共查询到20条相似文献,搜索用时 207 毫秒
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中空纤维封闭液膜用于乳酸分离 总被引:4,自引:0,他引:4
利用中空纤维封闭液膜技术对乳酸的分离进行了研究,采用三烷基胺(7301)+正辛醇+煤油混合溶剂为萃取剂,以水作为反萃剂,在聚砜中空纤维膜器中进行实验。研究结果表明,在中空纤维封闭液膜技术分离乳酸中,总传质阻力与料液相流速和反萃相流速的1/3次方均呈反比关系。实验研究了鼓泡技术对强化质的影响,在中空纤维膜器壳程中鼓入空气有利于提高传质系数。实验中还讨论了反萃液温度对过程的影响,传质阻力随着操作温度的 相似文献
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简述了中空纤维膜分离原理、开车步骤,分析了中空纤维膜氢回收系统标定数据,指出存在的问题,并进一步对比分析了加氢干气直接作为制氢原料和用中空纤维膜氢回收系统的非渗透气作为制氢原料的优缺点. 相似文献
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荷电聚砜中空纤维超滤膜的研究 总被引:3,自引:0,他引:3
以氯甲基化聚砜为原料,二甲基乙酰胺为溶剂,聚乙二醇为添加剂,研究了膜液组成和纺丝条件对膜性能的影响,选择适当的膜液组成和纺丝条件,可制得截留分子量为6万以上的中空纤维超滤膜,其截留率可达90%以上,用CMPS中空纤维膜经三甲胺水溶液处理后,可制得季铵化聚砜中空纤维荷正电超滤膜。 相似文献
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采用干湿法纺丝工艺纺制了聚砜中空纤维N2-H2分离膜,研究了料液伯浓度、温度、组成及中空纤维壁厚对膜性能的影响,用电镜照片观察和分析了膜的结构并结合相转化原理地讨论。 相似文献
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Laboratory research and engineering applications demonstrated that oxygen aeration can rapidly increase the level of dissolved oxygen in the water of severely polluted rivers.This method was capable of eliminating the odorous substances from black odorous water and reducing the color shade of water,but could not remove the NH3-N,COD,TP or other common pollutants.Therefore,oxygen aeration can be implemented to rapidly eliminate black odorous from rivers,lakes and reservoirs,but cannot be used as a permanent method for treating pollution of rivers. 相似文献
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H. Kenneth Hudnell David Green Ron Vien Scott Butler Greg Rahe Bruce A. Richards Joel Bleth 《Clean Technologies and Environmental Policy》2011,13(5):731-742
Electrical grid-powered aeration is used in most pond-based systems and equalization basins at activated sludge wastewater
treatment plants to provide the mixing and oxygenation that enables bacteria to digest organic-matter. Oxygen also is needed
in the near-surface water of all ponds and basins to provide an “odor cap” by oxidizing malodorous sulfur compounds, preventing
their release to air. Much more aeration typically is needed to mix than oxygenate the wastewater. This imbalance causes an
operational inefficiency in that grid-power is used to supply more oxygen than needed. The U.S. Environmental Protection Agency
concluded that the use of solar-powered circulation (SPC) technology reduces the need to aerate, operational costs, and greenhouse
gas emissions associated with electrical power generation. However, the Agency did not quantify electrical, water quality,
or other parameters. The New Hampshire Department of Environmental Services directed a 3-site study to quantify the ability
of SPC to replace some or all aeration while maintaining good effluent water quality. Water quantity and quality, odor event,
and kilowatt-hour consumption and expenditure data were collected 1 year prior to, and 2 years during, SPC treatment at pond-based
treatment plants in Pittsfield and Exeter, and at the activated sludge treatment plant in Rochester. Final effluent water
quality was maintained, no effluent violations or odor events occurred, and sludge buildup was minimal during the SPC study
period. Electricity usage and costs declined by about 38% in Pittsfield and Exeter, and by about 87% in Rochester, resulting
in carbon dioxide emission reductions of 273,161, 918,183, and 1,082,509 kg, respectively. Payback periods ranged from 1.9
to 3.7 years. SPC improved operational efficiency at the plants by reducing grid-power consumption while operational objectives
were met. The 25-year expected lifetime of SPC units with minimal maintenance requirements indicated long-term reductions
in operational expenses and greenhouse gas emissions. 相似文献
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An analysis of the catastrophic corrosion of the hot water pipeline system was made. The cause was oxygen, dissolved in water due to the malfunctioning of the degassing device in the water preparation phase. Because of differential aeration, cathodic and anodic areas formed underneath the oxide deposit on the bottom side of the pipeline. The consequence of the thus activated pitting corrosion was pipeline perforation. It is imperative to regularly test the water for dissolved oxygen and monitor its pH value. 相似文献
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Review on modelling of corrosion under droplet electrolyte for predicting atmospheric corrosion rate
Bangalore Gangadharacharya Koushik Nils Van den Steen Mesfin Haile Mamme Yves Van Ingelgem Herman Terryn 《材料科学技术学报》2021,62(3):254-267
