Removal of Chromium (III) Ions from Aqueous Solutions by Polymer Assisted Ultrafiltration Using Experimental and Calculation Approach. Part 1: Optimization of Complexation Conditions

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Hexavalent chromium compound is present at high concentration in the shovels and cranes factory, it is used in the electrodeposition container; after its reduction by sodium bisulfites it changes into 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=0.095 M for [Cr(III)]0=0.003 M), 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 hydroxides forms shows a little variation with experimental ones.