应用Wilson方程和均相溶液理论计算固液吸附平衡

固液吸附平衡计算对于吸附分离设计具有重要意义。采用吸附质固体溶液理论并用Wilson方程描述各组分之间的相互作用,计算了6个烃类二元液体混合物在分子筛NaX和KBaY、硅凝胶和活性炭上的吸附平衡数据,进一步考察了该理论的适用性和计算精度。结果表明,该理论模型可以较好地关联二元液相混合物在固体表面的吸附等温线,关联结果的总平均相对偏差为5.0%,而且该模型可以预测其他温度下的吸附平衡,预测精度也在5%之内。     

用晶格模型预测多组元固液界面上的吸附平衡

在晶格模型基础上，提出了预测多组元液体混合物在能量非均匀固体表面上吸附平衡的新方法，得到了吸附相活度系数表达式，计算多组元固液吸附平衡只需二元体系参数．对于硅胶自苯-甲苯-环己烷溶液、活性炭自苯-乙醇-环己烷溶液和活性炭自苯-乙酸乙酯-环已烷溶液中的吸附等3个三元体系，用本文方法进行了计算，预测结果令人满意．     

取代芳烃混合物吸附平衡特性的研究(Ⅲ)——不均匀势吸附模型在多组分吸附平衡推算中的应用

以不均匀势定域吸附假设为基础,采用统计热力学方法,建立了组成显式的多组分不均匀势吸附平衡模型,用于自二组分吸附平衡数据直接推算多组分吸附平衡关系.对文献报道的几组取代芳烃/沸石饱和吸附体系多组分吸附平衡关系的理论推算结果表明,在实验误差范围内,本文建立的不均匀势吸附平衡模型与实验数据吻合良好,优于最近文献报道的几种均匀势吸附平衡模型.     

含CO体系在载铜吸附剂上的吸附平衡

用动态法测定了含ＣＯ、ＣＯ２、ＣＨ４的单组分、二元、三元混合气体在负载铜吸附剂上吸附平衡数据,实验揭示了这一体系吸附平衡的规律,为吸附过程的设计提供必要的基础数据。用Ｌａｎｇｍｕｉｒ吸附等温模型对测定的平衡数据进行关联,仅用修正的纯组分模型参数就能很好地关联二元、三元的吸附平衡,满足了工程应用的要求。     

ZIF-8/乙二醇体系分离捕集CO_2溶解度的模拟计算

吸收-吸附耦合分离法在分离捕集CO_2方面表现出潜在的优势,应用Kurihara等提出的基于局部组成概念的混合规则与Patel-Teja状态方程相结合确定乙二醇与气体组分间的吸收平衡,由溶解度实验数据确定了混合规则中的二元交互作用参数;采用Langmuir等温吸附方程确定ZIF-8与气体组分间的吸附平衡,进而确定了ZIF-8表面乙二醇膜的选择渗透压与气体组分平衡逸度间的关联式。最后将热力学模型应用到了预测ZIF-8/乙二醇浆液分离捕集CO2体系。     

ZIF-8/乙二醇体系分离捕集CO2溶解度的模拟计算

吸收-吸附耦合分离法在分离捕集CO₂方面表现出潜在的优势,应用Kurihara等提出的基于局部组成概念的混合规则与Patel-Teja状态方程相结合确定乙二醇与气体组分间的吸收平衡,由溶解度实验数据确定了混合规则中的二元交互作用参数;采用Langmuir等温吸附方程确定ZIF-8与气体组分间的吸附平衡,进而确定了ZIF-8表面乙二醇膜的选择渗透压与气体组分平衡逸度间的关联式。最后将热力学模型应用到了预测ZIF-8/乙二醇浆液分离捕集CO₂体系。     

环丁砜-C_4烷烯体系相平衡的研究

建立了中低压体系相平衡数据的测定方法,使用静态法测定了正丁烷-1-丁烯-甲乙酮-环丁砜体系的多元气液相平衡数据。利用UNIQUAC热力学模型对所测定的二元TPx或TPxy数据进行了参数回归,并对该体系的三元数据进行了预测。与实验结果对比发现,该模型具有可靠性,对压力预测的平均相对偏差为0.88%,对气相组成预测的平均偏差为1.33%。     

同试剂修饰竹炭对直接混合黄染料吸附的热力学与动力学研究

本文从接触时间、温度、pH值、染料起始浓度和温度等研究了不同试剂修饰竹炭对直接混合黄染料的吸附性能、热力学和动力学特性,所得结果显示:接触时间21h,pH1,染料起始浓度24.62mg/L为最佳处理条件,得到最大去除率88%,最大吸附量1.23mg/g。以Langmuir和Freundlich等温式处理吸附平衡,以及拟一阶动力学模型、拟二阶动力学模型和内部粒子扩散模型处理动力学试验数据均得到很好相关性。热力学数据表明吸附过程是自发、吸热和熵增过程。     

