有机酸的聚硅氧烷膜渗透萃取特性研究

发布时间：2017-12-28 03:28

本文关键词：有机酸的聚硅氧烷膜渗透萃取特性研究　出处：《陕西科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：渗透萃取(Pertraction,PT)是固定膜界面萃取中比较前沿的一种技术。膜材料为具有选择性的无孔致密膜,能够应用于水中有机物的萃取回收,同时可将有机物与无机离子有效分离,从而实现含盐水的回用和有机废水的生化处理。国内外对于渗透萃取技术用于有机物处理的研究多涉及工艺条件及传质过程,而对于膜选择性萃取有机物机理以及复合膜组件处理废水的研究较少。渗透萃取膜对有机物的选择透过性与有机物本身的性质密切相关,采用分子结构参数对有机物分子结构进行定量描述,将抽象的物质结构特性参数化,有利于解释影响膜萃取有机物的本质因素。本文以聚硅氧烷膜---聚二甲基硅氧烷膜(PDMS膜)、聚甲基乙烯基硅氧烷膜(PVMS膜)、聚甲基苯基硅氧烷膜(PPMS膜)为渗透萃取膜材料,选取有机废水中常见的一类有机物---有机酸作为研究对象,结合目前广泛应用的10种有机物结构参数进行膜萃取特性研究,研究有机物结构参数与其在膜中萃取效果的关系,探讨膜萃取的机理及主要影响因素。根据萃取实验及透过实验研究结果,选取一种膜材料来萃取单一组分有机酸废水,同时组件复合膜组件处理混合有机酸废水,研究外部运行条件对渗透萃取过程的影响;基于实际废水处理进行电解-膜耦合工艺的摸索。主要结论如下:(1)通过三种膜对有机酸的渗透萃取研究发现,PVMS膜和PPMS膜相较于PDMS膜对有机酸有较好的萃取效果。(2)结构参数与膜萃取效果的关系研究中:辛醇-水分配系数和溶解度对三种膜萃取有机酸影响显著。膜对有机酸的萃取率总体趋势是随着lgP的增大而逐渐增大的,随着溶解度S的增大而下降的。有机物分子摩尔体积(Vm)、分子极化率(a)、解离常数(pKa)、最正电荷(q+)及最高轨道能量(EHOMO)对膜的萃取有一定的影响,但不是影响膜萃取的主要因素。(3)膜萃取高含盐戊酸废水,随着戊酸质量浓度的增大,其去除率先增加后降低,正戊酸质量浓度为7%时去除率可以达到94%;正戊酸质量浓度为2%时,膜对正戊酸的回收率可达到45.8%。化学反应力可以提高膜萃取效率。在料液循环流速为1~20mL/min变化时,随循环流速的增大,正戊酸的去除率和回收率都相应增加,实际工程中可通过适度地提高流速,增强有机物的分离效果。(4)复合膜组件处理模拟含盐混酸废水,当料液有机物质量浓度在100.5~2171.5mg/L的范围时,其去除率在约380.5mg/L时达到最大值。当进水流速在5~20mL/min范围内变化时,去除率在16mL/min时效果较好。萃取液pH值对有机酸的去除效果影响显著,当萃取液pH值由10.5变至13.5时,有机酸去除率提高了40%。盐离子浓度对有机物的去除是有促进作用的,含盐量由1%提高到20%时,去除率提高25%。在一定温度范围内,提高温度会促进有机物的去除,实验中系统运行温度30℃时膜萃取效果最好,考虑到膜的寿命,在实际工程应用中是可以考虑在室温条件下运行的。(5)分别用三种膜萃取电解后的甲基橙废水、直接深棕废水、活性艳蓝废水,发现PVMS、PPMS膜对电解后成分不明的废水有一定的处理效果,可以实现“膜+电解”技术的耦合。
[Abstract]:Pertraction (PT) is one of the most advanced technologies in the interface extraction of fixed film. Membrane material is a porous membrane without selectivity. It can be applied to the extraction and recovery of organic matters in water, and at the same time, it can effectively separate organic compounds from inorganic ions, so as to achieve the reuse of brine and biochemical treatment of organic wastewater. The study of osmotic extraction technology for organic matters involves the technology and mass transfer process at home and abroad. However, there is little research on the mechanism of membrane selective extraction of organic matter and the treatment of wastewater by composite membrane module. Osmotic extraction membrane is closely related to the selection and permeability of organic matter and the properties of organic matter. Molecular structure parameters are used to quantitatively describe the molecular structure of organic compounds. Parameterization of the abstract material structure characteristics will help explain the essential factors that affect the organic matter extraction of membrane. The polysiloxane film - two polydimethylsiloxane membrane (PDMS membrane), polymethylvinylsiloxane membrane (PVMS membrane), polymethylphenylsiloxane membrane (PPMS membrane) for pertraction membrane materials, selecting a kind of organic matter, organic acids common in organic wastewater as the research object, research combined with the characteristics of membrane extraction 10 kinds of organic structure parameters are widely used currently. Study on the relationship between the organic matter in the membrane structure parameters and its extraction effect factors, to explore the mechanism of membrane extraction and main effect. According to the experimental extraction and through experimental results, select a membrane material to extraction of single component organic acid wastewater, and the component