The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose th...The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose through cleavage of the glycosidic bonds,the dissociation energies of which were supplied by the impact of a ball on pine sawdust,during milling.The destruction of glycosidic and hydrogen bonds in pine sawdust resulted in a decrease of crystallinity and an increase of water solubility.The sulfuric acid could promote the hydrolysis of holocellulose and its hydrolysis products.It also destroyed the chemical linkages between holocellulose and lignin during ball milling.The cleavage of chemical linkages with holocellulose made lignin more difficult to hydrolyze in subcritical water,and higher activation energy was needed to hydrolyze pretreated pine sawdust at higher reaction temperatures.It also led to the formation of glucose char and aromatic-linked polymer char from the hydrolysis products of holocellulose.展开更多
The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of...The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of reaction temperature from 180-320℃, pressure from 5-26 MPa, and time from 5-60 rain. The quality and quantity of amino acids in hydrolysate were determined by bioLiquid chromatography, and 17 kinds of amino acids were obtained. For the important 8 amino acids, the experiments were conducted to examine the effects of reaction temperature, pressure and time on amino acids yield. The optimum conditions for high yield are obtained from the experimental results. It is found that the nitrogen and carbon dioxide atmosphere should be used for leucine, isoleucine and histidine production while the air atmosphere might be used for other amino acids. The reaction time of 30 rain and the experimental temperature of 220℃, 240℃ and 260℃ were adopted for reaction kinetic research. The total yield of amino acids versus reaction time have been examined experimentally. According to these experimental data and under the condition of water excess, the macroscopic reaction kinetic equation of fish proteins hydrolysis was obtained with the hydrolysis reaction order of 1.615 and the rate constants being 0.0017, 0.0045 and 0.0097 at 220℃, 240℃ and 260℃ respectively. The activation energy is 145.1 kJ·mol^- 1.展开更多
Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen...Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen peroxide to toluene is controlled within a reasonable range, the by-products may be neglected. The optimum technology of toluene oxidization to benzaldehyde is reaction time 60 min, reaction temperature 350℃, molar ratio of hydrogen peroxide to toluene 3.5. The yield of benzaldehyde can reach 17.2 % under the optimum condition. Research results of chemical reaction kinetics show that the consecutive reaction consists of two first-order reaction, and activation energy of these two reactions are 89 kJ·mol^-1 and 76 kJ·mol^-1 respectively,展开更多
For the first time,the solubility ofβ-carotene in pure and ethanol-modified subcritical water(SW)using the static method was determined.The experimental runs were performed at a temperature ranging from 298.15 to 403...For the first time,the solubility ofβ-carotene in pure and ethanol-modified subcritical water(SW)using the static method was determined.The experimental runs were performed at a temperature ranging from 298.15 to 403.15 K and 0–10%(w/w)of ethanol as a modifier at a constant pressure of 5 MPa.Samples were analyzed by UV–vis spectrophotometer.The solubility ofβ-carotene was found to range from 1.084×10^-8 to 227.1×10^-8 mol fractions in the subcritical water in above mentioned conditions.The obtainedβ-carotene solubility data were correlated using the linear model and modified Apelblat model.The obtained results showed the modified Apelblat model was better for estimating the solubility ofβ-carotene in SW.The values of the rootmean-square deviation(RMSD)between experimental and correlated data were calculated and used as the index of validity and accuracy for the model.Also,thermodynamic properties of the solution such as the Gibbs free energy of solution,enthalpy,and entropy of solution were estimated.展开更多
A method for decomposition of cellulose to produce 5-hydroxymethyl-furaldehyde （5- HMF） in subcritical water-carbon dioxide binary system was proposed. A series of experiments were performed in a batch reaction vess...A method for decomposition of cellulose to produce 5-hydroxymethyl-furaldehyde （5- HMF） in subcritical water-carbon dioxide binary system was proposed. A series of experiments were performed in a batch reaction vessel. Main products of the decomposition of cellulose are 5-HMF, furfural, levulinic acid and 1, 2, 4-benzenetrioI.The optimum condition for the preparation of 5-HMF was found as 523.15 K, 5.0% carbon dioxide mole fraction, and 30 min reaction time. The addition of carbon dioxide to water conduced to the decomposition of cellulose to 5-HMF. As can be seen from the distribution of the prod-ucts, the decomposition mechanism of cellulose is similar to the hydrothermal reaction of D-glucose and D-fructose.展开更多
