本文關(guān)鍵詞： 層層自組裝 聚電解質(zhì)多層膜 復(fù)合納濾膜 鹽截留　出處：《武漢工程大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：當(dāng)今社會(huì),隨著人口數(shù)量的增長(zhǎng)及社會(huì)經(jīng)濟(jì)的發(fā)展,優(yōu)質(zhì)水資源少、水體污染嚴(yán)重的問題逐漸凸顯出來(lái)。水處理技術(shù)作為解決水資源短缺問題的手段之一受到人們的廣泛關(guān)注。膜分離作為水處理手段之一除了具有能耗低、分離效果好、工作條件溫和、工藝簡(jiǎn)單等優(yōu)點(diǎn)外,還能濃縮回收廢水苦咸水中的有用物質(zhì),達(dá)到資源全利用的目的。目前用于水處理中的膜分離技術(shù)主要有微濾、超濾、納濾、反滲透,其中納濾主要用于飲用水的軟化以及工業(yè)用水的除鹽等。為了解決目前市場(chǎng)上商業(yè)納濾膜的通量低選擇性差的缺點(diǎn),我們以聚砜超濾膜為基膜,在其上組裝聚電解質(zhì)多層膜制備了高通量高選擇性的復(fù)合納濾膜。聚電解質(zhì)層層自組裝制備多層膜具有方法簡(jiǎn)單、膜組成和結(jié)構(gòu)易于控制、可制備具有特殊功能的功能性復(fù)合膜等優(yōu)點(diǎn),這一技術(shù)已經(jīng)成為制備多層超薄膜的重要方法之一。由于聚電解質(zhì)層層自組裝膜具有表面電荷強(qiáng)度高、厚度薄的特點(diǎn),非常適合將其應(yīng)用于兼具高通量和高選擇性的復(fù)合納濾膜超薄分離層。本文以聚乙烯亞胺(PEI)為聚陽(yáng)離子電解質(zhì),聚丙烯酸(PAA)、聚苯乙烯磺酸鈉(PSS)為聚陰離子電解質(zhì),利用聚電解質(zhì)自組裝技術(shù)對(duì)Alfa Laval UFX-10聚砜超濾膜進(jìn)行表面改性,制備了自組裝復(fù)合納濾膜并將其用于鹽類分離和濃縮的研究。實(shí)驗(yàn)研究了聚電解質(zhì)雙層數(shù)、自組裝時(shí)間、聚電解質(zhì)溶液pH值、聚電解質(zhì)濃度、最外層電解質(zhì)、支撐電解質(zhì)種類、支撐電解質(zhì)濃度等工藝參數(shù)對(duì)聚電解質(zhì)改性復(fù)合納濾膜水通量以及鹽截留率的影響,并考察了膜的穩(wěn)定性。實(shí)驗(yàn)結(jié)果表明,聚電解質(zhì)雙層數(shù)、自組裝時(shí)間、聚電解質(zhì)溶液pH、最外層聚電解質(zhì)層種類等條件對(duì)改性膜性能影響較大,支撐電解質(zhì)種類、聚電解質(zhì)濃度對(duì)多層膜的性能影響較小。隨著聚電解質(zhì)多層膜雙層數(shù)的增加,復(fù)合膜的截留性能提高,同時(shí)水通量降低。最外層聚電解質(zhì)層種類對(duì)膜的鹽截留性能影響較大,對(duì)水通量影響較小。通過(guò)衰減全反射紅外光譜對(duì)多層膜進(jìn)行分析。PEI/PSS多層膜ATR-IR譜圖與基膜基本重合,隨著雙層數(shù)的增加,1015cm-1處磺酸基的特征吸收峰峰強(qiáng)度略微增加,表明PSS層數(shù)增加。PEI/PAA多層膜ATR-IR譜圖我們可以明顯看出1738cm-1處的羧基吸收峰峰強(qiáng)度增大。通過(guò)ATR-IR表征表明PSF基膜上發(fā)生了聚電解質(zhì)層層自組裝過(guò)程。通過(guò)SEM對(duì)多層膜表面形貌進(jìn)行了表征,發(fā)現(xiàn)經(jīng)過(guò)聚電解質(zhì)層層自組裝改性后,膜的表面形貌發(fā)生了變化,多層膜表面變得更加光滑平整。對(duì)改性納濾膜表面接觸角的表征結(jié)果表明,基膜經(jīng)過(guò)聚電解質(zhì)自組裝改性以后膜表面的親水性顯著增強(qiáng)。通過(guò)研究各種工藝參數(shù)對(duì)膜性能的影響,獲得最佳的制膜工藝條件為:支撐電解質(zhì)NaCl濃度0.5 mol/L、聚電解質(zhì)濃度0.02 mol/L、聚電解質(zhì)溶液pH為7左右、聚電解質(zhì)組裝時(shí)間15分鐘。在此條件下制備的(PEI/PSS)5、(PEI/PSS)_(5.5)、(PEI/PAA)5、(PEI/PAA)_(5.5)的截留率分別為71.15%、79.5%、60.19%、42.13%,此時(shí)膜的通量分別為22.86L/(m2·h)、17.14 L/(m2·h)、4.29 L/(m2·h)、23.57 L/(m2·h)。所制得的膜穩(wěn)定性較好,在4bar壓力下連續(xù)運(yùn)行6小時(shí)、累積運(yùn)行18小時(shí)內(nèi)膜通量與鹽截留率變化較小。從多方面研究了聚電解質(zhì)改性膜的性能特征。實(shí)驗(yàn)結(jié)果表明,不同類型多層膜的鹽截留性能差別很大,同種多層膜對(duì)不同鹽溶液的截留率也不相同,具有一定的選擇性�？疾炝硕鄬幽そ亓粜阅芘c不同操作條件之間的關(guān)系,研究了料液溫度、pH、壓力、濃度等操作因素對(duì)膜截留性能的影響,并進(jìn)行了簡(jiǎn)單的鹽類分離實(shí)驗(yàn),總結(jié)了聚電解質(zhì)改性納濾膜的性能特點(diǎn)。
[Abstract]:In today's society, with the development of the growth of population and social economy, high-quality water resources, serious water pollution problem is more prominent. Water treatment technology as one of the means to solve the shortage of water resources have attracted extensive attention. As a means of water treatment in addition to membrane separation has the advantages of low energy consumption, good separation effect, work under mild conditions, simple process and other advantages, but also useful material in wastewater concentration and recovery of brackish water, to achieve full utilization of resources. Currently used for membrane separation technology in water treatment include microfiltration, ultrafiltration, nanofiltration, reverse osmosis nanofiltration, which is mainly used for drinking water and industrial water softening desalting to. To solve the current commercial nanofiltration membrane flux on the market low selectivity, we using polysulfone ultrafiltration membrane as support membrane, assembly of polyelectrolyte multilayer