Influence of different chromium species on smectite clay

Three different chromium solutions (S, T and M) containing different chromi um (Ni) species were prepared. The S solution contained monomeric chromium species, the T solution abundant trimeric species and M solution contained mixture of species (mainly trimeric and tetrameric). The S, T and M solutio ns were analyzed by absorption within the UV-visible range. One smectite clay was treated with these solutions and the solids were char acterized at room temperature and after thermal treatment by X-ray diffract ion (XRD) and differential thermal analysis (DTA). An increase of the interlamellar spacing, d(001) spacing, and a higher ther mal stability of the smectite was observed after it treatment with solution s containing more polymerized chromium species. However the crystallinity o f the smectite treated with solution containing abundant trimeric species ( T solution) was better than smectite treated with solution containing mixtu re of the polymeric chromium species (M solution).