Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2—12 Process parameters studied include pH, steady state temperature, concentration, and ...Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2—12 Process parameters studied include pH, steady state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water(SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20—70℃ proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.展开更多
The present situation of research on ultrasonic cavitation process at home and abroad is briefly reviewed. Ultrasonic cavitation mechanism, wastewaters, affecting factors and types of sonochemical reactors are describ...The present situation of research on ultrasonic cavitation process at home and abroad is briefly reviewed. Ultrasonic cavitation mechanism, wastewaters, affecting factors and types of sonochemical reactors are described. The future research orientation is pointed out.展开更多
A novel sonochemical method is described for the preparation of Fe_(3)O_(4)–TiO_(2)photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core.The Fe_(3)O_(4)nanopartic...A novel sonochemical method is described for the preparation of Fe_(3)O_(4)–TiO_(2)photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core.The Fe_(3)O_(4)nanoparticles were partially embedded in TiO_(2)agglomerates.TiO_(2)nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation.This method is attractive since it eliminated the high-temperature heat treatment required in the conventional sol–gel method,which is important in transforming amorphous titanium dioxide into a photoactive crystalline phase.In comparison to other methods,the developed method is simple,mild,green and efficient.The magnetization hysteresis loop for Fe_(3)O_(4)–TiO_(2)nanocomposites indicates that the hybrid catalyst shows superparamagnetic characteristics at room temperature.Photocatalytic activity studies confirmed that the as-prepared nanocomposites have high photocatalytic ability toward the photodegradation of RhB solution.Furthermore,the photodecomposition rate decreases only slightly after six cycles of the photocatalysis experiment.Thus,these Fe_(3)O_(4)–TiO_(2)nanocomposites can be served as an effective and conveniently recyclable photocatalyst.展开更多
In recent years,nanostructured photocatalysts have become the research focus due to their immense potential application in environmental purification and energy conversion.The photocatalytic performance of photocataly...In recent years,nanostructured photocatalysts have become the research focus due to their immense potential application in environmental purification and energy conversion.The photocatalytic performance of photocatalysts is closely related to their synthesis methods.High-intensity ultrasound irradiation could provide a unique tool for fabrication of photocatalysts with novel nanostructures.Ultrasound induces acoustic cavitation which generates unique physicochemical conditions,e.g.,hot spot（5000℃）,high pressure of 100 MPa,fast rate of heat conduction（〉〉1×10^10℃·s^-1）.These unique physicochemical conditions allow for the synthesis of various nanostructured photocatalysts.This review summarized the recent development in fabrication of photocatalysts with special nanostructures and their applications.The typical sonochemical reactors and parameters in sonochemical synthesis are introduced and discussed.Sonochemically prepared structures including nano-/microspheres,one-dimensional（1D） nanorods,two-dimensional（2D） nanosheets（nanoflakes,nanosquares）,noble metal nanoparticle（NP）-deposited and element-doped photocatalysts are described and summarized.It is believed that sonication is a green methodology,and it holds greatpotential in the near future for nanostructured photocatalyst fabrication.展开更多
文摘Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2—12 Process parameters studied include pH, steady state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water(SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20—70℃ proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.
文摘The present situation of research on ultrasonic cavitation process at home and abroad is briefly reviewed. Ultrasonic cavitation mechanism, wastewaters, affecting factors and types of sonochemical reactors are described. The future research orientation is pointed out.
基金support from National Basic Research Program of China(973 Program,Grant No.2007CB936800)SRFDP of China(Project No.20093402110010)are gratefully acknowledged.
文摘A novel sonochemical method is described for the preparation of Fe_(3)O_(4)–TiO_(2)photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core.The Fe_(3)O_(4)nanoparticles were partially embedded in TiO_(2)agglomerates.TiO_(2)nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation.This method is attractive since it eliminated the high-temperature heat treatment required in the conventional sol–gel method,which is important in transforming amorphous titanium dioxide into a photoactive crystalline phase.In comparison to other methods,the developed method is simple,mild,green and efficient.The magnetization hysteresis loop for Fe_(3)O_(4)–TiO_(2)nanocomposites indicates that the hybrid catalyst shows superparamagnetic characteristics at room temperature.Photocatalytic activity studies confirmed that the as-prepared nanocomposites have high photocatalytic ability toward the photodegradation of RhB solution.Furthermore,the photodecomposition rate decreases only slightly after six cycles of the photocatalysis experiment.Thus,these Fe_(3)O_(4)–TiO_(2)nanocomposites can be served as an effective and conveniently recyclable photocatalyst.
基金financially supported by the National Natural Science Foundation of China (Nos.21567008 and 21263005)the Young Scientist Training Project of Jiangxi Province China (No.20122BCB23015)+2 种基金Jiangxi Province Natural Science Foundation (No.20133BAB21003)the Landing Project of Science and Technology of Colleges and Universities in Jiangxi Province (No.KJLD14046)Yuan Hang Gongcheng of Jiangxi Province (2014)
文摘In recent years,nanostructured photocatalysts have become the research focus due to their immense potential application in environmental purification and energy conversion.The photocatalytic performance of photocatalysts is closely related to their synthesis methods.High-intensity ultrasound irradiation could provide a unique tool for fabrication of photocatalysts with novel nanostructures.Ultrasound induces acoustic cavitation which generates unique physicochemical conditions,e.g.,hot spot（5000℃）,high pressure of 100 MPa,fast rate of heat conduction（〉〉1×10^10℃·s^-1）.These unique physicochemical conditions allow for the synthesis of various nanostructured photocatalysts.This review summarized the recent development in fabrication of photocatalysts with special nanostructures and their applications.The typical sonochemical reactors and parameters in sonochemical synthesis are introduced and discussed.Sonochemically prepared structures including nano-/microspheres,one-dimensional（1D） nanorods,two-dimensional（2D） nanosheets（nanoflakes,nanosquares）,noble metal nanoparticle（NP）-deposited and element-doped photocatalysts are described and summarized.It is believed that sonication is a green methodology,and it holds greatpotential in the near future for nanostructured photocatalyst fabrication.
