Etude de l’Interaction des ions Cr(III) avec des Surfaces Solides dans l’Environnement et le Traitement des Eaux

Abstract

In the present work, the fixing of chromium (III) is studied using various solids encountered in aquatic environment and water treatment.

In the environment, sediments were collected from Rhumel and Hemimim rivers located in Constantine city in the North East Algeria. Commercial solid were used (alumina, calcite, kaolinite and ion exchangers) and others were prepared (iron and aluminum oxyhydroxides). All solids were characterized by XRD and FTIR analysis. The fixing of Cr (III) ions was evaluated according to different parameters in static mode. Kinetic and equilibrium studies were performed.

The obtained results show that for the used sediments, the binding capacity of Cr (III) ions is in relation to their constitution. The significant presence of quartz involves a decrease in fixing rates. The use of the different minerals encountered in the sediments shows that the fixing rate of chromium (III) increases in the order: kaolinite < calcite < alumina < ferrihydrite In all cases, fixing kinetic is best described by the second order model. The Temkin model is more appropriate to describe the fixing isotherms of chromium in the case of sediments. However, Langmuir and Freundlich models better describe in the case of ferrihydrite and alumina.

In water treatment, the effectiveness of Cr (III) removal by the oxyhydroxides of Fe (III) or / and Al (III) freshly prepared depends largely on the water pH. It follows the order: Al (III) < Fe(III)/Al(III) < Fe(III). The maximum exchange capacity of IR120 and IRC 86 resins towards Cr (III) ions are 112mg/g and 23mg/g respectively. The interaction of Cr(III) ions with the two resins is controlled by a diffusion process.