Three Dimensional Porous Graphene Materials For Sample Preparation

Three dimensional porous graphene materials(3DPGMs)are kinds of graphene based functional material derived from two dimensional graphene assemblies.The integration of individual graphene sheet into 3D macroscopic structure can not only maximally retain the intrinsic palmary properties of layered graphene materials,but also exhibit interesting features of the 3D porous architecture including huge specific surface areas,strong mechanical strengths,high electron conductivity and fast mass transport kinetics,which could lay the foundation of high-performance graphene materials for a wide range of theoretical research and practical applications.This dissertation focused on the expanding the potentials of 3DPGMs in analytical chemistry,and exploring the potential of 3DPGMs as adsorption material for sample preparation.The main contents are summarized as follows:(1)A novel GA monolith based solid-phase extraction method was investigated in the application of environment analysis.The GA monolith based solid-phase extraction cartridge was fabricated directly in the empty cartridge through freeze casting followed by hydrazine vapor reduction method.Due to the efficient mass transfer,more adsorption sites as well as effective retention for the analytes,the adsorption property of GA for bisphenol A revealed better performance than that of GS.What's more,GA also outperformed in loading and eluting for target analysis.On the basis of the above advantages,the obtained cartridge was applied for the separation of environmental pollutants from water samples.Taking endocrine disrupting chemicals and polychlorinated biphenyls as the polar and weak polar model analytes,the proposed analytical methods were applied for real samples analysis with high sensitivity and satisfactory recoveries.(2)The hierarchical porous graphene aerogel(HPGA)was fabricated for adsorption and preconcentration of chemical warfare agents in air samples.A template assisted freeze casting followed by thermal reduction approach was employed to prepare HPGA.The resultant HPGA exhibits 3D interpenetrating micron and submicron hierarchical porous structure with excellent thermal stability and large specific surface area,which facilitates the rapid diffusion of contaminated gas and thus helps dimethyl methylphosphonate molecules interact with the active adsorption sites through hydrophobic interaction.Thus the higher adsorption capacity was available on HPGA than that of ordinary GA and Tenax TA.For the application,the HPGA was used for the extraction of trace sarin from air samples in combination with thermal desorption gas chromatography-mass spectrometry.The novel sorbent exhibited excellent extraction efficiency towards sarin at comparatively high relative humidity owing to its hydrophobic property.(3)The HPGA based in-syringe solid-phase extraction device was designed for on-site sampling of pyrethroids in environmental water samples.The HPGA was prepared through template assisted freeze casting followed by hydrazine vapor reduction approach.The in-syringe solid-phase extraction device was miniaturized and portable,simple and reliable operation as well as convenient for mass production.Owing to the large specific surface area and hydrophobicity of HPGA,the target molecules could be completely extracted during one aspirating/dispensing cycle.The analytes could be stable on the sorbent for at least 72 h and would not be affected by the sample pH.All the results show clearly that the device could meet the requirements of on-site sampling.The proposed analytical method for pyrethroids was successfully applied to on-site sampling for real samples.It can also carves out the new ideas for sample preparation technology for on-site sampling.