Research On Graphite Oxide Enhanced Liquid Phase Exfoliation Of Clay Mineral Materials

Clay minerals are important raw materials for industrial production in nature.According to the different microstructure,it can be generally divided into two-dimensional nanosheet stacked layered structure and one-dimensional nanofiber aggregated chain layered structure.When layered mineral materials are exfoliated into two-dimensional nanomaterials and chain layered mineral materials are exfoliated into one-dimensional nanomaterials,their performance will be greatly improved.In this paper,the representative two-dimensional layered clay mineral kaolinite and one-dimensional chain layered clay mineral attapulgite are selected as raw materials,and graphite oxide is used as exfoliation assistant,and a series of studies are carried out on the technology and mechanism of green and efficient preparation of nano clay mineral materials and their functional composites by liquid phase exfoliation method.The main research contents are as follows:1.Graphite oxide is used as exfoliation assistant to study the liquid phase exfoliation of kaolinite by high-gravity rotating bed.The effects of graphite oxide addition,rotating speed,time and interlayer spacing on kaolinite exfoliation are systematically studied,and the liquid phase co-exfoliation of kaolinite and graphite oxide is realized.After exfoliation,the kaolinite sheets become smaller,the layers become less,and some layers curl automatically.The length of supernatant nanoscrolls is between 1-5 ?m,and the outer diameter is about 500 nm.The interaction between graphene oxide and kaolinite is studied by density functional theory,and it is confirmed that the surface groups of graphene oxide and kaolinite can realize surface-to-surface bonding by hydrogen bonds,which promotes the dispersion of kaolinite and its nanosheets,and enhances the exfoliation of kaolinite.This method provides a new way for low-cost,environmentally friendly,and large-scale preparation of nano kaolinite two-dimensional and their composites.Based on the above method,kaolinite-graphene oxide nanocomposite material is prepared,and nano kaolinite hydrophobic sponge is prepared by simple dip coating method,which shows good hydrophobicity with contact angle up to 130°.The hydrophobic sponge has good adsorption capacity for various oils and organic solvents and can be regenerated and recycled.In addition,it can also be used to efficiently remove water-soluble dyes.2.Graphite oxide is used as exfoliation assistant,and high-speed homogenizer is used as exfoliation device to compare with the high-gravity rotating bed liquid phase exfoliation of kaolinite.The effects of graphite oxide addition,shear rate,time and interlayer spacing on kaolinite exfoliation are investigated.Compared with the high-gravity rotating bed,the high-speed homogenizer is more efficient.After exfoliation under the optimal conditions,the lateral size of kaolinite nanosheets becomes smaller and the layers become thinner.The supernatant contains a large number of kaolinite nanoscrolls with a length of 0.2-0.9 ?m and an outer diameter of about 100 nm.After exfoliation,the specific surface area of kaolinite increases from initial 7.96 m2/g to 21.47 m2/g.After kaolinite intercalated with dimethyl sulfoxide,the interlayer spacing increases from 7.2 (?) to 11.3 (?).After graphite oxide assisted exfoliation,the supernatant can obtain kaolinite nanoscrolls with a larger aspect ratio,the length is between 1-7 ?m,and the outer diameter is between 100-400 nm.The kaolinite after liquid-phase exfoliation exhibits good dye adsorption performance.Based on the above method,nano kaolinite three-dimensional porous composite material is obtained by polyvinyl alcohol cross-linking and the template effect of ice crystals,which shows good ciprofloxacin adsorption capacity and recovery performance,and the maximum theoretical adsorption capacity can reach 408.16 mg/g.It is proved that the composite interacts with ciprofloxacin through electrostatic attraction,hydrogen bond and ?-? bond.3.Study on graphite oxide assisted liquid phase exfoliation of attapulgite.After graphite oxide assisted the liquid phase exfoliation of attapulgite by high-speed homogenizer,the rod crystal has achieved good dissociation and dispersion.The average particle size of attapulgite is reduced from above 100 nm to about 52 nm,and 79%of the rod crystals are distributed in the range of 10-70 nm.Under the action of shear exfoliation,the attapulgite rod crystal is dissociated,but its crystal structure is not destroyed.On this basis,attapulgite-graphene oxide nanocomposites and nano three-dimensional porous hydrogels are prepared.Due to the spatial hindrance effect of attapulgite,the self-aggregation of RGO sheets is effectively prevented,and the three-dimensional interconnected pore structure enables electrons and electrolyte ions to be rapidly transported,showing good electrochemical performance and good specific capacity(103.35 F/g,0.5 A/g).The assembled flexible solid-state supercapacitors have high operating voltage window(0-1.6 V),high area specific capacity(127.33 mF/cm2,0.1 mA/cm2),good flexibility and cycle stability.A series of solid-state supercapacitors can be used as the power supply for LED lights,and the lighting time exceeds 30 min.