Modification Of The Thermally Exfoliated Vermiculite By Sonication And Grafting Methods

In the present study, the thermally exfoliated vermiculite has been sonicated in order to grafting with the butyl-imidazolium. A suspension of vermiculite-water with 1% of concentration was sonicated at 20 KHz. This led to the decrease in the size of grains to16 µm after 2 h of treatment. Increasing of sonication time, presence of H2O2 , and the increase of the vermiculite concentration have caused an accentuation of sonication effect, this resulted the decreasing of the size to 10 µm. Moreover, a 2% fraction of submicron-sized particles was appeared. The pH of the vermiculite suspensions was increased. The number of the -OH sites was determined by acid-base titration using Gran method. The infrared spectra of the raw and sonicated vermiculites in H2O or containing H2O2 were very similar. In the presence of H2O2 , two bands were observed at 1380 and 1460 cm-1 . These are due to the presence of carbonates anions formed during sonication in H2O2 . XRD spectra showed that the sonication did not affect the vermiculite structure. The grafting was carried out on sonicated samples during 5 h in H2O. This was realized in two steps. In the first step, we grafted 3-chloropropyltrimethoxysilane instead of the –OH sites. In the second step, we conducted a nucleophilic substitution of chlorine with methyl-imidazole. We proved by infrared spectroscopy and Gran method that grafting was real and XRD that this was not an intercalation.