Preparation Of The Novel Magnetic Nano-adsorbents And Its Highly Selective Adsorption Properties For Hg(â…¡) In Aqueous Phase

The magnetic nano-absorbents prepared by modifid natural ploymer and magnetic nanoparticle, which combined the advantages of both two kinds of materials. The natural ploymer is low-cost, non-toxic and biocompatible, and the magnetic nanoparticle, with large surface area, could be separated and recycled easily. Thus, design of the magnetic nano-absorbent is became the hot research field of the adsorption matetials. This Dissertation summarized the research progress on magnetic nano-adsorbents, and synthesized3kinds of novel magnetic nano-adsorbents that used for adsorption of Hg(II) in aqueous phase.1. Preparation of multi-cyanoguanidine modified magnetic chitosan nano-adsorbent and its adsorotion properties.A new kind of nano-absorbent with the entirely novel structure, nano-absorbent of multi-cyanogunidine modified magnetic chitosan (CG-MCS nano-absorbent), has been firstly synthesized by using the functionalized chitosan and cross-linking agent with cyanoguanidine group simultaneously. The resulting nano-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). The resulting nano-absorbent basen on multi-cyanoguanidine modified magnetic chitosan has been demonstrated holding highly effective recovery for mercury ions, in other words, it showed both the extraordinary adsorption capacity for Hg(II) at high initial concentration and the strong removal ability for it at low concentration, meanwhile, the resulting CG-MCS nano-absorbent also showed a high selectivity adsorption for Hg(II) among coexisting heavy metals and the good regeneration performance.2. Preparation of aminothiourea modified magnetic chitosan nano-adsorbent and its adsorotion properties.Aminothiourea functionalized magnetic chitosan nano-biosorbent (AT-MCS), a new kind of bio-adsorbent, has been first synthesized by covalently linked chitosan and NH2-Fe3O4with gultaraldehyde and functionalized with aminothiourea group. The resulting bio-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM).With the excellent mono-dispersive ability in aqueous phase, the obtained biosorbent showed not only the good adsorption capacity for Hg(II) on high initial concentration but also the strong removal ability on low concentration. The maximum adsorption amount was up to246mg g-1and the removal percentage could reach98.7%at initial concentration of10mg L-1. Moreover, the nano-biosorbent has a unique selectivity for Hg(II) among the mixed metal ions solution and exhibited good regeneration performance.3. Preparation of aminothiourea modified magnetic dialdehyde starch nano-adsorbent and its adsorotion properties.By directive covalently link dialdehyde starch and amine functionalized Fe3O4nanoparticle, and modified with aminothiourea functional group, the novel monodisperse nano-composite has been successful synthesized without any toxic crosslink agent. The resulting nano-composite was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). As the new kind of low-cost and environmentally friendly adsorbent with the excellent mono-dispersive ability in aqueous phase, the obtained nano-composite showed not only the good adsorption capacity for Hg(II) on high initial concentration but also the strong removal ability on low concentration.Moreover, the unique selectivity for Hg(II) among the mixed metal ions solution and exhibited good regeneration performance of nano-composite has also been demonstrated by batch experiments.