The Preparation And Characterization Of Fe-Al-Pillared Montmorillonite

Ca-montmorillonite which is from Xinyang Henan provice is sodium-modified. Fe-Al-pillared agent is synthesized by ion-exchange method and then the Fe-Al-pillared montmorillonite is prepared. X-ray diffraction(XRD), infrared absorption spectrum(IR), thermal analysis (TG/DSC) and chemical analysis were applied to study the properties of Fe-Al-pillared montmorillonite. At the same time, the crystal structure of hydroxyl-iron-aluminum oligocation has been discussed.The experiment takes the basal spacing d₍₀₀₁₎ value as standard to judge the pillaring effect of Fe-Al-pillared montmorillonite. The better conditions of preparation are n(Fe³⁺):n(Al³⁺)=1:15,OH/cation=2.0,(Fe+Al)/montmorillonite=10mmol/g,the reactive temperature is 60℃,aging times of pillaring agent and pillaring product are both 2d. The results indicated that d₍₀₀₁₎ value of Fe-Al-pillared montmorillonite reached 1.91947nm, while the d₍₀₀₁₎ value of Na-montmorillonite was just 1.27263nm. That is to say hydroxyl-iron-aluminum oligocation has already inserted in the montmorillonite and made the basal spacing become larger.Fe-Al-pillared montmorillonite calcined at 500℃has excellent stability. However, when the temperature is higher than 500℃, the peak intensity of (001) face becomes weaker and weaker, the peak shape gets broader. The IR spectra of the Fe-Al-pillared montmorillonite calcined at different temperatures showed that the peak intensities changed a lot. After being calcined at 500℃for two hours, many absorption bands of Fe-Al-pillared montmorillonite disappeared.Fe in the Fe-Al-pillared agent may substitute partial Al which is in the Keggin ions in the form of octahedron or aberrance octahedron. And it may exist in the interlayer of montmorillonite in the form of the structure model of hydroxyl-silico-aluminum oligocation.