Here, the employment of subcritical water as an environmentally benign media has shown a certain potential for the hydrolysis ofiminodiaeetonitrile （IDAN）. Additives （such as NH3.H2O, （NH4）2CO3, K2CO3） were sele...Here, the employment of subcritical water as an environmentally benign media has shown a certain potential for the hydrolysis ofiminodiaeetonitrile （IDAN）. Additives （such as NH3.H2O, （NH4）2CO3, K2CO3） were selected to investigate the reactivity ofiminodiacetonitrile in the solutions of these species in the subcritical region for the possibility of preparing iminodiacetic acid （IDA） salts. A series of reactions were performed in a high temperature and pressure batch reactor with temperature ranging from 200 to 260 ℃, time ranging from 4 to 10 min, pressure ranging from 5 to 25 MPa and varying concentration of additives to consider the influence of these parameters on the yield of IDA salts. Reactivity of IDAN was not illustrated with the conversion but with respect to the yield of resultant IDA salts. The results demonstrate that hydrolysis reactivity of IDAN under the examined conditions has shown a remarkable sensitivity to the pH of the system at initial point of the reaction stage, and temperature effect is also obvious. Based on the results, possible reaction pathway and mechanism were proposed.展开更多
In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Sc...In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.展开更多
In this paper, subcritical water, an environmentally friendly solvent, was employed to degrade rhodamine B, which served as a model dye in textile industrial effluents. The effect of Cu（Ⅱ） on the degradation of rho...In this paper, subcritical water, an environmentally friendly solvent, was employed to degrade rhodamine B, which served as a model dye in textile industrial effluents. The effect of Cu（Ⅱ） on the degradation of rhodamine B was evaluated. Further, the degradation kinetics of rhodamine B in subcritical water was evaluated via a Weibull model. The results show that subcritical water could efficiently degrade and decolorize rhodamine B. The addition of Cu（Ⅱ） into subcritical water could accelerate the degradation of rhodamine B and lower the temperature for its com- plete degradation. The Weibull equation could well express the degradation kinetics of rhodamine B. The calculated rate constants showed Arrhenius behavior and presented high correlation coefficients. The activation energy was 109.4 kJ/mol for subcritical water degradation of rhodamine B, whereas it became lower（93.4 kJ/mol） when Cu（Ⅱ） was added to the subcritical water. The frequency factors for the degradation of rhodamine B by subcritical water without and with Cu（Ⅱ） were calculated to be 1.0×10n and 3.2×109 min-1, respectively. The above results indicate that subcritical water treatment is a promising process for degrading and decolorizing textile dyes. The results will provide a theoretic support for the industrial application of subcritical water treatment.展开更多
Objectives:Subcritical water extraction technique is considered as an environmentally extraction technique.The aim of this study was to compare the different characteristics of water extract and subcritical water extr...Objectives:Subcritical water extraction technique is considered as an environmentally extraction technique.The aim of this study was to compare the different characteristics of water extract and subcritical water extract of Helicteres isora L.Materials and Methods:Water extraction was performed under the following conditions:25℃,24 h,and solid-to-water ratio 1:30.Subcritical water extract was carried out under specific conditions(pressure=10 bar,temperature=160℃,solid-to-water ratio=1:30,time=30 min).Chemical composition analysis was performed using GC-Mass chromatography.Anti-biofilm activity in the terms of anti-attach and removal of biofilm were assessed using the ELISA reader method and reading absorbance at 570 nm.Anti-microbial activity against Bacillus cereus,Staphylococcus aureus,Staphylococcus saprophyticus,and Bacillus subtilis was investigated by measurement of inhibitory zone diameter.Anti-enzymatic and antioxidant properties were also assessed.Results:The results of GC-Mass analysis showed some components extracted in subcritical method which were absent in water extract such as octadecanoic acid,hexadecanoic acid,and berberin.Antioxidant activity of the two tested extracts revealed that subcritical water extract had more antioxidant capacity than water extract(P≤0.05).The two tested extracts exhibited anti-enzymatic activity against polyphenol oxidase enzyme with better performance of subcritical water extract.Anti-biofilm activity of the two extracts implies that,in the case of preventing biofilm formation,both extracts had similar efficiency but in the removal of biofilm,subcritical water extract showed better performance.Both extracts had anti-microbial activity against B.cereus,S.aureus,S.saprophyticus,and B.subtilis with better performance of subcritical water extract.Anti-enzymatic assay also showed similar results.Conclusions:Subcritical water extract of H.isora showed more antioxidant activity as well as anti-biofilm,anti-bacterial,and anti-enzymatic activity rather than ordinary water extract.展开更多
The transfer enthalpies and entropies of hydroxyl and nitryl in different mobile phase systems were compared by van＇t Hoff curve. Results suggest that the presence of acetonitrile and methanol in the mobile phase may...The transfer enthalpies and entropies of hydroxyl and nitryl in different mobile phase systems were compared by van＇t Hoff curve. Results suggest that the presence of acetonitrile and methanol in the mobile phase may decrease the interaction of solute and stationary phase with respect to subcritical water, thereby reducing the contribution of enthalpy to the retention. Retention mechanisms of phenolic compound appear to be more similar in subcritical water and water/methanol systems on the PRP-1 column. Hydrogen bond in subcritical water system plays a very important role in the retention of the phenols.展开更多
