本文選題：超濾膜污染　切入點：葡聚糖　出處：《山東大學》2017年碩士論文　論文類型：學位論文

【摘要】：膜污染現(xiàn)象是制約超濾技術發(fā)展的重要因素。混凝技術作為一種預處理措施,被應用到膜分離技術中來減緩膜污染。本研究運用XDLVO(extended Derjaguin-Landau-Verwey-Overbeek)理論定量解析在不同聚合氯化鋁(PACl)或Ca~(2+)濃度條件下葡聚糖超濾膜污染中的界面相互作用,評價不同界面作用力(范德華作用力、雙電層作用力以及極性作用力)對膜污染的貢獻程度,探究混凝預處理中絮凝劑濃度、Ca~(2+)濃度和pH影響葡聚糖超濾膜污染的主控機制。在對界面作用力進行定量解析的基礎上,分別對不同實驗條件下葡聚糖膜污染趨勢與界面作用能之間的線性關系進行定性分析與定量解析,從而更為全面、系統(tǒng)的對xDLVO理論描述葡聚糖預混凝-超濾膜污染行為的適用性做出評價。結(jié)果表明,在所有實驗條件下,AB作用是影響膜污染趨勢的主要因素。葡聚糖預混凝-超濾膜污染過程中的超濾膜-葡聚糖和葡聚糖-葡聚糖界面相互作用力隨著絮凝劑濃度和鈣離子濃度呈現(xiàn)一定的變化規(guī)律。當絮凝劑濃度逐漸升高時,超濾膜-葡聚糖和葡聚糖-葡聚糖界面相互作用能按照6930mg/l PACl的順序依次降低;當溶液中有鈣離子存在時,界面自由能有所下降,且隨著鈣離子濃度的升高進一步降低;在pH為7時,界面作用能最大,酸性和堿性環(huán)境下有所降低。PACl、Ca~(2+)和pH主要通過降低AB作用的排斥性或增強吸引性來影響膜污染趨勢,同時預混凝過程會顯著增大污染物粒徑,進而使界面自由能的絕對值增大。膜過濾初始和后期階段的相對膜通量下降量分別與膜和污染物以及污染物之間的界面作用能有較強的線性相關性,證明XDLVO理論對預測混凝預處理-超濾過程中的膜污染趨勢有較高的適用性。絮凝劑濃度、Ca~(2+)濃度和pH對葡聚糖預混凝-超濾膜污染行為具有重要的影響。隨著絮凝劑PACl濃度的升高,相對通量呈現(xiàn)先遞增后遞減的趨勢,且在PACl濃度為6mg/l時,相對通量達到最大。而隨著Ca~(2+)濃度的升高,PES膜葡聚糖超濾過程中的相對通量逐漸降低。在pH為7時,膜污染最輕,酸性和堿性環(huán)境下有所加重。不同絮凝劑濃度以及鈣離子濃度條件下,PES膜過濾初始階段和后期階段中的膜污染趨勢分別與超濾膜-葡聚糖和葡聚糖-葡聚糖界面相互作用能具有良好的負線性相關性。因此xDLVO理論適用于描述不同絮凝劑濃度、Ca~(2+)濃度和pH條件下的膜污染趨勢。不同絮凝劑濃度、Ca~(2+)濃度和pH對整個超濾過程中膜污染行為的影響主要是通過改變極性作用力來實現(xiàn)的。葡聚糖為親水性中性物質(zhì),表面zeta電位趨于0,因此靜電作用能對膜污染趨勢的影響很小。而范德華作用能與絮凝劑濃度和鈣離子濃度的變化沒有一致的規(guī)律性,其對膜污染趨勢的影響也很小。
[Abstract]:Membrane fouling is an important factor restricting the development of ultrafiltration technology. In this study, XDLVO(extended Derjaguin-Landau-Verwey-Overbeek theory was used to quantitatively analyze the interfacial interaction of dextran ultrafiltration membrane fouling with different concentrations of polyaluminum chloride (PACl) or Ca~(2. To evaluate the contribution of different interface forces (van der Waals force, double layer force and polarity force) to membrane fouling. The main control mechanism of the influence of flocculant concentration and pH on the fouling of dextran ultrafiltration membrane in coagulation pretreatment was investigated. The linear relationship between the fouling trend of dextran membrane and the interfacial interaction energy under different experimental conditions was analyzed qualitatively and quantitatively respectively. The applicability of xDLVO theory to describe the fouling behavior of dextran precoagulation-ultrafiltration membrane was systematically evaluated. Under all experimental conditions, the action of AB is the main factor affecting the trend of membrane fouling. Interaction between UF membrane and dextran and dextran interface with flocculant concentration in the process of Dextran precoagulation-UF membrane fouling. When the concentration of flocculant gradually increased, The interaction energy of ultrafiltration membrane and dextran / dextran interface decreased in the order of 6930 mg / l PACl, and the free energy of interface decreased with the increase of calcium ion concentration in the solution. When pH was 7:00, the interfacial energy was the largest, and the pH value was decreased in acidic and alkaline environment, and pH affected the fouling tendency of the membrane mainly by reducing the repellency or enhancing the attraction of AB, and the particle size of the pollutants was significantly increased during the pre-coagulation process. Then the absolute value of the interface free energy is increased, and the relative membrane flux decreases in the initial and late stages of membrane filtration have a strong linear correlation with the interface energy of the membrane, pollutants and pollutants, respectively. It is proved that XDLVO theory is more suitable for predicting membrane fouling tendency during coagulation pretreatment and ultrafiltration. The concentration of flocculant and pH have important effects on the fouling behavior of dextran precoagulation-ultrafiltration membrane. The increase of PACl concentration, The relative flux increased at first and then decreased, and the relative flux reached the maximum when the concentration of PACl was 6 mg / l. With the increase of Ca~(2 concentration, the relative flux of PES membrane decreased gradually. At pH 7:00, the membrane fouling was the least. The fouling tendency of PES membrane in the initial and late stage of filtration was different with the interface of ultrafiltration membrane dextran and dextran dextran under the condition of different flocculant concentration and calcium concentration. The interaction energy has a good negative linear correlation. Therefore, xDLVO theory can be used to describe the membrane fouling tendency under different flocculant concentration and pH. Different flocculant concentration and pH influence the whole ultrafiltration process. The effect of membrane fouling is mainly achieved by changing polarity force. Dextran is a hydrophilic neutral substance. The surface zeta potential tends to be zero, so the electrostatic action energy has little effect on the membrane fouling trend, while van der Waals interaction energy has no consistent regularity with the change of flocculant concentration and calcium ion concentration, and its influence on the membrane fouling trend is also very small.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X703;TU991.2

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1 田琳;xDLVO理論解析天然有機物存在下納米顆粒膜污染行為[D];山東大學;2017年

2 陳德坤;xDLVO理論解析混凝預處理對葡聚糖超濾膜污染的影響機理[D];山東大學;2017年

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本文編號：1611168