Preparation Of Hg²⁺-ion-imprinted Polymer And Its Application

Water is the most important part of nature resources, which is the foundation of human survival, production and life. Meanwhile, water is the material depositories of biochemical reactions. Water is the indispensable component of the ecological environment which is sensitive to the external environment change. In view of the influence of industrialization, the pollutants in water is increasing, headed by heavy metal pollution produced great harm to water body and the animals and plants in the water. Then through the food chain transmission to influence our physical health. Heavy metal is difficult to management because of its refractory and strong stability in environment.Heavy metal mercury is a kind of harmful substances which has high durability, volatility and accumulation. If exposed to the air, it will cause serious impact on the environment and human security. Now, mercury is not only one of thirteen kinds of metal elements on the list of the priority control pollutants of United States environmental protection agency（EPA）. At the same time, in the EU water framework directive, mercury has been black listed, belong to the priority control pollutants. So, find a suitable way to control mercury pollution is imminent.Molecular imprinting technology is also called molecular template technology, originally derived from the theory of template synthesis of antibodies to antigens. In synthetic materials, environmental monitoring, biological engineering and food industry formed a wide range of applications. Molecular imprinting technology developed today is mostly applied to the study of molecular recognition but rarely applied to the metal ion. In view of the metal ions and biological macromolecules, such as proteins or chelation of drug molecules have high selectivity and mild combining characteristics of the fracture, therefore, using this feature in metal ion imprinting have broad prospects for development.Hg²⁺-imprinted polymer particles were prepared by precipitation method with Hg²⁺ as the template, Maleimide as the functional monomer and Ethylene Glycol Dimethacrylate（EDGMA） as cross-linking agent in the second part. Hg²⁺-imprinted polymer particles was characterized by UV-spectra to analyze the combination between template and functional monomer, scanning electron microscopy（SEM） and FT-IR to display the configuration of surface and chemical construction. This study also confirmed the best adsorption condition: the adsorption time was 110 min, the adsorption temperature was 60℃ and the p H was 7. The maximum absorption capacity was 5.43μg/10 mg. In the selectivity experiment, the k value of Cu²⁺,Pb²⁺ and Co²⁺ were 12.33, 27.17 and 13.37. Reused the prepared ion imprinted polymer six times, the adsorption capacity in the sixth time was 86.3% that of the first time. The recoveries of practical samples（tap water and lake water） were in the range of 89.80% to 100.66%.Hg²⁺-imprinted polymer particles were prepared by surface imprinting method with Hg²⁺ as the template, Maleimide as the functional monomer and Ethylene Glycol Dimethacrylate（EDGMA） as cross-linking agent, grafting silica as carrier material. Hg²⁺-imprinted polymer particles was characterized by scanning electron microscopy（SEM） and to display the configuration of surface. Thermo-gravimetric experiment confirmed the quality changes before and after the polymer reaction. This study also confirmed the best adsorption condition: the adsorption time was 70 min, the adsorption temperature was 60℃ and the p H was 8. The maximum absorption capacity was 8.96μg/10 mg. In the selectivity experiment, the k value of Cu²⁺,Pb²⁺ and Co²⁺ were 90.77, 55.81 and 87.83. Reused the prepared ion imprinted polymer six times, the adsorption capacity in the sixth time was 86.3% that of the first time. The recoveries of practical samples（tap water and lake water） were in the range of 86.88% to 104.33%.Hg²⁺-imprinted polymer particles were prepared by double template imprinting method with Hg²⁺ and CTMAB as the template, Maleimide as the functional monomer and Ethylene Glycol Dimethacrylate（EDGMA） as cross-linking agent. Hg²⁺-imprinted polymer particles was characterized by scanning electron microscopy（SEM） and to display the configuration of surface. Thermo-gravimetric experiment confirmed the quality changes before and after the polymer reaction. This study also confirmed the best adsorption condition: the adsorption time was 110 min, the adsorption temperature was 50℃ and the p H was 7. In the selectivity experiment, the k value of Cu²⁺,Pb²⁺ and Co²⁺ were 111.08、93.18、49.7. The maximum absorption capacity was 61.23mg/g. Reused the prepared ion imprinted polymer six times, the adsorption capacity in the sixth time was 77.3% that of the first time. The recoveries of practical samples（tap water and lake water） were in the range of 90.72% to 101.44%.This experiment selected Maleimide as functional monomer, using the molecular structure of N, O atom of Hg²⁺ to prepare of molecular imprinted polymer. Precipitation polymerization is a kind of simple and feasible method to prepare molecular imprinted polymer, the surface of molecular imprinted polymer has specific adsorption hole, but the surface imprinting technique which has recognition sites can improve the recognition ability and the combination speed of the template ion and strengthen separation efficiency of the molecular imprinted. So the speed of the combination between molecular imprinted polymer and the template ion is much faster than the precipitation polymerization. The adsorption rate can reach about 90%. The selectivity of competitive ion is superior to the polymer by precipitation polymerization. Compared with the single template, molecular imprinted polymer prepared by the double template which introduced a new template has more advantages in all aspects. The above three kinds of different methods to prepare the polymer can all applicated in water samples and can be effectively adsorbed of Hg²⁺.