High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave a...High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.展开更多
The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural cha...The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.展开更多
Pretreatment is one of the most important steps in the production bioethanol from lignocellulose materials. Alkaline pretreatment is a common mean of pretreatment but microwave oven could assist its efficiency as it c...Pretreatment is one of the most important steps in the production bioethanol from lignocellulose materials. Alkaline pretreatment is a common mean of pretreatment but microwave oven could assist its efficiency as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. The aim of this paper is to determine lignin removal from banana trunk using microwave-assisted alkaline （NaOH and NH4OH） pretreatments. The best pretreatment conditions were used for mass pretreatment before hydrolysis and fermentation. The result shows that, optimum lignin removal was with microwave-assisted NaOH pretreatment with the removal of up to 98% lignin at 2% （w/v （weight/volum）） sodium hydroxide, 170 W microwave power at 10 rain. Microwave-assisted ammonium hydroxide pretreatment achieved 97% lignin removal at 1% ammonium hydroxide concentration and 680 W microwave power at 5 min. Microwave- alkaline assisted pretreatment increased the yield and quality of fermentable sugar after enzyme hydrolysis with NH4OH and ammonium hydroxide yielding 40% and 39% of ethanol, respectively. This result reveals that, well controlled microwave- alkaline assisted pretreatment of banana trunk could effectively remove lignin and give high bioethanol yield.展开更多
Sugarcane bagasse(SCB)is an important by-product in the sugar industry.It is a source of cellulose fibers or cellulose for paper mills and textiles factories.In this study,SCB was ethyl etherified in tetrahydrofuran(T...Sugarcane bagasse(SCB)is an important by-product in the sugar industry.It is a source of cellulose fibers or cellulose for paper mills and textiles factories.In this study,SCB was ethyl etherified in tetrahydrofuran(THF)after alkali pretreatment.The alkali concentration for the pretreatment,the ratio of ethyl bromide(EtBr)to dried SCB in the reaction,reaction time,and temperature were investigated for the etherification of SCB.The ethoxyl content and characterization of the product were determined using headspace gas chromatography(HS-GC),Fourier Transform Infrared(FT-IR)and 13C-NMR spectroscopy,respectively.It was found that SCB was well-etherified with EtBr in alkali-THF.Upon ethylation of SCB,the ethoxyl content of the product was high when the alkali concentration and the ratio of EtBr to dried SCB were controlled from 50%to 75%and 4:1(V/w)to 6:1(V/w),respectively.The reaction occurred optimally when the temperature was controlled below 110℃;above this temperature,the degree of etherification decreased.The thermal stability of ethylated SCB was higher than that of SCB but slightly lower than that of commercial ethyl cellulose.Ethylated SCB has the potential to form composites with many materials because it is soluble in a wide variety of solvents.展开更多
The complexity of plant cell walls impedes the conversion of cellulosic biomass to sugars. Pretreatment becomes a necessity to increase the digestibility of biomass. An in-depth understanding of the structure and unde...The complexity of plant cell walls impedes the conversion of cellulosic biomass to sugars. Pretreatment becomes a necessity to increase the digestibility of biomass. An in-depth understanding of the structure and underlying mechanisms governing deconstruction process is important. In the present study, the comprehensive investigation of morphological and structural changes in corn stover and sugarcane bagasse following ionic liquids dissolution and alkaline extraction was done using Fourier transform infrared spectroscopy, Thermogravimetric analysis, Confocal scanning laser microscopy, Atomic force microscopy and Dynamic light scattering studies. Both the substrates were pretreated with ILs 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate followed by alkaline extraction. The pronounced changes such as lignin, hemicelluloses removal and decreased cellulose crystallinity after the pretreatments lead to the structural transformation of matrix polymers. The enzymatic hydrolysis showed 90% theoretical sugar yield in case of sugarcane bagasse and 80% in corn stover following synergistically combined pretreatments.展开更多
