Extraction and separation of nickel chelate of 1-(2-thiazolylazo)-2-naphthol in nonionic surfactant solution

Abstract

Nickel was extracted with 1-(2-thiazolylazo)-2-naphthol (TAN) into the surfactant phase separated from the micellar solution of Triton X-100 at the temperature above 70°C, the cloud point of the micellar solution. An aliquot of a nickel solution (<6 µg of nickel) was placed in a test tube which has previously been weighed. Two mililiters of phosphate buffer solution (pH 7.0) and 2 ml of TAN solution (TAN, 0.02 g: Triton X-100, 20 g: water, 80 g) were added to the solution in the test tube, then the mixture was made up to 25 ml with water. This solution was kept at 95°C for 30 min in a hot-water bath. The nickel-TAN chelate extarcted in the surfactant phase (0.5 ml) precipitated at the bottom of the test tube. At 95°C the standing time required to reach a constant absorbance was 20 min. At room temperature the total quantity in the test tube was adjusted to 5.00 g by removing a supernatant solution, then the surfactant phase was redissolved in the supernatant solution remained in the test tube. The absorbance was determined at 595 nm (a maximum wavelength of nickel-TAN chelate) in a 1-cm cell. The initial volume of an aqueous solution could vary from 20 to 40 ml without affecting the absorbance. © 1976, The Japan Society for Analytical Chemistry. All rights reserved.