Lignin is a natural polymer,second only to cellulose in natural reserves.Degradation is one of the ways to achieve the high-value transformation of lignin.Deep eutectic solvent(DES)thermal degradation of lignin can be...Lignin is a natural polymer,second only to cellulose in natural reserves.Degradation is one of the ways to achieve the high-value transformation of lignin.Deep eutectic solvent(DES)thermal degradation of lignin can be used as an excellent green degradation method.This paper introduces the degradation mechanism and effect of the lactic acid-choline chloride DES system in dissolving and degrading alkaline lignin,and the final solvent recovery.It can also be found from the scanning electron microscope(SEM)images that the surface of the degraded solid product is transformed from smooth to disordered.Fourier transform infrared(FTIR)spectroscopy and 1H-NMR spectroscopy were used to characterize the changes in lignin functional groups during DES treatment.The results showed that the content of phenolic hydroxyl groups increased after degradation,indicating that theβ-O-4 ether bond was broken.The molecular weight of the degraded lignin was observed by gel permeation chromatography(GPC),and the lignin residue with low molecular weight and narrow polydispersity index was obtained.The lowest average molecular weight(Mw)reached 2512 g/mol.The ratio of oxygen to carbon atoms in lignin increased substantially during degradation as measured by X-ray photoelectron spectroscopy(XPS),probably because DES treatment was accompanied by many oxidation reactions,which led to significant structural changes in lignin and a large number of ether bond breakage reactions during the reaction.The main final degradation products are aromatic monomers,vanillin,butyrovanillone,etc.展开更多
The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidati...The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.展开更多
As a natural aromatic polymer,lignin has great potential but limited industrial application due to its complex chemical structure.Among strategies for lignin conversion,biodegradation has attracted promising interest ...As a natural aromatic polymer,lignin has great potential but limited industrial application due to its complex chemical structure.Among strategies for lignin conversion,biodegradation has attracted promising interest recently in term of efficiency,selectivity and mild condition.In order to overcome the issues of poor stability and non-reusability of enzyme in the biodegradation of lignin,this work explored a protocol of immobilized laccase on magnetic nanoparticles(MNPs)with rough surfaces for enhanced lignin model compounds degradation.Scanning electron microscope with energy dispersive spectrometer(SEM-EDS),flourier transformation infrared spectroscopy(FTIR)and thermal gravimetric analysis(TGA)were utilized to characterize the immobilization of laccase.The results showed a maximum activity recovery of 64.7%towards laccase when it was incubated with MNPs and glutaraldehyde(GA)with concentrations of 6 mg·ml^-1and 7.5 mg·ml^-1for 5 h,respectively.The immobilized laccase showed improved thermal stability and pH tolerance compared with free laccase,and remained more than 80%of its initial activity after 20 days of storage at 4℃.In addition,about 40%residual activity of the laccase remained after 8 times cycles.Gas chromatography–mass spectrometry(GC–MS)was utilized to characterize the products of lignin model compound degradation and activation,and the efficiency of immobilized laccase was calculated to be 1–5 times that of free laccase.It was proposed that the synergistic effect between MNPs and laccase displays an important role in the enhancement of stability and activity in lignin model compound biodegradation.展开更多
A hydrocarbon degrading bacterium KL2-13 was isolated from ten sites of oil contaminated soil in the Karamay oilfield. It was identified as the Bacillus fusiformis sp. bacterium based on its morphological and physiolo...A hydrocarbon degrading bacterium KL2-13 was isolated from ten sites of oil contaminated soil in the Karamay oilfield. It was identified as the Bacillus fusiformis sp. bacterium based on its morphological and physiological characteristics and the 16S rDNA sequence analysis. The factors influencing the hydrocarbon degradation by the bacterium KL2-13 were determined. The test results have showed that the hydrocarbon degrading bacterium KL2-13 requires an optimum pH range of 6-8, and the optimum inoculation quantity is 3%. The low-concentration metal ions Fe2+, Mg2+ and Ca2+ can improve the degradation ability of the bacteria KL2-13.Atoo low concentration of Tween-80 does not show obvious promotion to the de- grading bacterium KL2-13, and an excessively high concentration can decrease the degradation ability of the bacterium, the best dosage of which is 2%. The hydrocarbon degrading rate reached 59.07%±0.37% under the optimum culture conditions.展开更多
The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is si...The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77%under a relatively mild liquefaction condition of 10 wt% H2SO4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120?C for40 min. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C–C bonds, which gives an extra 29% of Caryl–Cα bond cleavage, and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions.The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.展开更多
