Waste to value addition: Utilization of waste Brassica nigra plant derived novel green heterogeneous base catalyst for effective synthesis of biodiesel

In the present study, the heterogeneous base catalyst was derived from the waste Brassica nigra plant and utilized as an efficient catalyst in the transesterification of soybean oil for biodiesel production. The catalyst was prepared by calcination of ash obtained after burning the dried waste Brassica nigra plant and well characterized using instrumental techniques like powder XRD, FT-IR, BET, XRF, AAS, XPS, SEM-EDX, and TEM. The analysis of the catalyst indicated potassium (56.13 wt%) as the major component followed by calcium (26.04 wt%) in the form of oxide, carbonate, and chloride. The catalyst showed excellent catalytic activity in converting soybean oil to biodiesel with 98.79% yield in a short time period of 25 min at 65 degrees C under the optimum conditions of 12:1 ratio of methanol to oil and 7 wt% of catalyst. The reaction yielded 98.87% biodiesel at room temperature of 32 degrees C within 75 min of reaction time under optimized conditions. The activation energy (27.87 kJ mol(-1)) indicates the reaction is a chemically controlled reaction. The catalyst was reused up to the third cycle of reaction which yielded 96% biodiesel without significant loss in catalytic activity. The biodiesel was characterized by FT-IR, H-1 NMR, C-13 NMR, and GC-MS. The fuel properties studied are well comparable with the international standards as well as with reported literatures. The synthesized heterogeneous catalyst is non-toxic, biodegradable, environmentally benign, green in nature, easy to handle, reusable and can be prepared with minimum cost as the raw materials are naturally plenty enough as wastes with free of cost which is a value addition to the generated wastes along with a viable capability in reduction of the overall biodiesel production cost. (C) 2019 Elsevier Ltd. All rights reserved.