Synthesis of nanoemulsions from palm oil stabilized by sorbitan monooleate and polyoxyethylene sorbitan monopalmitate for enhanced oil recovery application

The hydrocarbon production from a well is decreases naturally over time due to the depletion of reservoir pressure. The pressure then increases by using primary and secondary recoveries. The recovery increases further by an enhanced oil recovery method involving chemicals. Nanoemulsion is employed as a chemical because it effectively reduces the interfacial tension between the surfactant and the oil. This study is aimed at producing stable oil-in-water nanoemulsion at a lower cost using refined palm oil and a combination of typical surfactants (sorbitan monooleate and polyoxyethylene sorbitan monopalmitate). The effect of surfactant concentration (5-30 mL), sonication time (0-30 min), and sonication power (150-750 W) were studied using response surface methodology (RSM) to determine the significant parameters affecting the nanoemulsion synthesis, as well as for formulation optimization. It was found that the optimum conditions to prepare the nanoemulsions were 5 mL, 15 min, and 100 W of surfactant concentration, sonication time, and sonication power, respectively, which attained nanoemulsion with a droplet size of 320.2 nm and zeta potential of -20.6 mV. These results indicate that nanoemulsion can be prepared at a lower cost using refined palm oil. However, the nanoemulsion produced is not stable after five-day storage at room temperature. Therefore, further investigation needs to be carried out to enhance the nanoemulsion stability after synthesizing.