Polydopamine magnetic microspheres grafted with sulfonic acid groups for efficient adsorption of tetracycline

The abuse of antibiotics poses a serious threat to human health and ecosystems. In this study, magnetic polydopamine sub-microspheres (Fe3O4@PDA-SO3H) with many sulfonic acid groups were firstly synthesized to remove tetracycline antibiotics. The adsorption capability was examined under different conditions such as pH, initial concentration, and contact time. We found that the maximum adsorption capacity reached 138.98 mg/g, and equilibrium adsorption data were more consistent with the Langmuir isotherm and pseudo-second-order kinetic model. Additionally, the results showed that 7C-7C stacking interaction and electrostatic interaction might significantly affect the adsorption process. The adsorbent could maintain a high adsorption level after six cycles. Therefore, Fe3O4@PDA-SO3H could be considered as a promising adsorbent for wastewater treatment.