. Principe-du-spectrophotomètre-et-lois-générales, La spectrométrie d'absorption, qu'elle soit atomique ou moléculaire est basée sur la loi de Beer-Lambert pouvant être schématisée comme suit : Figure III: Schéma de principe d

L. Charlet and A. A. Manceau, X-ray absorption spectroscopic study of the sorption of Cr(III) at the oxide-water interface, Journal of Colloid and Interface Science, vol.148, issue.2, pp.443-458, 1991.
DOI : 10.1016/0021-9797(92)90182-L

L. Charlet, P. W. Schindler, L. Spadini, G. Furrer, and M. Zysset, Cation adsorption on oxides and clays: The aluminium case. Aquatic science 55, pp.291-303, 1993.

J. A. Davis, Adsorption of natural dissolved organic matter at the oxide, 1982.

V. Desjardin, Réduction du Cr(VI) par la souche Streptomyces Thermocarboxydus NH50 isolée à partir d'un sol pollué, Thèse de doctorat L'Institut National des Sciences Appliquées de Lyon, pp.15-28, 2002.

T. Delineau, Les argiles du bassin des Charentes (France) : Analyses typologique, cristallochimique, spéciation du fer et applications, Thèse INPL, 1994.

L. E. Eary and D. Rai, Kinetics of chromate reduction by ferrous ions derived from hematite and biotite at 25 degrees C, American Journal of Science, vol.289, issue.2, p.180, 1989.
DOI : 10.2475/ajs.289.2.180

R. Eisler and M. D. Laurel, Chromium hazards to fish, wildlife, and invertebrates: a synoptic review, Contaminated Hazard Reviews Report 6. US Department of the Interior, Fish and Wildlife Service, 1986.

P. Fallavier, D. Babre, and M. Et-breysse, Détermination de la capacité d'échange cationique des sols tropicaux acides, l'agronomie tropicale, pp.298-307, 1985.

V. C. Farmer, Differing Effects of Particle Size and Shape in the Infrared and Raman Spectra of Kaolinite, Clay Minerals, vol.33, issue.4, pp.601-604, 1998.
DOI : 10.1180/claymin.1998.033.4.07

F. Favre, A. M. Jaunet, M. Pernes, M. Badraoui, P. Boivin et al., Changes in clay organization due to structural iron reduction in a flooded vertisol Clay Minerals, pp.123-134, 2004.

S. E. Fendorf, G. M. Lamble, M. G. Stepleton, M. J. Kelly, and D. L. Sparks, Mechanisms of chromium(III) sorption on silica. 1. Chromium(III) surface structure derived by extended x-ray absorption fine structure spectroscopy, Environmental Science & Technology, vol.28, issue.2, pp.284-289, 1994.
DOI : 10.1021/es00051a015

A. P. Ferris and W. B. Jepson, The exchange capacities of kaolinite and the preparation of homoionic clays, Journal of Colloid and Interface Science, vol.51, issue.2, pp.245-259, 1976.
DOI : 10.1016/0021-9797(75)90110-1

F. Franco, F. Perez-maqueda, and J. L. Perez-dominguez, The influence of ultrasound on the thermal behaviour of a well ordered kaolinite, Thermochimica Acta, vol.404, issue.1-2, pp.71-79, 2003.
DOI : 10.1016/S0040-6031(03)00065-0

R. L. Frost, E. Mako, J. Kristof, E. Horvath, and J. T. Kloprogge, Modification of Kaolinite Surfaces by Mechanochemical Treatment, Langmuir, vol.17, issue.16, pp.4731-4738, 2001.
DOI : 10.1021/la001453k

C. J. Fysh and P. E. Clark, Mössbauer effect studies of iron in kaolin: I. Structural iron Clay Miner, p.31, 1983.

G. Klingelhöfer, R. V. Moris, B. Bernhardt, C. Schröder, D. S. Rodionov et al., Jarosite and Hematite at Meridiani Planum from Opportunity's Mossbauer Spectrometer, Science, vol.306, issue.5702, pp.1740-1745, 2004.
DOI : 10.1126/science.1104653

L. Grega, Modeling leaching behavior of solidified wastes using back propagation neutral networks Ecotoxicology and safety, 1994.

