BACKGROUNDThe process of producing biodiesel from various oil feedstocks is well known but developments of commercial plants are being hampered by the high cost of production. The paper reports an integrated method in which the oil obtained by solvent extraction of Calophyllum inophyllum seed is converted to biodiesel over a biomass derived catalyst. The catalyst derived from the residual cake of C. inophyllum obtained after oil extraction can be incompletely carbonized to obtain an amorphous carbon followed by sulfonation in concentrated sulphuric acid. RESULTSThe activity of the catalyst was tested through esterification of free fatty acid present in C. inophyllum oil and comparison was made with a similar catalyst derived from glucose. Superior activity over glucose-derived catalyst was related to the SO3H acid density and higher surface area. The catalyst also achieved high conversion of the non-edible oil to biodiesel (96.6 wt%) in a single step at the optimized reaction conditions. CONCLUSIONA solid acid catalyst capable of simultaneous esterification and transesterification of free fatty acids and triglycerides present in C. inophyllum oil has been synthesized. An integrated process in which the waste generated during the oil extraction process of biodiesel production is effectively utilized could lead to cost reduction and possibly successful commercialization. (c) 2013 Society of Chemical Industry