Formulation of biobased soap gels from waste-derived feedstocks

Abstract

Cooking fats and oils changes their material properties as they heat up and undergo hydrolysis, oxidation, and polymerization. Biobased soft materials including soap may be formulated using waste fats and oils. Gel formulations facilitate portioning and storage, do not spill, and their phase may be controlled using shear forces and heat. To evaluate waste lipids as replacements for edible or petroleum-derived soap feedstocks, cooked soybean oil and bacon fat are saponified and formulated into soaps and gels. To understand how cooked fats and oils and their sources impact soap solutions, viscometry and spectroscopy clarify how waste-derived products can be classified based on their material properties. Here, liquid soap mixtures made from waste lipids generate shear-thickening mixtures in contrast to those made from fresh oils which form shear-thinning mixtures. Gellants from renewable sources are screened for their compatibility with soap solutions and gel formulations are evaluated using infrared spectroscopy and melting points to evaluate the relationship between composition and function. A base soap gel formulation of saponified oil or fat, water, glycerol, and gelatin is described. Studying the design of biobased materials from waste resources allows future formulations to divert waste from drains and landfills to create functional biobased soft materials.