The nanometer TiO2 was prepared by pyrohydrolysis with titanic solution.The effects of species and content of the surfactants on the particle size,morphology and phase of TiO2 were studied by using LPA,XRD and TEM res...The nanometer TiO2 was prepared by pyrohydrolysis with titanic solution.The effects of species and content of the surfactants on the particle size,morphology and phase of TiO2 were studied by using LPA,XRD and TEM respectively.The results show that it is beneficial to reducing the aggregation of TiO2 particles with adding surfactants to the solution.Nanometer TiO2 powders with the size of 40-55 nm are obtained by adding the anion surfactants in the optimal content of 1.5%(mass fraction).The effect of cationic surfactant for reducing particle aggregation is not as good as that of anion.The crystal phase constitutent of TiO2 is dependent on the temperature of thermal treatment and complete anatase can be achieved after calcining in the temperature range of 350-750℃.展开更多
The pyrolysis properties of five different pyrolysis tars, which the tars from 1# to 5# are obtained by pyrolyzing the sewage sludges of anaerobic digestion and indigestion from the A2/O wastewater treatment process, ...The pyrolysis properties of five different pyrolysis tars, which the tars from 1# to 5# are obtained by pyrolyzing the sewage sludges of anaerobic digestion and indigestion from the A2/O wastewater treatment process, those from the activated sludge process and the indigested sludge from the continuous SBR process respectively, were studied by thermal gravimetric analysis at a heating rate of 10 ℃/min in the nitrogen atmosphere. The results show that the pyrolysis processes of the pyrolysis tars of 1#, 2#, 3# and 5# all can be divided into four stages: the stages of light organic compounds releasing, heavy polar organic compounds decomposition, heavy organic compounds decomposition and the residual organic compounds decomposition. However, the process of 4# pyrolysis tar is only divided into three stages: the stages of light organic compounds releasing, decomposition of heavy polar organic compounds and the residual heavy organic compounds respectively. Both the sludge anaerobic digestion and the "anaerobic" process in wastewater treatment processes make the content of light organic compounds in tars decrease, but make that of heavy organic compounds with complex structure increase. Besides, both make the pyrolysis properties of the tars become worse. The pyrolysis reaction mechanisms of the five pyrolysis tars have been studied with Coats-Redfern equation. It shows that there are the same mechanism functions in the first stage for the five tars and in the second and third stage for the tars of 1#, 2#, 3# and 5#, which is different with the function in the second stage for 4# tar. The five tars are easy to volatile.展开更多
基金Project(04GK2007)supported by the Key Project of Science and Technology Plan of Hunan Province,China
文摘The nanometer TiO2 was prepared by pyrohydrolysis with titanic solution.The effects of species and content of the surfactants on the particle size,morphology and phase of TiO2 were studied by using LPA,XRD and TEM respectively.The results show that it is beneficial to reducing the aggregation of TiO2 particles with adding surfactants to the solution.Nanometer TiO2 powders with the size of 40-55 nm are obtained by adding the anion surfactants in the optimal content of 1.5%(mass fraction).The effect of cationic surfactant for reducing particle aggregation is not as good as that of anion.The crystal phase constitutent of TiO2 is dependent on the temperature of thermal treatment and complete anatase can be achieved after calcining in the temperature range of 350-750℃.
基金supported by the project of Tianjin higher education under contract (20060522)the project of Tianjin Polytechnic University (2230004)
文摘The pyrolysis properties of five different pyrolysis tars, which the tars from 1# to 5# are obtained by pyrolyzing the sewage sludges of anaerobic digestion and indigestion from the A2/O wastewater treatment process, those from the activated sludge process and the indigested sludge from the continuous SBR process respectively, were studied by thermal gravimetric analysis at a heating rate of 10 ℃/min in the nitrogen atmosphere. The results show that the pyrolysis processes of the pyrolysis tars of 1#, 2#, 3# and 5# all can be divided into four stages: the stages of light organic compounds releasing, heavy polar organic compounds decomposition, heavy organic compounds decomposition and the residual organic compounds decomposition. However, the process of 4# pyrolysis tar is only divided into three stages: the stages of light organic compounds releasing, decomposition of heavy polar organic compounds and the residual heavy organic compounds respectively. Both the sludge anaerobic digestion and the "anaerobic" process in wastewater treatment processes make the content of light organic compounds in tars decrease, but make that of heavy organic compounds with complex structure increase. Besides, both make the pyrolysis properties of the tars become worse. The pyrolysis reaction mechanisms of the five pyrolysis tars have been studied with Coats-Redfern equation. It shows that there are the same mechanism functions in the first stage for the five tars and in the second and third stage for the tars of 1#, 2#, 3# and 5#, which is different with the function in the second stage for 4# tar. The five tars are easy to volatile.
