This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laborato...This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laboratory experiments to assess the percentage of dye removal across various temperature and pH conditions. The adsorption process is scrutinized under different parameters, encompassing contact time, initial dye concentration, adsorbent dosage, temperature, and pH. Results demonstrate that activated GWS surpasses its raw counterpart, showcasing superior MB dye removal percentages. Extended contact times increased initial dye concentrations, and higher adsorbent dosages contribute positively to removal efficiency, while temperature exhibits an inverse relationship with dye removal. Optimal adsorption occurs at a pH of 7.0, aligning with the adsorbent’s zero-point charge (pHzpc), underscoring the role of surface charge in the adsorption process. This study underscores the potential of activated GWS as an economical and promising adsorbent material for addressing pollutants. Furthermore, the utilization of activated carbon derived from abundant agricultural waste underscores an environmentally conscious approach to adsorption applications. The ability to tailor the size and properties of activated carbon particles opens avenues for optimizing adsorption capabilities, thereby presenting opportunities for enhanced water treatment solutions.展开更多
Polyvinyl alcohol (PVA) stabilized Polyvinyl acetate (PVAc) dispersions-based wood adhesive has poor water and heat resistance. Recently, the addition of fillers in the wood adhesive is one of the most effective ways ...Polyvinyl alcohol (PVA) stabilized Polyvinyl acetate (PVAc) dispersions-based wood adhesive has poor water and heat resistance. Recently, the addition of fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive. Inorganic fillers have unique characteristics to improve the performance of adhesive, such as small size, high surface energy and surface hardness. Hence, the present work investigates the applicability of calcium carbonate and clay incorporated 3% in situ emulsion polymerization PVAc wood adhesive. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with 3% calcium carbonate and 3% clay were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was reduced in the case of the addition of calcium carbonate and increased in the case of clay. The mechanical properties like tensile strength of adhesives with calcium carbonate and clay were measured by a universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that clay can improve bonding strength as compared to calcium carbonate of PVAc adhesive in wet conditions. The hardness of PVAc films was also changed positively by the addition of calcium carbonate and clay. Thermal stability of PVAc was significantly improved as calcium carbonate and clay were added to PVAc. Here, we did a comparative study of the effect of the addition of calcium carbonate and clay filler materials in situ polymerization of PVAc on their different properties.展开更多
Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the...Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.展开更多
Background: With the objective of increasing knowledge on biomass and carbon stocks, and thus improving the accuracy of published estimates, the present study explored wood density and carbon concentration of coarse w...Background: With the objective of increasing knowledge on biomass and carbon stocks, and thus improving the accuracy of published estimates, the present study explored wood density and carbon concentration of coarse woody debris (diameter≥10) by decay class in a Seasonal Semi-deciduous Forest (SSF) area in the Atlantic Rain Forest and in a Cerrado sensu-stricto (CSS) area (Brazilian savanna), in Brazil. Two strata were identified in each area and ten sampling units were systematic located in each stratum. Data were collected according to the line intersect sampling method. Each tallied element, the diameter, length, and perpendicular width were recorded at the transect intersection point. Each element was classified into a decay class, and the species was identified when possible. Sample discs were cut from each element, from which cylindrical samples were extracted and oven-dried to determine density. These cylinders were milled and analyzed using a LECO-C632 to determine carbon concentration as percentage of mass. Results: In both areas, wood density decreased as the decay class increased. For SSF the mean carbon concentration of all analyzed samples was 49.8% with a standard deviation of 3.3, with a range of 27.9–57.0% across 506 observations. For CSS the general mean was 49.6% with a standard deviation of 2.6, with a range of 31.2–54.5% over 182 observations. Carbon concentration barely change between decay classes. Carbon stock was estimated at 3.3 and 0.7 MgC/ha for the SSF and the CSS, respectively. Similar results were obtained when using a 50% conversion constant. Conclusions: The present study concludes that wood density decreases as the woody debris becomes more decomposed, a pattern found in many previous studies. The carbon concentration, however, barely changes between decay classes, and that result is consistent with most of the literature reviewed. Our carbon concentrations are very close to the 50% used most commonly as a conversion factor. We strongly recommend that future studies of CWD evaluate wood density and carbon concentration by decay class to address the uncertainty still found in the literature.展开更多
This research investigates several woods originated from trees of tropical virgin forest as raw material for the production of granular activated carbon. Mechanical strength of the activated carbons produced was relat...This research investigates several woods originated from trees of tropical virgin forest as raw material for the production of granular activated carbon. Mechanical strength of the activated carbons produced was related to wood hardness and lignin content but not to cellulose-lignin ratio. One of the eight woods studied (Dividivi) produced an activated carbon with a high mechanical strength similar to that produced from coconut shell, taken as a standard. Dividivi is also suggested as promissory for desert greening.展开更多
