重量法测定环戊烷在silicalite—l分子筛上的吸附特性

用智能重量分析技术（IGA）研究了环戊烷在silicalite-l分子筛上的吸附特性。结果表明，随着温度的降低，环戊烷的吸附等温线从第一类型过渡为第国类型，在254K和274K温度下吸附等温线呈现滞后环，为第四类型，而吸附等温线在304K、323K下为阶梯形，在354K、423K温度下呈第一类型，其中423K温度下的吸附等温线可准确的用Langmuir方程来描述。本文同时讨论了吸附质分子间以及吸附质和吸附剂间的相互作用、分子结构特性、分子筛对吸附质分子的空间位阻、分子筛的能量不均匀表面等对环戊烷在silicalite-l分子筛上吸附性能的影响。     

吸附质大小对吸附树脂粒内扩散行为的影响(Ⅰ)——大孔聚苯乙烯型吸附树脂粒内扩散机制的考察

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。     

一种确定煤基吸附剂内各扩散系数的简易方法

多孔介质内的扩散有分子扩散和表面扩散两种。在吸附温度较高时 ,表面扩散可忽略 ,而在温度较低的吸附过程中 ,两种扩散均须考虑。Ｓｃｈｎｅｉｄｅｒ和Ｓｍｉｔｈ[1 ] 曾用色谱法探讨了一种计算扩散系数的方法。他们认为等温吸附呈线性变化 ,引入了曲折系数 ,计算出分子扩散系数 (下称气相扩散系数 ) ,表面扩散系数 (下称吸附相扩散系数 )则由综合扩散系数减去分子扩散系数得到。文献 [2 ]则认为吸附过程非线性变化 ,服从Ｆｒｕｎｄｌｉｃｈ方程或Ｌａｎｇｍｕｉｒ方程。从质量平衡方程得出相对吸附量方程 ,再求出各扩散系数。前一种方法将…     

苯与丙烯在MCM-22型分子筛内吸附行为的Monte Carlo研究

采用巨正则统计系综Monte Carlo模拟方法研究了不同温度、不同吸附方式下纯硅MCM-22型分子筛ITQ-1上苯与丙烯分子的吸附行为. 分子筛内吸附质粒子云分布模拟结果显示, 苯和丙烯主要吸附在超笼和十元环孔道内, 其中丙烯分子几乎充满了孔道内部大部分区域, 在链接超笼之间的十元环窗口也充满了丙烯分子, 而苯分子在超笼内和十元环孔道内的吸附却较为分散、均匀. 丙烯与分子筛之间相互作用能高于苯与分子筛之间的相互作用能, 使苯分子吸附相对丙烯分子更为稳定. 温度变化对分子筛上丙烯吸附远大于对苯吸附的影响, 100 kPa时温度由298 K升高至443 K导致丙烯分子吸附量迅速减少, 而对苯分子却没有显著的影响. ITQ-1分子筛上存在苯和丙烯分子的竞争吸附, 使两者吸附相互作用能最可几分布朝着折中方向移动. 苯与丙烯在分子筛内吸附等温线的模拟结果表明, 在温度较高、压力较低时, 丙烯的吸附量小于苯的吸附量.     

重量法测定环戊烷在silicalite-1分子筛上的吸附特性

用智能重量分析技术 (IGA)研究了环戊烷在silicalite 1分子筛上的吸附特性。结果表明 ,随着温度的降低 ,环戊烷的吸附等温线从第一类型过渡为第四类型 ,在 2 5 4K和 2 74K温度下吸附等温线呈现滞后环 ,为第四类型 ,而吸附等温线在 30 4K、32 3K下为阶梯形 ,在 35 4K、42 3K温度下呈第一类型 ,其中 42 3K温度下的吸附等温线可准确的用Langmuir方程来描述。本文同时讨论了吸附质分子间以及吸附质和吸附剂间的相互作用、分子结构特性、分子筛对吸附质分子的空间位阻、分子筛的能量不均匀表面等对环戊烷在silicalite 1分子筛上吸附性能的影响     

