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分形理论研究吸附过程的特性 总被引:4,自引:0,他引:4
本文介绍分形理论研究吸附过程的特性。着重讨论利用吸附质-分子探针-电化法实验技术,研究固-液吸附过程的分形结构,定义和求取吸附质粒子在吸附过程中运动轨道的吸附分维Dw。 相似文献
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电化法研究壳聚糖树脂与游离酸的相互作用 总被引:12,自引:1,他引:12
利用电化实验技术,跟踪观察交联壳聚糖树脂吸附低浓度游离酸的行为,讨论了酸和甲醇浓度等因素对吸附的影响,利用固-液相互作用方程,求取吸附剂一吸附质相互作用能。实验结果表明,交联壳聚糖树脂吸附低浓度游离酸的过程是遵循单分子层机制进行的,表观吸附速率常数随着吸附质浓度和外加甲醇含量的增大而减小,表观吸附速率常数与吸附剂一吸附质相互作用能(U)存在线性相关。 相似文献
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固液界面是自然界普遍存在的一种界面。从生命起源到宇宙旅行,从工农业生产到日常生活,都离不开固液界面的问题。吸附作用就是发生在固液界面上最基本的一种现象。研究溶液吸附必须考虑吸附剂、溶质和溶剂三者的相互作用,以及界面分子定向的可能影响。在这方面,液相吸附与混合气体的吸附有相似之处。现时混合气体吸附理论还在萌芽时期,这就不难理解为何至今还没有一个完整的溶液吸 相似文献
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本文从研究液固吸附动态分析装置如何稳压、稳流及如何检测原位信息等关键问题入手,设计和建立了一套可用于液固体系离子吸附研究的动态分析装置,并通过实验证明该液固吸附动态分析装置能快速、准确地给出离子在吸附剂上的吸、脱附动态信息,为液固体系的吸附研究提供了一种可靠的手段。 相似文献
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制备了SO42-、NO3-、ClO4-和F-、Cl-、Br-、I-两种新型阴离子苯乙烯-二乙烯苯聚合物微球,基于吸附质-分子探针电导法,研究了阴离子聚合物吸附低浓度游离酸的性能,考察了阴离子类型和温度对吸附行为的影响。实验结果表明,在30℃时,吸附游离酸的过程,遵循单分子层机理进行吸附。吸附剂-吸附质相互作用能U制约表观吸附速率常数K,两者存在线性相关性,K、U均随阴离子的离子势增大呈逐渐减小的趋势。吸附过程为吸热的,吸附焓变ΔH为10.87 kJ.mol-1。吸附过程谱维数ds增大,导致表观吸附速率常数降低。吸附质对吸附剂的亲和能Ua随吸附质-吸附剂相互作用参数K2增大而减小。 相似文献
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介绍了氨基酸在固体表面吸附的常见吸附模式和吸附等温线类型。在常见的等温式中Sips等温式能处理液相中吸附质浓度从低到高、吸附剂表面从均匀到不均匀等各种情形下的固/液吸附体系,得到的等温线一般归属4类:S型、L型、H型和C型;总结和讨论了各吸附参数对氨基酸吸附的影响,具体考察了氨基酸种类、固体表面的性质、溶剂种类、介质的pH、介质离子强度和温度等因素对氨基酸吸附的影响,指出通过优化各吸附参数,可以调整氨基酸和固体吸附剂之间的静电吸引力或疏水作用,达到最好的吸附效果;对氨基酸的固体吸附剂进行了分类阐述。 相似文献
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Yu. K. Tovbin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(10):1611-1625
The conditions of layering of adsorbate molecules in porous systems with characteristic sizes of from 1 to 50–100 nm are discussed. The porous systems contain both very narrow pores, in which interaction potentials of pore walls overlap, and comparatively broad pores without overlapping of surface potentials. Three pore size intervals are distinguished. In the first interval, no adsorbate layering occurs, the second interval is characterized by capillary condensation with critical parameters different from their volume values, and, in the third interval, capillary condensation conditions are almost the same as in the volume adsorbtive phase. Criteria of the characteristic pore sizes of different geometries are formulated; the criteria correspond to small volumes in which first-order phase transitions are absent. The boundary between the first and second pore size regions is observed experimentally as the disappearance/appearance of hysteresis loops in adsorption-desorption isotherms measured under strictly equilibrium conditions as the size of pores decreases/increases. A nonuniform distribution of the surface potential is shown to be responsible for the multiplicity of local regions in porous media with their own vapor-liquid coexisting phases. The spinodal transitions in adsorption-desorption in pores can occur between various local regions. An analysis is performed in terms of the lattice gas model with short-range Lennard-Jones interaction of adsorbate molecules with each other and adsorbent walls. 相似文献
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Manfred Parschau Dr. Daniele Passerone Dr. Karl‐Heinz Rieder Prof. Dr. Hans J. Hug Prof. Dr. Karl‐Heinz Ernst Priv.‐Doz. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(22):4065-4068
