双层床与多层床MFEDI技术制备高纯水研究

发布时间：2018-02-25 15:58

本文关键词： 无膜电去离子(MFEDI) 高纯水离子交换树脂电再生树脂选择水回收率再生能耗　出处：《浙江大学》2014年博士论文　论文类型：学位论文

【摘要】：无膜电去离子(MFEDI)是本课题组研发的一项全新电去离子技术,其特征是在树脂层两端安放一对阴阳电极,采取交换处理与电再生交替操作。处理时,如同普通离子交换一样,依靠树脂的强交换能力除去水中的杂质离子；电再生时,对树脂层施加直流电使离子交换平衡朝着再生反应的方向移动,同时通以纯水将再生出来的离子排出树脂层。MFEDI工艺清洁,操作简便,因此在高纯水制备领域拥有十分广阔的应用前景。离子交换树脂是MFEDI的核心,树脂的特性和填充方式对MFEDI的净化效果和电再生性能影响很大。目前,MFEDI采用单层床弱酸强碱树脂制备高纯水存在净化效果不佳、再生电压过高等问题,限制了该技术在高纯水制备领域的推广应用。因此,进行MFEDI树脂选择及其床层结构优化研究,进而提高MFEDI制备高纯水性能,对该技术的发展具有重要意义。本论文系统地研究了适用于高纯水制备的双层床与多层床MFEDI技术。双层床是在MFEDI中,下层填充弱酸强碱树脂,上层填充强酸强碱树脂。多层床是在MFEDI中,树脂层每隔10cm插入一层强碱树脂。研究工作主要包括三部分：树脂选择、双层床MFEDI制备高纯水性能考察、多层床MFEDI制备高纯水性能考察。研究结果表明,弱酸强碱树脂和强酸强碱树脂均具备良好的去离子能力、电再生性能和导电性,适用于MFEDI制备高纯水研究。弱酸强碱树脂失效后容易获得电再生,但去离子能力和导电性不如强酸强碱树脂,可填充于MFEDI的进水端用以除去水中的大部分离子,并提高再生效果；强酸强碱树脂具有极佳的去离子能力和导电性,但电再生效果较差,可填充于MFEDI的出水端用以保证出水水质,并提高树脂层导电性。双层床MFEDI能有效地电再生失效离子交换树脂,经多次电再生后树脂仍然保持良好的处理效果,出水电导率为0.056～0.059μS/cm,满足高纯水水质要求。电再生过程,倒极可有效抑制离子的逆向电迁移,并使再生液pH值趋于中性。与单层术MFEDI相比,双层床MFEDI的净化效果和电再生性能均显著提高。电再生机理研究证实,树脂电再生所需H+和OH-离子主要由树脂间的水分解反应和电极的电解反应提供,前者贡献高于80%,后者贡献低于20%。利用强碱树脂层的阻断作用,多层床MFEDI可有效抑制阳离子的逆向电迁移,避免了MFEDI因频繁倒极导致再生液电导率下降、再生电压升高和电极损坏等问题。多层床MFEDI可长期稳定制备高纯水,30个制水周期内,出水电导率保持在0.055～0.060μS/cm之间,未出现水质恶化的趋势,水回收率90%,再生能耗0.71kWh/m3。
[Abstract]:MFEDI is a new electrodeionization technology developed by our team, which is characterized by the placement of a pair of anode and cathode electrodes at both ends of the resin layer and the alternating operation of exchange treatment and electrical regeneration. Depending on the strong exchange ability of the resin to remove impurity ions in water, direct current is applied to the resin layer during electrical regeneration so that the ion exchange equilibrium moves towards the direction of regeneration reaction. At the same time, pure water is used to remove the regenerated ions from resin layer. MFEDI process is clean and easy to operate, so it has a very broad application prospect in the field of high purity water preparation. Ion exchange resin is the core of MFEDI. The characteristics and filling methods of the resin have a great influence on the purification and electrical regeneration of MFEDI. At present, the preparation of high purity water by monolayer weakly acid-alkali resin has poor purification effect. The problems of high regeneration voltage limit the application of this technology in the preparation of high purity water. Therefore, the selection of MFEDI resin and the optimization of the bed structure are carried out to improve the performance of MFEDI in the preparation of high pure water. It is of great significance to the development of this technology. In this paper, the technology of double bed and multilayer bed MFEDI, which is suitable for the preparation of high purity water, is studied systematically. The double bed is filled with weak acid and strong base resin in MFEDI, and the upper layer is filled with strong acid and strong base resin. The multilayer bed is in MFEDI. A layer of strong alkali resin is inserted into the resin layer every 10 cm. The research work mainly includes three parts: selection of resin, study on the preparation of high pure water by MFEDI in double bed, and study on the preparation of high pure water in multilayer bed MFEDI. The results show that both weak acid strong base resin and strong acid strong base resin have good deionization ability, electrical regeneration property and electrical conductivity, which are suitable for the study of high purity water prepared by MFEDI. The weak acid strong base resin is easy to be regenerated after failure. However, the deionization ability and conductivity are not as good as those of strong acid and strong base resin, which can be filled in the influent end of MFEDI to remove most of the ions in water and improve the regeneration effect, and the strong acid strong base resin has excellent deionization ability and electrical conductivity. But the effect of electrical regeneration is poor and can be filled in the effluent end of MFEDI to ensure the effluent quality and improve the conductivity of resin layer. The two-layer bed MFEDI can effectively regenerate the failed ion exchange resin. After several times of electrical regeneration, the resin still has a good treatment effect. The effluent conductivity is 0.056 ~ 0.059 渭 s / cm, which meets the requirements of high purity water quality. The reverse electromigration of ions can be effectively inhibited and the pH value of regenerated solution tends to be neutral. Compared with monolayer MFEDI, the purification efficiency and electrical regeneration performance of MFEDI in double layer bed are significantly improved. The H and OH- ions needed for the electroregeneration of the resin are mainly provided by the water decomposition reaction between the resins and the electrolysis reaction between the electrodes. The former contribution is higher than 80%, the latter contribution is lower than 20%. By using the blocking effect of strong alkali resin layer, multilayer bed MFEDI can effectively inhibit the reverse electromigration of cations and avoid the decrease of electrical conductivity of regenerated solution caused by frequent inversion of MFEDI. High regeneration voltage and electrode damage. High purity water can be prepared by multilayer bed MFEDI for a long time. Within 30 water preparation cycles, the electrical conductivity of the effluent remains between 0.055 ~ 0.060 渭 S / cm, and there is no trend of water quality deterioration. The recovery rate of water is 90%, and the regenerative energy consumption is 0.71 kW 路m ~ (3) 路m ~ (3).
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU991.2;TQ425.23

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