Evolved Gases and Unified Kinetic Model for Low-temperature Thermal Decomposition of Rice Straw Hydrolysis Residue for Possible Value Addition

Abstract

Low-temperature thermal decomposition (LTTD) of Rice straw hydrolysis residue (RSHR) was studied using thermogravimetric analysis and Fourier Transform Infrared spectroscopy (TGA-FTIR) at different heating rates. During thermogravimetry, the maximum rate of mass loss of 135% per min was observed at 339 °C ( Tmax ) for heating rate of 50 °C per min. Tmax decreased to 323, 315, and 299 °C with decrease in heating rate to 40, 30, and 20 °C min−1, respectively. LTTD of RSHR yields volatile oxygenated organics – acids, esters, aldehydes, ketones, alcohols and phenols – as revealed by the FTIR spectra of evolved gases. At increased decomposition temperature, carbonyl moieties were less conjugated. The main gaseous products of LTTD were carbon dioxide, carbon monoxide, and methane. Kinetics of LTTD of RSHR was analysed using thermogravimetry results. Activation energy of LTTD followed a Lorentzian distribution with respect to residual mass fraction (RMF). Dependence of LTTD rate on RMF was found to adhere to the truncated Sestak and Berggren model.