Ferulic acid(FA)and p-coumaric acid(pCA)in bagasse,wheat straw,corn straw,and corncob were extracted by alkaline hydrolysis and characterized by gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS).It...Ferulic acid(FA)and p-coumaric acid(pCA)in bagasse,wheat straw,corn straw,and corncob were extracted by alkaline hydrolysis and characterized by gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS).It was found that the FA and most of the pCA in gramineous biomass could be dissociated and released after being treated with 1 M NaOH at 100℃for 4 h.The yields of pCA/FA in bagasse,wheat straw,corn straw,and corncob determined by GC-FID are 39.8/11.5,13.7/11.0,28.0/11.0,and 35.1/14.5 mg/g,respectively.The raw materials and the treated solid residues were characterized by gel-state 2D Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance(2D HSQC NMR).It was found that only a small amount of lignin was detected in the residue after alkali treatment,indicating that the alkali treatment conditions can effectively cleave the FA and pCA.Additionally,the lignin in the alkali solution was recovered and characterized by 2D HSQC NMR.The FA was not able to be detected by NMR,whereas a small amount of pCA remained in the alkali lignin.This study reveals the structural change of residual lignins during the quantitative isolation of FA and pCA,which is essential for the selective isolation of pCA/FA and valorization of residual alkali lignin.展开更多
Due to the presence of various types of hydrogen-producing bacteria and numerous organics such as protein and carbohydrate,sewage sludge is a potential material for biological hydrogen production.In this study,two bat...Due to the presence of various types of hydrogen-producing bacteria and numerous organics such as protein and carbohydrate,sewage sludge is a potential material for biological hydrogen production.In this study,two batch tests were carried out to investigate the impact of alkali and heat pretreatment on the pathway of hydrogen production from sewage sludge.The results showed that the heat treatment had a stronger lethal effect on bacteria than the alkali treatment,and could effectively kill hydrogen-consuming bacteria.The heat treatment was more suitable for enriching acidophilic hydrogen-producing bacteria,while the alkali treatment was more suitable for enriching basophilic hydrogen-producing bacteria.A maximum hydrogen production of 10.32 mL/g-COD from alkali pretreated sludge was obtained at an initial pH of 11;while a maximum hydrogen production of 8.94 mL/g-COD from heat pretreated sludge was obtained at an initial pH of 5.Hydrogen production in alkali conditions (pH>9) from alkali pretreated sludge mainly depended on the fermentation of protein by protein-utilizing bacteria;whereas hydrogen production in acidic conditions (pH<6) from heat pretreated sludge mainly depended on the fermentation of carbohydrate by glucose-utilizing bacteria.展开更多
Selective laser melting of nickel-titanium alloy(SLM-NiTi)can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect...Selective laser melting of nickel-titanium alloy(SLM-NiTi)can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect.However,the biological inertness and poor corrosion resistance of SLM-NiTi alloy limit their wide application as biomedical implant materials.In this study,polycaprolactone(PCL)coating was prepared on SLM-NiTi alloy by dipping and pulling method,and the effects of alkali heat pretreatment on the morphology,adhesion,corrosion resistance,long-term stability and biomineralisation of the PCL coatings were investigated.The results showed that PCL coating can substan-tially improve the performance of SLM-NiTi alloy,and the PCL coating after alkali heat pretreatment has higher adhesion(increased from 1,747 to 2,498 mN)and lower corrosion current density(reduced by about an order of magnitude compared to PCL coating alone).In addition,the necessary stability,biomineralisation and biocompatibility ability of coatings were also further improved.Therefore,the alkali heat pretreated PCL-coated SLM-NiTi alloy has good application prospects in implants due to its superior properties.展开更多
基金the National Key Basic Research Program of China (No. 2014CB238905)
文摘High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.
