本文選題：混凝 + 飲用水�。� 參考：《西安建筑科技大學》2013年碩士論文

【摘要】：腐殖酸（HA）廣泛存在于各類水體中，其在飲用水中的存在不利于其他有機物的去除，而且它是消毒副產物的前驅物，因此，腐殖酸的去除受到越來越多的關注。傳統(tǒng)的混凝-沉淀-過濾水處理工藝對腐殖酸等有機物的去除效果并不理想，而紫外光照除了能將水中的有機物直接礦化外，還能夠促進后續(xù)混凝過程的進行。本課題研究了紫外光照射后腐殖酸分子結構的變化特征，考察了水質條件對紫外照射前后腐殖酸混凝性能的影響規(guī)律，并對紫外預處理對腐殖酸混凝的促進作用機理進行了探討，得出如下實驗結論： 紫外光照射對腐殖酸溶液的pH值和TOC濃度均有一定的影響。堿性條件下，紫外照射后腐殖酸溶液pH顯著降低，氣相色譜數(shù)據(jù)表明，紫外光照射后溶液中生成了部分小分子酸；酸性條件下，紫外照射后腐殖酸溶液pH略微升高，，分析認為這與腐殖酸酸性基團的生成速率及礦化速率有關，當pH=7時，紫外照射后腐殖酸溶液的TOC下降率約為10%。此外，紫外輻射作用對腐殖酸分子結構也存在影響。pH=8和pH=10的兩種腐殖酸溶液的E4/E6值隨著輻射時間的增加而減小；紫外輻射后腐殖酸溶液的三維熒光強度減弱，且紅外光譜圖中的一些官能團也發(fā)生了改變。 水質條件對紫外照射前后腐殖酸的混凝性能具有一定的影響。改變溶液的pH值，不經紫外預處理的腐殖酸溶液最佳混凝效果出現(xiàn)在pH=5時，經過紫外預處理的腐殖酸溶液最佳混凝效果出現(xiàn)在pH=6時；當pH大于5.5時，紫外預處理對腐殖酸混凝具有促進作用，這種促進在pH=7時達到最大，pH=7時不經紫外預處理的PHA（上海巨楓腐殖酸）混凝出水殘余量為7.592mg/L，而經過紫外預處理后PHA混凝出水殘余量降低到1.935mg/L。研究發(fā)現(xiàn)，濁度和陽離子（Ca2+、Mg2+）會對聚合氯化鋁（PACl）混凝腐殖酸水樣起促進作用，但Ca2+、Mg2+的存在會抑制紫外預處理對腐殖酸混凝的促進作用；堿度對紫外照射前后腐殖酸的混凝影響較小，當堿度從5mg/L增加到100mg/L時，紫外預處理前后的腐殖酸溶液去除率降低值基本相同（約為15%）；腐殖酸分子結構也會影響其混凝效果，分子尺寸較大且親水基團少的腐殖酸分子更易于被混凝去除。 在常規(guī)水處理pH值范圍內，紫外輻射作用可以有效地促進腐殖酸的混凝。對于PHA來說，當pH=6.0-8.0時，腐殖酸溶液經紫外預處理后的混凝出水中PHA殘余量為1.5-3.0mg/L，明顯低于未經預處理出水殘余量（5-8mg/L），這可能與PHA的吸附聚集有關。對比不同pH值條件下紫外輻射前后腐殖酸的Zeta電位變化情況發(fā)現(xiàn)，相同條件下紫外照射后PHA的Zeta電位降低，雙電層被壓縮，這更易于膠體脫穩(wěn)聚集；原子力顯微鏡（AFM）成像圖譜也表明，紫外輻射后PHA的聚集體厚度和粒徑均小于光照前的，且對紫外照射前后腐殖酸分子量分級后發(fā)現(xiàn)，經紫外輻射后大于100kDa的PHA分子含量增加。
[Abstract]:Humic acid (HA) is widely used in various kinds of water bodies, and its presence in drinking water is not conducive to the removal of other organic compounds, and it is the precursor of disinfection by-products. Therefore, the removal of humic acid has attracted more and more attention. The traditional coagulation-precipitation-filtration water treatment process is not ideal for the removal of organic compounds such as humic acid, but UV irradiation can not only directly mineralize the organic matter in the water, but also promote the subsequent coagulation process. In this paper, the changes of humic acid molecular structure after ultraviolet irradiation were studied, and the influence of water quality on the coagulation properties of humic acid before and after ultraviolet irradiation was investigated. The promoting mechanism of UV pretreatment on the coagulation of humic acid was discussed, and the experimental results were as follows: UV irradiation has a certain effect on the pH value and TOC concentration of humic acid solution. In alkaline condition, the pH of humic acid solution decreased significantly after ultraviolet irradiation. The gas chromatographic data showed that some small molecular acids were formed in the solution after ultraviolet irradiation, and the pH of humic acid solution increased slightly after ultraviolet irradiation in acid condition. It is considered that this is related to the formation rate and mineralization rate of acid group of humic acid. When pH = 7, the TOC decrease rate of humic acid solution is about 10 after ultraviolet irradiation. In addition, the effects of ultraviolet radiation on the molecular structure of humic acid were also observed. The E4/E6 value of humic acid solution decreased with the increase of radiation time, and the fluorescence intensity of humic acid solution decreased with the increase of irradiation time. And some functional groups in the infrared spectra have also changed. The coagulation properties of humic acid before and after UV irradiation were influenced by water quality conditions. The best coagulation effect of humic acid solution without UV pretreatment is at pH = 5, the best coagulation effect of humic acid solution after UV pretreatment is at pH = 6, and when pH is greater than 5.5, the best coagulation effect of humic acid solution without UV pretreatment appears at pH = 5. Ultraviolet pretreatment can promote the coagulation of humic acid. When pH = 7, the maximum pH = 7 was reached, and the residual amount of PHA (Shanghai giant maple humic acid) coagulation effluent without UV pretreatment was 7.592 mg / L, while that of PHA coagulation effluent decreased to 1.935 mg / L after UV pretreatment. It was found that turbidity and cationic Ca ~ (2 +) _ (2) mg _ (2) could promote the coagulation humic acid water sample, but the presence of Ca2 _ (2) mg _ (2) inhibited the effect of UV pretreatment on the coagulation of humic acid. The alkalinity had little effect on the coagulation of humic acid before and after ultraviolet irradiation. When the alkalinity increased from 5mg/L to 100mg/L, the decreasing value of the removal rate of humic acid solution before and after UV pretreatment was basically the same (about 15%); the molecular structure of humic acid also affected the coagulation effect of humic acid. Humic acid molecules with larger molecular size and less hydrophilic groups are more easily removed by coagulation. In the range of pH value of conventional water treatment, ultraviolet radiation can effectively promote the coagulation of humic acid. For PHA, the residual amount of PHA in coagulation water after UV pretreatment is 1.5-3.0 mg / L when pH=6.0-8.0 is used, which is obviously lower than that of unpre-treated effluent (5-8 mg / L), which may be related to the adsorption and aggregation of PHA. Comparing the changes of Zeta potential of humic acid before and after ultraviolet irradiation under different pH conditions, it was found that the Zeta potential of PHA decreased and the double electric layer was compressed under the same conditions, which was more easy for colloidal destability and aggregation. Atomic force microscopy (AFM) images also showed that the aggregate thickness and particle size of PHA after UV irradiation were smaller than those before and after UV irradiation. After the molecular weight classification of humic acid before and after UV irradiation, it was found that the content of PHA molecule after UV irradiation was higher than that of 100kDa.
【學位授予單位】：西安建筑科技大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU991.2

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