Sodium dioctylphosphinate emulsifier properties

The properties of a scarcely studied twin-tailed surfactant, sodium dioctylphosphinate (SDOP), as emulsifier were studied. The SDOP hidrophile–lipophile balance (HLB) value was measured and the Davies HLB group number of the sodium phosphinate group was computed. The surfactant promotes the formation of water in petroleum ether emulsions. The emulsion was characterized by the employment of several techniques such as centrifuge test and turbidimetry and density measurements. The maximum stability was obtained by the surfactant concentration of 0.3 mol dm⁻³ with 14 g of water emulsified in 12.41 g oil/g surfactant was emulsified. Conductivity information was used to study the temperature effect on the emulsion droplets and the energy of the droplet clustering during percolation. The enthalpy of adsorption at the oil/water interface \({\left( {\Delta H^{{{\text{ads}}}}_{{\text{s}}} } \right)}\) was positive at all surfactant concentrations ([S]); its absolute value showed a maximum of [S]=0.1 mol dm⁻³ and subsequent decreased was attributed to a change in the droplet interface, which would provide the necessary energy for the adsorption of SDOP molecules. The determination of droplet clustering thermodynamic parameters during percolation showed that droplet clusters were formed spontaneously \({\left( {\Delta G^{{\text{0}}}_{{{\text{cl}}}} < 0} \right)}\) and the process driving force was a negative enthalpy contribution.