Preparation And Adsorption Performance Of A New Tetrazole Modified Chelating Resin

Chelating resin is widely used in removing heavy metal ions in sewage and ethanol fuel. Different functional groups on chelating resin reflect different adsorption capacities and selectivities. In order to achieve selective separation of different heavy metal ions, a new type of pyridine-tetrazole chelating resin is designed and the adsorption property for heavy metal ion is also investigated.1. The tetrazole modified chelating resin was prepared by anchoring5-aminopyridine-2-carbonitrile monomer onto chloromethylated polystyrene resin and subsequently translating cyano into tetrazolyl group using the [3+2] cyclization reaction. The new resin was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and the specific surface area and pore size analyzer. The results implied that the tetrazolyl group was connected to the resin successfully.2. The modified resin was used to adsorb Cu(II), Pb(II) and Hg(II) in aqueous solution. The effect of pH values, adsorption kinetics, adsorption isotherms, thermodynamic, desorption and regeneration experiments were investigated. The results showed that the resin possessed perfect adsorption capacity. The optimal pH values for Cu(II), Pb(II) and Hg(II) were5.0,6.0and2.0respectively. The whole adsorption process followed the pseudo-second-order kinetic modle. At298K,308K and318K, the adsorption isotherms for Cu(II) and Pb(II) could be better fitted by Langmuir model than Freundlich model, while for Hg(II) Freundlich model was the best. For the same metal ion, when the inital concentration was the same, the adsorption capacity increased with the temperature increasing, which indicated that the adsorption process was endothermic.0.20mol L-1EDTA solution which was choosen as desorption solution showed perfect desorption efficiency around99%. Five consecutive adsorption-desorption experiments were also tested, there was no obvious change in the adsorption capacity of the resin, reflecting good regeneration property.3. The modified resin was used to adsorb Cu(II), Ni(II) and Pb(II) in ethanol solution. The adsorption kinetics and adsorption isotherms were investigated. The results showed that the adsorption for Cu(II), Ni(II) and Pb(II) reached equilibrium at about12h. The adsorption isotherms for Cu(II), Ni(II) and Pb(II) at298K could be well fitted by Langmuir model. Comparing with other adsorbents, the resin showed relatively good adsorption performance.