Preparation And Adsorption Properties Of Polyamine Silica Hybrid Materials

Surface imprinting builds specific binding sites on the surface of adsorption materials by controlling spatial structure of imprinting cavities on the polymer surface, thus improve the selectivity to target ions, which can realize rapid integration and separation between imprinted polymer and template ion. This paper use the technology of surface ion imprinting to synthesis imprinted poly allyl amine silicone material(IIP-PAA/SiO2) which has selective adsorption recognition of Cu2+ with silica gel as matrix, poly(allylamine) (PAA) as surface modification agent and Cu2+ as template ion. The synthesis conditions of PAA/SiO2 and HP-PAA/SiO2 were inspected, the process of surface load and surface ion imprinting were researched, the adsorption characteristic of material to Cu2+ was measured and adsorption selectivity mechanism was explored.The PAA/SiO2 which prepared through PAA adsorpted on the surface of silica by physical coating method has high adsorption capacity for copper ions, the silica-supported PAA experiment shows that:5g activation silica gel as reference condition, ratio of the solvent and amount of functional monomer was 0.426, loading for 24h, operating temperature at room temperature, the surface polyamine load on the surface of PAA/SiO2 prepared was about 8%.On the basis of the synthesis of PAA/SiO2, new Cu2+ imprinted polyamine silicone material (IIP-PAA/SiO2)was prepared by surface ion imprinting technique that crosslink imprinting on material PAA/SiO2, using Cu2+as template ion and epichlorohydrin(ECH) as crosslinking agent. Optimization to obtain preparation conditions of IIP-PAA/SiO2:mol ratio of Cu2+and N before imprinting was 0.5, ECH crosslinking agent was 0.6 times of mole of atom N, reaction time was 3h, reaction temperature was 323 K and the methanol was chosen as solvent. In the presence of competing ion of Zn2+, and Cu2+and Zn2+mixed concentration ratio of about 1:1, the selectivity coefficient of IIP-PAA/SiO2 to Cu2+was 62.7, improved about 15 times relative to PAA/SiO2 of 4.13, it provides a new way for the selective separation and enrichment of copper ions in complex samples. The saturated adsorption capacity of IIP-PAA/SiO2 material also increased compared with PAA/SiO2.The adsorption capacity and selection performances of PAA/SiO2 and IIP-PAA/SiO2 material to Cu2+ were studied by static adsorption. The results showed that the optimum adsorption pH of Cu2+ was 4.0～5.0. In the range of experimental temperature, adsorption capacity of PAA/SiO2 for Cu2+ increased with temperature increased, while adsorption capacity of IIP-PAA/SiO2 for Cu2+ decreased with temperature increased, contrast with the temperature trend. The thermodynamic curves showed that adsorption equilibrium data of IIP-PAA/SiO2 was fitted by the Langmuir isotherm model. The thermodynamic parameters enthalpy of IIP-PAA/SiO2 was negative, free energy of adsorption Gibbs was negative. Kinetic experiments indicated the proposed second-order model displayed the best correlation with the adsorption behavior of imprinted polymer IIP-PAA/SiO2, the correlation coefficient over 0.95. Besides, the materials PAA/SiO2 and IIP-PAA/SiO2 have good regeneration properties. After 5 times adsorption-desorption cycles, the recycling rate remains above 90%, having good reusability.Adsorbent concentration effect exists during the adsorption process, adsorption amount decrease gradually with the increase of adsorbent concentration in a certain ion concentration. Equilibrium adsorption capacity Qe has unique corresponding value with Ce at given Wo level, so Qe is a function of Ce and Wo.