共查询到20条相似文献，搜索用时 15 毫秒
1.
The influence of several operational parameters, including pH, flow rate, total volume of water passed, and choice of eluants, upon the efficiency of extraction of organic matter from seawater by two forms of commercially-available resin, XAD-2 and XAD-8, is considered. The overall efficiency of adsorption is at best 40%. The main factor determining the adsorption efficiency of XAD resin for natural organic matter is pH. The efficiency at normal seawater pH is only half that at pH 2.0. Although the efficiency decreases with increasing flow rate, the decrease is not great up to 3 bed vol./min. With increasing volume of water passed, the adsorption capacity of the resin initially drops, but reaches an approximately constant level after 1000 bed volumes. Alkaline solutions, either NH4OH or NaOH, followed by methanol, completely recover adsorbed organic material from the resin. There is no significant advantage of XAD-8 over XAD-2 for seawater extractions, and the materials adsorbed by the two forms of resin are not substantially different.A new separation method combining XAD-2 resin and activated carbon as adsorbents in series in a column has been developed. Efficiencies of up to 90% were obtained in the extraction of acidified seawater. When the volume of water passed was less than 500 bed volumes, the adsorption as measured by UV-oxidation was quantitative. Elution of 90–100% of the adsorbed organic carbon was possible when ammonium hydroxide (7 M), methanol and an ammonium hydroxide—methanol mixture were used sequentially. 相似文献
2.
MECHANISM OF URANIUM ADSORPTION ON AMIDOXIME RESIN 总被引：1，自引：0，他引：1
The mechanism of uranium adsorption from seawater by polyacrylamidoxime resin is investigated by means of the experiments of adsorption isotherm and adsorption rate. The uranium uptake increases with the adsorption temperature and varies with the pH of seawater. Thermochemical and kinetic calculation show that the enthalpy change (△H) and the activation energy (E) of the uranium adsorption are 42.4 42.4 kJ mol-1 and 41.2 kJ mol-1 respectively, indicating that the uranium adsorption on the resin proceeds via a certain complex chemical reaction in which the amidoxime group in the resin chelates uranyl ions. 相似文献
3.
The adsorption behaviour for uranium of four kinds of amidoxime resinst RNH, RCH, RAH and RPH in seawater has been investigated. It has been found that all these resins are capable of adsorbing rapidly uranium from U-cnriched seawater with a high uranium uptake.RNH was able to adsorb uranium satisfactorily from natural seawater, and the uranium uptake of RNH with a degree of cross-linking of 3-5 mol % was above 200 μg/g-R (adsorption for 15 days). The uranium uptakes of RCH, RAH and RPH from natural seawater were much lower than the uranium uptake of RNH. The factors which caused the difference between resins RCH, RAH, RPH and resin RNH are discussed. 相似文献
4.
A novel approach to in situ extraction of Cs radionuclides from seawater is described which offers many advantages over previous methods. Cesium (stable and radioactive) is partially stripped from seawater as it passes in series through a tandem cartridge consisting of twin beds of ion exchange resin impregnated with cupric ferrocyanide. It is demonstrated that, when seawater passes through this cartridge at a constant flow-rate, collection efficiencies of each bed are the same, allowing the calculation of the seawater Cs nuclide concentration. The cartridge is made of inexpensive, readily available, PVC pipe fittings and is easily deployed under various field conditions. Procedures are described for resin preparation and desorption and radiochemical purification of the collected Cs. Thousands of liters of seawater can be stripped of Cs in this way, permitting substantial improvement in the sensitivity of measurement of 134Cs and 137Cs. 相似文献
5.
为了筛选纯化紫菜类菌孢素氨基酸(mycosporine-like amino acid,MAAs)的离子交换树脂,优化纯化工艺,并研究纯化后MAAs体外抗紫外辐射活性,本研究通过静态动力学吸附及解析实验,筛选纯化树脂;结合动态动力学吸附及解析单因素实验建立响应面法对SA-2型阳离子树脂纯化MAAs的二次多项式模型,对MAAs的纯化工艺进行优化;通过建立大肠杆菌、金黄色葡萄球菌的复合紫外线(UVA+UVB)损伤模型,分析纯化后MAAs样品的体外抗辐射活性。结果表明:静态动力学吸附及解析实验筛选出SA-2型阳离子树脂为纯化MAAs的最佳树脂,吸附率和解析率分别为86.01%和56.63%;吸附的最佳工艺条件为:上样液质量浓度3 g/L、上样流速1 m L/min、上样液pH为6、洗脱液体积分数为3%、洗脱流速为1.5 m L/min、洗脱液pH为6;在此条件下吸附率为79.21%,洗脱率为64.02%;纯化后的MAAs样品能有效抑制紫外辐射而造成的损伤,将菌种失活速度分别降低了39.10%和40.58%,表现出显著的抗紫外辐射活性。 相似文献
6.
