Kinetic and thermodynamic comparative study of quince bio-waste slow pyrolysis before and after sustainable recovery of pectin compounds

RODRIGO TORRES-SCIANCALEPORE; ANABEL FERNANDEZ; DANIELA ASENSIO; MATHIAS RIVEROS; MARÍA PAULA FABANI; FOUGA G. G.; ROSA RODRIGUEZ; GERMÁN MAZZA

Energy Conversion and Management

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2022 vol. 252

2590-1745

The aim of this work is to study theconsecutive processes of pectin compound extraction from quince waste (QW) andpyrolysis of the pectin-free waste (PFQW). This process is a sustainablealternative to upgrading the bio-waste to chemicals and fuel based on thebiorefinery scheme. QW was subjected to pectin extraction with acid treatmentduring the first valorization step. QW pectin yield was 0.8 % (wb). Thepyrolysis of QW and PFQW was conducted in a macro-TG reactor at three heatingrates (5, 10, and 15 K/min) and temperatures in the range 300-1173 K under a N2atmosphere. The pyrolysis kinetics was modeled using two alternativemechanisms: a single-step mechanism and a multi-step mechanism through parallelreactions. The activation energy, E, the Arrhenius pre-exponential factor, A,and the kinetic model, f(α), were determined for both mechanisms. The kineticbehavior of QW and PFQW pyrolysis was analyzed comparatively. A better fit ofthe experimental data was achieved by the multi-step mechanism modelconsidering three different parallel reactions. The results indicated that the Flynn-Wall-Ozawa (FWO) methodprovided the best R2, MSE, and AAD values. The resulting values ofthe thermodynamic parameters, ΔH, ΔG, and ΔS, were 53.28 – 89.36 kJ/mol, 114.54– 155.01 kJ/mol and -0.17 – (-0.04) kJ/(mol K) for pyrolysis of QW, and 29.97 –90.68 kJ/mol, 99.42 – 158.86 kJ/mol, and -0.23 – (-0.01) kJ/(mol K) for PFQW.According to bioenergy indicators, PFQW presented good characteristics as abiofuel feedstock. Based on the kinetic and thermodynamic parameters obtained,greater reactivity of the PFQW to pyrolysis was verified. The novelty of thepaper focuses on the analysis of sequential processes to valorize quincebio-waste, tending to zero-waste condition, and on providing valuable kineticand thermodynamic information, which is crucial to designing and verifyingindustrial units.