Preparation of Mg-vermiculite nanoparticles using potassium persulfate treatment.

Delamination/exfoliation process of the Mg-vermiculite (Letovice, Czech Republic), particles with size less than 5 microm, was studied after potassium persulfate treatment and compared with known method utilized hydrogen peroxide treatment. X-ray powder diffraction (XRPD) patterns showed that treatment of Mg-vermiculite with different molar concentration of potassium persulfate: c = 0.02, 0.04, and 0.08 mol x dm(-3) at the temperature 60 degrees C for 2 hr caused reduction of relative intensity (I(rel.)) of the basal 001 diffraction to the 15%, 9%, and 4%, respectively, compared to intensity of 001 diffraction of untreated Mg-vermiculite (I(rel.) = 100%). On the other hand I(rel.) of the 001 diffraction of Mg-vermiculite after treatment with 30% and 50% (c = 9.8 and 17.4 mol x dm(-3)) hydrogen peroxide at the 60 degrees C for 2 hr decreased only to I(rel.) = 36% and 32%, respectively. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) verified effect of potassium persulfate treatment on structure degradation which is connected with higher degree of delamination/exfoliation of the particles and their cracking into nano-sized particles.