Experimental Study and Simulation of Complexation Reaction of Chromium by EDTA for its Recovery by Ultrafiltration

Abstract

Aprocess forpurifyingaqueoussolutionscontainingheavyand toxicmetalssuch aschromiumhasbeen investigated. Hexavalent chromium compound is present at high concentration in the shovels and cranes factory, it is used in the electrodepositioncontainer; afterits reductionbysodiumbisulfites it changesinto trivalent chromium. The present work deals with the investigation and optimization of chromium (III) ions removal from aqueous solutions by complexation enhanced ultrafiltration using experimental and calculation approach; diamine tetra-acetic acid (EDTA) has been used as chelating agent for Chromium (III) complexation; in the first part the study of experimental optimum conditions of complexation reaction is carried out; the second one the calculation of optimum pH, initial concentration of chelating agent and the influence of chromium hydroxides forms on complexation reaction using MATLAB language has been determined. Its shown that the Complexation reaction is favoured at pH equal to 5.1, at excess EDTA concentration ([EDTA]0=0.095M for [Cr(III)]0=0.003M), at ordinary temperature (T=20°C), and 600 tr/min for agitation, trivalent chromium concentration at solution increases with ionic strengths, it also increases with high CaCO3 values. The calculated pH, initial concentration of ligand and presence of chromium hydroxidesforms shows a littlevariation with experimental ones.