苯与丙烯在β分子筛上吸附行为的蒙特卡罗研究

采用巨正则统计系综蒙特卡罗模拟方法研究了β分子筛上苯与丙烯分子的吸附行为. 由分子筛内吸附质粒子云分布可知, 在100 kPa时, 丙烯在分子筛上的吸附量要远远大于苯的吸附量. 由吸附相互作用能分布来看, 苯与分子筛之间相互作用能比丙烯与分子筛之间的相互作用能更负, 这就使苯分子的吸附相对于丙烯分子稳定. 相对而言, 温度变化对丙烯吸附影响远大于对苯吸附的影响, 如100 kPa时, 温度由298 K升高至443 K导致丙烯分子吸附量明显减少, 由每8个晶胞吸附98个丙烯分子减少到80个; 而对苯分子吸附却没有显著的影响. β分子筛上存在着苯和丙烯的竞争吸附, 并且吸附分子之间存在相互作用使两者与分子筛之间的相互作用能分布改变. 在压力范围1×10－3～5.0 kPa, 不同温度下苯与丙烯在分子筛内吸附等温线的模拟结果表明, 在较高温度、较低压力下丙烯的吸附量要小于苯的吸附量.     

应用Polanyi吸附势理论描述超高交联树脂对多环芳烃的吸附

研究了萘、苊、芴三种多环芳烃类化合物在超高交联吸附树脂HC-1上的静态吸附平衡行为,分别采用Langmuir、Freundlich和Poanyi-Dubinin-Manes模型方程对吸附平衡数据进行了拟合分析,并探讨了吸附机理。实验结果表明,基于微孔填充机理的Polanyi-Dubinin-Manes方程能较好地拟合吸附平衡数据,表明树脂的微孔区对吸附起着重要作用。实验结果也表明,吸附质分子尺寸是影响吸附效果的重要因素,吸附质分子越大则吸附量越小;采用吸附质分子尺寸对Polanyi-Dubinin-Manes方程中吸附势密度进行修正,以体积吸附量对修正后吸附势密度作图,可得到一条与吸附质无关的特性曲线,根据该曲线方程可有效预测二、三环的多环芳烃化合物在HC-1上的吸附性能。     

球形阳离子凝胶的制备及吸附性能研究

以醛、酮、胺为原料,采用溶液缩聚和反相悬浮聚合制备了新型高吸附容量球形阳离子凝胶,对产物的分子结构和表面形貌进行了表征。通过吸附实验,研究了其对阴离子染料氨基黑10B和表面活性剂十二烷基苯磺酸钠(SDBS)的吸附效果,并讨论了吸附行为和机理。实验结果表明,球形阳离子凝胶具有较高的阳离子度和大量极性官能团,其对氨基黑和SDBS的吸附是基于静电引力和氢键等分子间力共同作用的结果,凝胶吸附效果随溶液pH的降低而升高。吸附质分子随溶液渗透进入球形凝胶并被吸附于凝胶内表面,故该吸附主要由吸附质在凝胶内部的扩散过程控制,具有较高的饱和吸附量。     

ND-100超高交联吸附树脂对水中苯酚的吸附行为研究

通过静态吸附试验，研究了ND－100超高交联树脂对水溶液中苯酚的吸附动力学和热力学特性，探讨了初始浓度对吸附过程的影响。结果表明 ND－100树脂对苯酚的吸附速率同时受液膜扩散和颗粒内扩散过程控制。吸附符合Langmuir和Freundlich等温吸附方程，吸附量随着温度的升高而降低，随着平衡浓度的增大而增大，吸附表现为放热的物理吸附过程。     

