Gelation in the aqueous solutions of oxyethylated nonylphenols

The study was aimed at ascertaining gelation conditions for the systems water – oxyethylated nonylphenol and water – oxyethylated nonylphenol – salting agent. The work involved analyzing scientific and technical literature on the use of surfactants in extraction processes. Systems containing nonionic surfactants are shown to be promising extraction systems. The effect that the concentration of nonionic surfactants and temperature can have on gelation in aqueous solutions is examined. The problem of using oxyethylated nonylphenols in gel extraction is considered. The phase diagrams of the systems water – neonol AF 9-6 and water – neonol AF 9-6 – sodium sulfate were constructed using the visual polythermal method. Gelation conditions were ascertained for the systems water – neonol AF 9-6 and water – neonol AF 9-6 – sodium sulfate. For the gel to form in the system water – oxyethylated nonylphenol (neonol AF 9-6), the concentration of the surfactant must exceed 25 wt%. For achieving gelation at lower concentrations of neonol AF 9-6, it is necessary to introduce a salting agent (sodium sulfate). The phase diagrams of the systems water – oxyethylated nonylphenol – sodium sulfate were constructed within the temperature range of 20–65 °C. The gel structure was found to form at a 3:1 weight ratio of oxyethylated nonylphenol to sodium sulfate. It is shown that for gelation, the minimum concentrations of neonol AF 9-6 and sodium sulfate are 15 and 5 wt%, respectively. An increase in the concentrations of neonol AF 9-6 and sodium sulfate to 24 and 8 wt%, respectively, leads to a decrease in the gelation temperature to 46 °C.