气体膨胀液体处理松针落叶对水体中亚甲基蓝的吸附研究

探讨了高压气体膨胀液体(GXLs)提取松针落叶有效成分后的残渣作为生物质吸附剂对废水中亚甲基蓝(MB)的吸附性能。研究了吸附时间、温度和盐离子浓度等实验条件对吸附行为的影响;用Langmuir和Freundlich等温吸附模型对吸附平衡数据进行非线性回归评价分析。结果表明:Langmuir和Freundlich方程对MB吸附实验数据拟合良好;吸附动力学曲线符合伪二级动力学反应模型。热力学研究表明,吸附过程符合Langmuir吸附等温式,是以化学吸附为主的、吸热的自发过程;313K时,最大饱和吸附量为120.51mg·g-1。因此,GXLs处理后的松针残渣对MB具有良好的吸附性能,可以作为阳离子染料废水处理用的生物质吸附剂。     

H1020树脂吸附糖精的动力学和热力学研究

研究了大孔树脂H1020对糖精（邻苯甲酰磺酰亚胺）的吸附性能。在温度为303.15、308.15、313.15和318.15 K条件下分别测定了吸附平衡数据。分别采用了拟一级动力学模型和拟二级动力学模型对实验数据进行模拟,结果表明拟二级动力学方程更适合描述H1020型大孔树脂对糖精的吸附过程。用Langmuir和Freundlich吸附等温方程对实验数据进行拟合,结果表明糖精在大孔树脂H1020上的吸附平衡符合Freundlich吸附等温方程。计算糖精吸附过程的吸附焓变、吸附自由能和吸附熵变,根据吸附热力学值可判断出H1020型大孔树脂对糖精的吸附过程是自发的、放热的物理吸附。     

能量不均匀固体表面上多元非理想溶液的吸附等温线模型

通过正构碳6～碳8和异构碳8烷烃混合液在5A分子筛上的吸附实验,取得了293K、303K、313K、327K和338K温度下的吸附平衡数据．并提出了一种在能量非均匀表面上多元非理想溶液吸附等温线方程,经检验,预报结果与实验数据拟合性较好．     

蛋白质-磷酸钾-聚乙二醇双水相体系热力学研究

建立了由蛋白质、磷酸氢二钾、磷酸二氢钾、聚乙二醇所组成的双水相体系的平衡浓度分析测定方法,实验测定了6种蛋白质分子在25℃下的液液平衡分配数据,共23组.将Baskir等的吸附晶格模型和Pitzer的长程静电项相结合,扩展用于含电解质-高聚物双水相体系的热力学计算,仅用7组实验数据进行关联,得到2个吸附能参数,预测了其它16组蛋白质分配系数,结果满意。并提出了蛋白质分配系数与双水相成相物质在两相间浓度差的经验关系式。     

Generalization of thermodynamic Langmuir isotherm for mixed-gas adsorption equilibria

This work presents a comprehensive thermodynamic model for both pure component isotherms and mixed-gas adsorption equilibria. A generalization of thermodynamic Langmuir isotherm, the proposed model assumes competitive adsorption of multiple adsorbates on adsorbent surface for mixed-gas adsorption equilibria, and it applies an area-based adsorption nonrandom two-liquid activity coefficient model in the activity coefficient calculations for the adsorbate phase. The resulting generalized Langmuir isotherm properly captures both surface loading dependence and adsorbate phase composition dependence for mixed-gas adsorption equilibria. The model is validated with accurate representations of gas adsorption equilibrium data for varieties of unary, binary, and ternary gas systems. The model results are further compared with those calculated from extended Langmuir isotherm and Ideal Adsorbed Solution Theory.     

A dynamic adsorption model for the gas-phase biofilters treating ethanol: Prediction and validation

A dynamic adsorption model was proposed using the lumping process for an adsorption system. This novel approach uses a four-component structure model: gas phase, enclosed aqueous phase, sorption volume and porous media surface adsorption. A clouding effect represented by k _a (dynamic adsorption constant) was adopted to explain the adsorption process. The clouding effect assumes that the adsorption rate is decreased as the adsorption sites on the media surface are occupied. In the equilibrium stage the Freundlich adsorption isotherm was adopted. The proposed dynamic adsorption model was then predicted in comparison with the experimental data of an adsorption-column to estimate adsorption model parameter values in a biofilter fed with ethanol at 4,100 mg ethanol/m³ (or 2,000 ppmv). Model validation was performed for the adsorption column fed with ethanol at 2,050 mg ethanol/m³ (or 1,000 ppmv). Results showed that the mechanistic model was able to simulate the dynamic behavior of an adsorption process successfully according to the corresponding adsorption experimental data.     

