Chemical properties of some clay minerals

Abstract

Clay mineral used in this investigation were bentonite, kaolinite and marl. The cation exchange capacity (CEC) in both single exchangeable cation method and mixed exchangeable cation method apparently decreased in the order: Bentonite > Kaolinite > Marl In single exchangeable cation method the orders of CEC in these materials were all different. The investigation of intercalation was done by using x-ray diffraction and spectrophotometric techniques. The inorganic compounds used in this investigation were FeCl3.6H2O, KCl, NaCl, FeSO4.7H2O, CaCl2, Zn(NO3)2.6H2O, NH4NO3, CH3COOK and the organic compounds used were dimethylsulfoxide (DMSO), dimethylformamide (DMF) and paraquat. From x-ray diffraction techniques it was found that only kaolinite was capable of forming intercalation complexes with the organic reagents. X-ray diffraction patterns showed that the interlayer spacing of the complexes decreased in the order DMSO > DMF > paraquat Among the inorganic compounds, only CH3COOK could intercalated into kaolinite interlayers and cause the expansion. For bentonite and marl none of the salts was capable of forming an intercalation comples. In the i.r. study only the kaolinite DMSO system exhibited evidence of intercalation phenomena. Bond lengths and bond energies of interlayer hydrogen bonds in kaolinite were calculated using the Lennare-Jones potential function and semiempirical potential function respectively. Results of computation of bond length and bond energy were within limits of hydrogen bond energies as given by various authors. It can be concluded that the cohesion between the kaolinite layers may be considered as hydrogen bonding which can be described in terms of a linear model.