Adsorption Performance Of Nitrophenols On Imidazolium Ionic Liquid-modified Silica

In this paper, a series of imidazolium ionic liquid-modified silica were synthesized and used asadsorbents for separation and preconcentration of nitrophenols from aqueous solution. There are six partsas follows.Chapter1In this section, the determination and treatment techniques of phenolic compounds inwastewater were reviewed, the immobilization procedures of ionic liquids and the application ofimmobilized ionic liquids in separation techniques were also included. And the objective and significanceof the research were also elucidated.Chapter2Eight kinds of imidazolium ionic liquid-modified silica (named as SilprPImCl, SilprOImCl,SilprDImCl, SilprM4ImBF4, SilprM4ImPF6, SilprM4ImTf2N, SilprP3NImBr and SilprSP3NImBr) weresynthesized and characterized by Fourier transform infrared spectrum (FT-IR), Thermogravimetric analysis(TGA), Elemental analysis and BET analysis.Chapter3The adsorption of nitrophenols onto three types of N-alkylimidazolium modified silica(SilprPImCl, SilprOImCl and SilprDImCl) were discussed in this section. The adsorption capacitiesincreased with the increase of initial concentration and decreased with the increase of dosage of adsorbent,and were rarely affected by temperature. The adsorption capacities of nitrophenols onto SilprOImCl andSilprDImCl were contrary to the pKavalue of nitrophenols. When the length of alkyl branches wasincreased, lower amount of2,4-dinitrophenol and more2-nitrophenol,3-nitrophenol and4-nitrophenolwere extracted, and the recovery yields of2,4-dinitrophenol decreased meanwhile.Chapter4SilprM4ImBF4, SilprM4ImPF6and SilprM4ImTf2N, three kinds of4-methylimidazoliummodified silica with different counter anions were used as adsorbents for separation and preconcentration of2,4-dinitrophenol from aqueous solution. It was found that the adsorption capacity of2,4-dinitrophenolincreases according to the order: SilprM4ImTf2N<SilprM4ImPF6<SilprM4ImBF4, which was consistentwith the hydrophilicity of these counter anions and contrary to the van der Waals volume of these counteranions. With respect to the dynamic adsorption, SilprM4ImBF4and SilprM4ImTf2N had the similarrecovery yields of2,4-dinitrophenol, while SilprM4ImPF6had slightly low recovery yields. Chapter5Two types of amino-imidazolium modified silica (SilprP3NImBr and SilprSP3NImBr) wereapplied in the adsorption of2,4-dinitrophenol. Based on the results, it is clear that the adsorbents are ofprimary anion-exchange and electrostatic nature. The adsorption capacities achieved with SilprP3NImBrusing the propyl as the linker were higher than those of SilprSP3NImBr using the propyl sulfide as thelinker. The adsorption capacities remained constant in the pH range of4.0-9.0and increased with anincrease in the initial concentration. The experimental data were fitted well with the linear form ofLangmuir model and the adsorption kinetics followed a pseudo-second-order model. The two adsorbentscould be regenerated and reused by washing with HCl eight times at least without any appreciable loss oftheir original adsorption capacity.Chapter6Summary and outlook were introduced in this section.