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There are several environmental and human health impacts if human hair waste is not adequately disposed of. In this study, pyrolysis of discarded human hair was carried out. This research focused on the pyrolysis of discarded human hair under controlled environmental conditions. The effects of the mass of discarded human hair and temperature on bio-oil yield were studied. The proximate and ultimate analyses and calorific values of disposed of human hair, bio-oil, and biochar were determined. Further, chemical compounds of bio-oil were analyzed using a gas chromatograph and a mass spectrometer. Finally, the kinetic modeling and behavior of the pyrolysis process were characterized through FT-IR spectroscopy and thermal analysis. Based on the optimized mass of disposed of human hair, 250 g had a better bio-oil yield of 97% in the temperature range of 210-300 °C. The different parameters of bio-oil were: pH (2.87), specific gravity (1.17), moisture content (19%), heating value (19.34 MJ/kg), and viscosity (50 CP). C (56.4%), H (6.1%), N (0.16%), S (0.01%), O (38.4%), and Ash (0.1%) were discovered to be the elemental chemical composition of bio-oil (on a dry basis). During breakdown, the release of different compounds like hydrocarbons, aldehydes, ketones, acids, and alcohols takes place. According to the GC-MS results, several amino acids were discovered in the bio-oil, 12 abundant in the discarded human hair. The FTIR and thermal analysis found different concluding temperatures and wave numbers for functional groups. Two main stages are partially separated at about 305 °C, with maximum degradation rates at about 293 oC and 400-4140 °C, respectively. The mass loss was 30% at 293 0 C and 82% at temperatures above 293 0 C. When the temperature reached 410 0 C, the entire bio-oil from discarded human hair was distilled or thermally decomposed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Microwave technology is utilized to prepare porous carbon from the chili straw pyrolysis residue in this study. As the pyrolysis temperature increases, the thermal stability of biochar is higher. The carbon speciation of the porous carbon PC500 is closest to that of graphite, and its inorganic-C reaches to 51.21%. Notably, the specific surface area of the activated porous carbon increases with increasing pyrolysis temperature, with a maximum value of 2768.52 m 2 /g for PC500. Further testing of the electrochemical properties of the porous carbon, PC500 possesses a high specific capacitance of 352F/g at 1 A/g while that of conventional heating is only 226.1F/g. The porous carbon prepared by microwave heating has better electrical properties compared to conventional heating, and the biochar obtained at higher pyrolysis temperature has a richer pore structure after activation., (Copyright © 2022. Published by Elsevier Ltd.)

In recent years, biomass has been reported to obtain a wide range of value-added products. Biochar can be obtained by heating biomass, which aids in carbon sinks, soil amendments, resource recovery, and water retention. Microwave technology stands out among various biomass heating technologies not only for its effectiveness in biomass pyrolysis for the production of biochar and biofuel but also for its speed, volumetrics, selectivity, and efficiency. The features of microwave-assisted biomass pyrolysis and biochar are briefly reviewed in this paper. An informative comparison has been drawn between microwave-assisted pyrolysis and conventional pyrolysis. It focuses mainly on technological and economic scenario of biochar production and environmental impacts of using biochar. This source of knowledge would aid in the exploration of new possibilities and scope for employing microwave-assisted pyrolysis technology to produce biochar., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Samples of papers artificially (2 to 60 days) and naturally (10, 45, and 56 years) aged were studied by the Py-GC/MS method to identify decomposition products. Possible reaction scenarios for cellulose degradation were developed. One of the degradation products is acetic acid, which can (auto)catalyze the cleavage of cellulose β(1→4)-glycosidic bonds of cellulose polymer chains. However, during 20 s of Py-GC/MS analysis, temperatures of up to 300 °C did not significantly increase or modify the formation of decomposition products of paper components. At 300 °C, the amount of several cellulose decomposition products increased regularly depending on the number of days of artificial aging and natural aging, demonstrated mainly by the generation of 2-furancarboxaldehyde, 5-hydroxymethylfurfural, and levoglucosan and its consecutive dehydration products. No correlation between the amount of lignin decomposition products and the time of aging was found when the pyrolysis was performed at 300 °C and 500 °C. Compounds present in the products of decomposition at 500 °C bear the imprint of the chemical composition of the sampled paper. Pyrograms taken at 300 °C using the Py-GC/MS method can give additional information on the changes in the chemical structure of paper during natural or artificial aging, mainly about the cleavage of β(1→4)-glycosidic bonds during aging.

The chemical structure of lignin has an important effect on the lignin pyrolysis product distributions. Therefore, it is of great significance to regulate the selectivity of pyrolysis products by modifying the lignin structure. Herein, deep eutectic solvents (DESs) including choline chloride/ethylene glycol (CE), zinc chloride/ethylene glycol (ZE) and choline chloride/acetic acid, treatment of softwood kraft lignin (SKL) is demonstrated. Systematic characterization indicate that the DESs are not only highly conducive to increasing the hydrogen to carbon efficient ratio, reducing the molecular weight and β-O-4 linkage, but also contributes to the maximum degradation rate and thermal stability of SKL. Noticeably, CE and ZE treatment are significantly improved the amount of H-phenols and C-phenols derived lignin pyrolysis, respectively. In addition, DESs pretreatment are also beneficial to the increment of monomer aromatic hydrocarbons. More importantly, the CE pretreatment contributes to the improvement of bio-oil yield and decrease of char content from lignin pyrolysis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this work, an emerging and efficient strategy for the preparation of lignin samples with different acetylation degree by choline chloride/acetic anhydride (ChCl/Aa) treatment of pine kraft lignin (PKL) is reported, and the effects of efficient pre-acetylation of hydroxyl functional groups on subsequent lignin pyrolysis are also systematically investigated. The results show that the ChCl/Aa displays a high acetylation efficiency towards the aliphatic hydroxyl (~99.1%) and phenolic hydroxyl (~94.0%) of PKL, which enhances the hydrogen to carbon effective ratio of PKL. Noticeably, the ChCl/Aa has a slight effect on β-O-4 of PKL, and the acetylation of hydroxyl is beneficial for the improvement of the maximum degradation rate of PKL. In addition, the acetylation of hydroxyl is also significantly contributed to the increment of the pyrolysis bio-oil yield. Importantly, the relative content of the H-phenols obtained from acetylated lignins pyrolysis shows a positive correlation with the acetylation degree of hydroxyl., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, lignin with different phenolic hydroxyl contents and five model compounds are pyrolyzed to investigate the effect of the interaction of phenolic hydroxyl with a benzene ring on lignin pyrolysis. The results demonstrated that phenolic hydroxyl can reduce the stability of lignin and promote the elimination of the side chain on lignin during pyrolysis. The repolymerization during lignin pyrolysis, which results in increased activation energy and char yield during pyrolysis, can be mainly attributed to phenolic hydroxyl. Meanwhile, the repolymerization because of phenolic hydroxyl is obviously affected by the electron cloud density of the benzene ring. The repolymerization caused by the phenolic hydroxyl can be effectively reduced by increasing the electron cloud density. Furthermore, regulation of the product distribution obtained via lignin pyrolysis by changing the electron cloud density of the benzene ring and the phenolic hydroxyl content in lignin is proposed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)