Cloud Point Extraction of Direct Blue 71 Dye using Triton X-100 as Nonionic Surfactant

Abstract A surfactant-mediated cloud point extraction (CPE) method using the non-ionic surfactant Triton X-100 (TX-100) has been developed to remove the dye Direct Blue 71 (DB71) from a waste water. Most of the dye molecules are solubilized in the coacervate phase so that the dilute phase remains free of the dye. The effects of surfactant concentration, temperature and salt concentration on the different dye concentrations were studied to determine the optimal conditions for removing DB71. The concentration of DB71 in the dilute phase was measured using UV-Vis spectrophotometer. It was found that the separation of phases was complete and the recovery of DB71 was very effective in the presence of NaCl as an electrolyte. The results showed that up to 25 ppm DB71, i.e. more than 95%, can be quantitatively removed by cloud point extraction procedures in a single extraction at optimal conditions. It was also observed that at a dye concentration of 1 ppm, 100% of the blue dye DB71 can be directly removed with a TX-100 concentration of 12% by weight. At higher dye concentrations of up to 30 ppm, 94.7%-100% dye can be removed. The TX-100 concentration was 12 wt%, the salt concentration (NaCl) 0.005 M and the temperature 75°C. It is concluded that the surfactant mediated cloud point extraction method for dye removal can be an alternative to current dye removal methods.