Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and te...Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and temperature, a Taguchi experimental design was worked out. An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account. Response surface method was the tool used to analyze the experimental design results. Al/Ti, ethylene pressure and temperature were selected as experimental design factors, and catalyst activity and polymerization yield were the response parameters. Increasing pressure, due to an increment in monomer accessibility, and rising Al/Ti, because of higher reduction in the catalysts, cause an increase in both polymerization yield and catalyst activity. Nonetheless, a higher temperature, thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction, lead to a reduction in both response parameters. A synergistic effect was also observed between temperature and pressure. All catalyst activities will reduce in the presence of hydrogen. Molecular weight also shows a decline in the presence of hydrogen as a transfer agent. However, the polydispersity index remains approximately intact. Using SEM, various morphologies, owing to different catalyst morphologies, were seen for the polyethylene.展开更多
Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-b...Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-based process for enhanced lignin removal in wastewater using the fungus Neurospora discreta,which effectively degrades lignin and forms robust biofilms at the air–liquid interface under specific conditions.The process was optimised using the Taguchi design of experiments approach,and three factors including pH,copper sulphate concentration,and trace element concentration were evaluated at three levels.Experimental data were analysed against three responses:lignin degradation efficiency and the activities of two ligninolytic enzymes(polyphenol oxidase and versatile peroxidase).The results indicated that wastewater pH was the most significant parameter affecting lignin degradation efficiency and enzyme activities.Over 70%lignin degradation was achieved at pH levels of 5 and 6 with copper sulphate concentrations above 4 mg/L,while degradation efficiency drastically dropped to 45%at a pH value of 7.Reversed-phase high-performance liquid chromatography analysis demonstrated the effects of the three factors on the polar and non-polar components of lignin in wastewater,revealing a clear decrease in all peak areas after treatment.Additionally,significant relationships were observed between biofilm properties(including porosity,water retention value,polysaccharide content,and protein content)and lignin removal efficiency.This study also reported for the first time the presence of versatile peroxidase,a ligninolytic enzyme,in Neurospora sp.展开更多
To improve the power-extraction performance of the Savonius vertical-axis wind turbine(S-VAWT),additional cylinders,which are used to control the fluid flow around the wind turbine blade,were introduced into the blade...To improve the power-extraction performance of the Savonius vertical-axis wind turbine(S-VAWT),additional cylinders,which are used to control the fluid flow around the wind turbine blade,were introduced into the blade design.In contrast to the traditional numerical method,a mathematical model in the form of a dynamical system was used in this study.A numerical calculation program that could effectively solve the equations of wind-induced rotation of S-VAWT was developed,and combined with the Taguchi experimental method to investigate the influence of additional cylinders on the power-extraction characteristics of the S-VAWT.The results showed that the additional cylinders have a significant impact on the power-extraction performance of the S-VAWT.At 4-m/s wind speed,the average power coefficient of the S-VAWT with additional cylinders is 15%higher than that of the conventional S-VAWT.After construction of the wind turbine prototype and power-extraction tests,the results showed that compared with a conventional S-VAWT,the output power was 29%higher for the S-VAWT with additional cylinders under the same particular conditions.展开更多
文摘Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and temperature, a Taguchi experimental design was worked out. An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account. Response surface method was the tool used to analyze the experimental design results. Al/Ti, ethylene pressure and temperature were selected as experimental design factors, and catalyst activity and polymerization yield were the response parameters. Increasing pressure, due to an increment in monomer accessibility, and rising Al/Ti, because of higher reduction in the catalysts, cause an increase in both polymerization yield and catalyst activity. Nonetheless, a higher temperature, thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction, lead to a reduction in both response parameters. A synergistic effect was also observed between temperature and pressure. All catalyst activities will reduce in the presence of hydrogen. Molecular weight also shows a decline in the presence of hydrogen as a transfer agent. However, the polydispersity index remains approximately intact. Using SEM, various morphologies, owing to different catalyst morphologies, were seen for the polyethylene.
基金supported by the Leverhulme Trust Research Project(Grant No.RPG-2020-021).
文摘Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-based process for enhanced lignin removal in wastewater using the fungus Neurospora discreta,which effectively degrades lignin and forms robust biofilms at the air–liquid interface under specific conditions.The process was optimised using the Taguchi design of experiments approach,and three factors including pH,copper sulphate concentration,and trace element concentration were evaluated at three levels.Experimental data were analysed against three responses:lignin degradation efficiency and the activities of two ligninolytic enzymes(polyphenol oxidase and versatile peroxidase).The results indicated that wastewater pH was the most significant parameter affecting lignin degradation efficiency and enzyme activities.Over 70%lignin degradation was achieved at pH levels of 5 and 6 with copper sulphate concentrations above 4 mg/L,while degradation efficiency drastically dropped to 45%at a pH value of 7.Reversed-phase high-performance liquid chromatography analysis demonstrated the effects of the three factors on the polar and non-polar components of lignin in wastewater,revealing a clear decrease in all peak areas after treatment.Additionally,significant relationships were observed between biofilm properties(including porosity,water retention value,polysaccharide content,and protein content)and lignin removal efficiency.This study also reported for the first time the presence of versatile peroxidase,a ligninolytic enzyme,in Neurospora sp.
基金This work is supported by the National Natural Science Foundation of China(No.51975429).
文摘To improve the power-extraction performance of the Savonius vertical-axis wind turbine(S-VAWT),additional cylinders,which are used to control the fluid flow around the wind turbine blade,were introduced into the blade design.In contrast to the traditional numerical method,a mathematical model in the form of a dynamical system was used in this study.A numerical calculation program that could effectively solve the equations of wind-induced rotation of S-VAWT was developed,and combined with the Taguchi experimental method to investigate the influence of additional cylinders on the power-extraction characteristics of the S-VAWT.The results showed that the additional cylinders have a significant impact on the power-extraction performance of the S-VAWT.At 4-m/s wind speed,the average power coefficient of the S-VAWT with additional cylinders is 15%higher than that of the conventional S-VAWT.After construction of the wind turbine prototype and power-extraction tests,the results showed that compared with a conventional S-VAWT,the output power was 29%higher for the S-VAWT with additional cylinders under the same particular conditions.
