聚砜中空纖維載體上NaA型分子篩膜的制備
發(fā)布時(shí)間:2018-06-26 13:33
本文選題:NaA型分子篩膜 + 聚砜載體。 參考:《大連理工大學(xué)》2015年碩士論文
【摘要】:作為膜分離的一個(gè)重要分支,滲透汽化受到了許多學(xué)者的研究關(guān)注。中空纖維式膜組件與其他形式的膜組件相比,具有成本低、填充率高、有自支撐作用而占地面積小等優(yōu)點(diǎn)。目前受到廣泛關(guān)注的中空纖維滲透汽化膜材料主要是聚合物材料,但其存在溶脹、熱穩(wěn)定性差、滲透通量低和分離因子小等問(wèn)題。而常見(jiàn)的無(wú)機(jī)材料,如分子篩,需要制備在成本較高的支撐體上,且還存在制成的膜組件體積較大、填充率低的問(wèn)題。因此,在有機(jī)中空纖維上合成分子篩膜,對(duì)于解決上述問(wèn)題具有一定的實(shí)際意義。然而,有機(jī)載體與分子篩之間結(jié)合性差,分子篩容易從載體上脫落。如何實(shí)現(xiàn)在有機(jī)中空纖維載體制備無(wú)機(jī)分子篩膜,使制備的膜材料兼具聚合物和無(wú)機(jī)分子篩的性能,成為滲透汽化膜領(lǐng)域一個(gè)重要的研究?jī)?nèi)容。本文提出以聚砜(PSf)中空纖維為支撐體,通過(guò)在有機(jī)中空纖維表面涂覆中間層,采用水熱合成法在其表面合成NaA型分子篩膜,實(shí)現(xiàn)分子篩膜在有機(jī)中空纖維載體表面的連續(xù)致密生長(zhǎng)。首先,采用具有親水性PVA作為制備中間層的材料,成功在中空纖維表面制備了NaA型分子篩膜。考察了添加中間層與否、合成時(shí)間、晶種粒徑、涂晶次數(shù)對(duì)分子篩膜分離性能的影響,優(yōu)化了制膜的工藝。結(jié)果表明,PVA中間層的存在有利于在PSf中空纖維載體上合成連續(xù)致密,無(wú)明顯缺陷的NaA分子篩膜。該膜的分離性能在合成時(shí)間大于6 h、晶種平均粒徑90 nm、涂晶次數(shù)為3次時(shí)達(dá)到最佳,所制備的NaA型分子篩膜分離因子可達(dá)37.28,通量為3.53 kg·m-2·h-1。為了進(jìn)一步優(yōu)化膜的制備過(guò)程,減少涂晶步驟對(duì)制備工藝的影響,采用聚合物/NaA作為復(fù)合中間層,在中空纖維表面合成分子篩膜。考察了中間層材料、合成時(shí)間、涂膜方式、膜液晶種含量對(duì)分子篩膜分離性能的影響。結(jié)果表明,采用乙基纖維素(EC)/NaA復(fù)合中間層涂敷在中空纖維表面合成的分子篩膜,分離性能要高于采用PVA中間層涂敷在中空纖維表面合成的分子篩膜。涂膜方式對(duì)分子篩膜的分離性能影響很大,采用4wt%EC-50wt%NaA的復(fù)合晶種膜液一次浸涂,1.5wt%EC-xwt%NaA含量(xwt%為二次浸涂液中NaA含量)的復(fù)合晶種膜液二次浸涂的方法所制備的復(fù)合中間層較好,最佳的二次浸涂液NaA含量為80wt%,最佳合成時(shí)間大于6h,所制備的NaA型分子篩膜分離因子可達(dá)62.19,通量達(dá)到2.07kg·m-2·h-1。
[Abstract]:As an important branch of membrane separation, pervaporation has been studied by many scholars. Compared with other kinds of membrane assembly, hollow fiber membrane assembly has the advantages of low cost, high filling rate, self-supporting effect and small area. At present, the hollow fiber pervaporation membrane materials are mainly polymer materials, but there are many problems such as swelling, poor thermal stability, low permeation flux and small separation factor. The common inorganic materials, such as molecular sieve, need to be prepared on the high cost support, and there are many problems such as large volume of membrane assembly and low filling rate. Therefore, the synthesis of molecular sieve membrane on organic hollow fiber has certain practical significance for solving the above problems. However, the binding between the organic support and the molecular sieve is poor, and the molecular sieve is easy to fall off from the support. How to prepare inorganic molecular sieve membrane on organic hollow fiber carrier and make the membrane material have the properties of both polymer and inorganic molecular sieve has become an important research content in the field of pervaporation membrane. In this paper, using polysulfone (PSF) hollow fiber as support, NAA molecular sieve membrane was synthesized on the surface of polysulfone (PSF) hollow fiber by coating the intermediate layer on the surface of organic hollow fiber by hydrothermal synthesis. The continuous dense growth of molecular sieve membrane on the surface of organic hollow fiber carrier was realized. Firstly, NAA molecular sieve membrane was successfully prepared on hollow fiber surface by using hydrophilic PVA as intermediate layer. The effects of adding intermediate layer, synthesizing time, seed size and coating times on the separation performance of molecular sieve membrane were investigated, and the process of membrane preparation was optimized. The results show that the presence of PVA intermediate layer is beneficial to the synthesis of continuous dense NAA molecular sieve membrane without obvious defects on PSF hollow fiber carrier. When the synthesis time is more than 6 h, the average grain size is 90 nm, and the coating times are 3 times, the separation factor of NAA zeolite membrane is 37.28 and the flux is 3.53 kg m-2 -1. In order to further optimize the preparation process of the membrane and reduce the effect of coating on the preparation process, molecular sieve membrane was synthesized on the surface of hollow fiber using polymer / NAA as the composite intermediate layer. The effects of interlayer material, synthesis time, coating method and liquid crystal content on the separation performance of molecular sieve membrane were investigated. The results show that the separation performance of the composite interlayer coated with ethylcellulose (EC) / NAA on the surface of hollow fiber is higher than that on the surface of hollow fiber. The coating method has a great influence on the separation performance of molecular sieve membrane. The composite interlayer is better prepared by the method of 4wt-50wtNaA composite seed membrane solution once impregnated and 1.5wt-xwtNaA content (xwt% is the NaA content in the secondary impregnation solution). The optimum NaA content of secondary leaching solution is 80 wt.The optimum synthesis time is more than 6 h. The membrane separation factor of NAA molecular sieve can reach 62.19, and the flux can reach 2.07kg m-2 mh-1.
【學(xué)位授予單位】:大連理工大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類號(hào)】:TQ051.893
【共引文獻(xiàn)】
相關(guān)期刊論文 前5條
1 劉建華;于海波;楊海華;李琳;;滲透汽化傳質(zhì)模型的研究進(jìn)展[J];廣州化工;2013年17期
2 賀艷;崔學(xué)民;劉樂(lè)平;張尚;張偉鵬;;溶膠凝膠法制備高鈣離子交換量的NaA沸石(英文)[J];稀有金屬材料與工程;2012年S3期
3 韶暉;周軼;鐘t,
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