Manfred Ehrhardt 《Marine Chemistry》1989,26(4)
Lipophilic dissolved material was concentrated by in-situ liquid-solid adsorption on Amberlite XAD-2 resin from glass-fibre-filtered coastal seawater in the upper Arabian Gulf in the fall of 1986. 10% aqueous acetone was used for countercurrent desorption under reflux. In the concentrated eluate petroleum components were characterized and quantified by GC-MS as were ketonic photo-oxidation products of alkylbenzenes. Concentrations of the latter exceeded those of unaltered petroleum components by roughly a factor of 10. 相似文献
7.
Methyl esters of saturated and unsaturated fatty acids were isolated as trace components from organic material suspended in seawater. Methyl palmitate and methyl stearate were accumulated from the filtrate by adsorption onto Amberlite XAD-2 resin. Identification of most methyl esters is based on the comparison of gas chromatographic retention indices and mass spectrometric fragmentation with those of authentic standard compounds. In cases where reference substances were not available, identification is based on mass spectrometric and gas chromatographic properties of the unknown compounds. 相似文献
8.
厦门港表层沉积物对海水中铅的吸附动力学 总被引：1，自引：0，他引：1
模拟研究厦门港表层沉积物对海水中Ｐｂ的吸附动力学及水环境条件的影响,当海水温度由２０－３０℃、ＰＨ５－８和盐度３０－４变化时,吸附速率分别提高约５０％、、个数量和５倍。吸附速率与盐度之间呈负指数相关关系。吸附过程可用交换吸附动力学模式描述。测定吸附速率常数、表观活化能和平衡吸附量等参数研究表明,沉积物对Ｐｂ的吸附性质以华东作用为主。 相似文献
9.
沙滩水体中溶解性石油烃的降解及吸附研究 总被引：2，自引：0，他引：2
以海水体系和海水-砂体系作为对比,研究了沙滩水体中溶解性石油烃的降解及吸附作用。实验结果表明,1d内海水中石油浓度的降低主要是由于砂的快速吸附作用,3d以后生物对石油烃的降解作用逐渐占据优势。两种体系中降烃菌数量及石油浓度的变化曲线表明,砂对油的快速吸附显著降低了海水中石油污染物的浓度,使得海水含砂体系中石油降解菌的数量远高于海水体系。海水中石油污染物的降解符合一级动力学模式,当含砂体系中砂的粒径不同时,石油污染物降解的半衰期可由海水体系的31.9d缩短到22.4d和19.5d。系统中砂的存在有利于海水中石油污染物的去除,有约20%的石油污染物被吸附到砂上,然而这种去除是物理去除。 相似文献
10.
Velocity and suspension measurements in the logarithmic layer of hydraulically smooth turbulent tidal flow from the North Sea are reported. The data were not compatible with the assumption of Newtonian flow for the experimental seawater—clay suspension.Laboratory measurements were initiated with mud and seawater from the North Sea in which the boundary-layer structure of this two-phase flow was measured down into the viscous sublayer. The dilute seawater—clay suspension was a mixture of illite, kaolinite and chlorite minerals with concentrations less than 380 mg/l and exhibited turbulent drag reduction.By reviewing flow measurements of other authors it is suggested that turbulent drag reduction occurs on a geophysical scale if the flows transport cohesive sediments. It is proposed that drag reduction is caused by dynamic interaction between turbulent shear strain in the flow and deformation of aggregates.As a consequence, the values of the critical friction velocity and of erosion rates must be reviewed for cohesive bottom materials. Normally they were obtained under the assumption of a Newtonian flow structure which is not applicable if the flow transports cohesive sediments.To detect the occurrence of drag reduction in geophysical boundary layers (hydraulically smooth), flow measurements must be performed down into the viscous sublayer. The adequate velocity sensors must have a diameter of ?1 mm. 相似文献
11.
12.
Organic compounds which are chloroform extractible from seawater affect gypsum precipitation by inhibiting the nucleation of crystals. The effect is selective towards calcium-populated crystal habit faces and results in the growth of more tabular, equidimensional crystals. Studies using model organic compounds suggest that the inhibition takes place through an adsorption mechanism and show that longer-chained n-fatty acids are more actively adsorbed. The specific adsorption mechanism (at Ca2+ habit faces) is also supported by the fact that the free-acid (base-soluble) fraction of the chloroform extractibles from seawater is more active than the neutral fraction. The calcium ion complexing ability of model organic compounds is not correlatable with their inhibitory effects on gypsum crystal nucleation. 相似文献
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14.
