The Study Of Montmorillonite Adsorbing Bismuth And Preparation Of Intercalation Composites

Montmorillonite（MMT）, a phyllosilicate minerals clay has a strong acidand alkali resistance and high temperature resistance; its lamella structureconsists of three sub-layers: two sub-layer of silicon-oxygen tetrahedron and asub-layer of aluminum-oxygen octahedron. Between two tetrahedron sub-layer,there is an octahedron sub-layer. Each of sub-layers is connected with oxygenatom shared, forming a unit sheet layer of MMT. The different amouts of watermolecules exist in the space of distinct layers. Owing to negative charges in thespace of layers, MMT dispays the pefect properties of swelling, adsorption andcation exchange. In recent years, MMT, for its excellent properties are widelyapplied in the disposition of radioactive elements, the preparation of controlledrelease pharmaceutical, the dispersion of nano-particle, the immobilization ofbiological enzyme, the preparation of anti-compression and anti-fracturematerials and so on.This thesis select MMT as study object, and investgate the adsorption lawof bismuth ions of calcium montmorillonite and sodium montmorillonite in thestrong acid solution. Based on the preferable adsorption of sodiummontmorillonite, bismuth sulfide/MMT intercalation composites are prepared.Adopted solid-liquid adsorption models （Langmuir, Freundlich and D-R）,UV--visible spectrophotometer, X-ray diffraction （XRD）, Fourier transforminfrared infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM）,energy spectrum analysis （EDS）, fluorescence spectroscopy （PL） and UV-visiblediffuse reflectance spectra, the products are analyzed and characterized.Conclusions are as follows：1) Trivalent bismuth ions can be colour with color developing agent（thiourea, potassium iodide and ascorbic acid blend in a certain proportion） inthe strong acid solution. The vision absorbance peak of complex is465nm.Absorbance of the complexes gets stable for the reaction at5-8min. Therefore,Using the Lambert-Beer laws, the adsorbance of complexes would be measured and the amout of trivalent bismuth can be Fig.ured out in strong acid solution.2) The layers of Calcium montmorillonite are still remaining in the strongacid solution. Therefore, bismuth ions can be adsorbed by Calciummontmorillonite. Trivalent bismuth ions are regularly dispersed inner surface oflayers with the adsorption model of Langmuir, making hydrogen ion away fromMMT and the （001） basal spacing of MMT smaller. According to the Langmuirisothermal adsorption equation, the maximum of bismuth adsorbed by MMTcan reach220.9mg/g in the strong acid.3) Adsorbed by sodium montmorillonite, the bismuth ions are differentfrom calcium montmorillonite. The （001） basal spacing of sodiummontmorillonite increases, when the sodium montmorillonite is adsoption ofbismuth ions.4) Calcined in half a reducing atmosphere, sodium montmorillonite emitsweak fluorescence by exciting in500-700nm band, which may be attributed tobivalent bismuth.5) The complexes [Bi（Thioure）₃]³⁺, which bismuth and thiourea forms, canbe sufficiently adsorbed by sodium montmorillonite. Bismuth sulfide makes the（001） basal spacing increase from1.428nm to1.594nm, which is formed bymicrowave irradiation in the space of MMT. Comparision of bulk phase bismuthsulfide, The UV-visible diffuse reflectance spectra of bismuth sulfide/MMTintercalation composites shift short wavelength.6) Calcined in different temperature, sulfide/MMT intercalation compositesshow the properties of nano materials. Comparision of bismuth sulfide/MMTintercalation composites calcined by200℃, The UV-visible diffuse reflectancespectra of composites calcined by400℃shift long wavelength, which provesthat the particles of bismuth sulfide in the space of MMT become bigger.