Synthesis and properties of a novel bio-based branched heptadecylbenzene sulfonate derived from oleic acid

Abstract

Bio-based surfactants have attracted increasing attention because they are made from renewable resources and have excellent surface/interfacial properties. In this study we prepared a novel bio-based branched alkylbenzene sulfonate surfactant by a four- step route using renewable oleic acids as starting materials. We evaluated the surface behavior, wettability, and biodegradability of our surfactant. The surfactant, 4-(1-heptadecyl) benzene sodium sulfonate (9ΦC17S), was synthesized using a facile four-step route involving alkylation, decarboxylation, sulfonation and neutralization, respectively. The chemical structure of 4-(1- heptadecyl) benzene sodium sulfonate was confirmed by infrared (IR) spectroscopy, electrospray ionization high resolution mass spectrometry (ESI HRMS) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The surfactant demonstrated an excellent surface tension of 32.54 mN·m-1 at the critical micelle concentration (CMC) of 317.5 mg·L-1 and outstanding interfacial tension of ~10-2 mN·m-1 at 8.36 × 104 mg·L-1 with 8.48 ×104 mg·L-1 Na2CO3. The surfactant also showed good biodegradability with an ultimate biodegradation score of 2.99. The surfactant had good wettability with an air/water/solid contact angle (θaverage) of 63.08° for a 0.500 g·L-1 9ΦC17S solution. This novel bio-based branched surfactant contributes to the structural diversity of biobased surfactants from renewable feedstock.