Preparation and characterization of methylic and ethylic biodiesel from cottonseed oil and effect of tert-butylhydroquinone on its oxidative stability

► Methylic and ethylic biodiesels were obtained from cottonseed oil. ► Both biodiesel presented similar physical–chemical properties. ► The addition of 300mgkg−1 TBHQ provided acceptable oxidation stability values. ► Thermogravimetric analysis revealed similar profiles for both biodiesels. ► The use of renewable ethanol is feasible to produce cottonseed oil biodiesel. This work reports the preparation and characterization of methylic and ethylic biodiesel from cottonseed oil. Biodiesel was prepared by a transesterification process involving the reaction of the oil with methanol or ethanol using KOH as catalyst. The conversion of triglycerides to the corresponding methyl and ethyl ester was 91.5 and 88.5 (wt%). All the physical–chemical properties of the obtained biodiesels met the minimum or maximum limits of the EN 14214 except oxidation stability. The addition of the synthetic antioxidant tert-butylhydroquinone at the concentration of 300mgkg−1 was sufficient to obtain acceptable oxidation stability values (>6h). Thermogravimetric analysis was also performed and similar profiles were verified for both ethylic and methylic biodiesels. Therefore, this work demonstrates the feasibility of using the ethanolic route to produce cottonseed oil biodiesel.