Determination of probable mechanism function and kinetic parameters is important to hydrometallurgical kinetics.In this work,the most probable mechanism function and kinetic parameters of gibbsite dissolution in NaOH ...Determination of probable mechanism function and kinetic parameters is important to hydrometallurgical kinetics.In this work,the most probable mechanism function and kinetic parameters of gibbsite dissolution in NaOH solution are studied.The sample,the mixture of synthetic gibbsite and sodium hydroxide solution,was scanned in high-pressure differential scanning calorimetry(DSC) equipment with the heating rate of 10 K·min-1. Integral equation and differential equation of non-isothermal kinetics were solved to fit the data related to DSC curve.According to the calculation results,the most probable mechanism function for pure synthetic gibbsite dissolution in sodium hydroxide solution is presented based on the optimum procedure in the database of the mechanism function.The apparent activation energy obtained is(75±1) kJ·mol-1,the frequency factor is 10 8±1mol·s-1,and the reaction is a second order reaction.展开更多
With continuous and slow oxygen-release characteristic, calcium peroxide （CaO2） has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were co...With continuous and slow oxygen-release characteristic, calcium peroxide （CaO2） has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were conducted to evaluate the oxygen-release rate of CaO2reacting with water, the regulation of high pH, as well as the growth of mixed aerobic microbes in the medium containing CaO2, The results show that the oxygen-release process of CaO2 comprises three phases. In the first phase, dissolved oxygen levels of water increased sharply, and average oxygen-release rates increased as the adding weight of CaO2 increased, However, the rates almost kept invariable in the latter phases and were approximately 0.48; and 0. 084 mg O2·h^-1, respectively. As the necessary components of medium, potassium dihydrogen phosphate （KH2PO4 ） and amrnoniurn sulphate （（NH4）2SO4） at a certain ratio could regulate pH caused by CaO2 from 12, 1 to the range of 6.5 -8.5, which is helpful for microbial growth, In addition, diauxic growth curve observed in the medium containing CaO2 suggested that the growth of mixed aerobic microbes could be stimulated by the addition of CaO2.展开更多
基金Supported by the Research Fund for the Doctoral Program of Higher Education(20050145029)the Science and Technology Talents Fund for Excellent Youth of Liaoning Province(2005221012)
文摘Determination of probable mechanism function and kinetic parameters is important to hydrometallurgical kinetics.In this work,the most probable mechanism function and kinetic parameters of gibbsite dissolution in NaOH solution are studied.The sample,the mixture of synthetic gibbsite and sodium hydroxide solution,was scanned in high-pressure differential scanning calorimetry(DSC) equipment with the heating rate of 10 K·min-1. Integral equation and differential equation of non-isothermal kinetics were solved to fit the data related to DSC curve.According to the calculation results,the most probable mechanism function for pure synthetic gibbsite dissolution in sodium hydroxide solution is presented based on the optimum procedure in the database of the mechanism function.The apparent activation energy obtained is(75±1) kJ·mol-1,the frequency factor is 10 8±1mol·s-1,and the reaction is a second order reaction.
基金Supported by National Natural Science Foundation of China (No. 20276048).
文摘With continuous and slow oxygen-release characteristic, calcium peroxide （CaO2） has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were conducted to evaluate the oxygen-release rate of CaO2reacting with water, the regulation of high pH, as well as the growth of mixed aerobic microbes in the medium containing CaO2, The results show that the oxygen-release process of CaO2 comprises three phases. In the first phase, dissolved oxygen levels of water increased sharply, and average oxygen-release rates increased as the adding weight of CaO2 increased, However, the rates almost kept invariable in the latter phases and were approximately 0.48; and 0. 084 mg O2·h^-1, respectively. As the necessary components of medium, potassium dihydrogen phosphate （KH2PO4 ） and amrnoniurn sulphate （（NH4）2SO4） at a certain ratio could regulate pH caused by CaO2 from 12, 1 to the range of 6.5 -8.5, which is helpful for microbial growth, In addition, diauxic growth curve observed in the medium containing CaO2 suggested that the growth of mixed aerobic microbes could be stimulated by the addition of CaO2.
