Synthesis of epoxidized cardanol and its antioxidative properties for vegetable oils and biodiesel

Authors: Liu, Zengshe - Kevin; CHEN, JIE - Chinese Academy Of Forestry; Knothe, Gerhard; NIE, XIAOAN - Chinese Academy Of Forestry; JIANG, JIANCHUN - Chinese Academy Of Forestry

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2015
Publication Date: 1/11/2016
Citation: Liu, Z., Chen, J., Knothe, G., Nie, X., Jiang, J. 2016. Synthesis of epoxidized cardanol and its antioxidative properties for vegetable oils and biodiesel. ACS Sustainable Chemistry & Engineering. 4(3):901-906.

Interpretive Summary: We have developed a new bio-based antioxidant from a byproduct of cashew nut production. Vegetable oil-based lubricants and biodiesel have been topics of considerable interest over the last decade. One issue that comes up time and again is that they degrade, even under careful storage. Additives to slow down this reaction, antioxidants, are used in these materials. However, they are almost always made from petroleum and usually possess undesirable organic chemical structures. Many are also not compatible with vegetable oil. The use of a biobased alternative is a potential solution to all of these drawbacks. Cardanol is a liquid that can be derived from the cashew nut product. We have made a chemically modified version of this liquid and tested it as an additive in plant oils and biodiesel. It worked, and the new fluids show much higher stability when this promising bio-based antioxidant is used. The research here will offer a benefit to the biodiesel supply chain and also to the cashew nut producers who need a valuable outlet for this wasted product.

Technical Abstract: A novel antioxidant epoxidized cardanol (ECD), derived from cardanol, was synthesized and characterized by FT-IR, 1H-NMR and 13C-NMR. Oxidative stability of ECD used in vegetable oils and biodiesel was evaluated by pressurized differential scanning calorimetry (PDSC) and the Rancimat method, respectively. The results indicated that ECD exhibited antioxidative activity in soybean oil and increased its onset temperature (OT) by nearly 10 °C with 0.7 wt.% ECD. It was also observed that other vegetable oil oils showed significantly improved oxidative stability with the addition of 0.7 wt % ECD. Olive oil showed the highest increased OT by 19.5 °C. Furthermore, ECD has superior antioxidant activity compared to synthetic antioxidant butylated hydroxytoluene (BHT) and thus could be used as an optimized primary antioxidant for biodiesel. Thermogravimetric analysis (TGA) indicated that ECD shows better thermal stability than cardanol. The data presented in this study indicate that ECD could be a new biobased antioxidant with better thermal stability.