The Purification And Application Of Bentonite

Montmorillonite(MMT)is the main component of bentonite.Because of its superior physical and chemical properties,it is widely used and so called the "universal soil".The experimental material is based on the low grade bentonite ore which comes from the Liu Fangzi of JiLin province.We purificate it,and expand its application on the basis of purification in biological matrix composites.On one hand,we used the purified soil and sodium carboxymethyl cellulose(CMC)to make the high strength and high barrier property films.On the other hand,we added quantum dots into the film which make up with the chitosan and montmorillonite to prepare the fluorescent material,made in the application of bentonite.According to the characteristics of bentonite from Liufangzi,the wet-way method was used for purification.The single-factor experiments and orthogonal experiments evaluated the effects of liquid-solid ratio of bentonite slurry,sodium hexametahposphate,stirring time,and centrifugal speed on the purification of bentonite.The effect of purification was tested by the methods of blue adsorbed and X-ray diffraction photographs.The results showed that the best conditions for purification was when the liquid-solid ratio was 12:1(g/g),the concentration of dispersant was 0.075%,the stirring time was 0.5 h,and the centrifugal speed was 4000 revolutions per minute.The experiment showed that the expansion capacity can improve from 33 mL/g to 97 mL/g,the cation exchange capacity(CEC)can improve from 0.805 mmol/g to 1.190 mmol/g,and the purity of bentonite can improve from 60.84% to over 98% after purification.The results of the XRD showed that the SiO2 peaks of the purified bentonite was weakened,which indicates that the purification process can get higher quality of bentonite products.The montmorillonite was filled into sodium carboxymethylcellulose(CMC)films in order to reinforce modified CMC-based films.The influence of MMT content on mechanical properties and gas barrier property of the CMC composite materials was researched,and structures of the composite membranes were analyzed by XRD,SEM and TEM.The results indicated that the appropriate amount of MMT could improve the mechanical properties and gas barrier property of CMC-based films significantly.When the MMT was added with 10%,the tensile strength could be increased from 105 MPa to 375 MPa and the gas barrier property was improved obviously.A method was presented for fabricating the fluorescent nanocomposites containing CdTe quantum dots(QDs)and montmorillonite(MMT)-chitosan(CS).MMT-CS/CdTe QDs nanocomposites were prepared via a simple,versatile and robust approach combination of covalent and electrostatic assembly methods.This method of synthesis of composite materials in water showed good fluorescence property and stability,and contains the MMT-CS/QDs artificial imitation shell structure with high strength and stability of the fluorescence properties of thin film.