Biodiesel synthesis from Garcinia gummi-gutta (L. Robson) seed oil: fuel feasibility evaluation of a novel feedstock by homogeneous and heterogeneous transesterification

Abstract

ABSTRACTGarcinia gummi-gutta (L. Robson) seed oil (GGO), a novel feedstock with high oil content (33.5 wt%), was subjected to homogeneous and heterogeneous transesterification using NaOH, KOH and CaO. The low polyunsaturation (1.7 wt%), high monounsaturation (55.2 wt%) and moderate saturation (39.72 wt%) is a promising factor for biodiesel synthesis. A biodiesel yield of 97.2 and 97% was achieved using NaOH and KOH, respectively, during homogeneous transesterification under optimal conditions: catalyst 1.4wt% (NaOH) 1.6wt% (KOH), molar ratio 1:6, stirring rate 800 rpm, temperature 55°C, time 1.5 h. With CaO as basic heterogeneous catalyst, a yield of 96.5% was accomplished under optimal conditions: catalyst wt% 4.5, molar ratio 1:9, stirring rate 1000 rpm, temperature 60°C, time 2.5 h. High stirring rate played a significant role and resulted in better yield at economical catalyst wt%, moderate temperature and low methanol:oil molar ratio in a short interval of time. The reusability of the CaO catalyst offers a more economical, ecofriendly way of biodiesel synthesis compared to homogeneous alkali catalysts. Even after 10 cycles, CaO was effective for transesterification. The separation of biodiesel was easier in the order CaO > KOH > NaOH. The fuel properties were evaluated as per Bureau of Indian Standards.