Research To Montmorillonite Activation And Its Microstructure

This paper begin with acid activated treatment,thermal activation treatment,single nuclear and multi-nuclear pillared experiment method,and activated montmorillonite in several methods. We study the microstructure change,physics-chemistry characteristic between raw minerals and activated products,interpret the relationship of physics-chemistry characteristic and microstructure change of montmorillonite before and after activation. All of them concrete on following:The essence of acid activated treatment is that the surface structure of montmorillonite changes after treated by acid. After acid activated treatment,along with the cation in octahedron sheet of montmorillonite dissolved and the Si in tetrahedron sheet of montmorillonite structure recombined,make the surface structure of montmorillonite change greatly. This changes enhance the surface acidity of activated montmorillonite,accrete the adsorption characteristic of activated montmorillonite. There are some Q3 Si structure in montmorillonite transform to distortion QJ Si structure and Q4 Si structure through structure recombination. The distorted Q3 and Q4 Si structure in montmorillonite surface possess Bnjmsted acidity.It is found that montmorillonite dehydrate adsorbing water and interlayer water when the temperature is between 126C-148C,this process is reversible. When the thermal treatment temperature reach 659C,the hydroxyl in octahedra sheet begin dehydrating,but the layer structure is maintaining. When the temperature reach 900 C,the layer structure of montmorillonite is destroyed,and the new mineral phase SiO2-x is found,when the temperature reach 1200C. It appears cristobalite and mullite,when the temperature reach 1350C. It appears cordierite.The pillared montmorillonite was prepared by A13+ in Keggin ions which hzs Keggin structure. The results suggest when m=2.4 the quantity of Keggin ions in A1C13 solution is more. In natural state,the d(001) value of pillared montmorillonite is 2.53nm,after incandescing at 300 'C,the basal interlayer spacing is stabilized 1.83nm,with high stability. The pillared montmorillonite containing Fe3+ ion was prepared by substituting Fe3> for A13+ in Keggin ions which has Keggin structure. The results suggest that the structure of hydroxy-Fe-Al oligocation,d(OOI) values and the thermal stability of pillared clay are affected by the Fe/Al ratio in pillared solution. The d(001) values increase and the thermal stability decrease with increasing F;/A1 ratio. Excessive amounts of Fe3+ ions can destroy the Keggin structure. The existence of Keggin structure can improve the thermal stability of the pillared clays.Both inorganic and organic pillared montmorillonites are used to adsorb the phenol,to study their suitable conditions and adsorption isotherms of adsorbing phenol. It reveals that using modified pillared montmorillonite with surfactant can improve the adsorbing capacity greatly. The adsorbing capacity of phenol by pillared montmorillonites is depended on micropore structure andsurface component of modified clays mainly,not only surface area. After incandescing at 500C,the pillar structure and the basal interlayer spacing (1.83nm) are stable still. So the pillaredmontmorillonite can use recycle,it is a potential substance of Adsorption of environmental pollutants.