基于LbL自组装法改性的反渗透复合膜的制备与性能研究

发布时间：2018-06-08 00:39

本文选题：耐污染 + 反渗透复合膜　；参考：《浙江工业大学》2015年硕士论文

【摘要】：反渗透是一种有效的净水技术,在开辟新的水源方面起到了重要作用,目前通用的反渗透膜是聚酰胺复合膜,这种膜普遍存在易氧化、易污染两大问题。本文对反渗透膜污染情况进行考察,利用间苯二胺(MPD)和5-氯甲酸酯-异酞酰氯(CFIC)先制得MPDCFIC膜作为基底膜,然后利用LbL层层自组装技术对其进行改性调控。经过界面聚合制得的MPD-CFIC膜表面存在-COOH,先对MPDCFIC基底膜用NaOH溶液或NaCl O溶液进行预处理,使得膜表面的-COOH离子化,然后再组装上CS聚电解质,最后用GA对其进行固化,调节交联度,制得改性膜1(经NaOH处理后制得的MPDCFIC-CS-GA膜)和改性膜2(经NaClO处理后制得的MPD-CFICCS-GA膜)。在NaOH溶液预处理MPD-CFIC基底膜后,先于CS,用PDDA和PSS组装两层,再组装上CS,后用GA固化,制得改性膜3(经NaOH处理后制得的MPD-CFIC-PDDA-PSS-CS-GA膜)。考察了LbL自组装工艺如NaOH离子化条件、NaClO溶液浓度与处理时间、CS质子化条件、CS浓度、GA交联条件对膜分离性能的影响,并通过在不同浓度的NaCl溶液进水操作下,比较MPD-CFIC膜、改性膜1、改性膜2和改性膜3四种膜的分离性能,发现三种经过自组装改性后的膜的水通量和脱盐率均高于基底膜。通过全反射傅立叶红外光谱仪(ATR-FTIR)和X-射线光电子能谱(XPS)分析膜表面的有效分离活性层化学结构;通过扫描电镜(SEM)和原子力显微镜(AFM)观察膜表面形态;通过接触角仪研究膜表面的亲水性能。四种膜表面都呈典型的峰谷状,与基底膜相比,三种经过自组装改性后的膜表面更为光滑,亲水性也较好,且改性膜3最为光滑,改性膜2亲水性能最好。利用西湖原水浸泡污染实验,分析MPD-CFIC膜、改性膜1、改性膜2和改性膜3四种膜的耐污染性能,比较四种膜经污染后分离性能的恢复情况,并用SEM观察膜表面污染情况,发现经自组装改性后的膜耐污染性能优于未改性的基底膜。
[Abstract]:Reverse osmosis (RO) is an effective water purification technology, which plays an important role in opening up new water sources. At present, the universal reverse osmosis membrane is polyamide composite membrane, which is easy to oxidize and pollute. In this paper, the fouling of reverse osmosis membrane was investigated. MPDCFIC membrane was prepared by using MPD) and 5-chloroformate-isophthalic acid chloride (CFICC) as base membrane, and then modified by LBL layer by layer self-assembly technique. There is -COOH on the surface of MPD-CFIC film prepared by interfacial polymerization. The substrate membrane of MPDCFIC is pretreated with NaOH solution or NaCl O solution, the surface of MPD-CFIC film is ionized with -COOH, and then the CS polyelectrolyte is assembled. Finally, it is solidified by GA to adjust the crosslinking degree. The modified membrane (MPDCFIC-CS-GA) and the modified membrane (MPD-CFICCS-GA) were prepared by NaOH treatment. After pretreatment of MPD-CFIC base membrane with NaOH solution, MPD-CFIC substrate membrane was pretreated with NaOH solution, then two layers were assembled with PDDA and PSS, then CSS was assembled, then cured with GA, the modified membrane 3 (MPD-CFIC-PDDA-PSS-CS-GA film) was prepared after NaOH treatment. The effects of LBL self-assembly process, such as NaOH ionization condition, NaClO solution concentration and treatment time, CS concentration and GA crosslinking condition on membrane separation performance were investigated. The MPD-CFIC membrane was compared under the influent operation of NaCl solution with different concentration. The separation properties of modified membrane 1, modified membrane 2 and modified membrane 3 showed that the water flux and desalinization rate of the three modified membranes were higher than those of the base membrane. The chemical structure of the active layer on the membrane surface was analyzed by ATR-FTIR and X- ray photoelectron spectroscopy (XPS), and the morphology of the membrane was observed by scanning electron microscopy (SEM) and atomic force microscope (AFM). The hydrophilicity of the membrane surface was studied by contact angle meter. Compared with the base membrane, the surface of the three modified membranes is more smooth and hydrophilic, and the modified membrane 3 is the most smooth, and the modified membrane 2 has the best hydrophilicity. The pollution resistance of MPD-CFIC membrane, modified membrane 1, modified membrane 2 and modified membrane 3 were analyzed by soaking pollution experiment in raw water of West Lake. The recovery of separation performance of four kinds of membranes after polluted was compared, and the surface fouling of MPD-CFIC membrane was observed by SEM. It was found that the self-assembled modified membrane had better resistance to pollution than the unmodified substrate membrane.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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