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以疏水性离子液体1-甲基-3-丁基咪唑六氟磷酸盐([bmim]PF6)为萃取剂,液-液体系中对6种常见有机染料结晶紫、孔雀绿、罗丹明B、亚甲基蓝、铬天青S以及偶氮氯膦Ⅲ的萃取行为进行了研究,考察了溶液pH、萃取时间、离子液体浓度以及盐的含量对萃取率的影响.结果表明,离子液体对水中不同结构染料的萃取能力有很大差异:在pH 3—9的条件下,离子液体对结晶紫和亚甲基蓝的萃取能力很强,萃取率均在90%以上;在pH值3—5的条件下,对孔雀绿的萃取率在86%以上;在pH值为3的条件下,对罗丹明B的萃取率为94%,且酸度减小时萃取率下降;在pH 7—11时对铬天青S和偶氮氯膦Ⅲ的萃取率分别小于36%和29%,且酸度增大时萃取率下降.对各种染料均可在5—10 min内完成萃取,萃取后分相迅速,相界面清晰,无浑浊或第三相形成,有着传统有机溶剂无法比拟的优点.本研究对采用离子液体萃取净化染料废水和回收废弃燃料具有一定的参考价值. 相似文献
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采用NaClO催化氧化法对活性黄X-R废水进行了脱色降解的系统研究,探讨了反应条件对脱色效果的影响,分析了染料的降解机理.结果表明,该方法对染料的脱色率不到50%,脱色率随着染料和有效氯浓度的增加而略微增大,随着初始pH的上升而减小,催化剂的投加对脱色率的影响甚微.NaClO氧化法的对比实验结果表明,NaClO的直接氧... 相似文献
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采用渗流式电化学反应器,以碳纳米管和活性碳纤维作为反应器的阳极.选取活性艳蓝X-BR模拟废水作为实验对象,计算电化学过程的传质系数,考察电压、pH值和电解质对活性艳蓝脱色的影响,在优化条件下(电压为8V,pH=2,电解质浓度为1g·l-1),对浓度为200mg·l-1活性艳蓝X-BR的脱色率可达90%以上. 相似文献
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不同染料化合物在天然锰矿界面的脱色特性 总被引:41,自引:0,他引:41
本文考察了染料化合物在天然锰矿界面脱色特性,并探讨溶液pH值、环境温度、不 照射及颗粒物浓度和粒径对脱色效果的影响。实验表明,溶液pH值是影响染料脱色效果的最主要因素,光照对不同染料化合物脱色有不同程度的影响。颗粒物浓度升高及粒径降低有利于染料脱色,温度升高,直接耐晒红F3B脱色率提高,将不同温度下,该染料脱色率随时间的变化按一级反应动力学方程模拟,再依据阿累尼乌斯方程,求得直接耐晒红F3B在天然 相似文献
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本文以对位芳香族聚酰胺(PPTA)超滤膜为基膜,无水哌嗪(PIP)与1,3,5-苯三甲酰氯(TMC)分别作为水相单体和油相单体,采用界面聚合法制得高通量耐热PPTA/PA复合纳滤膜.研究了反应条件对PPTA/PA复合纳滤膜高温纳滤性能影响,观察了复合纳滤膜表面形貌与致密层结构,考察了渗透通量、耐热性以及抗污染等性能.结果表明,当PIP浓度为15%wt,TMC浓度为2.5%wt,热处理温度和时间分别为60℃和8 min时,所得PPTA/PA复合纳滤膜对不同染料分子截留率可达95%以上,对二价盐截留率可达90%以上.在高温条件下,所得PPTA/PA复合纳滤膜表现出优良的染料脱盐性能,在刚果红染料与Na2SO4截留率保持在99%的同时,渗透通量可达50 L·m-2·h-1·MPa-1以上. 相似文献
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采用静态箱-气象色谱法对干旱区不同种植年限苜蓿人工草地土壤系统、土壤-植被系统的CO2排放通量进行了测定,并对土壤 CO2排放通量的主要影响因素,包括土壤碳氮质量分数、土壤温度、气温、土壤水分体积分数、生物量进行了测定分析,从而得到了苜蓿生长季内CO2排放通量规律及影响土壤CO2排放的主要因素。结果表明:观测期内各个年限土壤-植被系统与土壤系统的CO2排放趋势基本一致,总体表现为4a〉5a〉8a〉3a〉1a,表现出“夏季高秋季低”的季节变化规律,具有明显的季节变化动态,各样地CO2通量在7月中旬达到最高排放通量;土壤CO2排放通量与0~20 cm土层内土壤有机碳质量分数、活性有机碳质量分数、土壤C:N及土壤全N质量分数都具有正相关关系,并且都达到了显著水平;土壤CO2排放通量与5 cm土壤温度和大气温度都有正相关关系,并且显著水平很高(P<0.001);土壤CO2排放通量与0~10 cm土壤水分体积分数之间没有显著的相关性(P〉0.05);土壤CO2排放通量与地上部分生物量的大小有直接的正相关关系,并且CO2排放通量与地上生物量具有相同的变化趋势。 相似文献
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Gravity driven flows on inclines can be caused by cold, saline or turbid inflows into water bodies. Another example are cold
downslope winds, which are caused by cooling of the atmosphere at the lower boundary. In a well-known contribution, Ellison
and Turner (ET) investigated such flows by making use of earlier work on free shear flows by Morton, Taylor and Turner (MTT).
