SiO2-Based Interfacial Destabilization of Oil–Water Emulsions: Review and Comparative Mechanistic Synthesis

Objective: This systematic review aimed to synthesize the available experimental evidence on the interfacial mechanisms governing the destabilization of oil–water emulsions and to comparatively evaluate how SiO2 nanoparticles, silica-containing materials, and industrial demulsifiers influence interfacial properties, emulsion stability, and phase-separation behavior. Methods: A systematic literature search was conducted in Scopus and Web of Science, supplemented by a ScienceDirect publisher-platform search, for relevant experimental studies published between 2005 and 2025. Study identification, screening, eligibility assessment, and reporting were structured according to the PRISMA 2020 framework. The search identified 1431 records, of which 348 duplicates were removed. After title and abstract screening and full-text eligibility assessment, 68 publications were retained for qualitative evidence mapping, with a subset of principal experimental studies included in the structured comparative synthesis. Extracted outcomes included interfacial tension, ζ-potential, droplet size and aggregation behavior, interfacial rheological properties, adsorption characteristics, and demulsification or phase-separation performance. Because the studies differed substantially in emulsion type, material characteristics, experimental conditions, outcome definitions, and statistical reporting, the evidence was synthesized comparatively rather than statistically pooled. Results: The reviewed works showed that the effects of SiO2-based materials and industrial demulsifiers on emulsion stability were strongly dependent on emulsion type, particle surface properties, wettability, concentration, demulsifier chemistry, and interfacial composition. Across the different experimental systems, directly reported observations indicated changes in interfacial adsorption, surface interactions, electrostatic stabilization, interfacial rheological behavior, droplet aggregation, coalescence, and phase separation. Comparative mechanistic synthesis suggests that interfacial restructuring and competitive adsorption can contribute to destabilization under specific experimental conditions. However, these effects were not uniform across oil-in-water, water-in-oil, Pickering, petroleum, heavy-oil, and other specialized emulsion systems. Substantial methodological heterogeneity and incomplete reporting of variance and sample-size data prevented a statistically defensible pooled quantitative synthesis. Conclusions: The available evidence supports interfacial adsorption-layer restructuring, changes in particle–interface interactions, and modification of interfacial mechanical and electrostatic properties as important, but context-dependent, mechanisms influencing the stability and destabilization of oil–water emulsions. SiO2 nanoparticles and industrial demulsifiers may promote phase separation under appropriate physicochemical conditions, but the current evidence does not establish a universal synergistic effect or superiority of combined SiO2–demulsifier systems. Standardized experimental protocols, consistent outcome definitions, and complete reporting of replicate numbers and measures of variability are needed to enable more robust quantitative comparisons in future studies.