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
Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the acce...Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the accessible total area according to the quantity of sugar cane molasses.The adsorption isotherms,the specific area,the adsorbed quantity of nitrogen on a Qm mono layer,the number of molecules constituting the adsorbed sugar cane molasses(n′)have been examined.The obtained results show that the quantity of sugar cane molasses in the material does not modify the adsorption isotherm of nitrogen of type IV that remains and a hysteria loop of type H4 in all samples,this justifies the monocoat-multicoat adsorption mechanism with capillary condensation and mesopores presence in the structure of materials.Materials with elaborated raw soil by clayey fine soil used are mesoporous materials.More of 50×1018 molecules constituting sugar cane molasses occupy the extreme area accessible to soil clay,without occupying on accessible sites.展开更多
Sugar cane molasses has proved cohesive and excellent performance on soil aggregates (fine particles). However, the microstructure of consolidated soil by the molasses is not yet subjected to research. The analysis re...Sugar cane molasses has proved cohesive and excellent performance on soil aggregates (fine particles). However, the microstructure of consolidated soil by the molasses is not yet subjected to research. The analysis results of sample without molasses (0%) and consolidated samples at 8%, 12%, and 16% show that the molasses acts on the structure of clayey fine soil developing its microstructure of airy matrix type (sample without molasses (0%) to a microstructure of a qualified type, more solid. Consolidated samples to 8%, 12%, 16% of molasses). We also observe the presence of inter-aggregate pores (mesopores) of similar size in all samples. The results of porosimetrical analyses (BJH) of the sample without molasses and consolidated samples to 8%, 12%, and 16% show that simultaneous porous volumes of samples are reduced with the increasing of molasses quantity. This latter, therefore, acts on the porous volume (micropore 2 nm and mesopore 9 nm) by reducing them which really means, molasses occupies the porous volume of the sample. However, this sample seems not to have any effect on the size of mesopores 9 nm. Thus, this product induces the evolution of the soil structure towards the highly dense and condensed structure. Consequently, materials in consolidated soil by molasses will have mechanical properties far superior to those of materials consolidated soil without molasses.展开更多
Biosurfactants are biomolecules produced by microorganisms, which possess several advantages over their chemical counterparts. Production can be cost-effective if renewable wastes are utilized as substrates. In this s...Biosurfactants are biomolecules produced by microorganisms, which possess several advantages over their chemical counterparts. Production can be cost-effective if renewable wastes are utilized as substrates. In this study, optimization of biosurfactant production by <i>Pseudomonas aeruginosa</i> strain CGA1 was carried out using response surface methodology. The conventional “One factor at a time” method of optimization was initially adopted to ascertain the impact of different renewable wastes on biosurfactant production. Four independent variables were tested: carbon and nitrogen concentration, medium volume, and inoculum size. Biosurfactant production was based on the emulsification index measurement. Results indicated that the preferred carbon source by the isolate was sugar cane molasses. A 2.31-fold increase in biosurfactant yield and emulsification index of 96.3% ± 0.75% under optimized cultural conditions of 20 g/L of molasses, 5 g/L of sodium nitrate, 1.93 ml inoculum size and 60 ml medium volume in 250 ml conical flask were obtained. The regression coefficient (R<sup>2</sup>) value of 84.15% implied adequate fitness of the model. The surface tension of distilled water was reduced from 72.1 mN/m to 35.0 ± 0.0 mN/m, and critical micelle concentration was attained at 60 mg·L<sup>-1</sup>. FTIR and GC-MS analysis indicated that the biosurfactant was a lipopeptide having characteristic lipid and peptide peak values. This study proves that the sole use of agro-industrial wastes for the production of biosurfactant is very efficient, and ensures the economic feasibility of biosurfactant production.展开更多
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Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the accessible total area according to the quantity of sugar cane molasses.The adsorption isotherms,the specific area,the adsorbed quantity of nitrogen on a Qm mono layer,the number of molecules constituting the adsorbed sugar cane molasses(n′)have been examined.The obtained results show that the quantity of sugar cane molasses in the material does not modify the adsorption isotherm of nitrogen of type IV that remains and a hysteria loop of type H4 in all samples,this justifies the monocoat-multicoat adsorption mechanism with capillary condensation and mesopores presence in the structure of materials.Materials with elaborated raw soil by clayey fine soil used are mesoporous materials.More of 50×1018 molecules constituting sugar cane molasses occupy the extreme area accessible to soil clay,without occupying on accessible sites.
文摘Sugar cane molasses has proved cohesive and excellent performance on soil aggregates (fine particles). However, the microstructure of consolidated soil by the molasses is not yet subjected to research. The analysis results of sample without molasses (0%) and consolidated samples at 8%, 12%, and 16% show that the molasses acts on the structure of clayey fine soil developing its microstructure of airy matrix type (sample without molasses (0%) to a microstructure of a qualified type, more solid. Consolidated samples to 8%, 12%, 16% of molasses). We also observe the presence of inter-aggregate pores (mesopores) of similar size in all samples. The results of porosimetrical analyses (BJH) of the sample without molasses and consolidated samples to 8%, 12%, and 16% show that simultaneous porous volumes of samples are reduced with the increasing of molasses quantity. This latter, therefore, acts on the porous volume (micropore 2 nm and mesopore 9 nm) by reducing them which really means, molasses occupies the porous volume of the sample. However, this sample seems not to have any effect on the size of mesopores 9 nm. Thus, this product induces the evolution of the soil structure towards the highly dense and condensed structure. Consequently, materials in consolidated soil by molasses will have mechanical properties far superior to those of materials consolidated soil without molasses.
文摘Biosurfactants are biomolecules produced by microorganisms, which possess several advantages over their chemical counterparts. Production can be cost-effective if renewable wastes are utilized as substrates. In this study, optimization of biosurfactant production by <i>Pseudomonas aeruginosa</i> strain CGA1 was carried out using response surface methodology. The conventional “One factor at a time” method of optimization was initially adopted to ascertain the impact of different renewable wastes on biosurfactant production. Four independent variables were tested: carbon and nitrogen concentration, medium volume, and inoculum size. Biosurfactant production was based on the emulsification index measurement. Results indicated that the preferred carbon source by the isolate was sugar cane molasses. A 2.31-fold increase in biosurfactant yield and emulsification index of 96.3% ± 0.75% under optimized cultural conditions of 20 g/L of molasses, 5 g/L of sodium nitrate, 1.93 ml inoculum size and 60 ml medium volume in 250 ml conical flask were obtained. The regression coefficient (R<sup>2</sup>) value of 84.15% implied adequate fitness of the model. The surface tension of distilled water was reduced from 72.1 mN/m to 35.0 ± 0.0 mN/m, and critical micelle concentration was attained at 60 mg·L<sup>-1</sup>. FTIR and GC-MS analysis indicated that the biosurfactant was a lipopeptide having characteristic lipid and peptide peak values. This study proves that the sole use of agro-industrial wastes for the production of biosurfactant is very efficient, and ensures the economic feasibility of biosurfactant production.
