Application Of Novel Functional Adsorption Materials In Microextraction

Liquid phase micro-extraction (LPME) and solid phase micro-extraction (SPME) are the greensample pretreatment technologies. Due to the simple, fast, environmental protection and suitablefor extraction of trace organic compounds, micro-extraction technology has found widelyapplications in food safety, environmental monitoring, drug analysis and other fields. However,common LPME solvent is mainly methylbenzene, carbon tetrachloride, ethyl acetate and that havevolatility, low viscosity, high toxicity and are easy to pollute the environment. Common SPMEdevices mainly use the coating type extraction medium, single variety, easy peeling off and badselectivity. Therefore, development of new and efficient micro-extraction materials becomes one ofthe research emphasis of the green sample preparation technology. Ionic liquid (ILs) and grapheme(G) become the preferred new and efficient micro-extraction materials for their environmentprotection and designability characteristic.In this work, a novel organophosphate functionalized ionic liquid (FILs),1-pentyl-3-(3-ethylphenphosphinyl) propylimidazolium bis(trifluoromethyl sulfonyl) imide salt was prepared andapplied to extract Nd(Ⅲ) in water as extraction medium of dispersive liquid-liquidmicroextraction(DLLME), coupled with ICP-AES determination. The effects of aqueous phaseacidity, extraction duration and interference ions on the extraction of Nd(Ⅲ) were examined,respectively. Under the optimized conditions, the method showed a good linear relationship in therange of0.1~5.0μg/mL. The detection limit is0.0025μg/mL. Stripping of Nd(Ⅲ) and reuse of theionic liquid were also researched. It was found that the elution rate of Nd(Ⅲ) up to70%in5%nitric acid medium when elution duration was30min, and the ionic liquid can be recycled.To overcome the shortcomings of the ionic liquid viscosity and slow mass transfer speed,Chapter3studied1-pentyl-3-(3-diphenphosphinyl) propylimidazolium bis (trifluoromethylsulfonyl) imide salt for extracting Sm(Ⅲ) in aqueous sample by in-tube circulation-flowliquid-liquid microextraction. The optimized experimental conditions were following: aqueousphase acidity pH8.0, sample solution velocity1.5mL/min, extraction duration time20min,saturated adsorption capacity118mg/g ILs at room temperature. This method showed a good linear relationship in the range of0.1~5.0μg/mL, with the correlation coefficient of0.9938and thedetection limit of0.0035μg/mL. The elution recovery of Sm(Ⅲ) is>98%by using2mL mixtureeluant (0.1mol/L citric acid+0.4mol/L formic acid+0.4mol/L hydrazine hydrate) for10min,and can realize the recycling of ionic liquid.A graphene/Fe3O4magnetic nanocomposite (G/Fe3O4) was synthesized and used as anadsorbent for the dispersive solid-phase microextraction of diethylstilbestrol (DES) fromenvironmental water. SEM、TEM、FT-IR and X-ray diffraction were used to investigate thechemical structure of graphene/Fe3O4magnetic nanocomposite. The effects of pH, adsorption timeand added salt on the adsorption of DES were examined, respectively. Results showed that the bestpH value is7.0, the balance adsorption time is20min, the obtained highest adsorption efficiency is88.2%. Absolute ethyl alcohol was effective in eluting DES on the G/Fe3O4and could realize therecycling of adsorbent. The adsorption behavior followed Langmuir adsorption isotherm with amaximum adsorption capacity of79.6mg/g and a Langmuir adsorption equilibrium constant of5.39mL/μg.In chapter5, a magnetic-sulfonic graphene nanocomposite (G-SO3H/Fe3O4) was synthesizedand characterized by SEM, TEM, FT-IR and XRD. It was used for removal of three cationic dyes:safranine T (ST), neutral red (NR), victoria blue (VB), and three anionic dyes: methyl orange (MO),brilliant yellow (BY), alizarin red (AR), from environmental water by the dispersive solid-phasemicroextraction. The experimental conditions were optimized, including pH, amount of adsorbent,ionic strength, etc. Adsorption kinetics follows the pseudo-second-order kinetic model well. Theadsorption isotherm coincided with Langmuir and Freundlich adsorption models. The maximumadsorption capacities of G-SO3H/Fe3O4for ST, NR and VB dyes were199.3,216.8and200.6mg/g. The adsorbed cationic dyes were eluted by using different pH values of ethanol as thesolvent. The established method was simple, sensitive and rapid, and was suitable for theadsorption of cationic dyes in environmental water.