Removal of chromate ions from water by anionic clays

The removal of chromate ions from aqueous solutions by [Mg-Al-Cl], [Zn-Al-C l] and [Zn-Cr-Cl] anionic clays was investigated. The solids, prepared by c oprecipitation at constant pH, were found to be pure upon characterisation by X-ray diffraction and Fourier-transform infrared spectroscopy. The inter action of the solid materials with CrO42- ions has been studied by W-visibl e spectroscopy. The treatment of solutions containing 15 to 300 ppm of CrO4 2- was successful. The sorption capacities of the anionic clays for the CrO 42- ions are close to 1 mmol/g.