In order to enlarge the utilization field of wood and decrease the costs of carbon fibers, carbon fiber precursors from liquefied wood were prepared by soaking liquefied wood in a solution containing hydrochloric acid...In order to enlarge the utilization field of wood and decrease the costs of carbon fibers, carbon fiber precursors from liquefied wood were prepared by soaking liquefied wood in a solution containing hydrochloric acid and formaldehyde, after melt-spinning by adding hexamethylenetetramine. The microstructure evolution of the precursor during carbonization was studied by FTIR, X-ray analysis and Raman spectroscopy. The results show that precursors from liquefied wood above 400℃had diffraction peaks corresponding to the （100） crystal plane. When the carbonization temperature reached 500℃, Raman spectroscopy showed the D peak at wave number of 1360 cm^-1 and the G peak at 1595 cm^-1. By increasing the carbonization temperature, the microstructure of the precursors became more ordered. Although the structure of the precursor changed at 500 and 800℃, the peaks at 1632 and 1454 cm^-1 corresponding to the characteristic vibrations of aromatic rings, remained during carbonization. This implies that the precursor from liquefied wood cannot be easily formed into graphite.展开更多
Two activated carbons with controlled pore size were prepared from Eucalyptus wood by physical activation with carbon dioxide, giving the BET surface area and pore volume of738 m2/g and0.39 cm3/g, and921 m2/g and0.53 ...Two activated carbons with controlled pore size were prepared from Eucalyptus wood by physical activation with carbon dioxide, giving the BET surface area and pore volume of738 m2/g and0.39 cm3/g, and921 m2/g and0.53 cm3/g for the carbon sample AC1 and AC2, respectively. These activated carbons were then used to remove the residual dye left after the silk-dyeing process. The dye solution used for adsorption study was a cationic aluminium dye complex of [Al(brazilein)2]+ derived from a mixture of alum and extract of the heartwood of Ceasalpinia sappan Linn., with initial dye concentration of 220 mg/l. Effects of adsorbent dosage, adsorption time and temperature in the range of 25℃40℃ on dye adsorption were investigated. It was found that the adsorption kinetics of this dye complex was best described by the pseudo-second order model. Adsorption isotherms of this dye complex were well fitted by Langmuir isotherm equation. The adsorption capacities for the uptake of this dye complex at 25℃, 30℃ and 40℃ were 718.7, 1240.4 and 1139.5 mg/g and 1010.5, 1586.1 and 1659.0 mg/g for carbon sample AC1 and AC2, respectively. From these results, it can be concluded that activated carbon containing a higher proportion of mesopores gave better dye removal efficiency, emphasizing the fact that a proper pore size distribution of carbon adsorbent is crucial for the effecttive removal of relatively large size of the dye molecules. Thermodynamic parameters, including free energy, enthalpy and entropy of adsorption, were also determined. The adsorption enthalpies for the removal of this dye complex of AC1 and AC2 were 105.3 and 55.6 kJ/mol, respectively, indicating that the adsorption is an endothermic process. It was found that the adsorption of this dye complex is spontaneous at the temperatures under investigation.展开更多
文摘This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laboratory experiments to assess the percentage of dye removal across various temperature and pH conditions. The adsorption process is scrutinized under different parameters, encompassing contact time, initial dye concentration, adsorbent dosage, temperature, and pH. Results demonstrate that activated GWS surpasses its raw counterpart, showcasing superior MB dye removal percentages. Extended contact times increased initial dye concentrations, and higher adsorbent dosages contribute positively to removal efficiency, while temperature exhibits an inverse relationship with dye removal. Optimal adsorption occurs at a pH of 7.0, aligning with the adsorbent’s zero-point charge (pHzpc), underscoring the role of surface charge in the adsorption process. This study underscores the potential of activated GWS as an economical and promising adsorbent material for addressing pollutants. Furthermore, the utilization of activated carbon derived from abundant agricultural waste underscores an environmentally conscious approach to adsorption applications. The ability to tailor the size and properties of activated carbon particles opens avenues for optimizing adsorption capabilities, thereby presenting opportunities for enhanced water treatment solutions.
文摘Polyvinyl alcohol (PVA) stabilized Polyvinyl acetate (PVAc) dispersions-based wood adhesive has poor water and heat resistance. Recently, the addition of fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive. Inorganic fillers have unique characteristics to improve the performance of adhesive, such as small size, high surface energy and surface hardness. Hence, the present work investigates the applicability of calcium carbonate and clay incorporated 3% in situ emulsion polymerization PVAc wood adhesive. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with 3% calcium carbonate and 3% clay were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was reduced in the case of the addition of calcium carbonate and increased in the case of clay. The mechanical properties like tensile strength of adhesives with calcium carbonate and clay were measured by a universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that clay can improve bonding strength as compared to calcium carbonate of PVAc adhesive in wet conditions. The hardness of PVAc films was also changed positively by the addition of calcium carbonate and clay. Thermal stability of PVAc was significantly improved as calcium carbonate and clay were added to PVAc. Here, we did a comparative study of the effect of the addition of calcium carbonate and clay filler materials in situ polymerization of PVAc on their different properties.
文摘Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.