AN EVALUATION OF ISOTHERMS IN THE DESCRIPTION OF COMPETITIVE ADSORPTION EQUILIBRIA

Since adsorption isotherm equations are widely used in the industry to model adsorption on substances like activated carbon, an investigation was done to determine the applicability of three of these equations, viz, the multi-component Freundlich, multi-component Langmuir and the isotherm equation proposed by Fritz and Schluender. Based on statistical thermodynamic principles a discrete adsorption model was recently proposed. This model was used to create sets of binary adsorption data with some non-ideal characteristics. These data sets were used to evaluate the isotherm equations

It was found that the Langmuir isotherm gave the best fits, except where the visible adsorption energy changes with the surface loading or where selective adsorption occurs. Under these conditions, the Freundlich equation or that proposed by Fritz and Schluender should be used. It is recommended that these equations should be used to model low coverage-low concentration regions, while the high coverage-high concentration regions should be modelled using the Langmuir isotherm if possible

Some recommendations are made in connection with the procedure to estimate parameters for these isotherm equations.     

Effect of adsorption of organic solvents on the band profiles in reversed-phase non-linear chromatography

The influence of the mobile phase composition on the adsorption equilibria in non-linear reversed-phase chromatography has been investigated. RP-18 and RP-18 endcapped columns have been selected with methanol-water and acetonitrile-water as a mobile phase and cyclopentanone as a solute. Due to its structure, cyclopentanone exhibited affinity to the active adsorption sites on alkyl chains as well as to the polar, uncovered surface of the adsorbent. The adsorption equilibria of solvents—methanol-water, acetonitrile-water on RP-18 and RP-18e columns—have been measured and the excess adsorption isotherms accounting for non-ideality of the mobile and adsorbed phase have been determined. The competitive heterogeneous adsorption model for the solute and organic solvent has been proposed and coupled with a model of column dynamics. The model predictions have been verified by comparison to experimental chromatograms.     

A THREE-PHASE MODEL FOR SORPTION ISOTHERM IN ZEOLITE ADSORBENTS

A three-phase model for adsorption in zeolite cavities is proposed. The adsorbed molecules are taken to be distributed between a surface layer and a dense phase filling the rest of the cavity volume. This model is a more realistic representation of molecules in zeolite cages especially at high pressures. The equation for the adsorption isotherm, based on this model, has two contributions: a surface term and a dense phase term. The dense phase contribution was estimated from a simple equation that obeys the limiting values at low and high pressures. The surface contribution can be estimated from the existing surface adsorption models. When all model parameters are estimated from molecular and literature data, the combination of the two terms was found to be an improvement over traditional treatment of adsorption data of a number of gases in zeolite-A for a wide range of pressures. However, new models for the adsorbed phase that account for sorbate-sorbate repulsive forces correctly are needed for accurate prediction of adsorption data.     

PREDICTION OF THE ASYMMETRIC PEAK PROFILE USING A MATHEMATICAL METHOD WITH A COMPETITIVE LANGMUIR ISOTHERM

The adsorption characteristics of a single component and a binary component in the stationary phase using preparative chromatography were investigated with a six-adsorption isotherm model. These analyses were based on the Langmuir model. Each parameter of the adsorption isotherm was obtained with the adsorption raw data that was calculated by frontal analysis (FA). The experimental data and the values calculated using the adsorption isotherm model were compared. The bi-Langmuir model showed good agreement for phenol while the tri-Langmuir model showed good agreement for caffeine. Each characteristic of adsorption was obtained from these results. The effect of competitive adsorption was investigated using the parameters of the adsorption isotherm model with a single component. There was good agreement between the experimental data and the calculated values.     

PREDICTION OF THE ASYMMETRIC PEAK PROFILE USING A MATHEMATICAL METHOD WITH A COMPETITIVE LANGMUIR ISOTHERM

The adsorption characteristics of a single component and a binary component in the stationary phase using preparative chromatography were investigated with a six-adsorption isotherm model. These analyses were based on the Langmuir model. Each parameter of the adsorption isotherm was obtained with the adsorption raw data that was calculated by frontal analysis (FA). The experimental data and the values calculated using the adsorption isotherm model were compared. The bi-Langmuir model showed good agreement for phenol while the tri-Langmuir model showed good agreement for caffeine. Each characteristic of adsorption was obtained from these results. The effect of competitive adsorption was investigated using the parameters of the adsorption isotherm model with a single component. There was good agreement between the experimental data and the calculated values.     

改性活性炭吸附H_2S总传质系数的测定及动力学研究

对H_2S-CO_2混合气在改性活性炭床层上的等温吸附过程进行了研究。建立了吸附数学模型,并给出数值解。由实验测得了上述体系的吸附穿透曲线,并与计算值加以比较。