高盐有机废水离子膜电解脱盐处理机制研究

发布时间：2018-07-26 18:30

【摘要】：高盐有机废水作为现代工业化的产物,不仅量大而且成分复杂,处理不当很容易造成水资源浪费和环境污染。目前,高盐有机废水的传统物理化学处理方法存在着诸如处理成本高,需投加额外药剂,容易造成二次污染等缺点,并且废水中的高盐环境会抑制微生物的活性,从而限制微生物方法的应用和发展。但高盐废水具有较好的导电性,可以为电化学的应用提供契机。膜电解技术作为电化学工艺中的重要组成部分,结合了传统电渗析分离提纯的作用和电解技术的特性,并具有能耗低、环境危害小等特点,该技术对高盐有机废水的处理而言,无疑是一种有着巨大应用潜力和研究价值的处理方法。本课题采用膜电解的方式对高盐度染料模拟废水进行了脱盐以及有机物降解处理,旨在研究高盐有机废水体系中盐离子的去除机制以及有机物降解过程对脱盐效果的影响和相互作用关系。研究采用自制的可拆卸多级膜电解槽装置,以Ti/RO2-Ir O2-Sn O2为阴、阳极板材料,以Na~+、Cl-为目标去除离子,分别在与甲基橙、酸性大红3R、直接深棕、活性艳兰X-BR等染料物质的混合体系下进行了直流电场作用下的膜电解脱盐实验。探讨了单膜电解过程中电流密度、极板间距、电解液浓度和进样流速等控制条件对离子膜电解脱盐效果的影响,以及双膜电解过程中的脱盐效果和有机物降解情况,并对实验中使用的均相阴、阳离子交换膜的污染清洗问题进行了浅析。通过对不同时间点所取水样的p H、电导率、盐离子(Na~+、Cl-)浓度、溶液中TOC浓度和色度的定量分析,以及对离子膜表面形貌的扫描电镜观察和有机物电解产物的红外光谱分析,得出以下结论:膜电解脱盐过程中电流密度对脱盐效果的影响最为显著,是引起膜表面发生极化现象的关键因素。在本实验的参数设置条件下,电流密度55.6m A/cm2、极板间距2cm、电解液浓度2g/L、进样流速50m L/min为最优条件。此条件下,单膜电解过程中Cl-和Na~+去除率分别为70%和90%左右;而在双膜电解处理模拟染料废水过程中两种盐离子的去除率均可达到90%左右,并且在一定程度上实现了几种染料物质的降解处理,其中甲基橙的降解效果最好,其TOC去除率可达到75%左右。同时,因为均相阴、阳离子膜的特殊结构,有效阻挡了有机物分子的迁移,从而实现了有机物与盐离子的分离。膜电解过程中,Na~+和Cl-在电场作用下发生定向迁移,同时,均相阳、阴离子交换膜表面和孔道内的静电作用会对相应的离子进行吸附,并发生迁移,从而实现Na~+和Cl-的去除。实验表明,该过程中,极板表面会发生一系列的电化学反应,阳极发生的析氯和析氧反应会使该侧溶液的p H维持在强酸性状态(p H 2-3),阴极发生的析氢反应则使该侧溶液的p H维持在13左右。当盐溶液中存在有机物时,电化学反应产生的活性氯物质(Cl2、HCl O、Cl-)和氢氧自由基(?OH)会对溶液中的有机物进行氧化降解。通过模拟染料废水的膜电解实验结果表明,该条件下的电解过程可有效去除染料废水的色度,并结合电解产物的红外光谱分析证明,几种染料物质的分子结构均遭到破坏,特别是-N=N-、=C=C=、=C=O等基团,并且分子结构越简单电解效果越好,色度取去除率也越高。最后,均相阴、阳离子交换膜的扫描电镜图像表明,均相阳离子交换膜使用后表面会吸附大量的物质,均相阴离子交换膜表面出现许多裂痕。通过酸碱清洗和超声清洗后,阳膜表面会变得平整光滑,而阴膜表面的裂痕并没有发生太大变化。经对清洗前后离子膜的脱盐效果的对比,结果表明清洗可使离子膜的离子去除率恢复到使用过一次时的状态,证明实验中所用的组合膜清洗方法可有效去除膜表面的有机物和无机盐沉淀造成的污染,进而在一定程度上恢复离子膜的脱盐性能。
[Abstract]:As a product of modern industrialization, high salt organic wastewater is not only large and complex, but it is easy to cause waste of water resources and environmental pollution. At present, the traditional physical and chemical treatment methods of high salt organic wastewater have the disadvantages such as high treatment cost, adding extra medicine agent, easily causing two pollution and so on, and waste water The high salt environment inhibits the activity of microbes and limits the application and development of microbiological methods. However, the high salinity wastewater has good conductivity and can provide an opportunity for the application of electrochemistry. As an important part of the electrochemical technology, membrane electrolysis technology combines the effect of traditional electrodialysis separation and purification and the characteristics of electrolysis technology. With the characteristics of low energy consumption and small environmental harm, this technology is undoubtedly a treatment method with great potential and research value for the treatment of high salt organic wastewater. This subject uses membrane electrolysis to desalination and organic degradation treatment of high salinity dyestuff wastewater, aiming at the study of high salt organic wastewater. The removal mechanism of salt ions and the influence of the organic matter degradation process on the desalting effect and the interaction relationship. The study uses a self-made detachable multistage membrane electrolyzer, taking Ti/RO2-Ir O2-Sn O2 as the shade, anode plate material, Na~+, Cl- as the target to remove ions, respectively, with the methyl orange, acid red 3R, direct dark brown, active bright brown. The membrane electrolysis desalination experiment under direct current electric field was carried out under the mixed system of blue X-BR and other dyes. The influence of current density, plate spacing, electrolyte concentration and injection velocity on the effect of electrolysis desalination in ion membrane electrolysis, as well as the effect of desalination and organic degradation in the process of double membrane electrolysis were discussed. The pollution cleaning problem of the cation exchange membrane used in the experiment was analyzed. The