Sustainable design of one-pot synthesis of Madhuca indica methyl ester via reactive extraction using a sulfonated heterogeneous catalyst and techno-economic analysis

Abstract

The growing demand for renewable energy and environmental sustainability has led to the exploration of biodiesel as an alternative to fossil fuels. In the meantime, sustainable biomass conversion is utilized by the biorefinery to generate a wide range of value-added products. Among the feedstocks for biodiesel production, Madhuca indica or Mahua, a non-edible oilseed emerges as a viable source. Despite the advantages, the oil cake produced in this process causes environmental pollution, when discarded. In this study, the sulfonated M. indica biomass produced as waste in a one-pot reactive extraction process undergoes calcination and is utilized as a novel heterogeneous catalyst for biodiesel production through the transesterification process. The thermophysical properties of the biodiesel produced were characterized by FTIR (Fourier transform infrared spectroscopy), GC-MS (Gas chromatography/mass spectrometry), H¹ and C¹³ NMR (Nuclear Magnetic Resonance) analysis. Response Surface Methodology (RSM) was used to optimize this process, and the optimum conditions for a maximum yield of 90.01 wt% were a temperature of 70°C, a methanol to oil molar ratio of 15:1, with a catalyst of 3 wt%. Additionally, the performance and emissions characteristics of the MME15 (a blend consisting of 15 % M. indica methyl ester and 85 % diesel) and commercial diesel were studied in a direct injection CI engine in a full load condition the MME15's CO and HC emissions were 28.3 % and 18.2 % lower, respectively than those of commercial diesel. For NO emissions compared with diesel, MME15 emits 2.56 % more. The techno-economical studies highlight the efficiency and significance of the biorefinery of M. indica biodiesel by using a sulfonated catalyst and the payback period was determined as 3.7 years using the Aspen Plus Economic Analyzer.