基金financial support from the Fundamental Research Funds for the Central Universities(No.JC2013-3,BLYJ201616)Beijing Higher Education Young Elite Teacher Project(No.YETP0763)
文摘The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.
文摘Pretreatment is one of the most important steps in the production bioethanol from lignocellulose materials. Alkaline pretreatment is a common mean of pretreatment but microwave oven could assist its efficiency as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. The aim of this paper is to determine lignin removal from banana trunk using microwave-assisted alkaline （NaOH and NH4OH） pretreatments. The best pretreatment conditions were used for mass pretreatment before hydrolysis and fermentation. The result shows that, optimum lignin removal was with microwave-assisted NaOH pretreatment with the removal of up to 98% lignin at 2% （w/v （weight/volum）） sodium hydroxide, 170 W microwave power at 10 rain. Microwave-assisted ammonium hydroxide pretreatment achieved 97% lignin removal at 1% ammonium hydroxide concentration and 680 W microwave power at 5 min. Microwave- alkaline assisted pretreatment increased the yield and quality of fermentable sugar after enzyme hydrolysis with NH4OH and ammonium hydroxide yielding 40% and 39% of ethanol, respectively. This result reveals that, well controlled microwave- alkaline assisted pretreatment of banana trunk could effectively remove lignin and give high bioethanol yield.
基金The authors are grateful for the financial support from the Science and Technology Program of Guangdong(2019A1515011890)National Key R&D Program of China(2017YFD0601003).
文摘Sugarcane bagasse(SCB)is an important by-product in the sugar industry.It is a source of cellulose fibers or cellulose for paper mills and textiles factories.In this study,SCB was ethyl etherified in tetrahydrofuran(THF)after alkali pretreatment.The alkali concentration for the pretreatment,the ratio of ethyl bromide(EtBr)to dried SCB in the reaction,reaction time,and temperature were investigated for the etherification of SCB.The ethoxyl content and characterization of the product were determined using headspace gas chromatography(HS-GC),Fourier Transform Infrared(FT-IR)and 13C-NMR spectroscopy,respectively.It was found that SCB was well-etherified with EtBr in alkali-THF.Upon ethylation of SCB,the ethoxyl content of the product was high when the alkali concentration and the ratio of EtBr to dried SCB were controlled from 50%to 75%and 4:1(V/w)to 6:1(V/w),respectively.The reaction occurred optimally when the temperature was controlled below 110℃;above this temperature,the degree of etherification decreased.The thermal stability of ethylated SCB was higher than that of SCB but slightly lower than that of commercial ethyl cellulose.Ethylated SCB has the potential to form composites with many materials because it is soluble in a wide variety of solvents.
文摘The complexity of plant cell walls impedes the conversion of cellulosic biomass to sugars. Pretreatment becomes a necessity to increase the digestibility of biomass. An in-depth understanding of the structure and underlying mechanisms governing deconstruction process is important. In the present study, the comprehensive investigation of morphological and structural changes in corn stover and sugarcane bagasse following ionic liquids dissolution and alkaline extraction was done using Fourier transform infrared spectroscopy, Thermogravimetric analysis, Confocal scanning laser microscopy, Atomic force microscopy and Dynamic light scattering studies. Both the substrates were pretreated with ILs 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate followed by alkaline extraction. The pronounced changes such as lignin, hemicelluloses removal and decreased cellulose crystallinity after the pretreatments lead to the structural transformation of matrix polymers. The enzymatic hydrolysis showed 90% theoretical sugar yield in case of sugarcane bagasse and 80% in corn stover following synergistically combined pretreatments.
基金grateful for the financial support for this work from the National Natural Science Foundation of China(31870560,22108088)the State Key Laboratory of Pulp and Paper Engineering(South China University of Technology),No.202105.
