Harnessing Neem Seed Oil for Sustainable Bio-Based Surfactant Synthesis: A Promising Agent for Enhanced Oil Recovery

Abstract

The declining productivity of mature oil reservoirs and the environmental concerns associated with synthetic surfactants have created a pressing need for sustainable chemical solutions in enhanced oil recovery (EOR) in reservoir-like conditions of elevated temperature, high-salinity brine, and crude oil interactions. This study aimed to develop and characterize a bio-based surfactant derived from the nonedible seed oil of Azadirachta indica (neem) for potential EOR application. The bio-based surfactant was synthesized through alkaline saponification using sodium hydroxide (NaOH) at 70–80°C for 3hours, yielding an anionic mixture of fatty acid sodium salts. The product exhibited an inherent alkaline pH of 9.0 and was evaluated for key performance properties using synthetic seawater as the aqueous medium. Surface tension measurements revealed a critical micelle concentration (CMC) of 1.0% w/v, at which the bio-based surfactant lowered the surface tension from 73.0 mN/m to an ultra-low value of 14.8 mN/m. A substantial foam half-life of 14.8 minutes was achieved from the foam stability test, while an emulsification index of 92% was produced from the emulsification studies, and thus, a stable emulsion that remained intact for over 24 hours as seen from the emulsification index. Following the results achieved, in particular, the 80% reduction in surface tension, foam stabilities and robust emulsion, showed a convincing interfacial activity and this was favorably compared with many bio-based surfactants described in the literature. These findings suggested that the neem-derived biobased surfactants possesses the surface activity, stability, and micellization efficiency required to mobilizing trapped residual oil in reservoir rock. This study established neem seed oil as technically feasible, non-toxic and renewable feedstock for EOR bio-based surfactants, and subsequently recommended coreflooding experiments and techno-economic analysis for field-scale validation.