生物碳质吸附剂对水中有机污染物的吸附作用及机理

以松针为生物质代表,通过控制不同炭化温度（100～700℃）,制备了一系列生物碳质吸附剂,表征了其结构和表面特征;以4-硝基甲苯为目标,探讨吸附剂在水中对有机污染物的吸附性能、机理及与其结构特征之间的定量关系,为制备经济高效吸附剂和预测其吸附性能与机制提供理论依据．结果表明,生物碳质吸附剂的芳香性随炭化温度的升高而急剧增加、极性指数（（N＋O）/C）则急剧降低,逐渐从“软碳质”过渡到“硬碳质”,同时其比表面积则迅速增大．生物碳质吸附剂对水中4-硝基甲苯具有强的吸附能力,等温吸附曲线符合Freundlich方程,N指数和1gKf与其芳香性呈良好的线性关系．定量描述了分配作用与表面吸附对生物碳质总的吸附作用的贡献．表面吸附的贡献量随炭化温度升高而迅速增大,表面饱和吸附量与吸附剂的比表面积呈良好的线性正关系;硬碳质吸附剂的最大表面吸附量（Qmax,SA）与理论计算值（2．45μmol／m^2）相当,而软碳质吸附剂的Qmax．SA值则高于理论值．生物碳质的分配作用（Kom）取决于分配介质与有机污染物的“匹配性”和“有效性”,Kom值随（N＋O）/C降低呈现先升高后降低的趋势．     

环戊烷和环己烷在silicalite-1上的吸附、扩散和热脱附

Adsorption,diffusion and thermal desorption features of cyclopentane and cyclohexane in silicalite-1 have beeninvestigated using the intelligent gravimetric technique.Both the saturation adsorption loadings and diffusion coef-ficient of cyclopentane were greater than those of cyclohexane.The diffusivity of cyclopentane was about one orderof magnitude greater than that of cyclohexane at the same temperature and initial loading.For cyclopentane,therewas only one kind of desorption process at adsorption loadings lower than 4 muc(molecule per unit cell),but twodesorption processes appeared at the adsorption loadings higher than 4 muc.While for cyclohexane,one desorptionprocess was found in the whole range of loadings.Both thermal desorption peaks of cyclopentane and cyclohexanemoved to higher temperature region with increasing loading.     

Study of benzene sorption in H-ZSM-5 zeolite under catalytic conditions

The equilibrium of the sorption of benzene in an H-ZSM-5 zeolite has been investigated in the temperature range of 100-400°С and at partial pressures 0.11÷0.57 аtm. The data on the sorption under these conditions could be fitted with the Langmuir isotherms taking into account a linear decrease in heats of sorption with the increase in the sorbate loading. The equilibrium constants and heat of the sorption have been determined. This revised version was published online in June 2006 with corrections to the Cover Date.     

芳香类化合物在ITQ-1分子筛中吸附特性的蒙特卡罗模拟

用巨正则统计系综蒙特卡罗模拟研究了苯、甲苯以及间二甲苯分子在ITQ-1分子筛中的吸附特性.从这3种分子的粒子分布云图上,可发现分子的扩散和吸附主要在十二元环超笼内发生,在十元环通道内的吸附和扩散则相对较难.从一系列不同压力下的蒙特卡罗模拟还预测了3种分子的吸附等温线,预测结果与实验结果相符.这3种分子在一定压力下,都可通过十元环通道或连接十二元环超笼的十元环窗口到达分子筛孔道内部,达到较好的吸附平衡状态.     

Sorption and diffusion of low molecular weight gases and vapors in glassy polymers at high concentration of sorbate

A theoretical approach has been developed to describe the sorption and diffusion processes of low weight molecular gases and vapors in polymers at wide ranges of sorbate concentration. The equation of an S‐shaped gas sorption isotherm in glassy polymer matrix has been derived. The concentration dependence of the sorbate molecule diffusion coefficient has been established. For an S‐shaped sorption isotherm, this dependence is nonmonotonous. The conditions of cluster formation of sorbate molecules have been analyzed within the proposed approach, in which it is possible to determine a correlation between these conditions and parameters of sorption isotherm. The comparison of the experimental and theoretical data provides an assessment of the microscopic characteristics of investigated polymer–vapor systems, such as the distances between vapor molecules in a matrix corresponding to intermolecular repulsion and attraction. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2314–2323, 1999     

Thermal stability of poly[1‐(trimethylsilyl)‐1‐propyne] and the gas chromatographic stationary phase based on it