One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·...One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·L -1 ) with two controls (normal saline,LB medium) was inoculated with the bacterium BR5-1 to see whether there was an increasement of the alive bacteria concentration after 48 h of the growth.The results showed that there was a significant rising of the alive bacteria concentration in the agar suspension (6.5×10 3 and 6.0×10 3 cfu·mL -1 ) compared to that in the normal saline control (6.1×10 2 cfu·mL -1 ),and it was far lower than that in LB (Luria-Bertani) control (1.1×10 8 cfu·mL -1 ).In conclusion,the bacterium strain BR5-1 could degrade agar.展开更多
Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and dif...Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and difficult biodegradation mainly limit its utilization.This work focused on the effect of hydroxylation of lignin on its microbial degradation.Butyloxy carbonyl-modified lignin,and hydroxylated-lignin were synthesized with di-tert-butyl dicarbonate and hydrogen peroxide,respectively,using lignin as raw material.The degradation of the modifiedlignins both by P.chrysosporium and B.subtilis were analyzed using UV-vis spectroscopy.Results revealed that the lignin degradation velocity raises with the increase hydroxylation level of lignin.Moreover,FTIR and 1H NMR analysis of the biodegradation products of lignin further indicated that higher content of hydroxyl groups in lignin facilitated the demethylation combined with the aromatic ring cracking in the presence of fungus and bacteria.展开更多
A bi-component alcoholysis agent containing propylene glycol(PG)and ethanolamine(ETA)was used to catalyst the degradation of the waste polyurethane rigid foam.The oligomer polyols obtained through degradation were use...A bi-component alcoholysis agent containing propylene glycol(PG)and ethanolamine(ETA)was used to catalyst the degradation of the waste polyurethane rigid foam.The oligomer polyols obtained through degradation were used as raw materials to produce recycled polyurethane rigid foam composites with lignin as reinforcing filler.The effect of alcoholysis mass ratio on degradation was investigated by analyzing the viscosity,hydroxyl content and chemical structure of the degradation products.The effect of lignin addition on the properties of regenerated polyurethane rigid foam were investigated by analyzing water absorption rate,compressive strength,porosity,thermal stability,thermal conductivity coefficient,morphology and thermal stability of the recycled polyurethane rigid foam.Results show that different mass ration of PG to ETA significantly affects the degradation of waste polyurethane rigid foam.Besides,only with the addition of appropriate amount of lignin,the regenerated polyurethane rigid foam composites can meet the Chinese national standard“rigid polyurethane foam for building thermal insulation”(GB/T21558-2008).At this point,the composite is with good mechanical and thermal prperties,including high compressive strength,excellent thermal insulation performance,complete cell morphology and good thermal stability.展开更多
Chemical modification of lignin was carried out by reacted it with HI acid, then the modified lignin treated with calcium hydroxide to prepare calcium-lignin chelating complex, this derivative was examined as thermal ...Chemical modification of lignin was carried out by reacted it with HI acid, then the modified lignin treated with calcium hydroxide to prepare calcium-lignin chelating complex, this derivative was examined as thermal stabilizer for PVC, thermal degradation of PVC neat as blank and containing three weight percents (1, 2, and 4) into polymer was accelerated by heat treatment at 190°C for 2 hr. then PVC films were casting from THF solvent with thickness 0.03 mm. Thermal stabilization activity of this derivative was investigated by using infrared spectroscopy, according to the results obtained calcium-lignin complex have suitable activity to increased PVC stability at low concentration depending on it’s ability to reaction with HCl as well as the chemical structure of lignin that contain phenolic properties.展开更多
After incubation for 6- 30 h,with the rapid increase of bacterial cell number,surface tension of bacterium BS-8 was reduced sharply from 63. 2 m N / m to 39. 4 m N / m. The production of biosurfactants by BS-8 was gro...After incubation for 6- 30 h,with the rapid increase of bacterial cell number,surface tension of bacterium BS-8 was reduced sharply from 63. 2 m N / m to 39. 4 m N / m. The production of biosurfactants by BS-8 was growth-dependent. Using glucose as the carbon source,bacterium BS-8 was incubated. Based on centrifugation,precipitation and chromogenic reaction of the culture solution,results indicated that the biosurfactants belonged to lipopeptides. The yield of biosurfactants isolated and purified from the culture solution was 0. 58 g / L,and the critical micelle concentration( CMC) was 90 mg / L. Under conditions of p H 4- 9,temperature 20- 70 ℃,Na Cl concentration 1%- 6%,biosurfactants produced by BS-8 exhibited the highest stability.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(31730106).
