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571.
文章建立了基于HLB固相萃取柱和气相色谱,电子捕获(GC/ECD)分析水体中有机氯农药的方法.并对方法的回收率、灵敏度进行了评价,同时分析了北京市燕山石油化工有限公司五个典型企业排放废水中有机氯农药的浓度,发现存在六六六(HCHs)。滴滴涕(DDT)等有机氯污染物,在5个采样点的水样中有机氯农药的浓度为(0.76-14.S)ng/L。其中六六六、滴滴涕的含量分别为(0.76~10.5)ng/L和(4.89-14.8)ng/L。方法对有机氯农药的空白加标回收率达到74.6%-118.4%。方法检测限为(0.27~2.90)ng/L。 相似文献
572.
利用CFD方法模拟了三相填料塔内部流场的速度分布。采用欧拉—欧拉多相流模型描述流场内固体及流体的运动情况。通过5种不同高径比填料塔的模拟结果表明,当高径比〉8时,可将填料塔看作理想的平推流,为填料塔设计提供了设计依据。 相似文献
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575.
利用固相萃取(SPE)-气相色谱-质谱法(GC-MS)对嘉陵江和长江重庆段河流和以这两条河流为水源的5个自来水厂水样中壬基粉(NP)进行了检测,河流水样中4月份NP的浓度范围为0.02-1.12μg/L,7月份为1.55-6.85μg/L,自来水厂的水样中,4月份NP浓度范围为<0.01-0.06μg/L,7月份为.10-2.73μg/L,方法的自来水加标回收率大于90%,环境水样中的加标回收率大于80%,检测限为0.01μg/L. 相似文献
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Base on the previous work in laboratory, a novel polyaniline doped with polydimethylsiloxane coating was developed on a stainless steel wire for solid phase microextraction(SPME) by electroplating method. This electroplating method not only has advantages of ease preparation and simple equipments required, but also increases the lifetime of the SPME fiber. The composite fiber(polyaniline/ polydimethylsiloxane(PANI/PDMS)) was evaluated by analyzing n-tridecane, n-tetradecane and n-pentadecane in aqueous sample. The new fiber coating showed comprehensive abilities to extract alkanes compounds. The relative standard deviations were found to be 6.8%-10.33%. 相似文献
578.
鉴于持久性有机物在环境中的结合和承载机制,作者认为,对于持久性有机物,环境可以抽象为气相、水相、有机碳相和脂相等四个均质、同结合作用的环境相,为描述持久性有机物在环境相间的平衡分配行为,引入了“泛逸度”的概念,建立了环境相间相平衡酌泛逸度模型,并以DDT为例尝试了模型的应用。 相似文献
579.
Two-dimensional multiphase flow and transport simulators were refined and used to numerically investigate the entrapment and dissolution behavior of tetrachloroethylene (PCE) in heterogeneous porous media containing spatial variations in wettability. Measured hydraulic properties, residual saturations, and dissolution parameters were employed in these simulations. Entrapment was quantified using experimentally verified hydraulic property and residual saturation models that account for hysteresis and wettability variations. The nonequilibrium dissolution of PCE was modeled using independent estimates of the film mass transfer coefficient and interfacial area for entrapped and continuous (PCE pools or films) saturations. Flow simulations demonstrate that the spatial distribution of PCE is highly dependent on subsurface wettability characteristics that create differences in PCE retention mechanisms and the presence of subsurface capillary barriers. For a given soil texture, the maximum and minimum PCE infiltration depth was obtained when the sand had intermediate (an organic-wet mass fraction of 25%) and strong (water- or organic-wet) wettability conditions, respectively. In heterogeneous systems, subsurface wettability variations were also found to enhance or diminish the performance of soil texture-induced capillary barriers. The dissolution behavior of PCE was found to depend on the soil wettability and the spatial PCE distribution. Shorter dissolution times tended to occur when PCE was distributed over large regions due to an increased access of flowing water to the PCE. In heterogeneous systems, capillary barriers that produced high PCE saturations tended to exhibit longer dissolution times. 相似文献
580.
Viscous, semi-rigid interfacial films that are formed at the interface of certain multi-component non-aqueous phase liquid (NAPLs) and water can significantly reduce the rates of mass transfer of solutes. Creosote-water systems were investigated for their ability to form interfacial films. The effects of these films on the creosote-water partition and on mass transfer of a representative solute, naphthalene, were investigated in a series of experiments. The area-independent mass transfer coefficient of naphthalene contained in creosote decreased by 30% over a 1-week period in systems containing creosote and water. Further aging for up to 21 days did not result in significant additional decreases in the mass transfer coefficient. The creosote-water partition coefficient, however, did not change with extended contact. The presence of viscous interfacial films in creosote-water systems was demonstrated in pendant drop tests. These interfacial films most likely caused the reduction in solute mass transfer coefficients by providing significant resistance to the diffusion of solutes through the interfacial film. Results from mass transfer experiments conducted under different system conditions suggested that hindered diffusion of naphthalene through the bulk creosote phase, changes in composition of creosote as a result of extended dissolution, or changes in creosote-water interfacial area did not contribute to the decrease in naphthalene mass transfer coefficient. 相似文献