Kinetics of SiO2 leaching from Al2O3 extracted slag of fly ash with sodium hydroxide solution was studied.The effect of leaching temperature,mass ratio of NaOH to SiO2 and stirring speed on SiO2 leaching rate was inve...Kinetics of SiO2 leaching from Al2O3 extracted slag of fly ash with sodium hydroxide solution was studied.The effect of leaching temperature,mass ratio of NaOH to SiO2 and stirring speed on SiO2 leaching rate was investigated.The results show that increasing leaching temperature,mass ratio of NaOH to SiO2 and stirring speed increases SiO2 leaching rate.The SiO2 leaching rate is 95.66%under the optimized conditions.There are two stages for the SiO2 leaching process,and the leaching reaction is very rapid in the first stage but quite slow in the second stage.The whole leaching process follows the shrinking core model,and the outer diffusion of no product layer is the rate-controlling step.The activation energies of the first and second stages are calculated to be8.492 kJ/mol and 8.668 kJ/mol,respectively.The kinetic equations of the first and the second stages were obtained,respectively.展开更多
The semimetal Bi has received increasing interest as an alternative to noble metals for use in plasmonic photocatalysis. To enhance the photocatalytic efficiency of metallic Bi, Bi microspheres modified by SiO2 nanopa...The semimetal Bi has received increasing interest as an alternative to noble metals for use in plasmonic photocatalysis. To enhance the photocatalytic efficiency of metallic Bi, Bi microspheres modified by SiO2 nanoparticles were fabricated by a facile method. Bi-O-Si bonds were formed between Bi and SiO2, and acted as a transportation channel for hot electrons. The SiO2@Bi microspheres exhibited an enhanced plasmon-mediated photocatalytic activity for the removal of NO in air under 280 nm light irradiation, as a result of the enlarged specific surface areas and the promotion of electron transfer via the Bi-O-Si bonds. The reaction mechanism of photocatalytic oxidation of NO by SiO2@Bi was revealed with electron spin resonance and in situ diffuse reflectance infrared Fourier transform spectroscopy experiments, and involved the chain reaction NO -> NO2 -> NO3- with center dot OH and center dot O-2(-) radicals as the main reactive species. The present work could provide new insights into the in-depth mechanistic understanding of Bi plasmonic photocatalysis and the design of high-performance Bi-based photocatalysts. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.展开更多
基金Project (2007CB613603) supported by the National Basic Research Program of ChinaProject (2013M530934) supported by the Postdoctoral Science Foundation of China
摘要Kinetics of SiO2 leaching from Al2O3 extracted slag of fly ash with sodium hydroxide solution was studied.The effect of leaching temperature,mass ratio of NaOH to SiO2 and stirring speed on SiO2 leaching rate was investigated.The results show that increasing leaching temperature,mass ratio of NaOH to SiO2 and stirring speed increases SiO2 leaching rate.The SiO2 leaching rate is 95.66%under the optimized conditions.There are two stages for the SiO2 leaching process,and the leaching reaction is very rapid in the first stage but quite slow in the second stage.The whole leaching process follows the shrinking core model,and the outer diffusion of no product layer is the rate-controlling step.The activation energies of the first and second stages are calculated to be8.492 kJ/mol and 8.668 kJ/mol,respectively.The kinetic equations of the first and the second stages were obtained,respectively.
基金supported by the National Natural Science Foundation of China(21501016,51478070,21406022,21676037)the National Key R&D Project(2016YFC0204702)+4 种基金the Innovative Research Team of Chongqing(CXTDG201602014)the Natural Science Foundation of Chongqing(cstc2016jcyjA 0481,cstc2015jcyjA 0061)the Science and Technology Project of Chongqing Education Commission(KJ1600625,KJ1500637)the Application and Basic Science Project of Ministry of Transport of People's Republic of China(2015319814100)the Innovative Research Project from CTBU(yjscxx2016-060-36)~~
摘要The semimetal Bi has received increasing interest as an alternative to noble metals for use in plasmonic photocatalysis. To enhance the photocatalytic efficiency of metallic Bi, Bi microspheres modified by SiO2 nanoparticles were fabricated by a facile method. Bi-O-Si bonds were formed between Bi and SiO2, and acted as a transportation channel for hot electrons. The SiO2@Bi microspheres exhibited an enhanced plasmon-mediated photocatalytic activity for the removal of NO in air under 280 nm light irradiation, as a result of the enlarged specific surface areas and the promotion of electron transfer via the Bi-O-Si bonds. The reaction mechanism of photocatalytic oxidation of NO by SiO2@Bi was revealed with electron spin resonance and in situ diffuse reflectance infrared Fourier transform spectroscopy experiments, and involved the chain reaction NO -> NO2 -> NO3- with center dot OH and center dot O-2(-) radicals as the main reactive species. The present work could provide new insights into the in-depth mechanistic understanding of Bi plasmonic photocatalysis and the design of high-performance Bi-based photocatalysts. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.