The thermal stability of poly[1‐(trimethylsilyl)‐1‐propyne] is investigated by heating the capillary column with this polymer as the stationary phase with the subsequent separation of the test mixture of light hydrocarbons. It is shown that heating of the column up to 130°C does not cause a decrease in efficiency or in the retention time of solutes. A further increase in temperature results in both decrease in column efficiency and sorbate retention. However, a decrease in column retentivity goes in one way for all the tested hydrocarbons. At the same time, the efficiency of the column is changed to a lesser degree for methane and ethane up to the temperature of polymer degradation, while for propane, butane, and iso‐butane the difference is rather sharp. The most expressed decrease in efficiency was found for iso‐butane: the column efficiency for this sorbate versus temperature of heating had two stages. The diffusion coefficients for sorbates in the polymeric phase were also evaluated and the sharp decrease in their values was found after the column heating.     

Estimation of the kinetic characteristics of sorption of an organic ion on a heterogeneous crosslinked polymer sorbent within the framework of a bidisperse model

For the sorption of rubomycin, an antitumor athracycline-type antibiotic, on BDM-12 carboxyl-containing heterogeneous crosslinked polymer sorbent, it was shown that the measured time dependences of the extent of process are determined by two characteristic times: τ₁ (in the range of short times) and τ₂ (at long times). A phenomenological theory of the kinetics of sorption on the heterogeneous sorbent was developed on the basis of a biporous sorbent model. The dependences of the characteristic times τ₁ and τ₂ on the sorbent grain radius were obtained. It was concluded that the theory makes predictions in good agreement with experimental data and allows calculating the most important kinetic parameters of sorption of organic ions on polymer sorbents: the time of diffusion of the sorbate into microgranules, the diffusion coefficient of the sorbate in transport pores, the effective coefficient of the sorbate diffusion into the heterogeneous sorbent, etc.     

柔性金属—有机骨架材料中已烷的扩散研究

本工作将MM3力场进行了扩展,使其可用于描述其它IRMOF材料的柔韧性;在此基础上,我们采用分子动力学模拟研究了柔性IRMOF-1和-16材料中已烷的扩散。 本文重点研究了温度和分子数对己烷自扩散系数、扩散机理,以及骨架柔性的影响。结果表明,分子数是影响扩散路径的重要因素。其次,IRMOF-16的柔性强于IRMOF-1。 工作的结论有助于进一步研究链状分子在柔性MOF材料中的扩散。     

溶胶-凝胶流动相异型直接甲醇燃料电池性能研究

以掺杂石墨粉的中间相碳微球(MCMB/G)烧结管为阴极支撑体,采用浸涂工艺分别制备了扩散层和催化层并在其外表面包裹Nafion膜,制得管状异型阴极并组装成异型直接甲醇燃料电池;采用溶胶-凝胶法制备了适用于直接甲醇燃料电池的溶胶-凝胶流动相。研究了溶胶-凝胶流动相异型直接甲醇燃料电池的阻抗,考察了阴极支撑体壁厚、阴极扩散层载量、实验温度和溶胶黏度等对电池极化性能的影响。结果表明,异型电池阻抗比传统平板电池大,但活化后电池阻抗明显下降;较低的溶胶黏度和较高的工作温度有利于提高电池性能;支撑体壁厚为1.3 mm、扩散层载量为3.5 mg/cm2时的电极性能最优。     

Sorption extraction of palladium(II) with modified polysiloxane

Sorption of palladium(II) from model solutions with polysiloxanes modified with amine and thiourea groups was stidied and it was found that the maximum sorption on aminopropyl polysiloxane is shifted slightly to alkaline region compared with a sulfur-containing sorbent. First time an effect of a series of external factors on a sorption kinetics of palladium with polysiloxanes was researched, diffusion coefficients of sorbate ions were calculated, and evaluation of their dependence on an initial concentration of metal, a grain diameter of the sorbent, and a temperature of sorption environment was carried out. It is shown that quantitative desorption of palladium from thiocarbamoylated polysiloxane is achieved by double treating the sorbent with hydrochloric acid solution of thiourea at high temperature.