Study On Adsorption And Desorption Performance Of Dye On Ion Exchange Membrane

Ion exchange membrane is membrane type ion-exchange resin. Itconsists of three basic components, i.e., polymer body, immobilized groupsand the movable ions on the immobilized groups. Therefore，the same asion exchange resin, according to the types of electric charge it is dividedinto cationic exchange membrane and anionic exchange membrane.Cationic exchange membrane contains negative charged acidic activegroups, which can selectively pass through cation but block the anion.Anion exchange membrane contains alkaline active groups with positivecharge, which can selectively pass through the anion but block the cation.Most of the dyes dissociate into electrically charged ionic state afterdissolving in water, one of the important treatment tasks for dye-containingwastewater is decolorization. In this paper, cationic exchange membranewas applied to absorb Cationic Brilliant Red X-5GN and Cationic RedX-GTL, anionic exchange membrane was used to absorb the Acid Scarlet3R Acid Red A， ReactiveRed K-2G and Reactive Red K-2BP, DirectBordeaux GB and Direct Blue2B under the conditions of differenttemperatures, pH, salt concentrations. The optimal absorption conditionswere obtained, the corresponding adsorption kinetics were discussed, andthe appropriate desorption methods were explored.The results showed that: cationic exchange membrane and anionicexchange membrane had fast adsorption velocity and the adsorption percentages were all above99%. The addition of sodium sulfate, thetemperature and pH values had little effect on dye adsorption percentage,and it is easy to handle. Accordingly, it is suitable for industrial wastewatertreatment. The more sulfonic group number containing in dye molecules,the faster the adsorption rate is, and equilibrium adsorption amount wouldbe reduced with the increase of sulfonic groups.All of the adsorption ofdyes fit for the pseudo-two adsorption kinetic model. Langmuir adsorptionmodel can well describe the ion-exchange membrane for dye adsorptionbehavior of the whole process, and the adsorption is monolayer adsorption.Using anhydrous ethanol, sodium chloride and water mixture as desorbent,the minimum and maximum desorption percentage were80.4%and98%,respectively. And the mechanical properties of ion exchange membranewere also good, which could meet the regeneration demand.