Co-pyrolysis of corn stalk and high-density polyethylene with emphasis on the fibrous tissue difference on thermal...

The thermal properties of various corn stalk tissues (including stem, husk, ear, cob, and leaf), high-density polyethylene (HDPE), and their blends were investigated using thermogravimetric analysis under a nitrogen atmosphere. The results indicate that the thermal decomposition process of corn stalk tissue/HDPE mixtures is delayed with an increasing heating rate, regardless of the tissue type. Besides, the structural differences among various corn stalk tissues significantly influence their thermal behavior, product distribution, and co-pyrolysis kinetics with HDPE. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was conducted to analyze the pyrolytic products of the blends with different corn stalk tissues, revealing that corn cob/HDPE blends produce a higher yield of valuable chemicals, such as the furan derivates and aromatic hydrocarbons. Kinetic analysis was further performed using Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods to determine the activation energy for the reactions occurring during co-pyrolysis. The co-pyrolysis of corn cob/HDPE blend requires the least activation energy (149.3 kJ/mol) among five blends, which was ascribed to the high hemicellulose content in corn cob. Moreover, machine learning algorithms, including random forest (RF) and gradient boost regression tree (GBRT), were applied to predict mass loss in the corn fiber/HDPE blends, which showed RF possessed superior accuracy over GBRT. These findings suggest that isolating plant tissues during the feedstock pre-management could enhance the valorization performance of lignocellulose-waste plastic co-pyrolysis.