Their entrainment relation is compared here with a spread relation based on a diffusion model for jets by Prandtl. This diffusion
approach is suitable for forced plumes on an incline, but only when the channel topography is uniform, and the flow remains
supercritical. A second aspect considered here is that the structure of ET’s entrainment relation, and their shallow water
equations, agrees with the one for open channel flows, but their depth and velocity scales are those for free shear flows,
and derived from the velocity field. Conversely, the depth of an open channel flow is the vertical extent of the excess mass
of the liquid phase, and the average velocity is the (known) discharge divided by the depth. As an alternative to ET’s parameterization,
two sets of flow scales similar to those of open channel flows are outlined for gravity currents in unstratified environments.
The common feature of the two sets is that the velocity scale is derived by dividing the buoyancy flux by the excess pressure
at the bottom. The difference between them is the way the volume flux is accounted for, which—unlike in open channel flows—generally
increases in the streamwise direction. The relations between the three sets of scales are established here for gravity currents
by allowing for a constant co-flow in the upper layer. The actual ratios of the three width, velocity, and buoyancy scales
are evaluated from available experimental data on gravity currents, and from field data on katabatic winds. A corresponding
study for free shear flows is referred to. Finally, a comparison of mass-based scales with a number of other flow scales is
carried out for available data on a two-layer flow over an obstacle. Mass-based flow scales can also be used for other types
of flows, such as self-aerated flows on spillways, water jets in air, or bubble plumes. 相似文献
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The flux of cohesive sediment in an estuary is determined by many factors, including tidal asymmetry, wave effect, fluvial
influence, phase difference between tidal velocity and tidal level fluctuations, sediment properties, flocculation, bed erodibility,
bathymetry effect and other nonlocal effects. Our capability in predicting sediment fluxes in tide-dominant environments is
critical to the morphodynamics and water quality of estuaries. Due to the difficulties in carrying out detailed measurement
of sediment flux with high spatial and temporal resolutions, an one-dimensional-vertical (1DV) numerical model for cohesive
sediment transport, previously verified and calibrated with field measured cohesive sediment concentration data, is utilized
here to study some of the aforementioned factors in affecting tidal-driven sediment fluxes in idealized condition. Tidal-averaged
sediment flux is shown to be correlated with tidal velocity skewness with a linear relationship. This linear relationship
is different from that of non-cohesive sediment and it is demonstrated here to be mainly due to variable critical shear stress
implemented for the mud bed in order to parameterize consolidation. The reason that tidal velocity skewness causes tidal-averaged
residual sediment transport is shown to be due to nonlinear intra-tidal interactions between flow velocity and sediment concentration.
Moreover, the effects of nonlinear intra-tidal interaction between tidal velocity and tidal level fluctuations is shown to
mainly cause seaward transport, which is the most significant under progressive wave system (phase difference 90°) and almost
negligible for standing wave system (phase difference 0°). 相似文献
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Nikolay A. Vinnichenko Yulia Yu. Plaksina Ksenia M. Baranova Alexey V. Pushtaev Alexander V. Uvarov 《Environmental Fluid Mechanics》2018,18(5):1045-1056
Dynamics of the surface layer in different liquids is examined by means of infrared thermography of the surface and simultaneous velocity fields measurements using surface and infrared Particle Image Velocimetry. This technique allows measurements and comparison of two velocity fields—at the surface and at small depth about 50–200 μm. In distilled water the velocity fields at the surface and at small depth exhibit significant dissimilarity. The flow field below the surface is essentially 3D, whereas the surface flow is characterized by vanishing 2D divergence of velocity, indicating predominantly planar motion. In contrast, in ethanol–butanol mixture two velocity fields are well correlated, both corresponding to 3D flow with continuous surface renewal. Thermal patterns, observed at the surface, and the flow field structure in different liquids are associated with different boundary conditions for velocity at the surface. Water surface is seldom renewed, which inhibits heat and mass exchange between the liquid and atmosphere. However, absence of vertical advection also enables organisms to live within the surface layer, to stand and walk on the free surface. This is illustrated by the difficulties a water strider faces on the surface of ultrapure water, which exhibits Marangoni convection. 相似文献
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Tao Ma Haiqing Hui Xiaofei You Zhiqiang Pei Miao Tian Bing Wu 《Frontiers of Environmental Science & Engineering》2022,16(9):118
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Runsheng Zhong Chunwei Zhu Xihui Zhang Yuntao Guan 《Frontiers of Environmental Science & Engineering》2007,1(3):276-279