文摘Lignin is a natural polymer,second only to cellulose in natural reserves.Degradation is one of the ways to achieve the high-value transformation of lignin.Deep eutectic solvent(DES)thermal degradation of lignin can be used as an excellent green degradation method.This paper introduces the degradation mechanism and effect of the lactic acid-choline chloride DES system in dissolving and degrading alkaline lignin,and the final solvent recovery.It can also be found from the scanning electron microscope(SEM)images that the surface of the degraded solid product is transformed from smooth to disordered.Fourier transform infrared(FTIR)spectroscopy and 1H-NMR spectroscopy were used to characterize the changes in lignin functional groups during DES treatment.The results showed that the content of phenolic hydroxyl groups increased after degradation,indicating that theβ-O-4 ether bond was broken.The molecular weight of the degraded lignin was observed by gel permeation chromatography(GPC),and the lignin residue with low molecular weight and narrow polydispersity index was obtained.The lowest average molecular weight(Mw)reached 2512 g/mol.The ratio of oxygen to carbon atoms in lignin increased substantially during degradation as measured by X-ray photoelectron spectroscopy(XPS),probably because DES treatment was accompanied by many oxidation reactions,which led to significant structural changes in lignin and a large number of ether bond breakage reactions during the reaction.The main final degradation products are aromatic monomers,vanillin,butyrovanillone,etc.
基金Supported by the National Natural Science Foundation of China（20876064） the Natural Science Foundation of Guangdong Province（9151064101000082） the Guangdong Provincial International Cooperation Fund（2008B05010006）
文摘The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.
基金supported by the Startup Foundation of Beijing Institute of Technology,China(3160011181808)。
文摘As a natural aromatic polymer,lignin has great potential but limited industrial application due to its complex chemical structure.Among strategies for lignin conversion,biodegradation has attracted promising interest recently in term of efficiency,selectivity and mild condition.In order to overcome the issues of poor stability and non-reusability of enzyme in the biodegradation of lignin,this work explored a protocol of immobilized laccase on magnetic nanoparticles(MNPs)with rough surfaces for enhanced lignin model compounds degradation.Scanning electron microscope with energy dispersive spectrometer(SEM-EDS),flourier transformation infrared spectroscopy(FTIR)and thermal gravimetric analysis(TGA)were utilized to characterize the immobilization of laccase.The results showed a maximum activity recovery of 64.7%towards laccase when it was incubated with MNPs and glutaraldehyde(GA)with concentrations of 6 mg·ml^-1and 7.5 mg·ml^-1for 5 h,respectively.The immobilized laccase showed improved thermal stability and pH tolerance compared with free laccase,and remained more than 80%of its initial activity after 20 days of storage at 4℃.In addition,about 40%residual activity of the laccase remained after 8 times cycles.Gas chromatography–mass spectrometry(GC–MS)was utilized to characterize the products of lignin model compound degradation and activation,and the efficiency of immobilized laccase was calculated to be 1–5 times that of free laccase.It was proposed that the synergistic effect between MNPs and laccase displays an important role in the enhancement of stability and activity in lignin model compound biodegradation.
基金supports provided by the Science Research and Technology Developing Program, CNPC (2008D-4704-2): "Microbial remediation technology of high-temperature and arid oil polluted soil"
文摘A hydrocarbon degrading bacterium KL2-13 was isolated from ten sites of oil contaminated soil in the Karamay oilfield. It was identified as the Bacillus fusiformis sp. bacterium based on its morphological and physiological characteristics and the 16S rDNA sequence analysis. The factors influencing the hydrocarbon degradation by the bacterium KL2-13 were determined. The test results have showed that the hydrocarbon degrading bacterium KL2-13 requires an optimum pH range of 6-8, and the optimum inoculation quantity is 3%. The low-concentration metal ions Fe2+, Mg2+ and Ca2+ can improve the degradation ability of the bacteria KL2-13.Atoo low concentration of Tween-80 does not show obvious promotion to the de- grading bacterium KL2-13, and an excessively high concentration can decrease the degradation ability of the bacterium, the best dosage of which is 2%. The hydrocarbon degrading rate reached 59.07%±0.37% under the optimum culture conditions.