实验测定了海水中氨基酸存在下Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附的等温线、Ｃｕ（Ⅱ）％－－ｐＨ曲线和Ｃｕ（Ⅱ）％－氨基酸深度曲线。结果表明，较低浓度氨基酸对Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附没有影响，而较高浓度氨基酸却起抑制作用，这主要是由于海水中Ｃｕ（Ⅱ）－氨基酸络合反应与ｒ－ＭｎＯＯＨ竞争Ｃｕ（Ⅱ）所致。此外，海水中较高浓度氨基酸只使Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附的表面分级离子交换稳定常数Ｋｉ（ｉ 相似文献
15.
大连大魏家滨海岩溶区海水入侵化学过程 总被引：10，自引：1，他引：9
通过不同比例的海水与淡水的混合作用及其混合水对碳酸盐岩的混合溶蚀作用的室内模拟实验,对滨海岩溶区海水入侵过程中的化学过程和水-岩作用进行了研究。在海水入侵过程中,海水与淡水的混合作用是以机械混合为基础的复杂化学过程;过渡带混合水对围岩(碳酸盐岩)的混合溶蚀作用则是以分子扩散和表面反应为主的复杂化学过程;而混合水与岩溶空间内的松散沉积物间的各种离子交换作用主要是阳离子交换吸附。室内模拟试验和野外实测地下水化学组分剖面资料对应说明,淡水、海水界面之间的过渡带中部区的混合溶蚀作用最强,亦可能是岩溶最发育的部位。 相似文献
16.
海洋浮游细菌生长率和被摄食的研究综述 总被引：2，自引：0，他引：2
海洋浮游细菌利用海水中的溶解有机碳合成自身物质,是海洋浮游生态系统的二次生产者。微型浮游动物是细菌的主要摄食者,也是细菌生产向较高营养级传递的中介。研究海洋浮游细菌的生长率和被(微型浮游动物的)摄食率对理解海洋浮游生态系统的功能具有重要作用。本文综述了利用改变海水中生物类群组成(或功能)的培养方法研究海洋浮游细菌生长率和被摄食率的历程和现状,为我国的同类研究提供借鉴。改变海水中生物类群组成(或功能)进行培养的方法有海水分粒级培养、海水稀释培养和添加选择性抑制剂培养。这些方法各有其局限性,应用并不广泛。细菌及其主要摄食者异养鞭毛虫群落在自然海区和实验室内都有生长周期,鞭毛虫的生长周期落后于细菌,因此细菌的生长率有时会小于被摄食率,有时会大于被摄食率。我国这方面的研究相对落后,应值得引起重视,建议从海水稀释培养法入手开展相关研究。 相似文献
17.
本研究建立了AMS(Accelerator mass spectrum,加速器质谱)测定海水中129 I的气载分离制样方法:对加入载体的海水样品进行氧化还原处理,在加热的条件下将生成的单质碘吹出,并使用吸收装置吸收,后经阴离子交换树脂富集纯化,最后生成用于AMS分析的AgI沉淀,本方法全程回收率50%~70%,在相对密闭的体系中进行,减少了碘的损失,相对于萃取-反萃取的制样方法具有可操作性强,避免有机试剂使用等优点,可用于固态、液态和气态样品中129 I的AMS分析制样。 相似文献
18.
Metal-organic complexes of transition elements removed by Amberlite XAD-2 resin from seawater pumped up from under the ground were determined. The proportions of iron, copper and zinc retained on the resin to dissolved forms of these metals were about 70, 40 and 5%, respectively, while manganese, cobalt and nickel were not retained on the resin. These results suggest that although iron may be retained in colloidal form, a significant fraction of copper is present in some organic form(s). 相似文献
19.
The natural “complexing capacity” of aquatic systems was determined using titration with cupric ions. It was compared with “complexing capacity” determined in the presence of both EDTA, used as a model for organic substances, and of EDTA and γ-Al2O3. The γ-Al2O3 was used as a model for solid particles of hydrous oxide in natural waters. The adsorption isotherm of copper in seawater on γ-Al2O3 particles was determined with and without EDTA.For EDTA alone and for the Cu—EDTA complex, it was found that they are not adsorbed on γ-Al2O3 in the natural seawater. However, by adsorption on solid particles, the labile ionic Cu-complex can be removed from the seawater. 相似文献
20.
用简化动力系统模型模拟海水入侵,评估未来漳浦县旧镇梅宅村海水入侵的发展趋势,提出减缓和预防海水入侵的措施,并预测监测点海水入侵的矿化度.结果表明:要减缓海水入侵的速度需要8 a时间,矿化度变为6.243 0 g/L,这表明如果发生海水入侵,恢复的时间比较漫长.但通过增加淡水水源,并淡水水头水位保持在6.2个单位(1单位... 相似文献