Comparative analysis of water-oil emulsion stabilizers: Biopolymers, surfactants, and nanoparticles

Emulsions play a vital role in various petroleum engineering applications, particularly in enhanced oil recovery (EOR). Traditionally, surfactants and polymers have been used to achieve emulsion stability. This study explores the potential of natural, eco-friendly biopolymers as stabilizers and compares their performance with conventional surfactants and nanoparticles. The performances of agar (extracted from red algae) and pectin (derived from citrus peels) biopolymers were evaluated alongside the synthetic polymer FLOPAAM, surfactants Cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), and hydrophobic silica nanoparticles. Comprehensive analyses, including interfacial tension (IFT) measurements, wettability assessments, dynamic light scattering (DLS), and microscopic imaging, were conducted on the most stable emulsions. The results demonstrated that agar and pectin significantly enhanced emulsion stability. For example, an agar-stabilized emulsion (0.3 wt%) exhibited only 30 % water separation after one week at 70 °C. However, excessive agar concentrations induced instability. In contrast, pectin required a higher concentration (1 wt%) to produce fully stable emulsions. Emulsions prepared with distilled water exhibited greater stability than those made with seawater, and high-speed mechanical stirring further improved stability. Agar reduced the IFT from 32.96 mN/m to 22.25 mN/m, decreased the contact angle, and promoted a water-wet condition. Moreover, microscopic and DLS analyses revealed that agar significantly decreased the dispersed droplet size, with droplet diameters reducing from 1590 nm to 450 nm. These findings highlight the potential of agar and pectin as sustainable alternatives for enhancing emulsion stability in petroleum applications.