A. Guinier, Théorie et technique de la radiocristallographie, 1964.

B. Heike and . Bradl, Adsorption of heavy metal ion on soils and soils constituents, J. Colloid. Interf. Sci, vol.277, pp.1-18, 2004.

J. Hizal and R. Apak, Modeling of copper(II) and lead(II) adsorption on kaolinite-based clay minerals individually and in the presence of humic acid, Journal of Colloid and Interface Science, vol.295, issue.1, pp.1-13, 2006.
DOI : 10.1016/j.jcis.2005.08.005

F. J. Huertas, L. Chou, and R. Wollast, Mechanism of Kaolinite Dissolution at Room Temperature and Pressure: Part 1. Surface Speciation, Geochimica et Cosmochimica Acta, vol.62, issue.3, pp.417-431, 1998.
DOI : 10.1016/S0016-7037(97)00366-9

M. L. Kraepiel, K. Keller, and M. M. Morel, A Model for Metal Adsorption on Montmorillonite, Journal of Colloid and Interface Science, vol.210, issue.1, pp.43-54, 1999.
DOI : 10.1006/jcis.1998.5947

L. Grega, M. D. Buckingham, P. L. Evans, and J. C. , Hazardous Waste Managemen, p.859, 1994.

K. Lackovic, M. J. Angove, J. D. Wells, and B. B. Johnson, Modeling the adsorption of Cd(II) onto Muloorina illite and related clay minerals, Journal of Colloid and Interface Science, vol.257, issue.1, pp.31-40, 2003.
DOI : 10.1016/S0021-9797(02)00031-0

M. E. Losi and C. Amrhein, -Factors affecting chemical and biological reduction of hexavalent chromium in soil. Environmental Toxicological and chemistry, pp.1727-1735, 1994.
URL : https://hal.archives-ouvertes.fr/hal-00573085

C. Lytle and F. W. Lytle, Reduction of Cr(VI) to Cr(III) by Wetland Plants:?? Potential for In Situ Heavy Metal Detoxification, Environmental Science & Technology, vol.32, issue.20, pp.3087-393, 1998.
DOI : 10.1021/es980089x

A. Manceau, D. Chateigner, W. P. Gates, and E. Polarized, Distance-valence leastsquares modeling (DVLS) and quantitative texture analysis approaches to the structural refinement, 1996.

S. Marlet and M. K. N-'diaye, Evolution temporelle et variabilité spatiale des indicateurs de la dégradation des sols par alcalinisation et sodisation de l, 1998.

M. B. Mcbride, Environmental chemistry of soils, 1994.

F. Michael, J. Hochella, F. Art, and . White, Mineral-water interface geochemistry, pp.288-289, 1990.

L. Michot, M. François, and J. M. Cases, Continuous volumetric procedure for gaz adsorption. A mean to study surface heterogeneity, Langmiur, vol.6, pp.667-681, 1990.

M. M. Motta and C. F. Miranda, Molybdate Adsorption on Kaolinite, Montmorillonite, and Illite: Constant Capacitance Modeling, Soil Science Society of America Journal, vol.53, issue.2, pp.380-385, 1989.
DOI : 10.2136/sssaj1989.03615995005300020011x

A. C. Newman and G. Brown, The chemical constitution of clays, In Chemistry of Clays and Clay Minerals, pp.1-128, 1987.

E. Nieboer and A. A. Jusys, Biologic chemistry of chromium, Advances in environmental Sciences and Technology, vol.20, pp.21-81, 1988.

J. Nordin, P. Persson, E. Laiti, and S. Sjöberg, Adsorption-desorption kinetics of dicarboxylic acids on synthesized iron oxid, 1997.

A. Otman, Impact des complexes de fer et de la lumière solaire sur le devenir de polluants de l'environnement aquatique, Thèse de doctorat, pp.48-61, 2005.