Atmospheric corrosion of metals is the most common type of corrosion which has a significant impact on the environment and operational safety in various situations of everyday life.Some of the common examples can be observed in land,water and air transportation systems,electronic circuit boards,urban and offshore infrastructures.The dew drops formed on metal surface due to condensation of atmospheric moisture facilitates corrosion as an electrolyte.The corrosion mechanisms under these droplets are different from classically known bulk electrolyte corrosion.Due to thin and non-uniform geometric thickness of the droplet electrolyte,the atmospheric oxygen requires a shorter diffusion path to reach the metal surface.The corrosion under a droplet is driven by the depletion of oxygen in the center of the droplet compared to the edge,known as differential aeration.In case of a larger droplet,differential aeration leads to preferential cathodic activity at the edge and is controlled by the droplet geometry.Whereas,for a smaller droplet,the oxygen concentration remains uniform and hence cathodic activity is not controlled by droplet geometry.The geometry of condensed droplets varies dynamically with changing environmental parameters,influencing corrosion mechanisms as the droplets evolve in size.In this review,various modelling approaches used to simulate the corrosion under droplet electrolytes are presented.In the efforts of developing a comprehensive model to estimate corrosion rates,it has been noted from this review that the influence of geometric evolution of the droplet due to condensation/evaporation processes on corrosion mechanisms are yet to be modelled.Dynamically varying external factors like environmental temperature,relative humidity,presence of hygroscopic salts and pollutants influence the evolution of droplet electrolyte,making it a complex phenomenon to investigate.Therefore,an overview of available dropwise condensation and evaporation models which describes the formation and the evolution of droplet geometry are also presented from an atmo s pheric corrosion viewpoint. 相似文献
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Short-wavelength near-infrared (SW-near-IR) spectroscopy (700-1100 nm) is used for the determination of ethanol during the time course of a fermentation. Measurements are performed noninvasively by means of a photodiode array spectrometer equipped with a fiber-optic probe placed on the outside of the glass-wall fermentation vessel. Pure ethanol/water and ethanol/yeast/water mixtures are studied to establish the spectral features that characterize ethanol and to show that determination of ethanol is independent of the yeast concentration. Analysis of the second-derivative data is accomplished with multilinear regression (MLR). The standard error of prediction (SEP) of ethanol in ethanol/water solutions is approximately 0.2% over a range of 0-15%; the SEP of ethanol in ethanol/yeast/water solutions is 0.27% (w/w). Results from the mixture experiments are then applied to actual yeast fermentations of glucose to ethanol. By use of a gas chromatographic method for validation, a good correlation is found between the intensity of backscattered light at 905 nm and the actual ethanol. Additional experiments show that a calibration model created for one fermentation can be used to predict ethanol production during the time course of others with a prediction error of 0.4%. 相似文献
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Clement Owusu Jonas Addai-Mensah Daniel Fornasiero Massimiliano Zanin 《Advanced Powder Technology》2013,24(4):801-809
Prudent control of ore pulp chemistry via parameters such as redox potential (Eh), dissolved oxygen (DO) and pH, can markedly improve the flotation recovery, grade and selectivity of sulphide minerals. In this paper, the electrochemical reactivities of two pyrite minerals and their impact on chalcopyrite flotation are investigated using oxygen demand test and froth flotation. Changes in the surface chemistry/speciation are also investigated using X-ray photoelectron spectroscopy (XPS) and EDTA extraction technique. The oxygen demand test shows that the different pyrite ores display significantly different electrochemical reactivity. Furthermore, continuous aeration of the pulp reduces the reactivity of the pyrite ores. Solution and surface analysis results suggest the formation of hydroxide surface coatings on the pyrite surface as aeration progresses, preventing or minimising further oxidative reactions from taking place in the pulp. Flotation results showed that the flotation response of chalcopyrite is influenced by the pulp DO/Eh, and therefore the type and reactivity of the pyrite associated with it. 相似文献
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影响一体式平板膜生物反应器临界通量的因素 总被引:1,自引:0,他引:1
利用阶梯式通量递增法测定了一体式平板膜-生物反应器中的临界通量,对不同操作条件下测定值的差异进行了考察.通过正交试验设计,研究了曝气强度、污泥浓度(MLSS)和滤液COD(SCOD)三个因素分别在0.8,1.2,1.5 m3/h;10,20,30 g/L和50,100和150 mg/L水平下对临界通量测得值的影响.研究发现,污泥浓度和SCOD均对临界通量测得值呈负影响作用,而曝气强度则起正作用.随着污泥浓度和SCOD的增大,临界通量测得值是逐步减小的;而曝气强度的增大在一定程度上可以提高临界通量值.其中,临界通量测定值受SCOD的影响最大,MLSS次之,曝气强度最小. 相似文献