Modification Of Montmorillonite And Its Application In Environmental Remedition

Montmorillonite(MMT) is a kind of typically layered silicate which has alot of special properties. MMT possesses large surface area, ion-exchangeproperty, adsorption property and their layered structure can be controlled. MMTis very cheap and abundant in our country. MMT as adsorbent or catalyst carrierwill have the huge economic efficiency to resolve the environment problem.However, natural MMT can’t meet the requirements well. In order to expand theapplication of MMT, it is necessary to modify natural MMT. In the thesis, thesynthesis process of organic and inorganic MMT have been studied. The mainworks are present as follows:1) A series of organic MMT(OMMT) were prepared via an aqueous methodwith the assistance of several surfactants. The effects of different organicmodifier on the structure and property of MMT were discussed. The properpreparation conditions of OMMT were obtained. Modified MMT werecharacterized by XRD, SEM, and FTIR. The results showed that the distancebetween MMT layers increased with the intercalation of cationic surfactant whileanionic surfactant was not. OMMT which was modified successfully had gooddispersibility in styrene and strong adsorption towards phenol. The interfacemicroenvironment of MMT was changed from hydrophilicity to lipophilicity.The sedimentation rate of MMT in styrene was slow and it required more time toachieve constant sedimentation volume.2) The hydrothermal preparation condition of inorganic modifier bismuthsulfide(Bi2S3) had been studied. Bi2S3sample were characterized by XRD, SEM,and UV-Vis. Comparison of different bismuth source and different mineralizer inpreparation of Bi2S3, it was clear that the presence of mineralizer had biginfluence on nucleation and growth of crystal. Compared to sodium hydroxide,urea as mineralizer reduced the temperature of hydrothermal reaction. Theproduct had high purity, crystallinity and catalytic activity. The samples preparedwith bismuth chloride exhibited high catalytic activity than that of bismuth nitrate pentahydrate.3) Bi2S3/MMT composite material was prepared by hydrothermal method.Composite material were characterized by XRD, SEM, and EDS. The resultsshowed that there existed interaction between bismuth sulfide and MMT. Bi2S3was successfully loaded in MMT and the layered structure of MMT was notdestroyed obviously. Since the structure of composite material was stable, it hada number of property of Bi2S3and MMT. The photocatalytic activity of Bi2S3was improved. With the increase of MMT, photocatalytic activity of Bi2S3decreased. The specific surface area of composite material was bigger than thatof Bi2S3. Inorganic active ingredient was significantly reduced in per unitsample. But photocatalytic performance is little difference. So specific surfacearea was the crucial factor that influencing the photocatalytic activity of bismuthsulfide.