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911.
高硅FAU沸石与甲胺吸附物的相互作用 总被引:1,自引:0,他引:1
合成高硅沸石中所用的模板剂胺类分子与沸石骨架 Si—O基团间的相互作用机理尚不清楚 .迄今为止 ,沸石与吸附胺之间的相互作用的研究还只限于测定沸石酸性质 [1,2 ]、表面羟基活性位或了解模板分子在沸石骨架中的位置和状态 [3,4 ] .甲胺、乙胺在骨架完美的高硅 FAU(Y型 )沸石上的亲和性指数 AT 值 ,即被吸附有机物脱附峰温与该有机物的沸点之差分别高达 1 60与 1 5 0℃[5] .而在高硅 MFI(Silicalite-1 )沸石上为 1 60与 1 2 7℃ [6 ] .与大多数有机物不同 ,被吸附的胺类脱附时的吸热效应十分明显 .上述现象表明胺与高硅沸石骨架 O2 -… 相似文献
912.
Recently, ozone concentrations have increased dramatically as a result of vehicle usage in metropolitan areas. Ozone precursors are composed of hydrocarbons of organic compounds. Because hydrocarbons are indicative of ozone formation, they need to be monitored in ambient air. Since ozone precursor are present at very low levels (from ppb to ppt) in ambient air, they are difficult to analyze accurately. This study investigates ozone precursors in ambient air. The main purpose of this study is to compare analytical methods for the measurement of ozone precursors in atmosphere. Two measurement methods were evaluated using canister (Silco-canister) and adsorbent (300-mg Carbopack B+150-mg Carbosieve SIII) tube. Differences in measurements for total ozone precursor emissions were 54.1% between the adsorption tube and canister-GC/MS, 51.1% between adsorption tube and canister-GC/FID, and 16.3% between canister-GC/MS and canister-GC/FID. 相似文献
913.
本文详细考察了大孔聚苯乙烯型吸附树脂对不同大小吸附质分子的吸附动力学行为,当吸附过程为粒扩散控制时,树脂孔径与分子尺寸的相对大小不仅决定了粒扩散速度的大小,也影响了粒扩散的控制机制.随着吸附质分子尺寸的增加,决定粒扩散速度的控速步骤也逐渐由表面扩散转向孔扩散。此外,还利用建立的扩散方程,测定了树脂吸附不间大小的吸附质时的粒扩散常数B和有效粒扩散系数De。 相似文献
914.
SDS micelles flocculate in the presence of Al3+, creating an aggregate with pollutant-removing properties. The fraction of SDS micelles flocculating depends on the concentrations
of SDS and Al3+. This paper describes how this fraction also changes with pH. There are two reasons for this dependence: a change in pH has
a strong effect in the solution chemistry of Al3+, converting it into the compound [Al13O4(OH)24]7+, a strong flocculant, or precipitating it as Al(OH)3; and at low pH protons may compete with Al3+ as binding counter-ions for micelles. An increase in pH allows flocculation of SDS at high concentrations of Al3+, which under unmodified pH does not occur. Micelle flocculates are reported in this work to exist between pH 5 and pH 8,
suggesting the potential use of Adsorptive Micellar Flocculation for the removal of anionic pollutants from waste waters not
necessarily limited to acidic solutions.
Received: 18 August 2000 Accepted: 5 October 2000 相似文献
915.
Understanding adsorption phenomena involving humic acids and clays is a difficult challenge owing to their complex nature.
Thus, to progress in the study of such systems, attempts were made to replace natural systems by polyacids and oxides of simpler
chemical and morphological structure. Since the present investigation was dedicated to determine some characteristics of acidic
soils which contain traces of aluminium ions, these ions were added to the adsorbent/polyacid systems as trace constituents.
Phenomena related to the interactions of humic or polyacrylic acid with aluminium oxide and kaolinite clay have been investigated
and the well-differentiated interfacial behaviour of the oxide and kaolinite was determined and discussed. The results of
electrophoretic mobility measurements demonstrated the huge time-dependent effect of polymeric layers adsorbed on oxides and
modified clays.
Received: 24 July 2000 Accepted: 20 December 2000 相似文献
916.
SHI Zuoqing XU Mancai LIN Xue XU Mingcheng FAN Yunge SHI Rongfu YANG Yizhong HE Binglin 《Chinese Journal of Reactive Polymers》2000,(1)
1 INTRODUCTIONPhenol and many substitUted phenols, such as nitrophenols, chlorophenols and aminophenolset al, are the common organic pollutantS existing in wane water of many chemical plants.Treatment of the wastewater containing phenols is an important project for environmentprotection and has been studied by various methods, such as dialysis ['l, microbial degradation ['1,oxidation l'l, extracting with solvents I4] and adsorption with polymeric adsorbents IS]. Theadsorption method is v… 相似文献
917.
XU Zhida ZENG Hanmin FENG Yangqiao Materials Science Institute of Zhongshan University Guangzhou China Research Institute of Guangzhou Petrochemical Complex Guangzhou China 《Chinese Journal of Reactive Polymers》2000,(2)
Sulfideisoneofthemainpollutionsources.Ifthereweremorethiolsingasoline,thiolswouldmakegasolinegivingoffafoulsmellandcausingcorrosionofmetal.Therefore,manycountriessetstrictdemandstothiolscontentingasoline.Ingeneral,thecontentofthiol-sulfuringasolineisrequestedtobelow10ppm.ActivatedCarbonFiber(ACF)isanewkindofecomaterial[1].Itssuperadsorptioncapacitymakesithavewiderandwiderapplicationprospectsinenvironmentalprotection.ThefurtherstudiesonACFareboththeoreticallyandpracticallyimportant.Therear… 相似文献
918.
919.
Changes in density and surface tension of water in silica pores 总被引:3,自引:0,他引:3
T. Takei K. Mukasa M. Kofuji M. Fuji T. Watanabe M. Chikazawa T. Kanazawa 《Colloid and polymer science》2000,278(5):475-480
The density and surface tension of water in small pores of silicas have been investigated. These physical properties of water
in the pores were calculated from a comparison of pore volumes and pore radii which were estimated from adsorption and desorption
isotherms of nitrogen and water. Below a pore radius of about 5 nm both the density and the surface tension of water in the
pores were smaller than those of the bulk liquid and decreased with a decrease in pore size. The density of water in the pores
decreased with an increase in the concentration of surface hydroxyl groups. Similarly the surface tension of water in the
pores is influenced by the surface hydroxyl groups. Anomalous changes in the density and surface tension of the water in the
pores are attributed to the interaction of water molecules with surface hydroxyl groups and hydrogen-bond formation among
water molecules.
Received: 20 April 1999 Accepted in revised form: 17 November 1999 相似文献
920.
Douglas M. Ruthven 《Adsorption》2000,6(4):287-291
The transient uptake response of an adsorbent particle, subjected to a step change in surface concentration, is considered. It is shown that, when the isotherm is highly favorable, the theoretical curves derived for a Langmuirian system reduce asymptotically to the much simpler form for a rectangular isotherm. The simple rectangular model provides a useful approximation even when the form of the actual isotherm is quite far from the rectangular limit. 相似文献