Solubilization of surfactant stabilized gold nanoparticles in oil – in – water and water – in – oil microemulsions

[Display omitted] •Solubilisation of gold nanoparticles as nano-pollutants.•Amount of emulsifier decides the solubilisation of nanometallic pollutants.•Study demonstrates the use of microemulsion in cleaning industrial effluents. W/O and O/W microemulsions were used for determining the solubilization capacity of surfactant stabilized Au nanoparticles (NPs) as metallic nano-pollutants. Tween 80 (emulsifier), hexane/dodecanethiol (oil), and isopropyl alcohol (cosurfactant) were used to prepare microemulsions along with aqueous Au NPs. Different kinds of surfactants were used to produce surfactant stabilized Au NPs. Solubilization studies were carried out by measuring the UV–visible spectra of Au NPs on the basis of their surface plasmon resonance (SPR), dynamic light scattering, and fluorescence measurements to determine the solubilization capacity of aqueous Au NPs. Results indicated that solubilization capacity showed little dependence on the nature of surfactant used for preparing surfactant stabilized Au NPs rather it depended more on the amount of Tween 80 in the preparation of microemulsion. Higher amount of Tween 80 provided greater solubilization capacity of microemulsion to solubilize Au NPs. Stability of the microemulsion was determined from the fluorescence measurements by using fluorescence active surfactant and found that the micromeulsion was stable up to 55 °C for solubilization study. The findings are expected to design microemulsion systems suitable for solubilizing metal industrial effluents.