Kinetic modeling and particulate characterization of selected bio-hazardous by-products from high temperature pyrolysis of goat meat

Abstract

Although molecular toxins and emission of particulates from the thermal degradation of biomass materials such as meat is a complex area of study, it has become necessary to investigate this phenomenon and determine how it affects biological functions and as precursors for cancer, degenerative diseases that stress the respiratory landscape. Accordingly, this study describes the pyrolysis of goat meat in the temperature range 300-525 ˚C. Goat meat sample of 10±0.2 g was heated under atmospheric conditions in an air depleted environment in a thermal degradation reactor (volume ~ 1.6 cm3) and the smoke effluent passed through a transfer column and collected over 10 mL dichloromethane and kept in crimp top amber vials. Evolution of selected molecular toxins was monitored using an in-line Gas Chromatography hyphenated to a mass spectrometer (GC-MS) while the particulate nature and morphology of particulate emissions was investigated using a scanning electron microscope (SEM). GC-MS analysis was carried out using an Agilent Technologies 7890A GC system coupled to an Agilent Technologies 5975C mass selective detector (MSD). The density functional theory (DFT) and Chemissian softwares were used to explore the thermochemistry and molecular geometries of 2-(ethylthio)phenol, 2,3-dimethylhydroquinone, and 1,1’-biphenyl. The major organic volatiles detected from GCMS were phenol, 2,3-dimethyl hydroquinone, 2-(ethylthio)phenol, indole and 1,1’-biphenyl. At a pyrolysis temperature of 500 ˚C, the mean particle size of particulates was found to be 7.72 ± 0.61 µm while at 700 ˚C, the particulate size of emissions was found to be 3.52 ± 0.31 µm. This particles are small in sizes and are possible to get into the lungs and cause respiratory problems Moreover, a kinetic model for the thermal destruction of indole, 2,3- dimethylhydroquinone, and 2-(ethylthio)phenol within a temperature region of 450 ˚C and 525 ˚C using pseudo-first order reaction kinetics has been proposed at a residence time of 2.0 s. Consequently, the temperature dependent rate constants for the destruction of 2,3 dimethylhydroquinone, 2-(ethylthio)phenol, and indole were estimated to be, k  x Tn x e RT411 101726310.s-1, k  x Tn x e RT110 1019283 38..s -1, and k  130 x 1021Tn x e RT 315 76 . . s -1 respectively. The electron density maps as well as the toxicity index of 2-(ethylthio)phenol are also reported in this study. The fundamental finding of this study is that most bio-hazardous byproducts were evolved in high yields above 300 ˚C.