Pumped up : Propene molecules form chiral complexes when adsorbed on a copper surface. Inelastically scattered tunneling electrons from the tip of a scanning tunneling microscope induce rotation or diffusion of the adsorbate on the surface. Higher tunneling currents can lead to conversion of the adsorbate into the opposite enantiomer.
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B. J. Winter T. D. Klots E. K. Parks S. J. Riley 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,19(4):381-384
Equilibrium reactions of ammonia with cobalt and nickel clusters are analyzed to determine cluster-adsorbate binding energies. The temperature dependence of reaction equilibrium constantsK eq are measured and ?ΔH 0 values obtained from plots of lnK eq vs 1/T. We find that binding energies generally decrease with increasing ammonia coverage, and that for a given number of NH3 molecules binding energies increase with increasing cluster size. The pattern of binding energies is found to be consistent with proposed geometrical structures for Co19 and for clusters in the 55-atom size range. Cluster-ammonia binding energies are generally somewhat higher than for bulk metal surfaces, an expected result considering the character of the cluster surface and the nature of the NH3-metal interaction. 相似文献
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M. Pons 《Adsorption》1998,4(3-4):299-311
Adsorption cycles with heat regeneration are a promising CFC-free alternative to compression cycles, for refrigeration or heat pumping purposes. However, the process is complex and therefore requires efficient analysis tools to understand correctly. These tools are now developed and used here for studying the phenomenon of internal adsorbate redistribution. This phenomenon takes place during the periods when the adsorber is pressurised, or depressurised, under globally isosteric conditions. It can be easily thought that internal adsorbate redistribution reduces the cycle performance. In order to avoid this reduction, the adsorbate redistribution can be reduced by implementing separate vapour compartments inside the adsorbers, which also requires the installation of additive check valves between the adsorber, condenser and evaporator.The present study shows that, in fact, this phenomenon does not affect performance. In addition, thanks to the different analysis tools, a physical explanation of this result, based on first and second laws of thermodynamics is developed. This result is then valid for any heat regenerative cycle using an adsorption pair. 相似文献
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Yuriy K. Tovbin 《Adsorption》2005,11(3-4):245-257
The equilibrium distribution and the concentration dependence of the local and average self-diffusion coefficients for pure
fluid and binary mixture components in narrow slitlike pores were analyzed. The coefficients were calculated using the lattice
gas model in the quasi-chemical approximation on the assumption of a spherical shape and approximately equal sizes of the
components. For the pure adsorbate, these calculations were compared with molecular dynamics simulations. Both methods gave
similar concentration profile changes and dynamic characteristics of interlayer particle redistributions in strong nonuniform
adsorption fields for dense fluids. A satisfactory agreement was obtained for the temperature dependences of the self-diffusion
coefficients along the pore axis. The influence of the molecule–wall potential and of intermolecular interaction were considered.
The self-diffusion coefficients of the adsorbate were shown to strongly depend on the density of the mixture and the distance
from pore walls. 相似文献