油水分离动态膜制备、应用及其形成机理研究

发布时间：2017-12-27 12:08

本文关键词：油水分离动态膜制备、应用及其形成机理研究　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：油水污染是工业废水中较难处理的一种,膜分离法较传统方法有操作简单、能耗低、不使用添加剂等优点,但也存在严重的膜污染、膜再生困难等缺点。为解决这些问题,许多膜的改性及过程优化技术应运而生,动态膜是其中非常有效的一种。本文以多孔管式陶瓷膜为基膜,以ZrO2、Kaolin、MnO2、TiO2为涂膜颗粒制备不同类型单层动态膜,首先设计正交实验优化制备条件,并考察主要因素对动态膜制备效果的影响,研究确定出单层动态膜制备最优条件为温度50℃、压力0.14MPa、流量120L/h、涂膜液浓度1.0g/L和涂膜颗粒为Zr02；其次,在最优条件下制备双层复合动态膜,并与单层单颗粒、单层双颗粒混合动态膜性能进行对比,发现通量最大的为Zr02单层动态膜,截留率最高的是Kaolin-ZrO2双层动态膜。在动态膜制备基础上,本文设计正交实验,由极差分析与综合平衡法确定动态膜油水分离的最优操作条件为乳化液浓度0.5g/L、pH值5、温度50-C、流量100L/h、压力0.14MPa。主要影响因素实验结果表明,油水分离通量随着压力的增大先增大后减小；随乳化液温度的升高先增大后减小；随乳化液pH值增大先增大后减小；乳化液中添加阳离子盐后,其通量大于加入阴离子盐,且阳离子强度越大渗透通量越大,阴离子反之。在分析油水分离膜污染机理的基础上,选择NaOH、HCl、吐温80和柠檬酸为清洗剂,确定最佳清洗顺序应采取“碱洗→吐温80→酸洗→柠檬酸”；设计实验进行单步和多步清洗,考察通量恢复情况,单步清洗确定各类化学试剂的最佳浓度与清洗时间；在此基础上,设计二步清洗、三步清洗和四步清洗实验,其中四步清洗最佳,通量总恢复率为79.8%；重复清洗后,陶瓷膜基膜能实现3或4次的重复使用。基于临界粒径模型,考虑了动态膜层孔隙率随时间的变化,建立预测错流微滤动态膜形成过程中颗粒沉积厚度的模型,并设计实验来验证模型；减小涂膜液浓度或增加错流速度,可以使动态膜层厚度变薄且均匀性变好；增大操作压力可以降低动态膜层厚度,但对均匀性几乎没有影响；在圆周方向上从0°到180°逐渐变薄,提高错流速度能减小此种差异；实验结果验证了模型的可靠性。本文构建了油水分离动态膜制备及分离实验条件优化、污染机理分析及清洗方案确定、动态膜厚度预测分析的一个完整的研究体系,将为动态膜的研究及应用奠定基础。
[Abstract]:Oil and water pollution is a difficult way to deal with in industrial wastewater. Membrane separation has many advantages, such as simple operation, low energy consumption and no additives. Compared with traditional methods, membrane fouling has many disadvantages, such as membrane fouling and membrane regeneration. In order to solve these problems, many membrane modification and process optimization techniques emerge as the times require. Dynamic film is one of the most effective ones. In this paper, porous tubular ceramic membranes were prepared with different types of dynamic membrane coating granules was monolayer with ZrO2, Kaolin, MnO2, TiO2, firstly, orthogonal experimental design to optimize the preparation conditions, and the influence factors of preparation effect of dynamic membrane system, studied the dynamic monolayer membrane preparation conditions for the optimal temperature of 50 C, pressure 0.14MPa, flow 120L/h, solution concentration and coating 1.0g/L particles as Zr02; secondly, the preparation of composite dynamic membrane under the optimal conditions, and single particles, single double particle mixing dynamic membrane properties were found through comparison, the largest amount of Zr02 single dynamic membrane, the highest retention is Kaolin-ZrO2 double dynamic membrane. On the basis of dynamic membrane preparation, the orthogonal experiment was designed in this paper. The best operation conditions of dynamic membrane oil and water separation were determined by range analysis and comprehensive balance method. The optimal operation conditions were emulsion concentration 0.5g/L, pH value 5, temperature 50-C, flow rate 100L/h and pressure 0.14MPa. The main factors that affect the experimental results show that the separation of oil and water flux increase with the pressure increases first and then decreases; the first increase with the emulsion temperature and then decreases; increase increased firstly and then decreased with the pH value of emulsion; emulsion adding cationic salt, the anion flux is greater than the added salt, and the greater the intensity of cation permeability the bigger the flux, whereas anion. Based on the mechanism of membrane fouling in water on the analysis of NaOH, HCl, Twain, 80 and citric acid as cleaning agents, cleaning should be taken to determine the optimal order of alkali washing, acid pickling, citric acid, Twain 80 "; experiments are designed for single step and multi-step cleaning, inspection flux recovery, to determine the optimal concentration and cleaning step the cleaning time of various chemical reagents; on this basis, the design of the two step of cleaning, three step and four step cleaning cleaning experiment, the four step of cleaning the best, the total flux recovery rate was 79.8%; after repeated cleaning, repeated use of ceramic membrane can achieve 3 or 4 times. The critical particle size based on the model, considering the dynamic film porosity changes with time, predict the dynamic cross flow microfiltration membrane formation thickness in the process of particle deposition model, and design experiment to verify the model; reduce the solution concentration or increasing the cross flow velocity, the dynamic film thickness becomes thinner and the better homogeneity increases; the dynamic pressure can reduce the thickness of the film, but has almost no effect on uniformity; in the circumferential direction from 0 degrees to 180 degrees gradually thinning, increase the cross flow velocity can reduce the difference; the experimental results verify the reliability of the model. A complete research system for the preparation and separation of oil and water separation dynamic membrane, the optimization of experimental conditions, the analysis of fouling mechanism, the determination of cleaning scheme and the prediction of dynamic membrane thickness will be established, which will lay a foundation for the research and application of dynamic membrane.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893;X703

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