基金funded by the Sao Paulo Research Foundation(FAPESP)through a doctorate scholarship(Grant no.2013/10922-2)Research Internship Abroad(Grant no.2014/14213-9)
文摘Background: With the objective of increasing knowledge on biomass and carbon stocks, and thus improving the accuracy of published estimates, the present study explored wood density and carbon concentration of coarse woody debris (diameter≥10) by decay class in a Seasonal Semi-deciduous Forest (SSF) area in the Atlantic Rain Forest and in a Cerrado sensu-stricto (CSS) area (Brazilian savanna), in Brazil. Two strata were identified in each area and ten sampling units were systematic located in each stratum. Data were collected according to the line intersect sampling method. Each tallied element, the diameter, length, and perpendicular width were recorded at the transect intersection point. Each element was classified into a decay class, and the species was identified when possible. Sample discs were cut from each element, from which cylindrical samples were extracted and oven-dried to determine density. These cylinders were milled and analyzed using a LECO-C632 to determine carbon concentration as percentage of mass. Results: In both areas, wood density decreased as the decay class increased. For SSF the mean carbon concentration of all analyzed samples was 49.8% with a standard deviation of 3.3, with a range of 27.9–57.0% across 506 observations. For CSS the general mean was 49.6% with a standard deviation of 2.6, with a range of 31.2–54.5% over 182 observations. Carbon concentration barely change between decay classes. Carbon stock was estimated at 3.3 and 0.7 MgC/ha for the SSF and the CSS, respectively. Similar results were obtained when using a 50% conversion constant. Conclusions: The present study concludes that wood density decreases as the woody debris becomes more decomposed, a pattern found in many previous studies. The carbon concentration, however, barely changes between decay classes, and that result is consistent with most of the literature reviewed. Our carbon concentrations are very close to the 50% used most commonly as a conversion factor. We strongly recommend that future studies of CWD evaluate wood density and carbon concentration by decay class to address the uncertainty still found in the literature.
文摘This research investigates several woods originated from trees of tropical virgin forest as raw material for the production of granular activated carbon. Mechanical strength of the activated carbons produced was related to wood hardness and lignin content but not to cellulose-lignin ratio. One of the eight woods studied (Dividivi) produced an activated carbon with a high mechanical strength similar to that produced from coconut shell, taken as a standard. Dividivi is also suggested as promissory for desert greening.
基金supported by the Na-tional Natural Science Foundation of China (Grant No. 30901133)
文摘In order to enlarge the utilization field of wood and decrease the costs of carbon fibers, carbon fiber precursors from liquefied wood were prepared by soaking liquefied wood in a solution containing hydrochloric acid and formaldehyde, after melt-spinning by adding hexamethylenetetramine. The microstructure evolution of the precursor during carbonization was studied by FTIR, X-ray analysis and Raman spectroscopy. The results show that precursors from liquefied wood above 400℃had diffraction peaks corresponding to the （100） crystal plane. When the carbonization temperature reached 500℃, Raman spectroscopy showed the D peak at wave number of 1360 cm^-1 and the G peak at 1595 cm^-1. By increasing the carbonization temperature, the microstructure of the precursors became more ordered. Although the structure of the precursor changed at 500 and 800℃, the peaks at 1632 and 1454 cm^-1 corresponding to the characteristic vibrations of aromatic rings, remained during carbonization. This implies that the precursor from liquefied wood cannot be easily formed into graphite.
文摘Two activated carbons with controlled pore size were prepared from Eucalyptus wood by physical activation with carbon dioxide, giving the BET surface area and pore volume of738 m2/g and0.39 cm3/g, and921 m2/g and0.53 cm3/g for the carbon sample AC1 and AC2, respectively. These activated carbons were then used to remove the residual dye left after the silk-dyeing process. The dye solution used for adsorption study was a cationic aluminium dye complex of [Al(brazilein)2]+ derived from a mixture of alum and extract of the heartwood of Ceasalpinia sappan Linn., with initial dye concentration of 220 mg/l. Effects of adsorbent dosage, adsorption time and temperature in the range of 25℃40℃ on dye adsorption were investigated. It was found that the adsorption kinetics of this dye complex was best described by the pseudo-second order model. Adsorption isotherms of this dye complex were well fitted by Langmuir isotherm equation. The adsorption capacities for the uptake of this dye complex at 25℃, 30℃ and 40℃ were 718.7, 1240.4 and 1139.5 mg/g and 1010.5, 1586.1 and 1659.0 mg/g for carbon sample AC1 and AC2, respectively. From these results, it can be concluded that activated carbon containing a higher proportion of mesopores gave better dye removal efficiency, emphasizing the fact that a proper pore size distribution of carbon adsorbent is crucial for the effecttive removal of relatively large size of the dye molecules. Thermodynamic parameters, including free energy, enthalpy and entropy of adsorption, were also determined. The adsorption enthalpies for the removal of this dye complex of AC1 and AC2 were 105.3 and 55.6 kJ/mol, respectively, indicating that the adsorption is an endothermic process. It was found that the adsorption of this dye complex is spontaneous at the temperatures under investigation.
