EXTRACTION, CHARACTERIZATION AND KINETICS OF THERMAL DECOMPOSITION OF LIGNIN FROM DATE SEEDS USING MODEL-FREE AND FITTING APPROACHES

Abstract

Lignin is known to have great potential for use as a renewable feedstock in a variety of industrial applications, including energy and chemicals. Furthermore, to ensure an efficient valorization of lignin, the efficiency of the isolation procedure and the knowledge of its properties are crucial. In the present study, we extracted lignin from date seeds using the Klason method. The extracted lignin was characterized by FT-IR spectrometry, XRD and SEM-EDX analysis. The thermal behavior of date seeds lignin has been investigated using TGA and DSC. Several isoconversional and model-fitting methods were employed to derive the kinetic parameters. A comparison between these procedures was carried out. Based on the results of activation energy (Ea) and pre-exponential factor (A) determined using Kissinger’s equation for date seeds lignin decomposition, some thermodynamic parameters (ΔS#, ΔH# and ΔG#) were determined. Following a broad endothermic stage, a large exothermic peak was observed in the DSC plots, attesting to the overall exothermicity of the lignin pyrolysis. From the derivative curve of DSC plots, the glass transition temperature Tg of the studied lignin was determined. High values of Tg, ranging from 102.62 to 127.28 °C, significantly affected by the heating rate, were found.