This result confirms the exchange of potassium by iron, while this band weakened in the case of AH-M because of the interaction of humic acids in clay layer (Tajeddine et al., 2008). The XRD measurements were performed using a Philips Xray diffractometer employing nickel filtered CuKa radiation. The X-ray diffraction pattern of clay fractions is given in Fig. 4. The equidistance appears to vary regularly according to the rate of hydration and the nature of exchanged cation. With the introduction of iron in montmorillonite, the reticular distance corresponds to plane 001 was evolved from 9.45 to 15.04; which indicates that the specific surface area was also increased. The presence of the equidistance 9.4 characteristic of K-M in the spectrum of Fe-M indicates that the substitution of K+ by Fe3+ was not complete.