共查询到18条相似文献,搜索用时 62 毫秒
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引 言离子交换层析具有分离容量大、选择性高和介质种类多、价格适中等特点 ,是蛋白质类生物大分子分离纯化的主要手段[1] .离子交换或吸附平衡研究是离子交换层析过程设计和优化分析的基础 ,也是分离实践中评价和选择离子交换介质的重要步骤 .目前已提出多种模型用于描述离子交换平衡 ,其中应用最多的是基于Langmuir理论的经验模型[2 ] .但是 ,Langmuir模型不能直接反映溶液离子强度对平衡的影响 ,不利于在盐浓度梯度洗脱的离子交换层析过程中的应用 .近年来 ,基于离子交换反应和蛋白质空间屏蔽作用的空间质量作用模型受… 相似文献
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本实验研究了离子交换色谱法和直接实验法建立蛋白质离子交换平衡等温线和确定平衡参数的问题。结果表明,在低浓度溶液中,用离子交换色谱法估算的平衡常数K与直接实验法确定的参数有很好一致性,而且色谱法还具有快速又经济的特点。 相似文献
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非缓冲体系中性氨基酸的离子交换平衡 总被引:1,自引:0,他引:1
研究了非缓冲体系中性氨基酸在732型强酸性阳离子交换树脂上的离子交换平衡,并提出了平衡模型。该理论模型考虑了氨基酸的两性弱解离性质和树脂能团的能量非均一性,可以很好地关联氨基酸与H^+的二元离子交换平衡,并且通过两个二元体系VAL/H^+和Na^+/H^+的平衡参数成功地预测了三元体系VAL/Na^+/H^+的平衡关系,表明该模型可以描述非缓冲体系中性氨基酸的多元离子交换平衡。 相似文献
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本文提出一种新的预测含盐溶液汽液平衡的方法.对Pitzer(1980)模型进行扩展后,将其简化成单参数形式,推广至多元电解质溶液;经过适当假定,得到计算含盐挥发性强电解质和水体系及含盐水醇体系的活度系数公式,这些公式仅含二元相互作用参数;由二元溶液的活度关联出该参数后,可用于含盐体系各种温度下汽液平衡的预测.关联了40个二元电解质水溶液及7个电解质甲醇溶液298.15K时的简化Pitzer方程的单参数;用以推算6个水盐体系和2个甲醇盐体系在320-403K的蒸汽压,得到满意的结果,182个数据点的平均偏差小于0.65kPa;用以预测5个不同类型的含盐三元体系的等温、等压汽液平衡,所得的平均偏差对于汽相组成、沸点、压力分别为0.015、1K和1.92kPa. 相似文献
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运用EVLAC模型由二元恒温VE-x数据推算25个二元体系的76组恒温γ-x数据,γ的相对均方根偏差为0.27~3.7%;推算了其中六个二元体系的12组恒压汽液平衡数据,t的平均绝对偏差为0.1~0.5℃,y的平均绝对偏差为0.0022~0.0092摩尔分率;同时由二元数据推算了一个三元体系的四组恒温γ-x数据,γ的相对均方根偏差为1.7~2.1%。 相似文献
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体积属性的群体平衡模型矩积分方法研究 总被引:1,自引:0,他引:1
研究以体积为内部属性的群体平衡模型的矩积分求解方法.以各向同性离散相系统的实体聚并、实体破碎和长大等为例,介绍了矩积分求解方法的求解过程.三个算例的模拟结果表明,与分析解相比,以体积为内部属性的群体平衡模型的矩积分求解方法相对误差在10-5以内,具有高精度、低计算量的特点,并具有数目和体积的自守恒性. 相似文献
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基于普遍化范德华配分函数理论,应用由局部组成概念导出的方阱流体配位数模型导出了链状分子混合物的配位数模型,并由此建立了一个新的活度系数模型;将其应用于高度非理想体系汽-液平衡活度系数的关联,结果与Wilson方程相当,但方程参数随温度变化较小;其于Newton-Raphson-Gauss液-液平衡算法,应用新模型对烃-水体系的液-液平衡进行了关联计算,结果优于NRTL方程 相似文献
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基于MPHC活度系数模型关联烃-水体系液-液平衡 总被引:2,自引:0,他引:2
基于普遍化范德华配分函数理论,应用由局部组成概念导出的方阱流体配位数模型导出了链状分子混合物的配位数模型,并由此建立了一个新的活度系数模型;将其应用于高度非理想体系汽-液平衡活度系数的关联,结果与Wilson方程相当,但方程参数随温度变化较小;其于Newton-Raphson-Gauss液-液平衡算法,应用新模型对烃-水体系的液-液平衡进行了关联计算,结果优于NRTL方程 相似文献
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To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑xiln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied [bij^1/2=1/2(bi1/2 bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters of i3 - 2- pure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results. 相似文献
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The purification of lactic acid based on the esterification of raw lactic acid from fermentation broth and then the catalytic distillation hydrolysis of methyl lactate simultaneously to achieve pure lactic acid is reported. The esterification kinetics of lactic acid with methanol catalyzed by strong-acid cation-exchange resins (Amberlyst-15,D001, D002, NKC, 002) was studied under the condition that simulates the real catalytic environment. Experimental results were correlated by a Langmuir-Hinselwood model and the nonideality of the solution was taken into account by using activities calculated by the universal quasichemical functional group activity coefficient (UNIFAC) method.A good agreement between the model and the experimental data was achieved. Continuous purification experiments were conducted to find the optimum column configuration and operation condition for the system. The effects of various parameters, e.g. the length of different section of the column, feed rate and ratio of reactants, packing material and catalyst type, were studied. This novel system shows good separation results in lab scale, and is potential for industrial application. 相似文献
