Efficient adsorption of antibiotics and heavy metals from aqueous solution by structural designed PSSMA-functionalized-chitosan magnetic composite

Abstract

The simultaneous removal of antibiotics and heavy metals is of great importance due to their harmful effects on the ecosystem and human health. In this work, a novel PSSMA-modified magnetic adsorbent (FO@CC-PM) with permanent porosity was designed and fabricated through polymer grafting and using freshwater snail shell as a pore-forming agent. FO@CC-PM was demonstrated to possess broad pH adaptability and excellent sorption capacities of 412.63, 214.07, 141.70, and 113.07 mg·g−1 for norfloxacin (NOR), sulfadiazine (SD), Cu(II), and Ni(II), respectively. They were significantly higher than other reported adsorbents due to the increased porosity, specific surface area, and functionalized sites. The adsorption process could be well described via the pseudo-second-order model and Langmuir isotherm. Besides, FO@CC-PM displayed satisfactory reusability in synthetic and model wastewater. In binary systems, the coexistence of Cu(II) and NOR promoted the sorption of each other, whereas no significant synergy was observed among Ni(II) and SD. This divergence was originated from the different coordination intensity between diverse co-existing contaminants. As demonstrated by FTIR and XPS analyses, electrostatic interaction, coordination, π-π stacking, hydrogen bonding, and hydrophobic effect were mainly involved in the adsorption mechanisms. This work provides an effective strategy for the custom design of novel adsorbents that can efficiently adsorb both heavy metals and antibiotics over a wide pH range.