Green chemicals from used cooking oils: Trends, challenges, and opportunities

Abstract

Food waste reduction is fundamental for sustainable development and pursuing this goal, recycling and the valorization of used cooking oil (UCO) can play a major contribution. Although it has been traditionally used for biofuel production, the oleochemical potential of UCOs is vast. UCOs can be used as feedstock for a large variety of value-added green chemicals including plasticizers, binders, epoxides, surfactants, lubricants, polymers, biomaterials, and different building blocks. Thus, UCO transformation into functional chemicals can bring long-term stability to the supply chain, avoiding the current dependence on commodity products. In this regard, this work describes some of the potential benefits of using UCOs as feedstock in oleochemical biorefineries. In addition, some of the most recent investigations on the valorization of UCOs other than biofuel are presented. Finally, major challenges and future directions are discussed.

Figure 1

Historical world production of vegetable oils and share among final uses [16].

Figure 2

Potential impact mitigation of using a circular economy approach in the exploitation of UCOs as oleochemical (OChe) feedstock considering life cycle stages (Cradletogate). Functional unit: 1 t vegetable oil. Assuming a 90% yield of refined UCO from the collected one. UCO, used cooking oil.

Figure 3

number of publications and patents on the valorization of used cooking oil in the last decades and share by major contributing countries (March, 2020). Searching terms: TITLE-ABS-KEY (“Used cooking oil” OR “Waste cooking oil” OR “Yellow grease” OR “Brown grease” OR “Trap grease”) (Source: [24, 25, 26]).