Surface activity of PDMS silicone oil applied as petroleum antifoamer

Abstract

AbstractIn petroleum production, silicone oil (polydimethylsiloxane or PDMS) remains the most efficient product for combating foam, despite its negative effects on petroleum contamination and catalytic refining processes. This study aimed to evaluate the defoaming action of silicone oils with varying molar masses (ranging from 3 to 110 kg·mol−1) as defoamers in crude oils with different densities (20, 26, and 30°API). The results were correlated with the dilatational rheology obtained through pendant drop tensiometry of the oil samples. The silicone samples were characterized using gel permeation chromatography and thermogravimetric analysis, while the petroleum samples underwent SARA (saturated, aromatics, resins, asphaltenes) composition analysis, density measurement, and assessment of water content. The PDMS range of 8 to 30 kg·mol−1 exhibited enhanced antifoaming efficiency for the tested oils. A plateau in efficiency was observed when antifoamers were dosed above 15 ppm. Additionally, a reverse relationship between the initial formation of foam and the elastic modulus (G') of the oil in the presence of the antifoamer was observed, suggesting that the more effective antifoamer actually increased the elasticity of the film.