Study On Hydration Swelling And Exfoliation Of Montmorillonite

Montmorillonite is a typical layered clay mineral with low price,abundant reserves,excellent chemical and thermal stability,and good mechanical properties,etc.,so it is widely used in many fields.Montmorillonite is easy to swell in the aqueous solution,causing the montmorillonite to be easily exfoliated under the action of external force.After the montmorillonite is exfoliated into two-dimensional nanosheets,the specific surface area,pore volume,and active site are significantly increased,and the application range of montmorillonite is more extensive,which makes montmorillonite exfoliation a hot spot for everyone to study and has great significance for enhancing the utilization value of montmorillonite resources.In this thesis,montmorillonite is taken as raw material,the degree of hydration swelling of montmorillonite is studied by swelling capacity and XRD,and the hydration swelling of montmorillonite is studied by CMC binding to montmorillonite and molecular simulation analysis.At the same time,the montmorillonite nanosheets were prepared by exfoliated using the freezing-thawing method and the freezingsublimation method.The influence of montmorillonite solution concentration,p H and interlayer cation type on the thickness and lateral size of exfoliated montmorillonite nanosheets was studied in detail.The main conclusions of this thesis are as follows:(1)Montmorillonite has good hydration swelling,the degree of hydration swelling is very high,the hydration swelling force is greater than the binding force of CMC on montmorillonite,the hydration swelling energy is higher than the reaction between CMC and montmorillonite Hydrogen bond energy.(2)Both the freezing-sublimation and the freezing-thawing can exfoliate montmorillonite,and the concentration of montmorillonite has no effect on exfoliation;when the p H is strongly acidic,the lower the p H,the worse the exfoliation effect;the higher the interlayer cation valence state,the better the exfoliation effect.(3)After the freezing-sublimation and freezing-thawing process,the thickness of the montmorillonite sheet is reduced,while the lateral dimension is basically unchanged,and the large montmorillonite flakes can be well protected from damage during the exfoliation process.The freezing-sublimation method has a better exfoliation effect on montmorillonite than the freezing-thawing method,and can also improve the exfoliation efficiency of montmorillonite.