Synthesis of branched surfactant via ethoxylation of oleic acid derivative and its surface properties

Abstract

A class of bio-based nonionic surfactants with double hydrophilic head groups (DMOE n ) was obtained from the waste cooking oil. • A new strategy for the preparation of branched surfactants from renewable oleic acid in waste cooking oil was proposed, and a class of bio-based nonionic surfactants with double hydrophilic head groups (DMOE n ) was obtained. • The ethoxylation reaction process of DMO and its reaction kinetic were both systematically optimized and studied. • The surface activities, aggregation and adsorption behaviors of DMOE n were investigated, and it was discovered that DMOE n had the characteristics of typical branched surfactant with good wetting performance, low foaming and strong defoaming ability. A new series of bio-based branched nonionic surfactants (ethoxylated dihydroxy stearic acid methyl ester, DMOE n ) was synthesized and characterized. DMOE n was based on a hydroxyoctadecanoic acid methyl ester, which was obtained from renewable oleic acid in waste cooking oil. These new polyoxyethylene surfactants contained double hydrophilic and hydrophobic chains, which shows the surface properties of the branched surfactant. The synthesis rules and reaction kinetics were studied in detail. The physicochemical properties and surface properties of the DMOE n with different degrees of ethoxylation at various concentrations were investigated. Furthermore, the surface tension results indicate that DMOE n reduced the surface tension reduction and increased the diffusion rate in an aqueous solution. The dynamic contact angle, wettability, foaming properties, and emulsifying capacity tests showed that DMOE n exhibited good wetting performance, low foaming, fast defoaming, and excellent emulsifying ability, which shows that the surfactant has potential application in industrial cleaning.