**Abstract**

The efficient and high yielding acid-base and Organosolv methods were studied for cellulose isolation from date palm lignocellulose waste biomass and thereafter analyzed for nonisothermal kinetic and thermodynamic parameter determination using model-free methods. The structural and chemical characterization of the isolated celluloses revealed structures and functional groups characteristics of cellulose. Thermal decomposition analysis revealed one major peak with average mass loss of 72.51 � 0.7% and 55.82 � 1.1% for the acid-base and Organosolv method, respectively. This occurred in the temperature region between 250 and 350°C associated with cellulose degradation and contrasted with the three peaks detected in the original biomass. The kinetic and thermodynamic results revealed a strong relationship between the average activation energy and average change in enthalpy with a difference of 5.23 and 147.07 kJmol�<sup>1</sup> for Organosolv and acid-base methods, respectively. The Gibbs's free energy results revealed that Organosolv cellulose pyrolysis would reach equilibrium faster in KAS, Starink and FWO models with average <sup>Δ</sup>G values of 115.80 � 36.62, 115.89 � 36.65, and 119.45 � 37.98 kJmol�<sup>1</sup> , respectively. The acid-base method for FWO model gave negative entropy values. The Malek method revealed the acid-base and Organoslv cellulose pyrolysis mechanism as (*g*ð Þ¼ � <sup>α</sup> ½ � ln 1ð Þ � <sup>α</sup> <sup>1</sup> <sup>4</sup><sup>Þ</sup> and (*g*ð Þ¼ � <sup>α</sup> ½ � ln 1ð Þ � <sup>α</sup> <sup>1</sup> <sup>3</sup>Þ, characterized by random nucleation and growth, respectively.

**Keywords:** lignocellulose biomass, nonisothermal kinetics, isolation methods, characterization
