Abstract

Karanja is a medium sized evergreen tree which has minor economic importance in India. The nonedible seed kernel contains 27–30% oil that is used for biodiesel production, leaving the remaining nonedible seed cake as a waste product. The aim of the present work was to obtain kinetic parameters in relation to technological parameters in nonedible seed cake biomass pyrolysis conversion process to bio-oil and biochar. Effects of heating rate on karanja seed cake slow pyrolysis behavior and kinetic parameters were investigated at heating rates of 5, 10, and 20°C/min using thermogravimetric analysis (TGA). Thermogravimetric experiments showed the onset and offset temperatures of the devolatilization step shifted toward the high-temperature range, and the activation energy values increased with increasing heating rate. In the present study, isoconversional method was applied for the pyrolysis of karanja seed cake biomass by TGA and the activation energies (118–124 kJ/mol) and the pre-exponential factors obtained using progressive conversion. Proximate–ultimate analyses, energy value, surface structure, and Fourier transform infrared spectra of the biomass processed under conditions were reported. The pyrolysis resulted in upgradation of the energy value of seed cake biomass from 18.1 to 24.5 MJ/kg, importantly with high carbon and low oxygen contents. The approach represents a novel method for the upgrading of karanja seed cake that has significant commercial potential.

Abstract

The muña leaf is consumed as an infusion, it has pharmacological properties and is used to relieve digestive and respiratory symptoms. Therefore, drying is important for preservation and storage until use or processing. The objective of this research was to evaluate the influence of drying temperature on kinetics, diffusion coefficient and thermodynamic properties. We worked with muña leaves that were subjected to different pretreatments (bleached at 1% ascorbic acid, immersion in water at 60 ° C and without pre-treatment) dried at three temperatures (40, 50 and 60 ° C). The effective diffusion coefficient, activation energy, was determined and the drying process was described using eight mathematical models to represent the drying curve. The Logarithmic model was selected as the one with the best fit to represent the drying kinetics of the muña. Activation energy values ​​were similar between treatments. The increase in temperature promotes: decrease in enthalpy and entropy; increase in Gibbs free energy and effective diffusion coefficient. Therefore, it is essential to reduce the water content by drying to maintain the quality of the muña leaves.