The Preparation, Characterization And Evaluation Of The Imidazoles-functionalized Silica

Five imidazoles-functionalized silica as adsorbent were synthesized and characterized. And the removal of Cr(VI) and phenolic compounds from the environmental water samples by the adsorbents was also investigated, respectively. This topic is a part of the national natural science fund projects (21107022) and there are four parts in this paper.Chapter1, the preparation methods and application of immobilized ionic liquids were summarized comprehensively in some areas. The chapter also illustrates research significance and the content of the topic.Chapter2, Imidazole,1-methyl imidazole,2-methyl imidazole,4-methyl imidazole and1,2-dimethyl imidazole were coupled with agent3-propyl chloride triethoxy silane respectively through chemical bonds in order to synthesize five kinds of immobilized ionic liquid adsorbent, and named respectively:SilprImCl, SilprMiImCl, SilprM2ImCl, SilprM4mCl and SilprM1M2ImCl. And their structures were characterized by scanning electron microscopy, infrared spectrum and thermogravimetric analysis.Chapter3, trace amounts of Cr (VI) was separated and preconcentrated from the aqueous solution by adsorbent SilprImCl. The adsorption performance of Cr (VI) in aqueous solution was investigated respectively from the pH, contact time, initial Cr(VI) concentration, adsorbent amount and temperature. The experimental results showed that the adsorption isotherms would be well defined with Langmuir model instead of Freundlich model. The maximum adsorption amount of Cr(VI) of47.79mg/g with an initial Cr(VI) concentration of150mg/L was achieved at pH of2.0. The adsorption-desorption experiments of the adsorbent exhibited that the adsorbent could be regenerated and reused eight times at least by simple washings with NaCl and water in turn. And the elution rate can reach up to99.3%.Chapter4, the adsorption performance of the adsorbent SilprlmCl for five kinds of phenolic compounds (Phenol,2-NP.3-NP,4-NP and2,4-DNP) was investigated. Experimental results show that the SilprImCl adsorption quantity on five kinds of phenolic compounds were sorted from big to small:2,4-DNP>4-NP>2-NP>3-NP> phenol. And the2,4-DNP elution rate reach up to91.6%under the flow rate of2mL/min with4mL0.25mol/L HC1elution solution. Experimental results also show that the recovery rate of2,4-DNP still is not low significantly, when the Column was repeated to inject sample and elution at least10times. The adsorption performance of2,4-DNP in aqueous solution was investigated respectively from the pH, contact time, initial Cr(VI) concentration, adsorbent amount and temperature by the SilprMiImCl, SilprM2ImCl, SilprM4mCl and SilprMi1M2ImCl. Experimental results show that absorption efficiency of2,4-DNP by the adsorbent SilprM1M2ImCl and SilprMiImCl is good in the solution pH=5-9, and adsorption reached maximum31mg/g in the pH=5and then remain unchanged. The experimental data were described by Langmuir model better than by Freundlich model. The pseudo-second order kinetic model gives satisfactory fitting.