Clouding of Triton X-100 solutions in the presence of resorcinol or β-naphthol and their application for mercury cloud point extraction

The clouding behavior of Triton X-100 solutions was investigated in the presence of resorcinol or β-naphthol. Both agents can effectively decrease the cloud point of Triton X-100 solutions. Resorcinol is active over a wider pH range, while β-naphthol is required at concentrations 10–50 times lower than resorcinol. It was also shown that about 60–70 % of β-naphthol transfers to the micellar phase, whereas resorcinol barely enters the micellar phase (about 10–15 %). Thermodynamic parameters of the clouding process were also calculated, revealing no significant differences between thermodynamic parameters for these two substances studied. Based on the results obtained, we assume different mechanisms of phase separation by these agents. Using the systems studied, mercury cloud point extraction was successfully carried out with 8-hydroxyquinoline as a ligand. The optimal parameters for extraction were determined as follows: pH of 8 (β-naphthol) and 6 (resorcinol), ligand concentration of 0.03–0.26 mmol L⁻¹, and surfactant concentration of 1.7 g L⁻¹.