In this study, high-pressure hydrothermal processing of different biomass sources and products, which include cellulose, xylan, lignin, pine wood, paper waste, and waste lignin was performed at 200-275 ℃ in presence ...In this study, high-pressure hydrothermal processing of different biomass sources and products, which include cellulose, xylan, lignin, pine wood, paper waste, and waste lignin was performed at 200-275 ℃ in presence of NiSO4 catalyst. Biomass slurry was prepared in distilled water containing NiSO4, loaded in a high-temperature high-pressure reactor and heated to different temperatures. The reaction was continued for 120 min and during the reaction gas samples were withdrawn and analyzed using Chrompack capillary column on the gas chromatograph equipped with thermal conductivity detector. The analysis of gas samples revealed the presence of H2, CO2, CO, and CH4 gases. Increase in catalyst concentration from 3 wt% to 10 wt% has significantly increased the H2 generation. Absence of catalyst, however, generated almost negligible amount of H2. Among the biomass sources and products investigated here, xylan has yielded maximum amount of H2. The liquid samples were analyzed by high-performance liquid chromatography （HPLC） and Fourier transform infrared （FTIR） spectroscopy which revealed the presence of sugars along with the other intermediates.展开更多
To explore the formation process and mechanism of organic matter and organic-mineral complex under humification and mineralization conditions, a series of samples including humic acid, kaolin, and humic acid-kaolin co...To explore the formation process and mechanism of organic matter and organic-mineral complex under humification and mineralization conditions, a series of samples including humic acid, kaolin, and humic acid-kaolin complex were prepared using a subcritical water treatment method（SWT） under specific temperature, pressure and reaction time conditions. HA was used as a surrogate for natural organic matter because it has a similar abundant pore structure,variety of carbon types, and chemical components. These samples were used in carbamazepine（CBZ） sorption experiments and characterized by a variety of techniques. The polymerization of humic acid under the conditions of increased temperature and pressure resulted in an increase in specific surface area and molecular quantity. In addition, the degree of aromaticity rose from59.52% to 70.90%. These changes were consistent with the transformation from ‘soft carbon＇ to‘hard carbon＇ that occurs in nature. The results of sorption experiments confirmed the interaction between humic acid and kaolin from the difference between the predicted and actual Qevalues. The conceptual model of humic acid-kaolin complex could be deduced and described as follows. Firstly, the aromatic components of humic acid preferentially combine with kaolin through the intercalation effect, which protects them from the treatment effects.Next, the free carboxyl groups and small aliphatic components of humic acid interact on the surface of kaolin, and these soft species transform into dense carbon through cyclization and polymerization. As a result, humic acid-kaolin complex with a mineral core and dense outer carbonaceous patches were formed.展开更多
Traditional disposal methods of biomass and plastic waste,such as landfill,combustion,and compost,no longer meet the requirements of carbon reduction,carbon neutrality,and sustain-able society due to low utilization e...Traditional disposal methods of biomass and plastic waste,such as landfill,combustion,and compost,no longer meet the requirements of carbon reduction,carbon neutrality,and sustain-able society due to low utilization efficiency and severe pollution.As a green,efficient and environmentally-friendly method,hydrothermal technology has been paid much attention to and has already been applied to recycle or reuse various plastic and biomass wastes.No matter for the single or mixed type of waste,it is expected to achieve efficient recycling and obtain value-added products through the hydrothermal process.This review summarized the basic knowledge of hydrothermal technology and the possible reaction mechanism of biomass and plastics un-der hydrothermal conditions and listed the previous reports on the application of hydrothermal technology for converting wastes of biomass,plastic,and biomass/plastic mixtures to solid fuels.Moreover,regarding the future of hydrothermal technology,four points related to reaction mech-anism,synergistic effect,catalysis,and scaled-up application,were provided for consideration.展开更多
基金supported by the National Natural Science Foundation of China(22078225)the Natural Science Foundation of Zhejiang Province(LGF22E080025 and LHY22E080005)。
文摘The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose through cleavage of the glycosidic bonds,the dissociation energies of which were supplied by the impact of a ball on pine sawdust,during milling.The destruction of glycosidic and hydrogen bonds in pine sawdust resulted in a decrease of crystallinity and an increase of water solubility.The sulfuric acid could promote the hydrolysis of holocellulose and its hydrolysis products.It also destroyed the chemical linkages between holocellulose and lignin during ball milling.The cleavage of chemical linkages with holocellulose made lignin more difficult to hydrolyze in subcritical water,and higher activation energy was needed to hydrolyze pretreated pine sawdust at higher reaction temperatures.It also led to the formation of glucose char and aromatic-linked polymer char from the hydrolysis products of holocellulose.
