Y-Shaping All Components in Waste Cooking Oil-Derived Epoxidized Fatty Acid Methyl Esters toward a Leaching-Resistant Bioplasticizer

Abstract

In the poly(vinyl chloride) (PVC) industry, waste cooking oil (WCO)-derived epoxidized fatty acid methyl esters (EFAMEs) represent a promising bio-alternative to conventional ortho-phthalate plasticizers that are being phased out due to their toxicity and nonrenewable nature. However, to improve the leaching resistance of EFAMEs, the WCO feedstock has to go through multistage distillation at particularly high temperatures under vacuum conditions for saturated component removal, resulting in intensive energy consumption, a significant waste of the feedstock, and a final bioplasticizer with a still faster leaching rate than those of ortho-phthalates. Here, we report a strategy that can Y-shape all components in WCO-derived EFAMEs with another short, polar ester chain via a nucleophilic substitution reaction of the feedstock mixture with dimethyl carbonate. This strategy entails no utilization of an energy-intensive procedure and, importantly, converts all components in the WCO feedstock into the final bioplasticizer. Relative to ordinary EFAMEs, the Y-shaped epoxidized fatty acid methyl diester exhibits a significantly suppressed leaching rate. Under certain scenarios, it even leaches at a rate equivalent to or slower than that of di-(2-ethylhexyl) phthalate (DEHP), the most ubiquitously applied member of the orthophthalate family. With this strategy in hand, the renewable WCO may be converted into a high-performance bioplasticizer in an energy-efficient and atom-economic manner to support the phase-out of ortho-phthalates in the PVC industry.

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“…Thus, converting WCO into beneficial products can not only eliminate potential hazards in regard to food safety, health and the environment, but also bring economic benefits, increase regional income, and create job opportunities [39]. Over the past two decades, significant advancements have been made in recycling and harnessing WCO, leading to the creation of diverse products such as biodiesel [40,41], biolubricants [42][43][44], alkyd resins [45], bioplasticizers [44,46,47], cleaning agents [48,49], and other related items [50][51][52]. However, it is worth noting that conventional products derived from WCO often yield narrow profit margins, often falling below 20% and thus necessitate robust policy and financial backing.…”