Evaluación de modelos cinéticos utilizados en el proceso termogravimétrico de la degradación del látex natural (Hevea brasiliensis) en el cantón Caluma

Abstract

The objective of this study was to study the kinetics of the thermogravimetric process of degradation of natural latex (Hevea Brasiliensis), analysing the change in mass as a function of time. In the first place, the biomass was characterized by infrared spectroscopy (FTIR), immediate analysis and calculation of calorific value, this characterization shows the characteristic bands of natural latex, mainly the functional group of polyisoprenes comprised in the range between 839.847 and 1646.91 1/cm. Also, the percentage of volatile compounds was 82,39% and a calorific value of 29,88 MJ / kg, which shows the feasibility of the study, then the thermogravimetric study was carried out in a Mettler Toledo TGA-1 equipment considering heating rates of 5 and 15 °C/min. Using the data from the thermogravimetric study and applying the Arrhenius equation, five kinetic models are proposed (Determination of order by amplification of Avrami, Coast-Redfern, Friedman, Flynn-Wall-Ozawa, and Kissinger). Finally, the kinetic model based on the Kissinger method was established as an adequate model for the thermal degradation of natural latex and to minimize the error between the experimental and calculated values, a new model is proposed, and the kinetic parameters were adjusted such as the activation energy and the pre-exponential factor. Through the use of Statgraphics software, a recalculation of the working temperatures was carried out which showed more adjusted kinetic parameters such as the activation energy of 180,967 KJ/mol, in the highest peak of 363,33 °C and a pre-exponential factor from 16,428 1/s. In the same way, the activation energy of 176,836 KJ/mol was obtained, at the highest peak of 379 °C and a pre-exponential factor of 16,467 1/s, for the two heating rates.