processing component composite film of mixed organic acid wastewater, influence of operating conditions on the external penetration of the extraction process; and explore practical wastewater treatment for electrolytic membrane coupling technology based on. The main conclusions are as follows: (1) through the osmotic extraction of three kinds of membranes, it is found that the PVMS film and the PPMS film have a better extraction effect on the organic acids than the PDMS film. (2) the relationship between the structure parameters and the effect of membrane extraction: the influence of the octanol water distribution coefficient and solubility on the three kinds of membrane extraction of organic acids is significant. The overall tendency of the extraction rate of organic acids to the organic acid gradually increased with the increase of lgP, and decreased with the increase of solubility S. The molecular molar volume (Vm), the molecular polarizability (a), the dissociation constant (pKa), the most positive charge (q+) and the highest orbit energy (EHOMO) have some influence on the extraction of the membrane, but not the main factor affecting the membrane extraction. (3) membrane extraction of valerate wastewater with high salt content. With the increase of valerate mass concentration, the removal rate increased first and then decreased. When the concentration of valerate acid was 7%, the removal rate could reach 94%. When the mass concentration of valerate was 2%, the recovery rate of membrane to valerate was 45.8%. The chemical reaction force can improve the efficiency of membrane extraction. When the flow rate of the feed liquid is 1~20mL/min, the removal rate and recovery rate of valerate increase with the increase of circulating flow rate. In practice, the separation rate of organic matter can be enhanced by increasing flow rate moderately. (4) composite membrane module is used to treat the simulated salt containing mixed acid wastewater. When the mass concentration of organic matter in the feed liquid is within the range of 100.5~2171.5mg/L, the removal rate reaches the maximum when it is about 380.5mg/L. When the influent velocity varies in the range of 5~20mL/min, the removal rate is better when the flow rate is 16mL/min. The pH value of the extract has a significant effect on the removal of organic acids. When the pH value of the extraction is changed from 10.5 to 13.5, the removal rate of organic acids is increased by 40%. The concentration of salt ions can promote the removal of organic matter, and the removal rate increases by 25% when the content of salt is increased from 1% to 20%. In a certain temperature range, increasing the temperature will promote the removal of organic matter. In the experiment, the effect of membrane extraction is the best when the system runs at 30 degrees centigrade. Considering the life of membrane, it can be considered in the actual engineering application at room temperature. (5) three kinds of membranes were used to extract methyl orange wastewater, direct Brown wastewater and reactive brilliant blue wastewater after electrolysis. It was found that PVMS and PPMS films had certain effect on the wastewater with unknown composition after electrolysis, and the coupling of membrane and electrolysis could be achieved.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

【参考文献】