Detellier, Christian,Dramé, Harouna.2009-03-192009-03-1919981998Source: Dissertation Abstracts International, Volume: 60-03, Section: B, page: 1079.9780612367739http://hdl.handle.net/10393/4274http://dx.doi.org/10.20381/ruor-13672Herein is reported a comparative study of the behaviour of four types of smectite clay minerals, mainly two poor iron bearing ones, SHCa-1 (hectorite from San Bernadino, California), SWy-1 (montmorillonite from Wyoming) and two ferruginous nontronites NG-1 (from Hohen Hagen, Germany) and SWa-1 (Grant County, Washington). The iron (III) exchange has been found to follow the cation exchange capacity (CEC) of the clays. This exchange has also been found to have no effect on the stability and the structure of the iron poor clay minerals while it has a slight effect on the crystallinity of the ferruginous clays and on their thermal stability. The intercalation has been found to be dependent on the expansibility of the clays, increasing from the nontronites (dioctahedral iron rich clays), to the montmorillonite (dioctahedral iron less rich clay) to hectorite (trioctahedral iron poor clay). This intercalation treatment has been found to have a slight effect on both the structure of the iron poor clays and their thermal stability. In contrast, the ferruginous ones undergo a dramatic change in both their structure and their thermal stability. The transition temperature to hematite occurred at 350°C as shown by an exotherm on the DSC curve of all the pillared materials. Furthermore the importance of iron oxyhydroxide and oxide phases formed were also found in both procedures to be dependent on the initial structural iron contents of the clays. We found that SH-modified SCa-3 and in SWa-1 have higher affinity for the metal ions than the SH-modified SWy-1 and in SHCa-1, because the pH of their solution is less acidic than those of SH-SWy-1 and SH-SHCa-1. All the adsorption isotherms followed the Langmuir model and the adsorbents could be easily regenerated by leaching out the metal with 0.1N HCl. Moreover, the adsorption study has shown a considerably higher affinity of the SH-clays towards Cd2+, Zn2+, than the iron modified clays (intercalated and pillared at 350°C and 600°C), the Na-clays, and the pure hematite. The competitive adsorption of the divalent metal cations showed a strong affinity of all the SH-clays for Cu2+ than for the Zn2+ and Cd2+, due to the low pH of the mixture solution which is equal to that of the Cu solution. (Abstract shortened by UMI.)343 p.Chemistry, Inorganic.Thesis