Thermokinetic study of macadamia carpel pyrolysis using thermogravimetric analysis

Abstract

The macadamia productive process generates a large amount of waste, such as walnut carpel, that is improperly disposed of in most instances. This residue is a promising feedstock for biofuel production and it can be converted through thermochemical routes. Liquid pyrolysis products obtained contain a bio-oil with great potential for the production of fuels and fine chemicals. The goal of this study was to characterize the macadamia carpel for the first time by ultimate, proximate, FTIR, and TG analysis, as well as HHV determination, which showed this is a potential candidate for thermochemical conversion processes. Thermodynamic and kinetic pyrolysis behaviours were evaluated using Ozawa, Kissinger, Starink, and KAS isoconversional models (140.12, 137.69, 137.41, and 146.63 kJ mol À1 , respectively), which attested to the product favourability and the operational viability. Additionally, the master plot method was applied to complete the kinetic description, which identified diffusion and nucleation mechanisms during the carpel degradation. After 50% conversion, the third-order reaction mechanism occurred due to a predominant lignin decomposition. The results showed that the macadamia carpel properties are similar to traditional feedstock, that it may be decomposed into bio-oil, and that it can be used as an alternative energy source or bio-chemicals precursor.

Analysis of the Physicochemical Characteristics of Biochar Obtained by Slow Pyrolysis of Nut Shells in a Nitrogen Atmosphere

“…It should be noted that, for the pistachio, peanut, and macadamia shell samples, the DTG curves are slightly different, which is associated with the formation of additional reflections at different temperatures. In general, the process of thermal conversion of the samples, in this temperature range, can be due to the decomposition of the main structural components of the biomass: hemicellulose (200-370 • C), cellulose (275-400 • C) and, to a lesser extent, lignin (above 400 • C) [25]. Thus, the main peak (290-400 • C) is mainly due to the pyrolysis of cellulose (∆m = 8.7-11.9 wt%), and the shoulder peak (210-275 • C) can be attributed to thermal decomposition of hemicellulose (∆m = 8.7-11.9 wt%).…”

Effect of Temperature and MgCl2 Concentration on the Catalytic Pyrolysis of Malt Waste Using Response Surface Methodology

“…Although, these values agree with other common biomasses. [63] The negative values of entropy change (ΔS) reflect a reduction in the disorder degree in a total reaction system, leading to more stable products. So, the catalyst decreases even more the entropy, from À 0.08 to À 0.26 kJ.mol À 1 , for F A = 10 %.…”

Produktion of Semi-Coke From Coffee Made as a Raw Material for Silicon Carbide Synthesis

“…Результаты термического анализа исходного образца кофейного жмыха представлены на рис. В целом процесс термического преобразования исследуемого образца в данном температурном интервале можно связать с разложением основных структурных компонентов биомассы: гемицеллюлоза (200-370 °C), целлюлоза (275-400 °C) и в меньшей степени лигнина (свыше 400 °С) [13]. Таким образом, основная часть потери массы (240-340 °С) обусловлена преимущественно пиролизом гемицеллюлозы (Δm = 33,4 мас.…”