基金supported by the National Basic Research Program of China(2012CB215302)Guangdong Provincial Natural Science Fund(9151064101000082)
文摘The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77%under a relatively mild liquefaction condition of 10 wt% H2SO4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120?C for40 min. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C–C bonds, which gives an extra 29% of Caryl–Cα bond cleavage, and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions.The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.
基金Supported by National High-tech Research and Development Program of China (863 Program) (20060110Z4023)
文摘One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·L -1 ) with two controls (normal saline,LB medium) was inoculated with the bacterium BR5-1 to see whether there was an increasement of the alive bacteria concentration after 48 h of the growth.The results showed that there was a significant rising of the alive bacteria concentration in the agar suspension (6.5×10 3 and 6.0×10 3 cfu·mL -1 ) compared to that in the normal saline control (6.1×10 2 cfu·mL -1 ),and it was far lower than that in LB (Luria-Bertani) control (1.1×10 8 cfu·mL -1 ).In conclusion,the bacterium strain BR5-1 could degrade agar.
基金This work was financially supported by the Science and Technology Innovation Program of Hunan Province(Contract Grant No.2018RS3101).
文摘Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and difficult biodegradation mainly limit its utilization.This work focused on the effect of hydroxylation of lignin on its microbial degradation.Butyloxy carbonyl-modified lignin,and hydroxylated-lignin were synthesized with di-tert-butyl dicarbonate and hydrogen peroxide,respectively,using lignin as raw material.The degradation of the modifiedlignins both by P.chrysosporium and B.subtilis were analyzed using UV-vis spectroscopy.Results revealed that the lignin degradation velocity raises with the increase hydroxylation level of lignin.Moreover,FTIR and 1H NMR analysis of the biodegradation products of lignin further indicated that higher content of hydroxyl groups in lignin facilitated the demethylation combined with the aromatic ring cracking in the presence of fungus and bacteria.
文摘A bi-component alcoholysis agent containing propylene glycol(PG)and ethanolamine(ETA)was used to catalyst the degradation of the waste polyurethane rigid foam.The oligomer polyols obtained through degradation were used as raw materials to produce recycled polyurethane rigid foam composites with lignin as reinforcing filler.The effect of alcoholysis mass ratio on degradation was investigated by analyzing the viscosity,hydroxyl content and chemical structure of the degradation products.The effect of lignin addition on the properties of regenerated polyurethane rigid foam were investigated by analyzing water absorption rate,compressive strength,porosity,thermal stability,thermal conductivity coefficient,morphology and thermal stability of the recycled polyurethane rigid foam.Results show that different mass ration of PG to ETA significantly affects the degradation of waste polyurethane rigid foam.Besides,only with the addition of appropriate amount of lignin,the regenerated polyurethane rigid foam composites can meet the Chinese national standard“rigid polyurethane foam for building thermal insulation”(GB/T21558-2008).At this point,the composite is with good mechanical and thermal prperties,including high compressive strength,excellent thermal insulation performance,complete cell morphology and good thermal stability.
文摘Chemical modification of lignin was carried out by reacted it with HI acid, then the modified lignin treated with calcium hydroxide to prepare calcium-lignin chelating complex, this derivative was examined as thermal stabilizer for PVC, thermal degradation of PVC neat as blank and containing three weight percents (1, 2, and 4) into polymer was accelerated by heat treatment at 190°C for 2 hr. then PVC films were casting from THF solvent with thickness 0.03 mm. Thermal stabilization activity of this derivative was investigated by using infrared spectroscopy, according to the results obtained calcium-lignin complex have suitable activity to increased PVC stability at low concentration depending on it’s ability to reaction with HCl as well as the chemical structure of lignin that contain phenolic properties.
基金Supported by Key Science and Technology Program of Henan Province(132102310253,122102310350)Natural Science Research Program of Education Department of Henan Province(15A210020,12A180008)
文摘After incubation for 6- 30 h,with the rapid increase of bacterial cell number,surface tension of bacterium BS-8 was reduced sharply from 63. 2 m N / m to 39. 4 m N / m. The production of biosurfactants by BS-8 was growth-dependent. Using glucose as the carbon source,bacterium BS-8 was incubated. Based on centrifugation,precipitation and chromogenic reaction of the culture solution,results indicated that the biosurfactants belonged to lipopeptides. The yield of biosurfactants isolated and purified from the culture solution was 0. 58 g / L,and the critical micelle concentration( CMC) was 90 mg / L. Under conditions of p H 4- 9,temperature 20- 70 ℃,Na Cl concentration 1%- 6%,biosurfactants produced by BS-8 exhibited the highest stability.
