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
The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips an...The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.展开更多
The lack of synergy between infrastructure financing mechanisms and mechanisms for combating climate change does not favor the definition of sustainable infrastructure in Cameroon. The definition of a sustainable infr...The lack of synergy between infrastructure financing mechanisms and mechanisms for combating climate change does not favor the definition of sustainable infrastructure in Cameroon. The definition of a sustainable infrastructure could meet the requirements of these mechanisms, thanks to the control of Greenhouse Gas (GHG) emissions during its installation, in relation to a predefined value. However, the promotion of efforts to reduce emissions from new infrastructures is not subject to a local market. This situation is a limit in the implementation of the policies defined in the Nationally Determined Contribution (NDC). This article proposes a framework for promoting reduction efforts for a national carbon market, in favor of hydroelectric infrastructures. Thanks to the Life Cycle Assessment (LCA) environmental assessment tool, we are going to determine the carbon quota for a specific power. The study carried out on the hydroelectric power station of Mekin (HydroMekin) leads us to a reduction effort of 68.2% compared to the threshold defined at 14.057 gCO<sub>2eq</sub>/kWh<sub>e</sub>. The framework, developed, contributes to defining the environmental parameters in the decarbonation strategy during the implementation of new hydroelectric infrastructures and the market carbon design elements special to the construction phase of these infrastructures.展开更多
This present research work is on the characterization of bauxite red mud (waste material) from Ngaoundal for the manufacture of ceramic products. After the extraction process, the raw material was characterized using ...This present research work is on the characterization of bauxite red mud (waste material) from Ngaoundal for the manufacture of ceramic products. After the extraction process, the raw material was characterized using Scanning Electron Microscopy (SEM). Morphology, mineral phases and chemical composition were determined by using energy-dispersive X-ray (EDX) analysis, X-ray diffractometer (XRD), X-ray fluorescence (XRF). Differential Scanning Calorimetry and Thermal Gravimetric Analysis (DSC-TGA), Infra-Red (IR), Particle size (PS) were also used. Results of red mud analysis show that major oxides were Fe<sub>2</sub>O<sub>3</sub> (37.21%), Al<sub>2</sub>O<sub>3</sub> (19.6%), SiO<sub>2</sub> (7.68%), TiO<sub>2</sub> (1.07%), Na<sub>2</sub>O (4.71%), and CaO (2.75%). These last oxides require low temperature to melt and act as binders which link particles of red mud during the sintering process. Presence of alkaline oxides is an appeal to reduce energy consumption during ceramic manufacture process and to protect our environment for sustainable development. Physical and mechanical properties of fired red mud showed that the firing shrinkage, bulk density, and flexural strength increase with firing temperature. Porosity and water absorption had the same pattern and they decreased with the increase of temperature. Chemical stability reveals that 10% material loss is obtained after 7 days of treatment under acid-base conditions.展开更多
This work present<span style="white-space:normal;font-family:;" "="">s</span><span style="white-space:normal;font-family:;" "=""> the thermal, p...This work present<span style="white-space:normal;font-family:;" "="">s</span><span style="white-space:normal;font-family:;" "=""> the thermal, physical and chemical characterization of <i>Coffee</i> <i>canephora</i>, from littoral region of Cameroon, for their use as reinforcement for polymeric materials. The infrared of coffee hulls shows the presence of a large peak intensity at 3299 cm<sup>-1</sup> that can be attributed to O</span><span style="white-space:normal;font-family:;" "="">-</span><span style="white-space:normal;font-family:;" "="">H stretching group of alcohol (cellulose content in coffee pulp). The intensity 2926 cm<sup>-1</sup> can be attributed to C</span><span style="white-space:normal;font-family:;" "="">-</span><span style="white-space:normal;font-family:;" "="">H stretching group of alkanes or the vibration of methoxy group of lignin. Thermo gravimetric analysis shows that around 440<span style="white-space:nowrap;">°</span>C, the biomass has been completely consumed;the temperature profiles show a peak at 86<span style="white-space:nowrap;">°</span>C that could correspond to the loss of water as evaporation at a percentage of 8%;the peak at 321<span style="white-space:nowrap;">°</span>C is accompanied by a water loss of 64.50%</span><span style="white-space:normal;font-family:;" "="">;</span><span style="white-space:normal;font-family:;" "=""> this temperature is assimilated to the degradation of hemicelluloses;the temperature range from 321<span style="white-space:nowrap;">°</span>C to 401<span style="white-space:nowrap;">°</span>C is accompanied by a loss of mass of 22.80%, which would be due to the degradation of cellulose. SEM images of the surface of raw coffee hulls, coffee hulls treated with caustic soda respectively clearly reveal gaps between the fibers. The results showed that the incorporation of coffee hulls fiber in LLDPE matrix might result in composites with suitable property application for various industrial fields</span><span style="white-space:normal;font-family:;" "="">;</span><span style="white-space:normal;font-family:;" "="">especially those </span><span style="white-space:normal;font-family:;" "="">that </span><span style="white-space:normal;font-family:;" "="">were mechanical features are crucial, such as the replacement of engineering plastics.</span>展开更多
