Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article Efect of biomass addition on the devolatilization kinetics, mechanisms and thermodynamics of a northeast Indian low rank sub-bituminous coal Kaberijyoti Konwar a , Hari Prasad Nath a , Nilutpal Bhuyan a,1 , Binoy K. Saikia b , Ramesh Chandra Borah c , Alok Chandra Kalita d , Nabajyoti Saikia a, ⁎ a Department of Chemistry, The Assam Kaziranga University, Jorhat 785006, Assam, India b Polymer, Petroleum and Coal Group, CSIR-North East Institute of Science and Technology, Jorhat 785006, Assam, India c Department of Mechanical Engineering, The Assam Kaziranga University, Jorhat 785006, Assam, India d Department of Chemistry, Cotton University, Guwahati 781001, Assam, India GRAPHICALABSTRACT ARTICLEINFO Keywords: Sub-bituminous coal Biomass Co-pyrolysis Synergistic efect Decomposition mechanisms Kinetics and thermodynamics ABSTRACT Theefectofadditionofbiomassonthepyrolysisbehavioursofalowranksub-bituminouscoalwasinvestigatedusing thermogravimetric methods (TG and DTG). Results reveal the presence of interaction between coal and biomass residues. Such synergistic efect is observed to be dependent on heating rate, coal to biomass ratio and chemical constituents present in coal-biomass blends. Thermal decompositions of coal and coal-biomass blends follow order based models involving one or two nuclei initially and three nuclei at the latter stages of conversion. Evaluations of synergistic, kinetics and thermodynamic properties show that 25% replacement of coal by biomass gives best results and therefore can be considered as ideal composition for coal devolatilizing process. Results also reveal that biomass addition lowers the mean values of activation energies (E o ) and Arrhenius constants (A o ) of coal devolatilization process. The E o and A o values for coal determined by KAS/DAE methods are 282kJ.mol −1 and1×10 21 min −1 respectively. Similarly, E o and A o values for 25% biomass containing blend are 218kJ.mol −1 and4×10 15 min −1 respectivelyandminimumamongtheblendedcompositions.Resultsalsorevealthatthekineticparameterspredicted byisoconversionalmethodsaresimilartothevaluespredictedbyKissingermethod.Consideringthesimplicity,itcan therefore be concluded that Kissinger method is one of the best methods to determine kinetic parameters of coal devolatilization process with and without the presence of biomass. Our results also reveal that the approach used for analysing TG data by Friedman method helps signifcantly to fnd the meaningful activation energies. https://doi.org/10.1016/j.fuel.2019.115926 Received 1 March 2019; Received in revised form 26 July 2019; Accepted 30 July 2019 ⁎ Corresponding author. E-mail addresses: saikianj@gmail.com, nabajyoti@kazirangauniversity.in (N. Saikia). 1 Current address: Department of Energy, Tezpur University, Tezpur, Assam, India. Fuel 256 (2019) 115926 Available online 07 August 2019 0016-2361/ © 2019 Elsevier Ltd. All rights reserved. T