Synthesis, Characterization And Application New Materials For Separation And Enrichment Of Environmentally Hazardous Substances

Sample pretreatment techniques as the key technique of enrichment, separation and analysis of environmentally hazardous substances have caused wide concern, in which the solid phase extraction and solid phase microextraction is widely used, while the used extraction packing will directly determine the efficiency of preconcentration and separation of the sample. Therefore, the development of novel and efficient enrichment separation materials has become a research hotspot in this field, it also plays an important role of separation and analysis of complex system science.This thesis summarized the type, synthesis and modification methods, structural characteristics and properties of magnetic materials, mesoporous materials and molecular imprinted polymer materials, as well as the current progress and development trend of separation and enrichment of environmentally hazardous substances; studied the synthesis and characterization of uniform and monodisperse magnetic core-shell carbon nanospheres, and its adsorption performance for anthracene in water; prepared Ce-SBA-15, an mesoporous material loaded by CeSiO4, and investigated its adsorption properties for B(a)P in cyclohexane solution, also discussed the adsorption mechanism; synthesized uniform monodispersed hollow molecular imprinted polymer nanospheres and investigated the adsorption of bisphenol A and selective enrichment and separation performance; synthesized hollow porous molecular imprinted polymer nanospheres with high specific surface area and uniform pore size, and investigated the adsorption of bisphenol A and selective enrichment and separation performance.By adopting improved Stober method, using resorcinol and formaldehyde as precursor in aqueous solution to prepare Fe3O4@polymer, after high temperature carbonization, Fe3O4@C nanoparticles were obtained. The SEM and TEM were used to characterize the prepared Fe3O4@C, found that Fe3O4@C has fairly good uniformity and dispersion. By optimizing the synthesis process, found that the concentration of ammonia and group citric acid on the surface of Fe3O4nanoparticles were the key factors to influence the successful synthesis of Fe3O4@polymer. By simple adjusting the mass ratio of the reaction precursor and Fe3O4nanoparticles, carbon shell thickness of Fe3O4@C nanoparticles can be controlled easily. Taking Fe3O4@C as the separation and enrichment materials of anthracene in aqueous solution, found that Fe3O4@C has a fairly high adsorption rate and large equilibrium adsorption capacity for anthracene, which shows good application prospect in the rapid separation and enrichment of environmental pollutants.Using in situ one-step hydrothermal method, with three triethylamine as alkali source, Ce-SBA-15mesoporous materials were prepared loading by the CeSiO4. By using XRD, TEM and nitrogen adsorption/desorption to characterize the structures of the samples, the results showed that, the component material Ce-SBA-15possessed relatively large specific surface area and uniform pore diameter distribution, also the structures were highly ordered. At the same time the active CeSiO4phase were observed in the pre-synthesised and the calcined Ce-SBA-15samples, and uniformly dispersed in the mesoporous pore. Through the study of adsorbability of the Ce-SBA-15material with different doping amount of cerium for B(a)P in cyclohexane solution, the results show that the amount of doped cerium has great influence on the adsorption results. Through the observation of the adsorption phenomena and characterization of IR, UV-vis, FLD, El and NMR of methanol eluent of materials after adsorption B(a)P, the possible adsorption mechanism is proposed, that is B(a)P was first adsorbed onto the Ce-SBA-15mesoporous materials, and then the CeSiO4phase oxidizing B(a)P into benzo(a)pyrene-6,12-quinone with high polarity by a free radical oxidation mechanism, which greatly improves the adsorption performance of Ce-SBA-15mesoporous materials for B(a)P in cyclohexane.Through one-step precipitation polymerization technique, using unmodified SiO2ball as hard template, taking advantage of esterification of the carbonyl of functional monomers and Si-OH on the surface of SiO2sphere to promote the molecularly imprinted polymer coating on the surface of SiO2sphere to obtain SiO2@MIPs, and then by HF etching to simultaneous remove SiO2and molecular imprinting to obtain the hollow molecularly imprinted polymer nanospheres (MHMIPs). SEM and TEM techniques were used to characterize the characteristics of the sample, the results show that the prepared SiO2@MIPs and MHMIPs have fairly uniformity and dispersion. By optimizing ratio of functional monomer of the imprinted precursor, the right ratio of functional monomer which has high adsorption amount and excellent selectivity was found, that is BPA:MMA:EGDMA=1:6:20; by adjusting the mass ratio of imprinted precursor and SiO2nanoparticles, thickness of imprinted shell can be easily adjusted; by comparing adsorption performance of MHMIPs with different thickness for bisphenol A (BPA), it shows that the increase of shell thickness is detrimental to improve the adsorption capacity of MHMIPs for BPA. The adsorption properties of BPA and other structural analogues on MHMIPs and MHNIPs were studied, the results show that the MHMIPs has higher adsorption rate and high adsorption capacity for BPA, and has high selectivity enrichment performance for BPA in mixed solution of BPA and its structural analogs.Using mesoporous SiO2as "nanoreactors" and hard template, bisphenol A as template molecule,4-vinylpyridine as functional monomer, EGDMA as crosslinking agent, through the control dipping strategy and the etching technology, hollow porous molecular imprinted polymer nanospheres were prepared. SEM, TEM and BET were employed to characterize the morphology and physical properties, the results show that the prepared molecularly imprinted polymers possess hollow spherical structure and high specific surface area up to607m2·g-1, the pore size distribution is uniform. The adsorption properties of HPMIPs and HPNIPs for BPA and other structural analogues were studied, the results show that the HPMIPs has higher adsorption rate and high adsorption capacity for BPA, and has high selectivity of enrichment performance on adsorption of BPA in mixed solution of BPA and its structural analogs.