基金Supported by the National Natural Science Foundation of China （50578091） and Shanghai Leading Academic Discipline Project （T-105）.
文摘The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of reaction temperature from 180-320℃, pressure from 5-26 MPa, and time from 5-60 rain. The quality and quantity of amino acids in hydrolysate were determined by bioLiquid chromatography, and 17 kinds of amino acids were obtained. For the important 8 amino acids, the experiments were conducted to examine the effects of reaction temperature, pressure and time on amino acids yield. The optimum conditions for high yield are obtained from the experimental results. It is found that the nitrogen and carbon dioxide atmosphere should be used for leucine, isoleucine and histidine production while the air atmosphere might be used for other amino acids. The reaction time of 30 rain and the experimental temperature of 220℃, 240℃ and 260℃ were adopted for reaction kinetic research. The total yield of amino acids versus reaction time have been examined experimentally. According to these experimental data and under the condition of water excess, the macroscopic reaction kinetic equation of fish proteins hydrolysis was obtained with the hydrolysis reaction order of 1.615 and the rate constants being 0.0017, 0.0045 and 0.0097 at 220℃, 240℃ and 260℃ respectively. The activation energy is 145.1 kJ·mol^- 1.
文摘Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen peroxide to toluene is controlled within a reasonable range, the by-products may be neglected. The optimum technology of toluene oxidization to benzaldehyde is reaction time 60 min, reaction temperature 350℃, molar ratio of hydrogen peroxide to toluene 3.5. The yield of benzaldehyde can reach 17.2 % under the optimum condition. Research results of chemical reaction kinetics show that the consecutive reaction consists of two first-order reaction, and activation energy of these two reactions are 89 kJ·mol^-1 and 76 kJ·mol^-1 respectively,
基金The authors tend to appreciate for the partial financial support from Semnan University Science and Technology Park.
文摘For the first time,the solubility ofβ-carotene in pure and ethanol-modified subcritical water(SW)using the static method was determined.The experimental runs were performed at a temperature ranging from 298.15 to 403.15 K and 0–10%(w/w)of ethanol as a modifier at a constant pressure of 5 MPa.Samples were analyzed by UV–vis spectrophotometer.The solubility ofβ-carotene was found to range from 1.084×10^-8 to 227.1×10^-8 mol fractions in the subcritical water in above mentioned conditions.The obtainedβ-carotene solubility data were correlated using the linear model and modified Apelblat model.The obtained results showed the modified Apelblat model was better for estimating the solubility ofβ-carotene in SW.The values of the rootmean-square deviation(RMSD)between experimental and correlated data were calculated and used as the index of validity and accuracy for the model.Also,thermodynamic properties of the solution such as the Gibbs free energy of solution,enthalpy,and entropy of solution were estimated.