文摘Ferulic acid(FA)and p-coumaric acid(pCA)in bagasse,wheat straw,corn straw,and corncob were extracted by alkaline hydrolysis and characterized by gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS).It was found that the FA and most of the pCA in gramineous biomass could be dissociated and released after being treated with 1 M NaOH at 100℃for 4 h.The yields of pCA/FA in bagasse,wheat straw,corn straw,and corncob determined by GC-FID are 39.8/11.5,13.7/11.0,28.0/11.0,and 35.1/14.5 mg/g,respectively.The raw materials and the treated solid residues were characterized by gel-state 2D Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance(2D HSQC NMR).It was found that only a small amount of lignin was detected in the residue after alkali treatment,indicating that the alkali treatment conditions can effectively cleave the FA and pCA.Additionally,the lignin in the alkali solution was recovered and characterized by 2D HSQC NMR.The FA was not able to be detected by NMR,whereas a small amount of pCA remained in the alkali lignin.This study reveals the structural change of residual lignins during the quantitative isolation of FA and pCA,which is essential for the selective isolation of pCA/FA and valorization of residual alkali lignin.
基金supported by the National Natural Science Foundation of China (Grant No.50621804)
文摘Due to the presence of various types of hydrogen-producing bacteria and numerous organics such as protein and carbohydrate,sewage sludge is a potential material for biological hydrogen production.In this study,two batch tests were carried out to investigate the impact of alkali and heat pretreatment on the pathway of hydrogen production from sewage sludge.The results showed that the heat treatment had a stronger lethal effect on bacteria than the alkali treatment,and could effectively kill hydrogen-consuming bacteria.The heat treatment was more suitable for enriching acidophilic hydrogen-producing bacteria,while the alkali treatment was more suitable for enriching basophilic hydrogen-producing bacteria.A maximum hydrogen production of 10.32 mL/g-COD from alkali pretreated sludge was obtained at an initial pH of 11;while a maximum hydrogen production of 8.94 mL/g-COD from heat pretreated sludge was obtained at an initial pH of 5.Hydrogen production in alkali conditions (pH>9) from alkali pretreated sludge mainly depended on the fermentation of protein by protein-utilizing bacteria;whereas hydrogen production in acidic conditions (pH<6) from heat pretreated sludge mainly depended on the fermentation of carbohydrate by glucose-utilizing bacteria.
基金The Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2021QE263The Open Project Program of Key Laboratory for Cross‐Scale Micro and Nano Manufacturing,Minstry of Education,Changchun University of Science and Technology,Grant/Award Number:CMNM‐KF202109+5 种基金The Ascl‐zytsxm,Grant/Award Number:202013The Interdisciplinary Research Fund for Doctoral Postgraduates of Jilin University,Grant/Award Number:101832020DJX052National Natural Science Foundation of China,Grant/Award Number:51975246The Program for JLU Science and Technology Innovative Research Team,Grant/Award Number:2019TD‐34Science and Technology Development Program of Jilin Province,Grant/Award Number:YDZJ202101ZYTS134The Interdisciplinary Cultivation Project for Young Teachers and Students,Grant/Award Number:415010300078。
文摘Selective laser melting of nickel-titanium alloy(SLM-NiTi)can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect.However,the biological inertness and poor corrosion resistance of SLM-NiTi alloy limit their wide application as biomedical implant materials.In this study,polycaprolactone(PCL)coating was prepared on SLM-NiTi alloy by dipping and pulling method,and the effects of alkali heat pretreatment on the morphology,adhesion,corrosion resistance,long-term stability and biomineralisation of the PCL coatings were investigated.The results showed that PCL coating can substan-tially improve the performance of SLM-NiTi alloy,and the PCL coating after alkali heat pretreatment has higher adhesion(increased from 1,747 to 2,498 mN)and lower corrosion current density(reduced by about an order of magnitude compared to PCL coating alone).In addition,the necessary stability,biomineralisation and biocompatibility ability of coatings were also further improved.Therefore,the alkali heat pretreated PCL-coated SLM-NiTi alloy has good application prospects in implants due to its superior properties.