The turbidity variation in artificial water and samples from a water plant was investigated in the presence of organics with different relative molecular mass. The results show that recessive turbidity existed when water chemical conditions were changing. The formation of turbidity depended on organic relative molecular mass and their conformations on particles. At higher pH and lower ionic strength, the organic chains with a more extended conformation resulted in rising turbidity of the suspension. At lower pH, the reconformation of organics took place due to charge neutralization by the proton, resulting in a decline in turbidity. The addition of NaCl and MgCl2 at pH 7.00 also resulted in a decrease of turbidity in the suspension. It is believed that the occurrence of recessive turbidity has a significant influence on the stability of water supply quality. 相似文献
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The vertical diffusional mass (solute) transfer through a suspended sediment layer, e.g. at the bottom of a lake, reservoir or estuary, by the propagation of velocity fluctuations from above was investigated. The attenuation of the velocity fluctuations in the suspension layer and the associated effect on solute transfer through the suspension layer was simulated. To represent large eddies traveling downstream in water over a high-concentration suspended sediment layer, a streamwise velocity fluctuation moving in downstream direction was imposed along the upper boundary of the suspension layer. Velocity fluctuations and downstream velocity were normalized by the shearvelocity (U*) at the top of the suspension layer. Streamwise and vertical velocity components inside the suspension layer, were obtained from the 2-D continuity and the Navier–Stokes equations. The persistence of turbulence with depth—as it penetrates from the overlying water into the suspension layer—was found to depend on its amplitude, its period, and on the apparent viscosity of the suspension. The turbulence was found to propagate efficiently into the suspension layer when its frequency is low, and the apparent viscosity of the suspension is high. Effects on vertical mass transfer were parameterized by penetration depth and effective diffusion coefficient, and related to apparent viscosity of the suspension, Schmidt number and shear velocity on top of the suspension layer. The enhancement of turbulence penetration by viscosity is similar to the flow near an oscillating flat plate (Stokes’ second problem), but is opposite to turbulence penetration into a stationary porous and permeable sediment bed. The information is applicable to water quality modeling mear the sediment/water interface of lakes, river impoundments and estuaries. 相似文献
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Khosa MK Sidhu BS Benbi DK 《Journal of environmental biology / Academy of Environmental Biology, India》2010,31(3):281-285
A field experiment was conducted for two years on a sandy loam (Typic Ustochrept) soil of Punjab to study the effect of organic materials and rice cultivars on methane emission from rice fields. The methane flux varied between 0.04 and 0.93 mg m(-2) hr(-1) in bare soil and transplanting of rice crop doubled the methane flux (0.07 to 2.06 mg m(-2) hr(-1)). Among rice cultivars, significantly (p < 0.05) higher amount of methane was emitted from Pusa 44 compared to PR 118 and PR 111. Application of organic materials enhanced methane emission from rice fields and resulted in increased soil organic carbon content. The greatest seasonal methane flux was observed in wheat straw amended plots (229.6 kg ha(-1)) followed by farmyard manure (111.6 kg ha(-1)), green manure (85.4 kg ha(-1)) and the least from rice straw compost amended plots (36.9 kg ha(-1)) as compared to control (21.5 kg ha(-1)). The differential effect of organic materials in enhancing methane flux was related to total carbon or C:N ratio of the material. The results showed that incorporation of humified organic matter such as rice straw compost could minimize methane emission from rice fields with co-benefits of increased soil fertility and crop productivity. 相似文献
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An Ding Yingxue Zhao Zhongsen Yan Langming Bai Haiyang Yang Heng Liang Guibai Li Nanqi Ren 《Frontiers of Environmental Science & Engineering》2020,14(4):59
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Jonathan O. Okonkwo Linda L. Sibali Rob McCrindle Zachary N. Senwo 《Environmental Chemistry Letters》2007,5(3):121-123
Currently, South Africa is designing a strategy for surface water protection involving organic contaminants such as dichlorodiphenyltrichloroethane
(DDT), which is currently used for malaria control in mosquito-infested areas. Here, we demonstrate the successful use of
an improved activated carbon technique using dichloromethane instead of chloroform, and slower leaching rate of 15 mL/min
to quantify DDT and its metabolites in surface water. The recovery tests for 2,4′DDT, 2,4′DDD, 2,4′DDE, and 4,4′DDT, 4,4′DDD,
4,4′DDE ranged from 75 to 84% and 87 to 96%, respectively (DDE: dichlorodiphenyldichloroethylene, DDD: dichlorodiphenyldichloroethane).
The main advantages of this technique over conventional liquid–liquid extractions are reduced amount of organic solvent, little
sample preparation, and larger sample throughput. Because activated charcoal is fairly cheap, the technique can be routinely
used to quantify and monitor DDT and its metabolites in surface water samples. 相似文献