文摘A method for decomposition of cellulose to produce 5-hydroxymethyl-furaldehyde （5- HMF） in subcritical water-carbon dioxide binary system was proposed. A series of experiments were performed in a batch reaction vessel. Main products of the decomposition of cellulose are 5-HMF, furfural, levulinic acid and 1, 2, 4-benzenetrioI.The optimum condition for the preparation of 5-HMF was found as 523.15 K, 5.0% carbon dioxide mole fraction, and 30 min reaction time. The addition of carbon dioxide to water conduced to the decomposition of cellulose to 5-HMF. As can be seen from the distribution of the prod-ucts, the decomposition mechanism of cellulose is similar to the hydrothermal reaction of D-glucose and D-fructose.
文摘Here, the employment of subcritical water as an environmentally benign media has shown a certain potential for the hydrolysis ofiminodiaeetonitrile （IDAN）. Additives （such as NH3.H2O, （NH4）2CO3, K2CO3） were selected to investigate the reactivity ofiminodiacetonitrile in the solutions of these species in the subcritical region for the possibility of preparing iminodiacetic acid （IDA） salts. A series of reactions were performed in a high temperature and pressure batch reactor with temperature ranging from 200 to 260 ℃, time ranging from 4 to 10 min, pressure ranging from 5 to 25 MPa and varying concentration of additives to consider the influence of these parameters on the yield of IDA salts. Reactivity of IDAN was not illustrated with the conversion but with respect to the yield of resultant IDA salts. The results demonstrate that hydrolysis reactivity of IDAN under the examined conditions has shown a remarkable sensitivity to the pH of the system at initial point of the reaction stage, and temperature effect is also obvious. Based on the results, possible reaction pathway and mechanism were proposed.
基金supported by the project of National Natural Science Foundation of China (21206182)Qingdao Agricultural University High-Level Personnel Starting Fund (631203)Qingdao Science and Technology Achievements Transformation Boot Program (Applied Basic Research, 13-1-4-233-jch)
文摘In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.
基金Supported by the Natural Science Foundation of Zhejiang Province, China（No.LQ17B060006）, the Science and Technology Planning Project of Zhejiang Province, China（No.2013C31016） and the National Natural Science Foundation of China （No.21406044）.
文摘In this paper, subcritical water, an environmentally friendly solvent, was employed to degrade rhodamine B, which served as a model dye in textile industrial effluents. The effect of Cu（Ⅱ） on the degradation of rhodamine B was evaluated. Further, the degradation kinetics of rhodamine B in subcritical water was evaluated via a Weibull model. The results show that subcritical water could efficiently degrade and decolorize rhodamine B. The addition of Cu（Ⅱ） into subcritical water could accelerate the degradation of rhodamine B and lower the temperature for its com- plete degradation. The Weibull equation could well express the degradation kinetics of rhodamine B. The calculated rate constants showed Arrhenius behavior and presented high correlation coefficients. The activation energy was 109.4 kJ/mol for subcritical water degradation of rhodamine B, whereas it became lower（93.4 kJ/mol） when Cu（Ⅱ） was added to the subcritical water. The frequency factors for the degradation of rhodamine B by subcritical water without and with Cu（Ⅱ） were calculated to be 1.0×10n and 3.2×109 min-1, respectively. The above results indicate that subcritical water treatment is a promising process for degrading and decolorizing textile dyes. The results will provide a theoretic support for the industrial application of subcritical water treatment.
文摘Objectives:Subcritical water extraction technique is considered as an environmentally extraction technique.The aim of this study was to compare the different characteristics of water extract and subcritical water extract of Helicteres isora L.Materials and Methods:Water extraction was performed under the following conditions:25℃,24 h,and solid-to-water ratio 1:30.Subcritical water extract was carried out under specific conditions(pressure=10 bar,temperature=160℃,solid-to-water ratio=1:30,time=30 min).Chemical composition analysis was performed using GC-Mass chromatography.Anti-biofilm activity in the terms of anti-attach and removal of biofilm were assessed using the ELISA reader method and reading absorbance at 570 nm.Anti-microbial activity against Bacillus cereus,Staphylococcus aureus,Staphylococcus saprophyticus,and Bacillus subtilis was investigated by measurement of inhibitory zone diameter.Anti-enzymatic and antioxidant properties were also assessed.Results:The results of GC-Mass analysis showed some components extracted in subcritical method which were absent in water extract such as octadecanoic acid,hexadecanoic acid,and berberin.Antioxidant activity of the two tested extracts revealed that subcritical water extract had more antioxidant capacity than water extract(P≤0.05).The two tested extracts exhibited anti-enzymatic activity against polyphenol oxidase enzyme with better performance of subcritical water extract.Anti-biofilm activity of the two extracts implies that,in the case of preventing biofilm formation,both extracts had similar efficiency but in the removal of biofilm,subcritical water extract showed better performance.Both extracts had anti-microbial activity against B.cereus,S.aureus,S.saprophyticus,and B.subtilis with better performance of subcritical water extract.Anti-enzymatic assay also showed similar results.Conclusions:Subcritical water extract of H.isora showed more antioxidant activity as well as anti-biofilm,anti-bacterial,and anti-enzymatic activity rather than ordinary water extract.
