COMPETITIVE ADSORPTION OF COPPER, CADMIUM AND ZINC IONS ON SODIUM DODECYLBENZENE SULFONATE (SDBS) AT LOW CONCENTRATION BY MICELLAR-ENHANCED ULTRAFILTRATION (MEUF)

In this paper, removal of three divalent metal ions, copper, cadmium and zinc ions, from simulated wastewater was performed by micellar-enhanced ultrafiltration (MEUF) using sodium dodecylbenzene sulfonate (SDBS) with concentrations less than its critical raicellar concentration (CMC), when the metal ions were present either as a single species or as a ternary mixture. The retention efficiency of a cation in the mixture was greatly less than that when it was ultra-filtrated solely. The competitive adsorption characteristics of Cu, Cd and Zn ions on SDBS were investigated on the basis of adsorptive gross capacity, adsorption capacity, competitive adsorption coefficient, and concentration ratio of SDBS to metal ions. The competitive adsorption of metal ions on SDBS micelles existed and the capability of competitive adsorption was in the order Cu > Cd similar to Zn. The correlation analysis of competitive adsorption coefficients indicated that antagonistic adsorption existed between Cu and Cd, Cu and Zn, and Cd and Zn ions.