Improving oxidation stability of biodiesels derived from Karanja, Neem and Jatropha: step forward in the direction of commercialisation

• Karanja, Neem and Jatropha biodiesel were tested for oxidation stability.
• Jatropha biodiesel showed higher oxidation stability than Karanja & Neem.
• 1,2,3 Tri-hydroxy benzene and 3,4,5-tri hydroxy benzoic acid were effective.
• 2,6-Di-tert butyl-4-methyl phenol, 2-tert butyl-4-methoxy phenol were less effective.
• 2-Tert butyl hydroquinone was least effective.

Poor oxidation stability is the main technical hurdle associated with the commercialization of biodiesel. Adding antioxidants is a suitable method for enhancing the oxidation stability of biodiesel. This study investigates the effectiveness of five cheap and commercially available antioxidants namely 2,6-di-tert butyl-4-methyl phenol (BHT), 2-tert butyl-4-methoxy phenol (BHA), 2-tert butyl hydroquinone (TBHQ), 1,2,3 tri-hydroxy benzene (PY) and 3,4,5-tri hydroxy benzoic acid (PG) on biodiesel produced from non-edible, locally grown vegetable oils of South Asian origin namely Karanja, Neem and Jatropha. The antioxidants were dosed in concentrations ranging from 100 to 1000 ppm and corresponding induction period was measured using Rancimat test. Objective of the present study is to evaluate optimal dosage level and comparative effectiveness of these antioxidants. Jatropha biodiesel showed higher oxidation stability than Karanja and Neem based biodiesel however it was still unable to meet the prevailing ASTM biodiesel oxidation stability specifications. PY and PG demonstrated effective results for improving oxidation stability of biodiesel samples while BHA and BHT were less effective and TBHQ was the least effective among the investigated antioxidants.