INFLUENCE DE PARAMETRES REACTIONNELS SUR LA STOECHIOMETRIE SULFATE D’ALUMINIUM /SUBSTANCES AROMATIQUES ACIDES DANS DES EAUX A MINERALISATION VARIABLE

Abstract

The aim of this study is to appreciate the influence of several reaction parameters on the stoichiometry’s mixture coagulant/ organic matter during the removal of organic matter by coagulation-flocculation with aluminium sulphate. Trials of Jar-test have been conducted on synthetic solutions of aromatic organic compounds dissolving into distilled water then on mineralized waters. The organic compounds tested are humic acid and pyromellitic acid which are showed carboxyl and/or hydroxyl functions with aromatic structure. The trials of flocculation have for object to evaluate the removal efficiency of organic compounds by varying several reaction parameters such as dose of coagulant, initial concentration of organic compounds, pH and ionic strength of solutions. The determination of stoichiometry of reactions between each organic compounds and aluminium sulphate has underlined that the stoichiometric laws depended not only of the compound’s structure but also on the pH and mineralization of waters. The predominant mechanisms in the process of removing organic acids tested could be phenomena of complexation or ligand exchange with the soluble or insoluble aluminic species.