Formation of persistent free radicals in biochar derived from rice straw based on a detailed analysis of pyrolysis kinetics

Tao, Wenmei; Duan, Wenyan; Liu, Chunbo; Zhu, Dengsong; Si, Xiaoxi; Zhu, Ruizhi; Oleszczuk, Patryk; Pan, Bo

doi:10.1016/j.scitotenv.2020.136575

Cited by 65 publications

(40 citation statements)

References 43 publications

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“…The other peak was the maximum weight loss accompanied by an extra “shoulder” peak. According to the DTG curves of HC and CL (Figure S1b) as well as our previously reported results, the shoulder peak at approximately 279 °C was mainly attributed to the thermal degradation of HC, while the maximum mass loss peak centered at 311 °C was ascribed to the decomposition of CL. Comparing the DTG curves, the maximum mass loss rate of RS (7.51%/min) was lower than PS (9.77%/min), probably because of the lower CL content in RS (Table S1).…”

Section: Resultssupporting

confidence: 86%

“…PFRs were detected previously in cigarette smoke and proven to produce reactive oxygen species in liquid environments and further induce cancer and heart and lung diseases . Previous researchers suggested that hydroquinone was a primary progenitor of semiquinone type radicals, which were the main type of PFRs produced in the residual particles during the pyrolysis of lignocellulose biomass. − However, it is still unknown whether the volatiles during biomass pyrolysis contain PFRs and which biopolymers in lignocellulose biomass are the structural origin to induce the formation of PFRs in pyrolytic volatiles.…”

Section: Introductionmentioning

confidence: 99%

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Components and Persistent Free Radicals in the Volatiles during Pyrolysis of Lignocellulose Biomass

Tao

Yang

et al. 2020

Environ. Sci. Technol.

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Persistent free radicals (PFRs) may cause negative impacts to human health and the environment because of the induced reactive oxygen species. We expect that PFRs could be generated in the condensable volatiles formed during lignocellulose biomass pyrolysis. Elucidating the structural origin and the formation mechanism of PFRs is important for an in-depth understanding of air pollutants from the pyrolysis or combustion of lignocellulose biomass. This work selected rice straw and pine sawdust to represent agricultural and forest biomass residues. The pyrolysis mechanism, volatile components, and PFR generation were discussed based on the analysis of thermogravimetry−Fourier transform infrared spectroscopy−mass spectrometry (MS), pyrolysis−gas chromatography/MS, and electron spin resonance (ESR). Levoglucosan, furans, and 2-methoxyphenols were the main pyrolytic compounds for cellulose (CL), hemicellulose (HC), and lignin (LG), respectively. Obvious ESR signals were detected in the condensable volatiles of LG, while no ESR signals were detected for those of CL and HC. Higher ESR signals were detected in lignocellulose with a higher content of LG. Therefore, LG was the main structural basis to generate PFRs in lignocellulose condensable volatiles, mostly attributed to the methoxyphenol components. This study provides useful information regarding the generation mechanisms of and the structures related to PFRs, which is essential to understand the risks of lignocellulose pyrolytic volatiles.

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Section: Resultssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Components and Persistent Free Radicals in the Volatiles during Pyrolysis of Lignocellulose Biomass

Tao

Yang

et al. 2020

Environ. Sci. Technol.

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“…Still much lower DOC concentrations of DHEM400 (3.21 ± 1.96 mg/L), DCEL400 (3.56 ± 0.62 mg/L) and DCEL500 (1.37 ± 0.24 mg/L) than those of DLIG400 (22.15 ± 1.15 mg/L) and DLIG500 (14.71 ± 0.69 mg/L) indicated that most pyrolysis products of CEL and HEM may be volatiles when producing biochar following the increase of HTT. This is also supported by the result of thermogravimetric analysis that the fraction of residue weights was LIG (33.0%) > HEM (9.05%) > CEL (0.44%) in the whole pyrolysis (Tao et al, 2020). Therefore, the obtained DBC was most likely to be composed by the pyrolysis products of LIG, especially at high temperatures.…”

Section: Dbc Formationsupporting

confidence: 60%

Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar

Han

Nie

Wei

et al. 2021

Science of The Total Environment

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“…could be a result of their compositional differences [ 12 ]. Wood-based feedstocks include a greater proportion of lignin, which is more thermally stable and rapidly generates fixed carbon rather than DOC [ 17 ]. In contrast, other feedstocks contain a greater proportion of hemicellulose and cellulose, which are more lead to DOC formation.…”

Section: Introductionmentioning

confidence: 99%

Investigating Biochar-Derived Dissolved Organic Carbon (DOC) Components Extracted Using a Sequential Extraction Protocol

et al. 2022

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Biochar-derived dissolved organic carbon (DOC), as the most important component of biochar, can be released on farmland, improving fertility and playing a role in soil amendment and remediation. The complexity of molecular structures and diversity of DOC compounds have influenced these functions to some extent. A sequential extract protocol consisting of water (25 °C), hot water (80 °C), and NaOH solution (0.05 M) was used to fully extract DOC compounds and gain a thorough understanding of the possible DOC components released from biochar. Rape straw (RS), apple tree branches (ATB), and pine sawdust (PS) were pyrolyzed at 300, 500, and 700 °C, respectively, to make nine distinct biochars. A TOC analyser, ultraviolet-visible spectroscopy (UV–vis), and excitation–emission fluorescence (EEM) spectrophotometer were used in conjunction with parallel factor analysis (PARAFAC) to determine the distribution of DOC content, the diversity of aromaticity, molecular weight characteristics and components of biochar-derived DOC. The results show that the relative distribution of water-extractable fractions ranged from 3.21 to 35.57%, with a low-aromaticity and extremely hydrophilic fulvic-acid-like compounds being found in the highest amounts (C2 and C3). The smallest amount of hot water-extractable components was produced from the release of small-molecule aliphatic compounds adsorbed on biochar and susceptible to migration loss once in a soil solution. More than half of the biochar-derived DOC was released in a NaOH solution, which primarily consisted of humic-acid-like compounds (C1), with higher molecular weights, more aromaticity, and lower bioavailability, according to the distribution of DOC in various extractants. In addition, the pyrolysis temperature and biomass type had a significant impact on the DOC properties released by biochar. As a result, the findings of this study showed that using a sequential extract protocol of water, hot water, and NaOH solution in combination with spectroscopic methods could successfully reveal the diversity of biochar-derived components, which could lead to new insights for the accurate assessment of potential environmental impacts and new directions for biochar applications.

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Formation of persistent free radicals in biochar derived from rice straw based on a detailed analysis of pyrolysis kinetics

Cited by 65 publications

References 43 publications

Components and Persistent Free Radicals in the Volatiles during Pyrolysis of Lignocellulose Biomass

Components and Persistent Free Radicals in the Volatiles during Pyrolysis of Lignocellulose Biomass

Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar

Investigating Biochar-Derived Dissolved Organic Carbon (DOC) Components Extracted Using a Sequential Extraction Protocol

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