Evaluation of antioxidant action by electrochemical and accelerated oxidation experiments of phenolic compounds derived from cashew nut shell liquid

• Antioxidant activity of technical cashew nutshell liquid components were evaluated.
• Electrochemical and accelerated oxidation (Rancimat) experiments were performed.
• Biodiesel samples additivated with these antioxidants presented higher stability.
• Rancimat analyses corroborate the results obtained by electrochemical techniques.

This paper describes the use of electrochemical methods and accelerated oxidation experiments (EN 14112, Rancimat method) for the determination of antioxidant activity of phenolic compounds (cardanol, cardol and tert-butylated cardanol) derived from cashew nut shell liquid (CNSL), a byproduct obtained during the processing of cashew nuts classified as a renewable raw material, natural of low-value. Through the electrochemical study, having as reference the anodic peak potential (Epa) and peak current (Ip), was observed that the cardol had the best performance, followed by tert-butylated cardanol and this by cardanol, showing that the presence of electron-donating groups as tert-butyl and hydroxyl exerts a positive influence on the antioxidant action of these compounds. These analyzes showed also that unsaturated compounds presented current values superior than saturated ones, indicating that the unsaturated molecules participate in greater number of the electro-oxidation process. The accelerated oxidation experiments were performed through analysis of biodiesel samples additivated with CNSL-based antioxidants at 500 ppm, and the same sequence of activity presented by the electrochemical study was observed, showing that this class of compounds can be applied effectively to inhibit the oxidative process of biofuel.