Facile fabrication of core–shell/bead-like ethylenediamine-functionalized Al-pillared montmorillonite/calcium alginate for As(V) ion adsorption

In this study, a MT(Al)/calcium alginate [MT(Al)@CA] microsphere structure was prepared using sodium alginate (SA) and MT(Al). In order to achieve [MT(Al)@CA] microspheres with a high stability and chemical resistance, glutaraldehyde was used as the crosslinking agent to graft the microspheres and ethylenediamine (ED) into a new type of ED-functionalized MT(Al)@CA microsphere structure similar to a core–shell-type structure [MT(Al)@CA-ED]. This core–shell/bead-like structure was characterized and analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption performance of the core–shell/bead-like structure for As(V) in solution was studied. The effects of the initial As(V) concentration, reaction time, pH, and different reaction temperatures on the reaction process were studied. The results indicate that at a pH of 4, the removal rate of As(V) by the core–shell/bead-like MT(Al)@CA-ED could reach 94.85% after 150 min. The adsorption process is highly consistent with the Langmuir isotherm model (R 2  = 0.9983) and pseudo-second-order kinetic model (R 2  = 0.9973). The maximum adsorption capacity could reach 61.94 mg/g. Regeneration experiments showed that the adsorption efficiency of As(V) after six cycles was >80%.