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An operational model is developed to evaluate and predict the permeation performance of mixed gas through poly(dimethylsiloxane) (PDMS) membranes by combining the ideal gas permeation model with the experimental analysis of the mixed gas transport character. This model is tested using the binary and ternary mixed gas with various compositions through the PDMS membranes, and the predicted data of the permeation flux and the compositions of the permeated gas are in good agreement with the experimental ones, which indicates that the operational model is applicable for the evaluation of the permeation performance of mixed gas through PDMS membranes. 相似文献
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In this study, the Gibbs-Duhem equation was applied to make the thermodynamic consistency test and thermodynamic model estimation for systems of CO2-DME (dimethyl ether), DME-CH3OH, CO2-CH3OH and DME-C2H5OH systems on the basis of the vapor-liquid equilibrium (VLE) experimental data in published reports. And the NRTL binary interaction parameters of the systems mentioned above were regressed by the VLE data and were subjected to a thermodynamic consistency test because the study showed that PR-NRTL model combination was appropriate for the four systems mentioned above. The regressed binary interaction parameters were used to estimate the VLE for DME-CO2-CH3OH at temperatures of 313.15K and 333.15K, and the estimated result was coincident with the experimental data. On the basis of the predicted VLE data for systems of DME-CO2-CH3OH and DME-CO2-C2H5OH, the VLE behaviors of the two systems were studied by the phase diagrams of these two ternary systems, with the forms of both the two dimensional and three dimensional phase diagrams, respectively. 相似文献
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1 INTRODUCTION Gas hydrates are serious problems in the petroleum and petrochemical industries since it may cause the plugging of production facilities and trans- portation pipelines during gas and oil production. It is known to all that gas hydrates have three poten- tial hydrate formation structures: structure- structure- and structure-H (SH). The two for- mer structures have been studied extensively and their phase equilibrium conditions are well characterized. For a long time, molecu… 相似文献
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Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measured systems were correlated by UNIFAC group contribution method. A new main group (aromatic ester, ACCOO) was defined to express the activity coefficients of the aromatic ester. New interaction parameters of the ACCOO group were expressed as the first-order function of temperature and were determined from the experimental data. The calculated results for the new interaction parameters were satisfactory. The measured systems were also correlated with the Wilson and 2-h models, and the results were compared with those of the UNIFAC model. 相似文献