本文關(guān)鍵詞： 正滲透 碳納米管 膜蒸餾 FO-MD耦合工藝 高鹽廢水　出處：《湘潭大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：正滲透(FO)及膜蒸餾(MD)由于特有的優(yōu)勢(shì),在高鹽廢水處理方面應(yīng)用得越來(lái)越多,但正滲透面臨著缺乏高性能正滲透膜以及選取合適汲取液的問(wèn)題,而膜蒸餾膜容易被表面活性有機(jī)物潤(rùn)濕,造成膜污染。本文探究了如何制備高水通量、截鹽效果好、機(jī)械性能優(yōu)異的正滲透膜,并將正滲透膜應(yīng)用在正滲透-膜蒸餾(FO-MD)耦合工藝中,探究了兩種工藝的影響參數(shù)以及FO-MD耦合工藝處理污染廢水的效果,最后對(duì)耦合工藝的傳質(zhì)傳熱過(guò)程進(jìn)行了探究。主要成果如下:(1)以聚丙烯腈、摻入碳納米管和石墨烯的聚丙烯腈作為原料液,制得正滲透膜基底,在界面聚合一層聚酰胺功能層,制成正滲透膜�？疾炝酥颇し绞健⒓徑z電壓、接收距離和原料液組成對(duì)膜結(jié)構(gòu)的影響,重點(diǎn)探究了靜電紡絲法中PAN濃度和MWCNT濃度對(duì)膜形貌、親水性和機(jī)械性能的影響。隨著電壓增大,纖維直徑先增大后減小,隨著接收距離增大,纖維直徑變小。PAN濃度增大使纖維直徑和機(jī)械強(qiáng)度變大,孔隙率增大后減小。多壁碳納米管降低了平均直徑,增強(qiáng)了膜的親水性,提高了膜的機(jī)械強(qiáng)度,但使膜韌性變差。(2)分別以相轉(zhuǎn)化法和靜電紡絲制備PAN正滲透基底,但相轉(zhuǎn)化法水通量較低。用靜電紡絲法制備了聚丙烯腈/石墨烯和聚丙烯腈/碳納米管正滲透膜,結(jié)果表明石墨烯和碳納米管都提高了膜水通量,且碳納米管影響更大。著重研究了PAN和MWCNT對(duì)正滲透膜性能的影響,一定范圍內(nèi)PAN濃度增大、f-MWCNT增加有利于提高膜水通量和截鹽率。聚丙烯腈濃度為12%,f-MWCNTs濃度為1.44%的正滲透膜,表現(xiàn)出高水通量和高截鹽率,以1.0 mol/L NaCl為汲取液,純水作為原料液,水通量可達(dá)到70.1 L/(m2·h),反向鹽通量?jī)H50.4(g/m2·h)。(3)探究了汲取液濃度、溫度、流速等參數(shù)在正滲透過(guò)程對(duì)水通量和反向鹽通量的影響,以及在膜蒸餾過(guò)程中待處理液熱端進(jìn)料溫度、膜兩側(cè)流速對(duì)水通量、水質(zhì)的影響。結(jié)果表明正滲透過(guò)程水通量隨著汲取液濃度、溫度、流速的增大都有一定程度的增大,升溫對(duì)水通量的影響最大,對(duì)溶質(zhì)反向滲透量的影響不大。溫差增大、膜厚度減小、流速的增大都會(huì)促進(jìn)膜蒸餾水通量的增大。(4)對(duì)比經(jīng)MD過(guò)程與RO過(guò)程,MD過(guò)程、與FO-MD集成過(guò)程處理的廢水,結(jié)果顯示FO-MD集成系統(tǒng)處理的膜污染較低,且長(zhǎng)時(shí)間運(yùn)行結(jié)果穩(wěn)定,具有良好的耐污性。對(duì)不同汲取液選擇的能耗計(jì)算,表明使用NaCl溶液為正滲透單元汲取液時(shí),相比于NH4HCO3為汲取液能耗更低。而且NaCl溶液濃縮回收具有良好效果,可以實(shí)現(xiàn)零排放。
[Abstract]:Due to its unique advantages, normal osmosis (FOO) and membrane distillation (MDD) are more and more widely used in the treatment of high salt wastewater. However, due to the lack of high performance forward osmotic membrane and the selection of suitable solution, positive osmosis is faced with many problems. However, membrane distillation membrane is easy to be wetted by surface active organic compounds, resulting in membrane fouling. In this paper, the preparation of high water flux, good salt cutting effect, excellent mechanical properties of normal osmotic membrane has been investigated. The normal osmotic membrane was applied to the FO-MD coupling process. The influence parameters of the two processes and the effect of the FO-MD coupling process on the treatment of polluted wastewater were explored. Finally, the mass transfer and heat transfer process of the coupling process is studied. The main results are as follows: (1) Polyacrylonitrile (pan) with carbon nanotube (CNT) and graphene as the raw material liquid is used to prepare the normal permeable membrane substrate, and a layer of polyamide functional layer is polymerized at the interface. The effects of film preparation mode, spinning voltage, receiving distance and composition of raw material liquid on the membrane structure were investigated. The effects of PAN concentration and MWCNT concentration on the morphology of the membrane were investigated. The effect of hydrophilicity and mechanical properties. With the increase of voltage, the diameter of the fiber increases first and then decreases, and with the increase of the receiving distance, the diameter of the fiber becomes smaller and the concentration of pan increases, the diameter and mechanical strength of the fiber become larger. With the increase of porosity, the average diameter was decreased, the hydrophilicity and mechanical strength of the membrane were enhanced, but the toughness of the membrane became worse, which resulted in the preparation of PAN positive permeable substrates by phase inversion and electrospinning, respectively. But the water flux of phase inversion method was low. Polyacrylonitrile / graphene and polyacrylonitrile / carbon nanotubes were prepared by electrospinning. The results showed that both graphene and carbon nanotube increased the water flux of the membrane. The effects of PAN and MWCNT on the properties of the membrane were studied. The increase of PAN concentration in a certain range is beneficial to the increase of water flux and salt interception rate of the membrane, and the concentration of polyacrylonitrile is 12% f-MWCNTs with the concentration of 1.44%. Using 1.0 mol/L NaCl as absorbent, pure water as feedstock solution, water flux can reach 70.1 L / m ~ 2 路hm ~ 2 路h ~ (-1), reverse salt flux is only 50.4 g / m ~ (2 路h ~ (2) 路h ~ (-1)). The influence of flow rate and other parameters on water flux and reverse salt flux during the normal osmotic process, as well as the feed temperature at the hot end of the liquid to be treated during membrane distillation, and the water flux on both sides of the membrane were studied. The results show that the water flux increases to a certain extent with the concentration, temperature and flow rate of the solution in the normal osmotic process, the effect of heating on the water flux is the greatest, and the effect on the reverse osmotic capacity of solute is not significant, but the temperature difference increases. Compared with MD process, RO process, MD process and FO-MD integrated process, membrane fouling was lower in FO-MD integrated system. The results of long time operation are stable and have good resistance to pollution. For the calculation of energy consumption of different extraction fluids, it is shown that when NaCl solution is used as normal osmotic unit extract solution, Compared with NH4HCO3 solution, the energy consumption is lower, and NaCl solution concentration and recovery have good effect, and can achieve zero emission.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ028.8;X703

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