In this work fibers derived from coffee</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> hulls ha</span><span style="font-f...In this work fibers derived from coffee</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> hulls ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">thermal and physicomechanical properties of the composites obtained was assessed. The results showed that the incorporation of fibers was able to improve the thermostability of LLDPE/Coffee hulls fibers;comparing the treated fiber composite with untreated fiber composites, the chemical treatment reduces by 58.3% the water absorption, while increasing the elongation and tensile strength by about 48% and 17% respectively. Moreover, due to better interfacial interaction induced by MAPE, the corresponding composite exhibited better properties compared to the untreated fiber composite. Results are indicative of the fact that both mercerization and MAPE (coupling agent) have significant positive effects on the fib</span><span style="font-family:Verdana;">er</span><span style="font-family:Verdana;">-matrix interaction in terms of adhesion, wetting and dispersion, this treatment produced a better fiber distribution and consequently a more uniform composite morphology without voids and gaps between the fibers and the matrix, allowing the possibility to use higher fiber contents (up to 30% wt.) with acceptable mechanical properties.展开更多
The energy transition,validated by 194 countries at the end of CoP21 in Paris,requires new development design methods.This requirement,for the sub-Saharan African countries(SAC),could be an opportunity to finance thei...The energy transition,validated by 194 countries at the end of CoP21 in Paris,requires new development design methods.This requirement,for the sub-Saharan African countries(SAC),could be an opportunity to finance their development.Following the mixed results of the Clean Development Mechanism(CDM),partly due to its rather restrictive selection criterion,the desire to implement carbon asset transfer mechanisms is proposed by many countries including Cameroon.However,the success of such a mechanism would be guaranteed by encouraging policies to regulate emissions.It is in this perspective that our work falls.It aims at proposing a regulation approach for major projects.We have dwelt on hydroelectric projects.To do this,we ordered considering their quantitative feature,113 projects or visions proposed by 37 countries.Subsequently,a classification of projects according to compartments and trends was made.We finally pointed out 6 visions,including the mitigation in production,mitigation in distribution or service,adaptation in production,mitigation in transport,adaptation in distribution or service,and the adaptation in transport.The regulation methodology proposed for mitigation projects in the hydroelectric sector on a variable threshold hypothesis has led us to three trends in regulation.展开更多
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The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.
文摘The lack of synergy between infrastructure financing mechanisms and mechanisms for combating climate change does not favor the definition of sustainable infrastructure in Cameroon. The definition of a sustainable infrastructure could meet the requirements of these mechanisms, thanks to the control of Greenhouse Gas (GHG) emissions during its installation, in relation to a predefined value. However, the promotion of efforts to reduce emissions from new infrastructures is not subject to a local market. This situation is a limit in the implementation of the policies defined in the Nationally Determined Contribution (NDC). This article proposes a framework for promoting reduction efforts for a national carbon market, in favor of hydroelectric infrastructures. Thanks to the Life Cycle Assessment (LCA) environmental assessment tool, we are going to determine the carbon quota for a specific power. The study carried out on the hydroelectric power station of Mekin (HydroMekin) leads us to a reduction effort of 68.2% compared to the threshold defined at 14.057 gCO<sub>2eq</sub>/kWh<sub>e</sub>. The framework, developed, contributes to defining the environmental parameters in the decarbonation strategy during the implementation of new hydroelectric infrastructures and the market carbon design elements special to the construction phase of these infrastructures.
文摘This present research work is on the characterization of bauxite red mud (waste material) from Ngaoundal for the manufacture of ceramic products. After the extraction process, the raw material was characterized using Scanning Electron Microscopy (SEM). Morphology, mineral phases and chemical composition were determined by using energy-dispersive X-ray (EDX) analysis, X-ray diffractometer (XRD), X-ray fluorescence (XRF). Differential Scanning Calorimetry and Thermal Gravimetric Analysis (DSC-TGA), Infra-Red (IR), Particle size (PS) were also used. Results of red mud analysis show that major oxides were Fe<sub>2</sub>O<sub>3</sub> (37.21%), Al<sub>2</sub>O<sub>3</sub> (19.6%), SiO<sub>2</sub> (7.68%), TiO<sub>2</sub> (1.07%), Na<sub>2</sub>O (4.71%), and CaO (2.75%). These last oxides require low temperature to melt and act as binders which link particles of red mud during the sintering process. Presence of alkaline oxides is an appeal to reduce energy consumption during ceramic manufacture process and to protect our environment for sustainable development. Physical and mechanical properties of fired red mud showed that the firing shrinkage, bulk density, and flexural strength increase with firing temperature. Porosity and water absorption had the same pattern and they decreased with the increase of temperature. Chemical stability reveals that 10% material loss is obtained after 7 days of treatment under acid-base conditions.