文摘The transfer enthalpies and entropies of hydroxyl and nitryl in different mobile phase systems were compared by van＇t Hoff curve. Results suggest that the presence of acetonitrile and methanol in the mobile phase may decrease the interaction of solute and stationary phase with respect to subcritical water, thereby reducing the contribution of enthalpy to the retention. Retention mechanisms of phenolic compound appear to be more similar in subcritical water and water/methanol systems on the PRP-1 column. Hydrogen bond in subcritical water system plays a very important role in the retention of the phenols.
文摘In this study, high-pressure hydrothermal processing of different biomass sources and products, which include cellulose, xylan, lignin, pine wood, paper waste, and waste lignin was performed at 200-275 ℃ in presence of NiSO4 catalyst. Biomass slurry was prepared in distilled water containing NiSO4, loaded in a high-temperature high-pressure reactor and heated to different temperatures. The reaction was continued for 120 min and during the reaction gas samples were withdrawn and analyzed using Chrompack capillary column on the gas chromatograph equipped with thermal conductivity detector. The analysis of gas samples revealed the presence of H2, CO2, CO, and CH4 gases. Increase in catalyst concentration from 3 wt% to 10 wt% has significantly increased the H2 generation. Absence of catalyst, however, generated almost negligible amount of H2. Among the biomass sources and products investigated here, xylan has yielded maximum amount of H2. The liquid samples were analyzed by high-performance liquid chromatography （HPLC） and Fourier transform infrared （FTIR） spectroscopy which revealed the presence of sugars along with the other intermediates.
基金supported by the Fundamental Research Funds for the Outstanding Teachers in the Central Universities(No.35832015023)
文摘To explore the formation process and mechanism of organic matter and organic-mineral complex under humification and mineralization conditions, a series of samples including humic acid, kaolin, and humic acid-kaolin complex were prepared using a subcritical water treatment method（SWT） under specific temperature, pressure and reaction time conditions. HA was used as a surrogate for natural organic matter because it has a similar abundant pore structure,variety of carbon types, and chemical components. These samples were used in carbamazepine（CBZ） sorption experiments and characterized by a variety of techniques. The polymerization of humic acid under the conditions of increased temperature and pressure resulted in an increase in specific surface area and molecular quantity. In addition, the degree of aromaticity rose from59.52% to 70.90%. These changes were consistent with the transformation from ‘soft carbon＇ to‘hard carbon＇ that occurs in nature. The results of sorption experiments confirmed the interaction between humic acid and kaolin from the difference between the predicted and actual Qevalues. The conceptual model of humic acid-kaolin complex could be deduced and described as follows. Firstly, the aromatic components of humic acid preferentially combine with kaolin through the intercalation effect, which protects them from the treatment effects.Next, the free carboxyl groups and small aliphatic components of humic acid interact on the surface of kaolin, and these soft species transform into dense carbon through cyclization and polymerization. As a result, humic acid-kaolin complex with a mineral core and dense outer carbonaceous patches were formed.
文摘Traditional disposal methods of biomass and plastic waste,such as landfill,combustion,and compost,no longer meet the requirements of carbon reduction,carbon neutrality,and sustain-able society due to low utilization efficiency and severe pollution.As a green,efficient and environmentally-friendly method,hydrothermal technology has been paid much attention to and has already been applied to recycle or reuse various plastic and biomass wastes.No matter for the single or mixed type of waste,it is expected to achieve efficient recycling and obtain value-added products through the hydrothermal process.This review summarized the basic knowledge of hydrothermal technology and the possible reaction mechanism of biomass and plastics un-der hydrothermal conditions and listed the previous reports on the application of hydrothermal technology for converting wastes of biomass,plastic,and biomass/plastic mixtures to solid fuels.Moreover,regarding the future of hydrothermal technology,four points related to reaction mech-anism,synergistic effect,catalysis,and scaled-up application,were provided for consideration.
