有机相纳滤溶剂传递机理的研究
发布时间：2019-02-17 15:18
【摘要】：纳滤是介于超滤与反渗透之间的一种膜分离技术,在水处理、食品、制药、化学等行业中已经有了广泛的应用。耐溶剂纳滤是把纳滤过程引入到了有机相当中。随着高稳定性、性能突出的耐溶剂纳滤膜的制备开发,对耐溶剂纳滤膜传质过程的研究得到了越来越多的关注。与传统的纳滤过程相比,由于膜、溶剂、溶质三元体系间复杂的相互作用,耐溶剂纳滤传质过程比较复杂。而且对耐溶剂膜的传质过程研究尚不透彻,比如溶剂/溶质透过膜的过程是靠粘性流还是扩散,至今没有一个定论。目前的传递模型有不同的缺陷,且没有普适性比较好的模型,这无疑阻碍了耐溶剂纳滤的实际应用。因此对耐溶剂纳滤传质机理的应用是目前一个比较热门的研究领域。本文首先研究了甲醇、乙醇、甲苯、丙酮等一系列纯溶剂通过耐溶剂纳滤膜的过程,考虑到溶剂的通量与溶剂的性质、膜的性质关系比较大,采用相关性分析的方法对它们之间的关系进行了分析。发现溶剂通量与溶剂的黏度、介电常数关系比较大,同时与溶剂/膜之间的溶解度参数差和表面张力差关系也比较大。基于这些研究结论,建立了一个基于不完全溶解扩散模型的半经验模型,该模型的适用性在一系列溶剂中都都得到了验证。本文系统地研究了耐溶剂纳滤膜用于分离二元溶剂混合物地可行性。选取了在介电常数、表面张力、Hansen溶解度参数、黏度不同的二元溶剂体系,并用单因素分析的方法来考察不同的商用耐溶剂纳滤膜(MPFTM系歹、StarMemTM系列、DuraMemTM系列)对于这一系列溶剂的分离效果。发现DuraMemTM 150对于乙醇／正己烷体系的分离因子高达6左右,这是目前耐溶剂纳滤领域对于容积分离发现的最好地结果。对有分离效果的体系进行了深入的考察,发现溶剂优先通过地现象主要取决于膜的类型、以及膜一溶剂之间的Hans en溶解度参数差和极性差。并第一次提出了耐溶剂纳滤膜用于溶剂分离的一些基本假设。本文基于传统的溶解一扩散模型,提出了一个专门用于描述耐溶剂纳滤溶剂分离过程的经验模型。本模型主要包含两个参数：Hans en溶解度参数和介电常数。可以较好的用来描述一些致密性膜如DuraMemTM 150,200,300和MPF-44对二元溶剂的分离现象。而对于疏松膜如DuraMemTM 500 和 DuraMemTM 900的描述效果则比较差,这和该模型的假设是一致的。该模型提供了一种理解耐溶剂纳滤膜用于二元溶剂分离的新思路,为该领域进一步的研究工作打开了一个良好的突破口。
[Abstract]:Nanofiltration is a membrane separation technology between ultrafiltration and reverse osmosis, which has been widely used in water treatment, food, pharmaceutical, chemistry and other industries. Solvent-resistant nanofiltration is the introduction of nanofiltration processes into organic equivalents. With the preparation and development of solvent-resistant nanofiltration membranes with high stability and outstanding properties, more and more attention has been paid to the mass transfer process of solvent-resistant nanofiltration membranes. Compared with the traditional nanofiltration process, the solvent-resistant nanofiltration mass transfer process is more complex due to the complex interaction among membrane, solvent and solute ternary system. The mass transfer process of solvent-resistant membranes has not been thoroughly studied, such as whether the solvent / solute permeation process depends on viscous flow or diffusion, so far there is no final conclusion. The present transfer model has different defects, and there is no universal model, which undoubtedly hinders the practical application of solvent resistance nanofiltration. Therefore, the application of solvent resistance nanofiltration mechanism is a hot research field. In this paper, a series of pure solvents, such as methanol, ethanol, toluene, acetone and so on, have been studied. Considering the flux of solvent and the properties of solvent, the relationship between the properties of membrane and the flux of solvent is relatively large. The relationship between them was analyzed by the method of correlation analysis. It is found that the solvent flux has a great relationship with the viscosity and dielectric constant of the solvent, and also with the solubility parameter difference and the surface tension difference between the solvent and the membrane. Based on these conclusions, a semi-empirical model based on incomplete solution diffusion model is established, and its applicability is verified in a series of solvents. The feasibility of solvent-resistant nanofiltration membrane for separation of binary solvent mixtures has been systematically studied in this paper. Binary solvent systems with different dielectric constants, surface tension, Hansen solubility parameters and viscosity were selected, and different commercial solvent-resistant nanofiltration membranes (MPFTM series, StarMemTM series) were investigated by single factor analysis. DuraMemTM series) for the separation of this series of solvents. It is found that the separation factor of DuraMemTM 150 for ethanol / n-hexane system is as high as 6, which is the best result of volume separation in the field of solvent resistance nanofiltration. It is found that the preferential passage of solvent depends mainly on the type of membrane and the difference of Hans en solubility parameter and polarity between membrane and solvent. Some basic assumptions of solvent-resistant nanofiltration membrane for solvent separation were proposed for the first time. Based on the traditional solution-diffusion model, an empirical model is proposed to describe the solvent resistant nanofiltration separation process. The model consists of two parameters,: Hans en solubility parameter and dielectric constant. It can be used to describe the separation of binary solvents by some dense membranes such as DuraMemTM 150200300 and MPF-44. However, the description of loose films such as DuraMemTM 500 and DuraMemTM 900 is poor, which is consistent with the assumption of the model. The model provides a new way to understand the application of solvent-resistant nanofiltration membrane in binary solvent separation and opens a good breakthrough for further research in this field.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TQ028.8