films were prepared in the high throughput Composite nanofiltration membrane selectivity. Polyelectrolyte self-assembled multilayer film has the advantages of simple method, film composition and structure is easy to control, can be prepared with special functional composite film and other advantages, this technology has become one of the important methods for preparing multilayer ultrathin films. The polyelectrolyte self-assembled film has the surface charge characteristics of high strength, thin thickness, very suitable for its application in both high throughput and high selectivity of the composite membrane. The ultrathin separating layer with polyethyleneimine (PEI) as polycation electrolyte, polyacrylic acid (PAA), sodium polystyrene sulfonate (PSS) as polyanion electrolyte, using self-assembled polyelectrolyte technology of Alfa Laval UFX-10 polysulfone ultrafiltration membrane surface modification, preparation of self assembled composite nanofiltration membrane was used in the study of separation and concentration of salts. Experimental study of polyelectrolyte Self-assembled Bilayer number. With time, the polyelectrolyte solution pH, concentration of polyelectrolyte, the outermost layer of supporting electrolyte, electrolyte species, supporting electrolyte concentration and other parameters on the effect of polyelectrolyte modified composite nanofiltration membrane water flux and salt rejection rate, and the effect of membrane stability. The experimental results show that the number of polyelectrolyte bilayers, self-assembly time. Polyelectrolyte solution pH, the outermost layer of the polyelectrolyte layers and other types of conditions have a greater impact on the modified membrane performance, supporting electrolytes, polyelectrolytes concentration affects the performance of multilayer small. With the increase of the number of bilayers of polyelectrolyte multilayers, improve the rejection performance of the composite membrane, and the water flux decreased. The outermost layer of polyelectrolyte type the membrane salt rejection performance influence on small water flux affected by attenuated total reflection infrared spectroscopy analysis of multilayer.PEI/PSS multilayer ATR-IR spectra and membrane basic weight He, along with the increase of the number of bilayers, characteristics of 1015cm-1 sulfonic acid absorption peak strength increased slightly, showed that PSS increased layers of.PEI/PAA multilayer ATR-IR spectrum we can clearly see that 1738cm-1 at the carboxyl absorption peak intensity increases. The results indicated that PSF membrane had polyelectrolyte layer by layer self-assembly process characterized by ATR-IR through SEM. The surface morphology of the multilayer films were characterized by polyelectrolyte layer by layer self-assembly modification, changes in surface morphology of the film, multilayer film surface becomes more smooth. Show that the modified nano characterization of membrane surface contact angle of the membrane by self assembled polyelectrolyte modified after the hydrophilicity of the membrane surface significantly enhanced. By studying the effect of different process parameters on membrane performance, obtained the optimum process conditions for membrane supporting electrolyte NaCl concentration of 0.5 mol/L, the polyelectrolyte concentration 0.02 mol/L, poly 鐢?shù)瑙ｈ川婧舵恫pH涓，

本文編號(hào)：1507331