Studies On Design, Synthesis And Properties Of Fatty Polyamines-bonded Silica-gel Adsorption Materials

The fatty polyamines are a kind of separating materials that have the character of chelating bonds with some metal ions. Because of their excellent adsorbing selectivity to rare and heavy metal ions, they are widely used in the fields of water treatment, metallurgy, analysis, and marine chemistry, etc. This thesis has designed and prepared twelve silica-gel (SG) bonded polyamines adsorption materials of three series by probing the different preparation method and the molecular designing. These adsorption materials were systematically characterized by elemental analysis, infrared spectroscopy (FT-IR), X-ray diffractometry, porous analysis, and thermogravimetry analysis.Using 3-chloroprophtrimethoxysilane (CPTS) as coupling agent, four kinds of silica-gel bonded diethylenetriamine (DETA) adsorption materials, SG-DETA-1, SG-DETA-2, SG-DETA-3, and SG-DETA-4, were prepared by so-called heterogeneous direct-amination, homogeneous direct-amination, heterogeneous end-group protection, and homogeneous end-group protection methods, respectively. Several metal ions, such as Ag(I), Cu(II), Ni(II), Hg(II), Zn(II) and Pb(II), were chosen as representatives to investigate the relationship between adsorption properties and the content of functional group onto the surface of silica-gel. The experiments results showed that homogeneous method and direct method were favorable to improve the content of functional group and the adsorption capacities for metal ions, while the end-group protection method can enhance the utilization ratio of functional group.Using 3-glyciddoxypropyltrimethoxysilane (GPTS) as coupling agent, four kinds of silica-gel supported diethylenetriamine adsorbents with different structures, were prepared by so-called heterogeneous direct-amination, homogeneous direct-amination, heterogeneous end-group protection, and homogeneous end-group protection methods, respectively. The obtained products were named SG-HE-dD, SG-HOdD, SG-HE-pD and SG-HO-pD, respectively. The adsorption capabilities of such adsorption materials towards Cu(II), Hg(II), Ni(II), Pb(II) were studied to probe the relationship between adsorption properties and the methods. The experimental results indicated that the adsorbents prepared by heterogeneous end-group protection and homogeneous end-group protection methods possessed lower contents of DETA, while their adsorption capacities and the utilization ratios of functional groups were much higher than the corresponding counterparts prepared by heterogeneous direct-amination and homogeneous direct-amination methods. The kinetics data indicated that the adsorption process was governed by the film diffusion and followed pseudo-first-order rate model for SG-HE-dD, SG-HO-dD and SG-HE-pD and pseudo-second-order model for SG-HO-pD. The isotherm adsorption results revealed that the linear Langmuir, non-linear Langmuir and non-linear Redlich-Peterson isotherm models are the best-fit models to predict the experimental data. Four adsorption materials possess well desorption and regeneration capacities. When 5% thiourea in 0.1 mol L-1 HNO3 was used, the adsorbed Hg(II) could be completely eluted and the adsorption capacities of four adsorption materials remain approximately the same via 5 adsorption-desorption cycles.Silica-gel supported low-generation DETA and triethylenetetramine (TETA) dendrimer adsorption materials, SG-DETA, SG-DETA2, SG-TETA and SG-TETA2, were prepared by divergent method. We investigate the adsorption properties of these materials for Au(III). The adsorption capacity increased with the increase of the generations and the chain length of the polyamine. The kinetic adsorption results showed that the adsorption process of four adsorption materials for Au(III) was controlled by the film diffusion and well followed pseudo-second-order rate model. The adsorption isotherms results showed that linear Langmuir, and non-linear Redlich-Peterson isotherm models could be well interpret the adsorption of four adsorption materials for Au(III). Thermodynamic analysis revealed that the adsorption behaviors of four adsorption materials for Au(III) could be considered as spontaneous, monolayer and chemical sorption. Four adsorption materials had good selective properties for Au(III) and can recovery Au(III) from some mixture solution. And four adsorption materials possess well desorption and regeneration capacities. When 4% thiourea in 0.1 mol L-1 HCl was used, the adsorbed Au(III) could be completely eluted, and the decrease of adsorption and desorptin capacity of regenerated adsorbents maybe caused by oxidation-reduction.