The Preparation And Characterization Of Si-Pillared Montmorillonite

Pillared clay is a kind of the mineral materials, which is synthesized by pillaring inorganic polycations or organic ionic groups (molecules) into clay minerals. Modified clay is a two-dimensional mineral material with large surface area, high thermal stability, strong acidity and variable pore size, therefore it is widely used in such field as petrochemical, sewerage treatment, and antibacterial materials.Ca-montmorillonite was from Xinyang, Henan province and was sodium-modified as raw material. Si, Si-Fe, Si-Al, and Si-Ti pillared montmorillonite was prepared via ion-exchange method by the reaction of Na-montmorillonite with silicon sol agent, silica-iron particles, silica-aluminium particles, and colloidal silica-titanium agent separately.The basal spacing d(001) value was considered as standard to judge the pillaring effect. The result indicated that d(001)) value of Si, Si-Fe, Si-Al, and Si-Ti pillared montmorillonite reached 1.6114nm,1.6747nm, 2.0701nm, and 1.6341nm respectively from 1.2741nm which was the d(ooi) value of Na-montmorillonite. It showed that the polymerized hydroxyl obigocation (Si, Si-Fe, Si-Al, and Si-Ti) had already inserted into the montmorillonite and made the basal spacing become larger. Comparing with different Si-pillared montmorillonite, Si-Al pillared montmorillonite was better than others. The better conditions of preparation were selected that the molar ratio of Si4+and Al3+was 1:1, the volume of 0.4 mol/L NaOH was 100mL, the reactive temperature was 60℃and the aging time of pillaring agent and pillaring product are both a day. The results showed that the d(001) value of Si-Al pillared montmorillonite was 1.9178nm and still presented as meso-microporous properties and fine thermal stability when calcined after 500℃. The infrared spectrometer of the Si, Si-Fe, Si-Al, and Si-Ti pillared montmorillonite calcined at different temperatures showed that the peak shapes of pillared montmorillonite and Na-montmorillonite were similar to each other.With the help of X-ray diffraction (XRD) patterns analysis, Fourier-transform infrared spectrometer (IR) analysis, Chemical analysis and Thermal Analysis (TG/DSC), the properties of Si, Si-Fe, Si-Al, and Si-Ti pillared montmorillonite had been revealed. The crystal structures of different silicon polymerized hydroxyl obigocation had been discussed respectively. It showed that Si-Al polymerized hydroxyl obigocation based on Al13 Keggin type of [Al13O4(OH)24(H2O)12]7+ which might reat with the silicon-oxy tetrahedron sheet and formed stable covalent bond of [Si-O]…[H(O)-Al(Si)] in [AlO4Al12-xSix(OH)24(OH2)12](7+x)+, which was similar to Si-Fe agent. The structure of Si-Ti agent was Dawson type of [Ti20032(OH)12(OH2)18]4+ which formed covalent bond of Si-O-H-OH-Si(Ti) in [(TiO4)2Ti18.xSixO24(OH)12(OH2)18](4+x)+by reacting with Si(OH)4 in the layer of montmorillonite.