，
本文编号：2425302
[Abstract]:Nanofiltration is a membrane separation technology between ultrafiltration and reverse osmosis, which has been widely used in water treatment, food, pharmaceutical, chemistry and other industries. Solvent-resistant nanofiltration is the introduction of nanofiltration processes into organic equivalents. With the preparation and development of solvent-resistant nanofiltration membranes with high stability and outstanding properties, more and more attention has been paid to the mass transfer process of solvent-resistant nanofiltration membranes. Compared with the traditional nanofiltration process, the solvent-resistant nanofiltration mass transfer process is more complex due to the complex interaction among membrane, solvent and solute ternary system. The mass transfer process of solvent-resistant membranes has not been thoroughly studied, such as whether the solvent / solute permeation process depends on viscous flow or diffusion, so far there is no final conclusion. The present transfer model has different defects, and there is no universal model, which undoubtedly hinders the practical application of solvent resistance nanofiltration. Therefore, the application of solvent resistance nanofiltration mechanism is a hot research field. In this paper, a series of pure solvents, such as methanol, ethanol, toluene, acetone and so on, have been studied. Considering the flux of solvent and the properties of solvent, the relationship between the properties of membrane and the flux of solvent is relatively large. The relationship between them was analyzed by the method of correlation analysis. It is found that the solvent flux has a great relationship with the viscosity and dielectric constant of the solvent, and also with the solubility parameter difference and the surface tension difference between the solvent and the membrane. Based on these conclusions, a semi-empirical model based on incomplete solution diffusion model is established, and its applicability is verified in a series of solvents. The feasibility of solvent-resistant nanofiltration membrane for separation of binary solvent mixtures has been systematically studied in this paper. Binary solvent systems with different dielectric constants, surface tension, Hansen solubility parameters and viscosity were selected, and different commercial solvent-resistant nanofiltration membranes (MPFTM series, StarMemTM series) were investigated by single factor analysis. DuraMemTM series) for the separation of this series of solvents. It is found that the separation factor of DuraMemTM 150 for ethanol / n-hexane system is as high as 6, which is the best result of volume separation in the field of solvent resistance nanofiltration. It is found that the preferential passage of solvent depends mainly on the type of membrane and the difference of Hans en solubility parameter and polarity between membrane and solvent. Some basic assumptions of solvent-resistant nanofiltration membrane for solvent separation were proposed for the first time. Based on the traditional solution-diffusion model, an empirical model is proposed to describe the solvent resistant nanofiltration separation process. The model consists of two parameters,: Hans en solubility parameter and dielectric constant. It can be used to describe the separation of binary solvents by some dense membranes such as DuraMemTM 150200300 and MPF-44. However, the description of loose films such as DuraMemTM 500 and DuraMemTM 900 is poor, which is consistent with the assumption of the model. The model provides a new way to understand the application of solvent-resistant nanofiltration membrane in binary solvent separation and opens a good breakthrough for further research in this field.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TQ028.8
，
本文编号：2425302
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