A new technology for ceramics matrix composites-ceramics matrix composite thixoforming in pseudo-semi-solid state based on semi-solid metal process and powder metallurgy technology were proposed. The rheological behav...A new technology for ceramics matrix composites-ceramics matrix composite thixoforming in pseudo-semi-solid state based on semi-solid metal process and powder metallurgy technology were proposed. The rheological behavior of Al2O 3n/Alμ composite was studied by isothermal compression in pseudo-semi-solid state. The variation rules of the true stress-true strain, rheological behavior and the influencing factors were also analyzed. The results show that the flow stress decreases evidently with the increasing pseudo-semi-solid temperature, and that the trend of the true stress-true strain curve of the composite in pseudo-semi-solid state can be divided into four stages: increase, decline, re-increase and re-decline.展开更多
<strong>Problem Statement:</strong> Surface Water Treatment for potable supplies typically involves coagulation, flocculation, and processes. All water treatment plants produce sludge, during the purificat...<strong>Problem Statement:</strong> Surface Water Treatment for potable supplies typically involves coagulation, flocculation, and processes. All water treatment plants produce sludge, during the purification of raw water, according to the level of the water turbidity. The aluminum sulfate is the most common coagulant used in water treatment plants of Morocco, as well as in many countries all over the world. It is difficult to manage sludge produced by the treatment plant. However, several studies, based on a set of jar test experiments, have demonstrated that it can be used in the process to improve the quality of the treated water and reduce the aluminum sulfate dose. <strong>Approach:</strong> In this study, the raw water treated and sludge produced in water treatment plant of Meknes, Morocco are investigated for chemical and bacteriological proprieties. The texture characterization of the dried sludge produced through the process of coagulation/flocculation and that of aluminum sulfate, used as coagulant aid, are obtained by nitrogen adsorption isotherms. <strong>Results:</strong> The physical properties of the raw water indicate its high turbidity during periods of heavy rainfall in the Bittit and Ribaa springs catchment area. However, these chemical properties indicate the quality of fresh water rich in magnesium, related to the dolomitic nature of the liastic aquifer. The bacteriological analysis of sludge produced in the treatment plant, confirms the elimination of pathogenic germs by the treatment process used. As regards the texture characterization the results demonstrated that the sludge presents some similarities with the sulfate. However, a clear difference is observed between the two solids, according to the pores distribution. <strong>Conclusions/Recommendations:</strong> Taking aluminum sulfate and sludge in comparison, it is possible to use the sludge for improving the coagulation process in water treatment.展开更多
In this research work,three kinds of activated bentonite used as solid acid catalysts had been synthesized and studied on removal of olefins from the reformate oil.Activated bentonite samples were analyzed using the B...In this research work,three kinds of activated bentonite used as solid acid catalysts had been synthesized and studied on removal of olefins from the reformate oil.Activated bentonite samples were analyzed using the BET and pyridine-FTIR measurements to investigate their physical and chemical properties.The results showed that both textural properties and surface acidity of the bentonite could affect the catalytic activity.Among the catalyst samples,one kind of bentonite purchased from Hubei with high surface area,high pore volume and more acid sites revealed high activity in removing olefins from the reformate.展开更多
The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. T...The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.展开更多
文摘A new technology for ceramics matrix composites-ceramics matrix composite thixoforming in pseudo-semi-solid state based on semi-solid metal process and powder metallurgy technology were proposed. The rheological behavior of Al2O 3n/Alμ composite was studied by isothermal compression in pseudo-semi-solid state. The variation rules of the true stress-true strain, rheological behavior and the influencing factors were also analyzed. The results show that the flow stress decreases evidently with the increasing pseudo-semi-solid temperature, and that the trend of the true stress-true strain curve of the composite in pseudo-semi-solid state can be divided into four stages: increase, decline, re-increase and re-decline.
文摘<strong>Problem Statement:</strong> Surface Water Treatment for potable supplies typically involves coagulation, flocculation, and processes. All water treatment plants produce sludge, during the purification of raw water, according to the level of the water turbidity. The aluminum sulfate is the most common coagulant used in water treatment plants of Morocco, as well as in many countries all over the world. It is difficult to manage sludge produced by the treatment plant. However, several studies, based on a set of jar test experiments, have demonstrated that it can be used in the process to improve the quality of the treated water and reduce the aluminum sulfate dose. <strong>Approach:</strong> In this study, the raw water treated and sludge produced in water treatment plant of Meknes, Morocco are investigated for chemical and bacteriological proprieties. The texture characterization of the dried sludge produced through the process of coagulation/flocculation and that of aluminum sulfate, used as coagulant aid, are obtained by nitrogen adsorption isotherms. <strong>Results:</strong> The physical properties of the raw water indicate its high turbidity during periods of heavy rainfall in the Bittit and Ribaa springs catchment area. However, these chemical properties indicate the quality of fresh water rich in magnesium, related to the dolomitic nature of the liastic aquifer. The bacteriological analysis of sludge produced in the treatment plant, confirms the elimination of pathogenic germs by the treatment process used. As regards the texture characterization the results demonstrated that the sludge presents some similarities with the sulfate. However, a clear difference is observed between the two solids, according to the pores distribution. <strong>Conclusions/Recommendations:</strong> Taking aluminum sulfate and sludge in comparison, it is possible to use the sludge for improving the coagulation process in water treatment.
文摘In this research work,three kinds of activated bentonite used as solid acid catalysts had been synthesized and studied on removal of olefins from the reformate oil.Activated bentonite samples were analyzed using the BET and pyridine-FTIR measurements to investigate their physical and chemical properties.The results showed that both textural properties and surface acidity of the bentonite could affect the catalytic activity.Among the catalyst samples,one kind of bentonite purchased from Hubei with high surface area,high pore volume and more acid sites revealed high activity in removing olefins from the reformate.
基金supported by the National Basic Research Program of China (2003CB615705)Chemistry & Chemical Technology Research Center Plan of Shanghai Huayi Group Company (A200-8608 and A200-80726)
文摘The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.
