Specific heat measurements and thermal behaviour analysis of argan residues for pyrolysis applications

Argan waste has significant potential for conversion into biofuels via pyrolysis, thus the necessity to investigate its thermal properties to evaluate the pyrolysis’ energy performance. Accordingly, this study aims to measure the specific heat capacity (Cp) of argan nut shells (ANS), argan pressed cake (APC), and argan pulp (AP). Experimental measurements were conducted using differential scanning calorimetry under pyrolysis conditions, across a temperature range of 35–430 °C with various particle sizes. Multiple regression models were developed to correlate Cp to temperature and particle size. Experimental results showed that Cp varies significantly with thermal process phases, identified by thermogravimetric analysis: dehydration, hemicellulose and cellulose decomposition, and carbonisation. During dehydration, Cp of ANS, APC, and AP increase gradually with temperature, ranging from 0.5 to 1.5 J/g °C, 0.8–1.7 J/g °C, and 0.7–2 J/g °C, respectively. In decomposition and carbonisation phases, Cp exhibited irregular variations, generally decreasing with temperature due to energy fluctuations from complex reactions. Statistical analysis shows that temperature is the dominant factor affecting Cp. Particle size effects varied with biomass composition: Cp increased with size for lignocellulosic-rich ANS, decreased for sugar-rich AP, and showed no clear trend for APC, which is rich in proteins and lipids.