The Experts below are selected from a list of 825 Experts worldwide ranked by ideXlab platform
Flaviano Oliveira Silvério - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
Luiz C A Barbosa - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
Jinhua Zhan - One of the best experts on this subject based on the ideXlab platform.
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theoretical studies on the heterogeneous ozonolysis of Syringol on graphene mechanism kinetics and ecotoxicity assessment
Chemical Engineering Journal, 2021Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Ju Xie, Dudley E Shallcross, Haijie Cao, Jinhua ZhanAbstract:Abstract It has been found that soot particles with a graphene-like structure play an important role in heterogeneous oxidation. However, little is known about the mechanism at the atomic-level. Therefore, we studied the heterogeneous ozonolysis mechanism of Syringol onto graphene (GP) sheets using density functional theory (DFT) methods. The results show that the GP sheet plane plays an adsorbent role in the ozonolysis of Syringol. Results suggest that the adsorbed Syringol will prefer to degrade in wet weather. Moreover, Criegee intermediates generated from the primary ozonolysis steps will undergo subsequent reactions in the presence of NO and H2O. The total rate constants for the ozonolysis of Syringol are 4.62 × 105 and 4.77 × 107 M−1 s−1 in the condensed phase and aerosol particles, respectively (298 K, 1 atm). Based on toxicity assessments, most transformation products are eco-friendly. Our results provide a better understanding of the environmental fate of Syringol and can be a supplement to the experimental research in the future.
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effect of ph on oh induced degradation progress of Syringol syringaldehyde and health effect
Chemosphere, 2020Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Xueyu Wang, Ju Xie, Jinhua ZhanAbstract:Abstract Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOx regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their · O H -initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the · O H -initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy− and Sya− (anionic species of Syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of Syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of Syringol and syringaldehyde with · O H in wastewater increased from 5.43 × 1010 to 9.87 × 1010 M−1 s−1 and from 3.70 × 1010 to 1.14 × 1011 M−1 s−1, respectively. In the NOx-rich environment, 4-nitroSyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOx-poor environment. On the whole, the NOx-poor environment could decrease the toxicities during the hydroxylation processes of Syringol and syringaldehyde, which was the opposite in a NOx-rich environment. · O H played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOx-poor environment.
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effect of ph on formula omitted induced degradation progress of Syringol syringaldehyde and health effect
Chemosphere, 2020Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Ju Xie, X Q Wang, Jinhua ZhanAbstract:Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOₓ regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the ·OH-initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy⁻ and Sya⁻ (anionic species of Syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of Syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of Syringol and syringaldehyde with ·OH in wastewater increased from 5.43 × 10¹⁰ to 9.87 × 10¹⁰ M⁻¹ s⁻¹ and from 3.70 × 10¹⁰ to 1.14 × 10¹¹ M⁻¹ s⁻¹, respectively. In the NOₓ-rich environment, 4-nitroSyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOₓ-poor environment. On the whole, the NOₓ-poor environment could decrease the toxicities during the hydroxylation processes of Syringol and syringaldehyde, which was the opposite in a NOₓ-rich environment. ·OH played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOₓ-poor environment.
Jianfei Sun - One of the best experts on this subject based on the ideXlab platform.
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theoretical studies on the heterogeneous ozonolysis of Syringol on graphene mechanism kinetics and ecotoxicity assessment
Chemical Engineering Journal, 2021Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Ju Xie, Dudley E Shallcross, Haijie Cao, Jinhua ZhanAbstract:Abstract It has been found that soot particles with a graphene-like structure play an important role in heterogeneous oxidation. However, little is known about the mechanism at the atomic-level. Therefore, we studied the heterogeneous ozonolysis mechanism of Syringol onto graphene (GP) sheets using density functional theory (DFT) methods. The results show that the GP sheet plane plays an adsorbent role in the ozonolysis of Syringol. Results suggest that the adsorbed Syringol will prefer to degrade in wet weather. Moreover, Criegee intermediates generated from the primary ozonolysis steps will undergo subsequent reactions in the presence of NO and H2O. The total rate constants for the ozonolysis of Syringol are 4.62 × 105 and 4.77 × 107 M−1 s−1 in the condensed phase and aerosol particles, respectively (298 K, 1 atm). Based on toxicity assessments, most transformation products are eco-friendly. Our results provide a better understanding of the environmental fate of Syringol and can be a supplement to the experimental research in the future.
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effect of ph on oh induced degradation progress of Syringol syringaldehyde and health effect
Chemosphere, 2020Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Xueyu Wang, Ju Xie, Jinhua ZhanAbstract:Abstract Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOx regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their · O H -initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the · O H -initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy− and Sya− (anionic species of Syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of Syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of Syringol and syringaldehyde with · O H in wastewater increased from 5.43 × 1010 to 9.87 × 1010 M−1 s−1 and from 3.70 × 1010 to 1.14 × 1011 M−1 s−1, respectively. In the NOx-rich environment, 4-nitroSyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOx-poor environment. On the whole, the NOx-poor environment could decrease the toxicities during the hydroxylation processes of Syringol and syringaldehyde, which was the opposite in a NOx-rich environment. · O H played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOx-poor environment.
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effect of ph on formula omitted induced degradation progress of Syringol syringaldehyde and health effect
Chemosphere, 2020Co-Authors: Jianfei Sun, Dandan Han, Qiong Mei, Bo Wei, Ju Xie, X Q Wang, Jinhua ZhanAbstract:Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOₓ regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the ·OH-initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy⁻ and Sya⁻ (anionic species of Syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of Syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of Syringol and syringaldehyde with ·OH in wastewater increased from 5.43 × 10¹⁰ to 9.87 × 10¹⁰ M⁻¹ s⁻¹ and from 3.70 × 10¹⁰ to 1.14 × 10¹¹ M⁻¹ s⁻¹, respectively. In the NOₓ-rich environment, 4-nitroSyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOₓ-poor environment. On the whole, the NOₓ-poor environment could decrease the toxicities during the hydroxylation processes of Syringol and syringaldehyde, which was the opposite in a NOₓ-rich environment. ·OH played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOₓ-poor environment.
Claudio F Lima - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (Syringol, 4-methylSyringol, 4-vinylSyringol and trans -4-(prop-2-enyl) Syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
