Preparation And Regultation Of The Ordered Mesoporous Materials For Solid-phase Microextraction

In modern society with a low-carbon economy,solid-phase microextraction(SPME)has attracted strong interest as an emerging organic sample pretreatment technique due to its simplity,convenience and non-secondary pollution.Normally,the extraction performance of SPME techique heavily depends on characteristics of the coating materials.Therefore,rational design and regulation of the structure and composition of coating materials to acuquire high SPME performance is of great significance.In this thesis,from the standpoint of pursuing SPME coating with outstanding extraction performance and stability,several ordered mesoporous nanomaterials with controllable porous structuresand chemistry compositions were explored.Moreover,the structure-function relationship between the mesoporous nanomaterials and SPME performance were also profoundly investigated.The main research contents and conclusions are presented as follow.(1)A one-step strategy for prapration the ordered mesoporous SPME coating was developed by the solvent evaporation induced self assembly(EISA)incombination with the dip-coating method.Infrared spectroscopy and thermal analysis shows the formation mechanism of the supported OMC film.XRD,TEM and N₂ isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure.The specific surface area and pore volume are 616.4 m² g^-1 and 0.41 cm³ g^-1,respectively.SEM shows that the OMC film is complete and combines with the matrix tightly.Thickness of the supported film can be controlled in the range of 1-14?m through different pulling times.(2)The SPME performance of the OMC-fibers was studied.Results show that the extraction capability and sensitivity changes with the preparation conditions.The OMC fibers acquired under different pyrolisis temperatures of 350 and 700 ^oC present different extraction sensitivity towards benzene series(BTEX),polycyclic aromatic hydrocarbon(PAHs)and chlorophenols(CPs).OMC700 fibers present higher extraction efficiency towards BTEX and PAHs because the non-polaritiy and?-?interaction between the coating and benzene rings.The OMC350 fiber which contains several hydrophilic groups and polar groups tends to extract polar CPs.Effects of coating thickness on the extraction performance were evaluated using BTEX and PAHs.For BTEX,extraction efficiencies increase with the increasing of coating thickness.However,extraction efficiencies for PAHs with more than three benzene rings increase slightly.The whole evaluation of the OMC coating was carried by five typical BTEX compounds.Compared with commercial PDMS fiber,the OMC fiber presents improved excellent stability in thermal and organic solvents.The extraction efficiency of OMC fbier are 2.0-5.5 times higher than that of the commercial PDMS fiber and.The OMC fiber was successfully used for the analysis of BTEX from aqueous media with satisfactory linear range,detection limits and recovery.(3)OMS film supported on anodized titanium wire was fabricated as a new SPME fiber for the extraction of CPs from aqueous media.The N₂adsorption-desorption results show the OMS material has well-ordered mesostructure with uniform pore diameter.The SEM images verify that the OMS film was successfully grafted onto the surface of anodized titanium wire.The OMS fiber was successfully applied to the extraction and determination of three CPs compounds.The resultant method based on the OMS fiber exhibits wide linear ranges(0.2-200?g L^-1),low detection limits(0.03-0.12?g L^-1)and good satisfactory recovery(81.4-102.4%).(4)Supported OMC film with large pore(LP-OMC)has been synthesized using laboratory-made PEO₁₁₃-b-PS₁₉₂diblock copolymers as templates and PF resols as carbon resource.N₂ sorption isotherms reveal a large mesopore at the mean value of 13 nm with a narrow pore-size distribution.It was fabricated as new SPME fiber for the extraction of PAHs.The LP-OMC fiber shows obvious extraction selectivity towards PAHs from the complicated matrix containing both BTEX and PAHs compounds.The LP-OMC was successfully applied for the analysis of PAHs in real environmental water samples with linear ranges of 0.05-50?g L^-1,detection limits of 1.6-10.0 ng L^-1and recoveryof 78.1-112.1%.