Environmental sustainability assessment of mustard straw torrefaction: Insights from thermo-kinetics, product distribution analysis, product characterization and life cycle assessment

We investigated state-of-the-art torrefaction of mustard stalk (MS) using the temperature range of 200–400 °C aimed to obtain optimal product distribution and subsequent characterization. The iso-conversional kinetic analyses of MS torrefaction were validated using the robust Tang method followed by the Miura-Maki method for Distributed Activation Energy Model. The kinetics was further examined by a thermodynamic analysis focusing on the thermodynamic triplets – changes in enthalpy, Gibb's free energy and entropy. The experimental analysis revealed that the yield of char decreased from 67.89 % at 200 °C to 34.33 % at 400 °C whereas the yield of gas increased from 20.31 % to 44.75 % in the same ranges. The maximum yield of bio-oil of 21.32 % was obtained at 300 °C. The proximate analysis, elemental analysis, thermogravimetric analysis, Fourier transform infrared analysis, X-ray diffraction pattern, field emission electron microscopy, gas chromatography-mass spectrometry (GC-MS), and life cycle analyses were performed for validation and robustness of the applied state-of-the-art. • Experimental investigation of torrefaction of mustard straw (MS) in the temperature range of 200–400 °C has been conducted. • Iso-conversional kinetic analysis of MS torrefaction has been performed. • The experimental analysis reveals that the biochar decreases from 67.89 % at 200 °C to 34.33 % at 400 °C. • The biochar has been characterized using proximate, elemental, thermogravimetric, Fourier transform infrared, X-ray diffraction and field emission electron microscopy analysis. • Life Cycle Assessment of MS torrefaction has been conducted using the SimaPro software.