Removal and Recovery of Acid Azo Dyes by Solvent Extraction using Cetyltrimethylammonium Chloride

Abstract

Synthetic organic dyes contained in industrial effluents should be removed to avoid health hazards and destruction of the ecosystem. In this study, the extraction of acidic azo dyes to cetyltrimethylammonium chloride (CTAC)/1-hexanol/isooctane solution was investigated. It was found that acidic dyes were extracted to the organic solution by electrostatic interaction between sulfo group of dyes and CTAC. The extraction ratio of dyes increased with an increase in CTAC concentration and with a decrease in NaCl concentration, and generally was not affected by dye concentration and pH. The extraction of acidic dyes by CTAC was explained by ion-exchange mechanism and the extraction equilibrium constants were estimated from the experimental data. AR13 and AR27 extracted to CTAC organic solution were recovered into stripping solution of high NaCl concentration, and AO52 was recovered into that of low pH. There was no deterioration of the forward and backward extraction behavior by the reused CTAC organic solution.

Keywords:

• solvent extraction
• acid azo dyes
• cetyltrimethylammonium chloride
• sulfo group of dyes
• extraction equilibrium constant