Fabrication of modified alginate-based biocomposite hydrogel microspheres for efficient removal of heavy metal ions from water

Thiol and amido modified alginate was prepared and combined with graphene oxide to fabricate the biocomposite hydrogel microsphere adsorbent for the removal of heavy metal ions from water. Fourier transform infrared (FTIR), scanning electron microscope (SEM) and thermogravimetric analyzer (TGA) were used to characterize the structure and thermal stability of hydrogel microspheres. The adsorption performance and mechanism of the biocomposite hydrogel microspheres for the removal of Pb2+ and Cu2+ from water have also been investigated. The results indicated that the hydrogel microspheres exhibited rapid adsorption process and excellent adsorption capacity for both heavy metal ions. The experimental maximum adsorption capacities for Pb2+ and Cu2+ were 369.6 and 124.1 mg⋅g−1, respectively. The adsorption isothermal and kinetics were well described by Langmuir and pseudo-second-order models. After five consecutive adsorption-desorption cycles, the adsorption capacity of microspheres on Pb2+ and Cu2+ remained above about 90%, indicating their excellent reusability. The rapid and high adsorption efficiency and outstanding regeneration ability suggest that the modified alginate-based biocomposite hydrogel microspheres have potential applications in the field of water treatment.