Chelating Resins Silica Gel Supported Aminophosphonic Acids Prepared by a Heterogeneous Synthesis Method and a Homogeneous Synthesis Method and the Removal Properties for Hg(II) from Aqueous Solutions

Two kinds of composites silica gel supported by aminophosphonic acids SG-T-P-1 and SG-T-P-2 were prepared successfully by functionalization of silica gel via a heterogeneous synthesis method and a homogeneous synthesis method, respectively, and they were characterized by infrared spectra (IR), scanning electron microscope (SEM), and energy dispersive X-ray analysis system spectrum (EDXAS). Moreover, the static adsorption capabilities of these two chelating resins toward transition-metal ions were studied. Our objective was to choose the adsorbent with high adsorption capacities via different synthesis methods, and the results showed that SG-T-P prepared via a homogeneous synthesis method had excellent adsorption capacities and high adsorption selectivity for Hg(II) ions. The Langmuir model was better than the Freundlich model to fit the adsorption isotherms of SG-T-P for Hg(II), and the maximum adsorption capacity was 303.03 mg/g at 15 °C. Thus, the novel chelating resin silica gel supported by aminophosphonic acids SG-T-P prepared by a homogeneous synthesis method is favorable and useful for the removal of Hg(II) ions from aqueous solutions.