -BC composites for ciprofloxacin (CIP) were investigated with an aim to exploit its high efficiency toward soil amendment. The specific surface area and the pore structures of biochar coated g-MoS 2 nanosheets were significantly increased. The g-MoS 2 -BC composites provided more it electrons, which was favorable in enhancing the it-it electron donor-acceptor (EDA) interactions between CIP and biochar. As a result, the g-MoS 2 -BC composites showed faster adsorption rate and greater adsorption capacity for CIP than the original biochar. The coated g-MoS 2 nanosheets contributed more to CIP adsorption on the g-MoS 2 -BC composites due to their greater CIP adsorption capacity than the original biochar. Moreover, the synergistic effect was observed for CIP adsorption on g-MoS 2 -BC700, and suppression effect on g-MoS 2 -BC300. In addition, the adsorption of CIP onto g-MoS 2 -BC composites also exhibited strong dependence on the solution pH, since it can affect both the adsorbent surface charge and the speciation of contaminants. It was reasonably suggested that the mechanisms of CIP adsorption on g-MoS 2 -BC composites involved pore-filling effects, it-it EDA interaction, electrostatic interaction, and ion exchange interaction. These results are useful for the modification of biochar in exploiting the novel amendment for contaminated soils.