抄録
Synthetic mica, NaMg2.5 (Si4O10) F2 (Na-TSM), was treated with HCl solution and the correlations between the dissolutions of chemical components and the changes ofspecific surface area caused by the collapse of crystal structure were investigated.
3.00g of Na-TSM was dispersed in 300ml of 0.1N HCl at 60°C. The replacement of Na2+ ion in the interlayer space and of Mg2+ ion dissolved from octahedral layer by H+ ion took place fast. The dissolution of Mg2+ ion facilitated the dissolution of Fion accompanied with Si4+ ion coordinated in tetrahedral layer and then resulted in making mica particles fine. Meanwhile, MgF2 would first presipitate from the liquid phase and then the decrease of F- ion concentration in the liquid resulted in the precipitation of silica gel.
The maximum values of specific surface area of 1 hour treated Na-TSM obtained by N2 adsorption method and ethyleneglycol monoethyl ether adsorption method were 210 m2/g and 1100 m2/g respectively. Na-TSM decomposed completely to MgF2 and silica gel within 24 hours. The measurement of pore size distribution of 1 hour treated Na-TSM showed the existence of many micro pores with radii less than 40Å.
Na-montmorillonite was also similarly treated with HCl solution. The rate of ion dissolution from Na-montmorillonite was found to be slower than that from Na-TSM.
The maximum values of specific surface area obtained by N2 adsorption method and ethyleneglycol monoethyl ether adsorption method were 50 m2/g for 4 hours treated Namontmorillonite and 880m2/g for 1 hour treated Na-montmorillonite respectively.