文摘This work present<span style="white-space:normal;font-family:;" "="">s</span><span style="white-space:normal;font-family:;" "=""> the thermal, physical and chemical characterization of <i>Coffee</i> <i>canephora</i>, from littoral region of Cameroon, for their use as reinforcement for polymeric materials. The infrared of coffee hulls shows the presence of a large peak intensity at 3299 cm<sup>-1</sup> that can be attributed to O</span><span style="white-space:normal;font-family:;" "="">-</span><span style="white-space:normal;font-family:;" "="">H stretching group of alcohol (cellulose content in coffee pulp). The intensity 2926 cm<sup>-1</sup> can be attributed to C</span><span style="white-space:normal;font-family:;" "="">-</span><span style="white-space:normal;font-family:;" "="">H stretching group of alkanes or the vibration of methoxy group of lignin. Thermo gravimetric analysis shows that around 440<span style="white-space:nowrap;">°</span>C, the biomass has been completely consumed;the temperature profiles show a peak at 86<span style="white-space:nowrap;">°</span>C that could correspond to the loss of water as evaporation at a percentage of 8%;the peak at 321<span style="white-space:nowrap;">°</span>C is accompanied by a water loss of 64.50%</span><span style="white-space:normal;font-family:;" "="">;</span><span style="white-space:normal;font-family:;" "=""> this temperature is assimilated to the degradation of hemicelluloses;the temperature range from 321<span style="white-space:nowrap;">°</span>C to 401<span style="white-space:nowrap;">°</span>C is accompanied by a loss of mass of 22.80%, which would be due to the degradation of cellulose. SEM images of the surface of raw coffee hulls, coffee hulls treated with caustic soda respectively clearly reveal gaps between the fibers. The results showed that the incorporation of coffee hulls fiber in LLDPE matrix might result in composites with suitable property application for various industrial fields</span><span style="white-space:normal;font-family:;" "="">;</span><span style="white-space:normal;font-family:;" "="">especially those </span><span style="white-space:normal;font-family:;" "="">that </span><span style="white-space:normal;font-family:;" "="">were mechanical features are crucial, such as the replacement of engineering plastics.</span>
文摘In this work fibers derived from coffee</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> hulls ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">thermal and physicomechanical properties of the composites obtained was assessed. The results showed that the incorporation of fibers was able to improve the thermostability of LLDPE/Coffee hulls fibers;comparing the treated fiber composite with untreated fiber composites, the chemical treatment reduces by 58.3% the water absorption, while increasing the elongation and tensile strength by about 48% and 17% respectively. Moreover, due to better interfacial interaction induced by MAPE, the corresponding composite exhibited better properties compared to the untreated fiber composite. Results are indicative of the fact that both mercerization and MAPE (coupling agent) have significant positive effects on the fib</span><span style="font-family:Verdana;">er</span><span style="font-family:Verdana;">-matrix interaction in terms of adhesion, wetting and dispersion, this treatment produced a better fiber distribution and consequently a more uniform composite morphology without voids and gaps between the fibers and the matrix, allowing the possibility to use higher fiber contents (up to 30% wt.) with acceptable mechanical properties.
文摘The energy transition,validated by 194 countries at the end of CoP21 in Paris,requires new development design methods.This requirement,for the sub-Saharan African countries(SAC),could be an opportunity to finance their development.Following the mixed results of the Clean Development Mechanism(CDM),partly due to its rather restrictive selection criterion,the desire to implement carbon asset transfer mechanisms is proposed by many countries including Cameroon.However,the success of such a mechanism would be guaranteed by encouraging policies to regulate emissions.It is in this perspective that our work falls.It aims at proposing a regulation approach for major projects.We have dwelt on hydroelectric projects.To do this,we ordered considering their quantitative feature,113 projects or visions proposed by 37 countries.Subsequently,a classification of projects according to compartments and trends was made.We finally pointed out 6 visions,including the mitigation in production,mitigation in distribution or service,adaptation in production,mitigation in transport,adaptation in distribution or service,and the adaptation in transport.The regulation methodology proposed for mitigation projects in the hydroelectric sector on a variable threshold hypothesis has led us to three trends in regulation.