quantitative analysis of the P H, electrical conductivity, salt ion (Na~+, Cl-) concentration, TOC concentration and chromaticity in the solution at different time points, and the scanning electron microscope observation of the surface surface morphology of the ionic membrane and the infrared of the organic matter electrolysis products were analyzed. The following conclusion is drawn by spectral analysis: the effect of current density on desalination is the most significant in the process of membrane electrolysis desalination, which is the key factor causing polarization on the membrane surface. Under the conditions of setting the parameters of this experiment, the current density is 55.6m A/cm2, the spacing of the plate is 2cm, the electrolyte concentration is 2g/L, and the inlet velocity 50m L/min is the best condition. In the process of single film electrolysis, the removal rates of Cl- and Na~+ were 70% and 90%, respectively, while the removal rate of two kinds of salt ions could reach about 90% in the process of electrolytic treatment of dyestuff wastewater with double membrane electrolysis, and the degradation of several dyes was achieved to a certain extent. The degradation of methyl orange was the best, and the removal rate of TOC could be reached. At the same time, the special structure of the cationic membrane has effectively blocked the migration of organic molecules, thus realizing the separation of organic compounds from salt ions. In the process of membrane electrolysis, Na~+ and Cl- have directed migration under the action of the electric field. At the same time, the electrostatic action of the surface of the anion exchange membrane and the channel in the channel will be corresponding to the electrostatic action of the surface of the exchange membrane and the channel. The ions are adsorbed and migrate to remove the Na~+ and Cl-. The experiment shows that a series of electrochemical reactions occur on the surface of the plate in this process. The chlorine evolution and oxygen evolution of the anode will keep the P H of the side solution in the strong acid state (P H 2-3), and the hydrogen evolution reaction of the cathode causes the P H of the side solution to be maintained at 13. When organic matter exists in the salt solution, the active chlorine substance (Cl2, HCl O, Cl-) and hydrogen oxygen free radical (? OH) produced by the electrochemical reaction will oxidize and degrade the organic matter in the solution. The electrosolution process of the simulated dye wastewater shows that the chromaticity of the dye wastewater can be effectively removed and combined with electrolysis under this condition. The infrared spectrum analysis of the products showed that the molecular structures of several dyes were destroyed, especially the groups such as -N=N-, =C=C=, =C=O and other groups, and the more simple the molecular structure was, the better the electrolysis effect and the higher the chromaticity removal rate. There are many cracks on the surface of the homogeneous anion exchange membrane. After cleaning and ultrasonic cleaning, the surface of the film will become smooth and smooth, and the cracks on the surface of the film have not changed too much. The results show that the removal rate of ion membrane can be removed by the comparison of the effect of the desalination of the ion membrane before and after the cleaning. It was restored to the state when used once, and it was proved that the cleaning method used in the experiment can effectively remove the pollution caused by the organic matter and the inorganic salt precipitation on the surface of the membrane, and then to some extent, it can restore the desalination performance of the ion membrane to some extent.
【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

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