Use of copper(II)/ethylene diamine‐cotton complex for the adsorption of residual dyes

The chemical modification of cotton is performed by successive reactions with thionyl chloride followed by ethylene diamine (ED) to prepare aminoalkyl amino cotton namely ED-cotton. Evidence of attaching ethylene diamine groups onto cotton is provided by nitrogen determination and thermogravimetry analysis. Because of complexation, the ethylene diamine-grafted groups immobilizes Cu(II) ions from buffered solution at pH 6. The formation of a 1/1 complex is assessed by the adsorption limit values. The binary system [Cu(II)/ED-cotton] is then tested for the adsorption of two acid dyes (Acid Blue 25 and Calmagite) as ligands in the metal-coordinating process. The adsorption of Cu(II) onto ED-cotton and of the dyes onto Cu(II)/ED-cotton is followed spectrometrically. The observed stoichiometries of the ternary-formed complex [Dye/Cu(II)/ED-cotton] are 1/1/1 with Acid Blue 25 and 0.75/1/1 with Calmagite at 20°C. The Langmuir and Freundlich isotherms constants for the adsorption of the tested dyes onto Cu(II)/ED-cotton are evaluated from the experimental data, but better agreement is obtained by using the composite isotherm of Jossens. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1389–1396, 2007