T. W. Parker, A classification of kaolinites by Infra Red Spectroscopy Clays Minerals, pp.135-141, 1969.

A. Plançon, R. F. Giese, and R. Snyder, The Hinckley Index for Kaolinites, Clay Minerals, vol.23, issue.3, pp.249-260, 1988.
DOI : 10.1180/claymin.1988.023.3.02

C. Poinsignon, . Djurado, H. Klein, P. Strobel, and F. Thomas, Electrochemical and surface properties of nanocrystalline ??-MnO2 in aqueous electrolyte, Electrochimica Acta, vol.51, issue.15, pp.3076-3085, 2006.
DOI : 10.1016/j.electacta.2005.08.049
URL : https://hal.archives-ouvertes.fr/hal-00090766

S. M. Sajidu, I. Persson, W. R. Masamba, E. M. Henry, and D. Kayambazinthu, Removal of Cd 2+, 2+ and Zn 2+ cations and AsO 4 3? anions from aqueous solutions by mixed clay from Tundulu in Malawi and characterisation of the clay, Water SA, pp.519-526, 2006.

D. Samaké, V. Jacob, F. Thomas, S. Baup, J. L. Debionne et al., A natural nanokaolinite clay from Niono (Mali) II Study of the properties and adsorption of Cr(III)Water Resources, 2008.

H. M. Sayed, F. Villieras, A. Razafitianamaharavo, and L. Michot, Role of exchangeable Cations on Geometrical and Energetic Surface heterogeneity of Kaolonites, Langmuir, vol.21, pp.12283-12289, 2005.

M. Schegel, Adsorption du cobalt et du zinc sur l'hectorite et le quartz, 2000.

S. Semeguem, Etude de quelques aspects de la pollution du fleuve Niger à Bamako, 1999.

S. Serrano, F. Garrido, C. G. Campbell, and M. T. Garcia-gonsalez, Competitive sorption of cadmium and lead in acid soils of Central Spain, Geoderma, vol.124, issue.1-2, pp.91-104, 2005.
DOI : 10.1016/j.geoderma.2004.04.002

P. Sherrer, Bestimmung der grosse und der inneren Struktur von Kolloidteichen mittels Rôntgenstrahlen, Nach. Ges. Wiss. Gôttingen, vol.2, pp.96-100, 1918.

K. M. Spark, J. D. Wells, and B. B. Johnson, Characterizing trace metal adsorption on kaolinite, European Journal of Soil Science, vol.58, issue.4, pp.633-640, 1995.
DOI : 10.1016/0016-7037(92)90383-T

G. D. Sposito and D. L. Sparks, The Surface Chemistry of Soils The use of XAFS to distinguish between inner-and outersphere lead adsorption complexes on montmorillonite, Colloid Interf. Sci, pp.216-257, 1984.

. F. Sylla, Caractérisation de trois échantillons d'argile en provenance de Djenné et du pays Dogon, 2004.

R. Thorsten and M. J. , Dissolved organics in tannery wastewaters and their alteration by combined anaerobic and aerobic treatment Wat, Res, issue.5, pp.31-1035, 1997.

L. Togola, Problématique de l'efficacité du traitement des effluents industriels de tanneries : Cas de la West African Tannery et de la Tannerie du Mali, impact sur l'eau du fleuve Niger, 2004.

N. Torapava, D. Davydov, and I. Persson, Hydration and hydrolysis of chromium (III) in aqueous solution, 2008.

A. Touré, S. Zanen, and N. Koné, La restructuration de l'Office du Niger, 1997.

I. Arpon, Coopération néerlandaise, Office du Niger

N. De, cristallisé, pur à 99% minimum de la firme Labosi, ont été dissous dans l'eau désionisée dans une fiole de 500mL, puis remplie jusqu

. De-naoh and . De-la-firme-fluka, Chemika Teneur 98% min ont été pesés et dissous dans l'eau désionisée dans une fiole de 100mL puis remplie jusqu'au trait de jauge. 4) Solution de HCl à 1mol/L Environ 0,31 mL de HCl, de la firme BAKER