Thermal degradation and pyrolysis kinetics of two Indian rice husk varieties using thermogravimetric analysis
Pratap Singh, Rajnish Kumar Singh, Prithvi Gokul, Shabih-Ul Hasan, Ashish N. Sawarkar
Abstract
Agricultural crop residues are making significant inroads in the broad spectrum of lignocellulosic biomass for energy recovery and in realizing prospective potential of bio-based economy. In the present work, comprehensive physicochemical characterization of two rice husk varieties (RH-B and RH-P) of Indian origin, their thermal degradation behavior, and pyrolysis kinetics were studied via thermogravimetric analysis. Thermogravimetric experiments were conducted at five heating rates, viz. 2, 5, 10, 15 and 20°C/min. The activation energy for the thermal decomposition was calculated using Coats–Redfern and Distributed Activation Energy Model (DAEM) method. The ash content was found to be significantly less in RH-P (10.17 wt%) vis-a-vis RH-B (20.07 wt%) which infers that there will be fewer residues left after pyrolysis as compared to RH-B. The cellulose and hemicellulose contents put together was high in RH-P (60.1 wt%) as compared to RH-P (56.92 wt%), which was reflected in terms of average weight loss of 55.15% and 41.863% for RH-P and RH-B, respectively, just above 230ºC due to rapid decomposition. The maxima of the f(E) curve was found to appear at 192.77 kJ/mol and 229.12 kJ/mol for the RH-B and RH-P, respectively. The experimental data for the pyrolysis of RH-B and RH-P were found to fit well with the Ginstling–Brounshtein diffusion model from amongst various solid-state kinetic models.