Fabrication of poly(β-cyclodextrin)-conjugated magnetic graphene oxide by surface-initiated RAFT polymerization for synergetic adsorption of heavy metal ions and organic pollutants

Abstract

In order to realize synergetic adsorption of heavy metal ions and organic pollutants, poly(β-cyclodextrin)-conjugated magnetic graphene oxide (MGO@poly(β-CD)) was designed and fabricated. The MGO@poly(β-CD) was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and vibrating sample magnetometry, respectively. Results indicated that the MGO@poly(β-CD) was successfully prepared and the adsorbent could be separated easily once an external magnetic field was applied. The adsorption behaviors of Cd²⁺ and sulfamethazine (SMT) by MGO@poly(β-CD) in the single and binary systems were investigated. The adsorption amounts of both Cd²⁺ and SMT were pH-dependent, and the increase in the ionic strength of solutions resulted in significant decrease of their adsorption amounts. The adsorption of Cd²⁺ and SMT on MGO@poly(β-CD) was achieved by different mechanisms, respectively. The sorption of Cd²⁺ was related to complexation and electrostatic interactions, while the removal of SMT was realized by hydrogen bonding, host–guest supramolecular and π–π interactions. The synergetic adsorption of Cd²⁺ and SMT in the binary systems was attributed to interactions between loaded Cd²⁺ (SMT) and free SMT (Cd²⁺) in solutions. These results provided valuable information for designing novel adsorbents that can be used for synergetic adsorption of heavy metal ions and organic pollutants.