Physico-chemical properties and thermal degradation studies of commercial oils in nitrogen atmosphere

Thermal properties and reaction kinetics of commercial oils play prominent role in design, operation and modeling of systems with various industrial applications including cosmetics, lubrication, fuel and food processing. In the present work, thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTG) techniques were used to study the thermo-chemical behavior of four varieties of oils (mustard, soybean, olive and karanja). The thermal degradation was studied in an inert (N2) atmosphere from ambient temperature to a temperature of 600 °C using a heating rate of 10, 20, 30, 50, 100 °C min−1. The chemical composition and thermal properties were investigated by measuring FTIR, DSC, CHNS and 1H NMR. Physical properties such as moisture content, viscosity, ash content, flash, fire, pour and cloud points were also determined. The model-free iso-conversional methods were used to determine kinetic parameters without making any assumptions about the reaction function and reaction order which avoids the risk of obtaining wrong kinetic parameters, especially activation energy, due to pre-assumption of inappropriate reaction function. Four degradation models including modified Coats and Redfern, Friedman, Kissinger and Flynn-Wall-Ozawa methods were used to determine the apparent activation energy.