5.4. Neem

them, J. curcas, A. indica, C. inophyllum, and P. pinnata were found to be the most suitable for use

Most of the researchers [20, 36, 43, 44] used two stage (acid catalyzed and alkaline catalyzed) esterification for biodiesel production from J. curcas oil due to its high free fatty acid content. Ortho-phosphoric acid is used as catalyst and degumming agent in acid esterification stage [20]. Pre-esterification is the first stage that uses sulfuric acid prepared by calcination of metatitanic acid as a catalyst. The conversion of FFAs was higher than 97% under the reaction conditions of 90C, 2 h, 4% solid acid, and molar ratio of 20:1 of methanol to FFA. Then alkaline catalysis was carried out for 20 min, 64C using 1.3% KOH as catalyst and molar ratio of 6:1 of methanol to oil. Berchmans and Hirata [43] achieved 90% yield in 2 h alkaline transesterification and Sahoo and Das [20] achieved 93% yield. Lu et al. [44] produced biodiesel and achieved yield up to 98% from jatropha oil with FFA over 20%. Complete conversion and the highest yield was conducted in supercritical methanol [36] within 4 min with temperature at 320C, pressure 8.4 MPa, molar ratio absolute methanol to oil was 43:1 as optimum ratio [45]. Supercritical was success at temperature above 327C and pressure above 8 MPa since ester yield increase rapidly at that state. From technical and environmental point of view, supercritical is appropriate for biodiesel production due to less glycerol waste but from economic analysis point of view; this method is not appropriate due to its high operating skill and cost. Two stages process can be a good choice, since it can reduce FFA to proper amount below

Two-stage process was conducted in producing biodiesel (up to 20% FFA) from P. pinnata seed oil [19]. Acid-catalyzed esterification was adopted by using 0.5% (w/w) H2SO4, molar ratio of alcohol to oil of 6:1 at 65C. Next step was alkali-catalyzed transesterification by 1% (w/w) KOH, molar ratio of methanol:oil of 6:1, which was the optimum condition [46]. The yield of biodiesel

Crude polanga oil generally has 22% free fatty acid. Hence, it must be carried out in three-stage process for producing appropriate biodiesel [6, 20, 47]. Three-stage transesterification process was zero catalyzed transesterification, acid catalyzed transesterification, and alkaline catalyzed transesterification. The oil was purified from organic matter and other impurities by mixing 0.5%v toluene and 35%v methanol as reagent. The reaction was carried out at 65C for 2 h. Acid catalyzed esterification was conducted by 0.65% v H2SO4, molar ratio of alcohol to oil of 6:1 for 4 h. This process reduced FFA less than 2%. Sahoo and Das [20] added 0.5%v orthophosphoric acid as a reagent that reduced FFA from 14.5 to 1.62%. Alkaline catalyzed transesterification process was conducted by using 1.25% w KOH, molar ratio of methanol to oil of 8:1, 60C for 2 h. Biodiesel from polanga still gets unsatisfactory yield below 90%. Further

as biodiesel and they met the major specification of biodiesel for use in diesel engine.

5.1. Jatropha

208 Advances in Biofuels and Bioenergy

to 1%.

5.2. Karanja

5.3. Polanga

(96.6–97%) was achieved at 65C.

Neem seed contains 20–30% and kernel contains 30–52% oil [23]. The oil of neem seed has several uses from making soap, pesticides, and pharmaceuticals to biodiesel. The seed oil contains 29.30% saturated fatty acid (14.90% palmitic acid, 14.40% stearic acid) and 69.40% unsaturated fatty acid (61.90% oleic acid, 7.50% linoleic acid) [11]. Biodiesel production from neem seed oil is quite the same with other non-edible oil resources in order to get appropriate product.
