A non-isocyanate-based polyurethane(NIPU)wood adhesive was produced from organosolv lignin,which is a bio-sourced raw material,available in large quantities and produced as a by-product of the paper industry.The formu...A non-isocyanate-based polyurethane(NIPU)wood adhesive was produced from organosolv lignin,which is a bio-sourced raw material,available in large quantities and produced as a by-product of the paper industry.The formulation of this new lignin-based NIPU adhesive,which is presented,was chemically characterised by Matrix-Assisted Laser Desorption Ionization Time of Flight(MALDI ToF)mass spectrometry and by Fourier Transform Infra-Red(FTIR)spectrometry analyses.The oligomers formed were determined and showed that the three species involved in the NIPU adhesive preparation were formed by the co-reaction of the three reagents used:lignin,dimethyl carbonate,and hexamethylene diamine.Linear and branched structures were both identi-fied.Mechanical properties of the adhesive were determined using the Automated Bonding Evaluation System(ABES)and internal bond(IB)strength test of the laboratory particleboard bonded with it.The adhesive has shown satisfactory mechanical properties after hot pressing at 230℃.Such a temperature is used industrially in the most modern particleboard factories,but since it is hardly feasible for more conventional wood bonding equipment,the reactivity of the NIPU adhesive was successfully increased with the addition of a small percentage of a silane coupling agent.With the addition of the silane,the proposed NIPU adhesive could also be used at a hot-pressing temperature lower than 200℃.展开更多
The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were cho...The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were chosen and tested. Results obtained using the methyl linoleate method have shown a correlation between oxygen uptake index and the combined severity. It was found that lignin extracted at higher severity pre-treatment and with a higher phenolic hydroxyl content, lower aliphatic hydroxyl content, molecular weight and polydispersity has the highest antioxidant capacity.展开更多
Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study...Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.展开更多
The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production ...The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min<sup>-1</sup>, 5358.1461 J·mol<sup>-1</sup>, 1383.03691 min<sup>-1</sup>, 51577.6100 J·mol<sup>-1</sup> respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.展开更多
Energy is a crucial material for the development of our economy.Access to sufficient energy remains a major concern for developing countries,particularly those in sub-Saharan Africa.The major challenge lies in access ...Energy is a crucial material for the development of our economy.Access to sufficient energy remains a major concern for developing countries,particularly those in sub-Saharan Africa.The major challenge lies in access to clean,environmentally friendly,quality and low-cost energy in different households in our municipalities.To cope with this vast energy gap,many households are dependent on fossil fuels.In Cameroon,the consumption of wood for the supply of energy is increasing by 4%per year.Overall,approximately 80%of households in Cameroon depend on woody biomass as the sole main source of energy supply in Cameroon and demand is growing over time.In view of the climatic variations that our countries,particularly Cameroon,undergo through deforestation,the use of wood as a source of energy is expensive and harmful to the environment,hence the urgency of replacing wood with renewable energy.Biogas is one of the most versatile sources of renewable energy.On an industrial scale,it is important to automate the process control.The main objective of the present work is to model the anaerobic digestion of coffee and cocoa hulls using the particle swarm optimisation method.Pretreatment using the organosolv process was done.This resulted in 48%lignin removal and 22%cellulose increase.For the pretreated biomass,the maximum production rate was 21 NmLCH4 per day with a biomethane yield of 90 NmLCH4/gVS.This represents an enhancement of 117%in biomethane yield.A positive flammability test was recorded after the 10th day of retention time.Moreover,the data collected during anaerobic digestion allowed implementation of a two-phase mathematical model.The thirteen parameters of the model were estimated with particle swarm optimisation method in Matlab.The model was able to simulate the biomethane production kinetics and variation of volatile fatty acid concentration.展开更多
基金This research was financed by the ERA-CoBioTech project WooBAdh(Environmentally-friendly bioadhesives from renewable resources).The University of Ljubljana,Biotechnical Faculty was financed by the Slovenian Ministry of Education,Science and Sport and the Slovenian Research Agency within the framework of program P4-0015.The LERMAB was financed by the French Agence Nationale de la Recherche(ANR)as part of the laboratory of excellence(LABEX)ARBRE.
文摘A non-isocyanate-based polyurethane(NIPU)wood adhesive was produced from organosolv lignin,which is a bio-sourced raw material,available in large quantities and produced as a by-product of the paper industry.The formulation of this new lignin-based NIPU adhesive,which is presented,was chemically characterised by Matrix-Assisted Laser Desorption Ionization Time of Flight(MALDI ToF)mass spectrometry and by Fourier Transform Infra-Red(FTIR)spectrometry analyses.The oligomers formed were determined and showed that the three species involved in the NIPU adhesive preparation were formed by the co-reaction of the three reagents used:lignin,dimethyl carbonate,and hexamethylene diamine.Linear and branched structures were both identi-fied.Mechanical properties of the adhesive were determined using the Automated Bonding Evaluation System(ABES)and internal bond(IB)strength test of the laboratory particleboard bonded with it.The adhesive has shown satisfactory mechanical properties after hot pressing at 230℃.Such a temperature is used industrially in the most modern particleboard factories,but since it is hardly feasible for more conventional wood bonding equipment,the reactivity of the NIPU adhesive was successfully increased with the addition of a small percentage of a silane coupling agent.With the addition of the silane,the proposed NIPU adhesive could also be used at a hot-pressing temperature lower than 200℃.
文摘The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were chosen and tested. Results obtained using the methyl linoleate method have shown a correlation between oxygen uptake index and the combined severity. It was found that lignin extracted at higher severity pre-treatment and with a higher phenolic hydroxyl content, lower aliphatic hydroxyl content, molecular weight and polydispersity has the highest antioxidant capacity.
文摘Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.
文摘The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min<sup>-1</sup>, 5358.1461 J·mol<sup>-1</sup>, 1383.03691 min<sup>-1</sup>, 51577.6100 J·mol<sup>-1</sup> respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.
文摘Energy is a crucial material for the development of our economy.Access to sufficient energy remains a major concern for developing countries,particularly those in sub-Saharan Africa.The major challenge lies in access to clean,environmentally friendly,quality and low-cost energy in different households in our municipalities.To cope with this vast energy gap,many households are dependent on fossil fuels.In Cameroon,the consumption of wood for the supply of energy is increasing by 4%per year.Overall,approximately 80%of households in Cameroon depend on woody biomass as the sole main source of energy supply in Cameroon and demand is growing over time.In view of the climatic variations that our countries,particularly Cameroon,undergo through deforestation,the use of wood as a source of energy is expensive and harmful to the environment,hence the urgency of replacing wood with renewable energy.Biogas is one of the most versatile sources of renewable energy.On an industrial scale,it is important to automate the process control.The main objective of the present work is to model the anaerobic digestion of coffee and cocoa hulls using the particle swarm optimisation method.Pretreatment using the organosolv process was done.This resulted in 48%lignin removal and 22%cellulose increase.For the pretreated biomass,the maximum production rate was 21 NmLCH4 per day with a biomethane yield of 90 NmLCH4/gVS.This represents an enhancement of 117%in biomethane yield.A positive flammability test was recorded after the 10th day of retention time.Moreover,the data collected during anaerobic digestion allowed implementation of a two-phase mathematical model.The thirteen parameters of the model were estimated with particle swarm optimisation method in Matlab.The model was able to simulate the biomethane production kinetics and variation of volatile fatty acid concentration.
