Optimization of long-term storage stability of Jatropha curcas biodiesel using antioxidants by means of response surface methodology

The present paper reports the results of the study of the effect of metal contaminants on the storage stability of Jatropha curcas biodiesel (JCB) with and without antioxidants. Taking 1,2,3 -Trihydroxybenzene/Pyrogallol (PY) as the most effective antioxidant based on the earlier work of the authors, JCB was mixed with different transition metals – Fe, Ni, Mn, Co and Cu in different concentrations. Induction period (IP) was measured using Rancimat method (EN 14112) as the stability parameter. Based on results, several correlations were developed for assessing the storage stability in terms of IP as a function of antioxidant, metal concentration and storage time. For the purpose of design of experiment, response surface methodology (RSM) has been used. From the experiments it is found that if metal concentration is 0 then, 200 g m−3 of PY is sufficient to make biodiesel stable for 6 months. If metal (Fe) concentration is 2 g m−3 or more, then 800 g m−3 PY is sufficient to make biodiesel stable for 5.5 months. The value of storage time for Ni, Mn, Co and Cu contaminated JCB is found as 3.62, 3.24, 2.76 and 2.07 months respectively if metal and antioxidants concentration is same in all the cases.The models developed by RSM shall be highly useful for predicting the optimum antioxidant concentration to achieve maximum storage stability of JCB as well as biodiesel from other resources under the conditions set for 3 factors (antioxidant concentration, metal concentration and time).

► Storage stability of Jatropha curcas biodiesel (JCB) is studied in the present paper.
► Models were developed for storage stability as a function of antioxidant, metal concentration and storage time.
► Response surface methodology is used for modeling of storage stability.
► 200 mg/L of PY is sufficient to make pure fresh JCB stable for 6 months of metal concentration is zero.