本文關(guān)鍵詞： SBA-15 長(zhǎng)孔道 短孔道 PVC膜 鈾 吸附　出處：《中國(guó)海洋大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著現(xiàn)代工業(yè)的迅速發(fā)展,能源問題日益突出。鈾作為新能源核能的一種重要原料,被認(rèn)為是最有發(fā)展前景的戰(zhàn)略能源。然而陸地鈾礦資源有限且面臨著過度開采。而海水中鈾總量達(dá)到45億噸,約為陸地儲(chǔ)量的1000倍,因此從海水中提取鈾具有重要的戰(zhàn)略意義。但是海水中鈾的濃度很低,只有3.3μg/L,因此其分離和提取技術(shù)顯得尤為重要。近年來,多種方法被應(yīng)用于鈾的提取,如離子交換、吸附、溶劑萃取、化學(xué)沉淀、超濾、納濾以及反滲透等。吸附法由于經(jīng)濟(jì)高效、環(huán)境友好、操作簡(jiǎn)單等優(yōu)點(diǎn),成為從海水中提取鈾的主要方法,因此尋找一種合適的吸附劑是研究的關(guān)鍵。近年來介孔二氧化硅作為一種新興的無機(jī)材料逐漸吸引了人們的注意,因?yàn)槠渚哂懈弑缺砻娣e、均勻有序的介孔孔道、較大的孔體積、形貌和結(jié)構(gòu)組成可控、孔徑可調(diào)、表面富含羥基等優(yōu)點(diǎn)。與其他介孔材料相比,SBA-15囚具有較大孔徑、較厚的孔壁及更高的水熱穩(wěn)定性而表現(xiàn)出更加優(yōu)異的性能。傳統(tǒng)方法制備的SBA-15孔道走向平行于長(zhǎng)軸,不利于孔道內(nèi)能量傳遞以及物料傳輸,并且易引起孔的堵塞。相比之下,具有短孔道的SBA-15因孔道走向平行于短軸而利于物質(zhì)運(yùn)輸和能量傳遞,應(yīng)用前景廣闊。然而無論是純二氧化硅基SBA-15還是功能化的SBA-15均為粉末狀使其具有不易操作及難回收重復(fù)利用等不足,難以被應(yīng)用于工業(yè)化操作及商業(yè)領(lǐng)域。因此,本論文將粉末狀吸附劑添加到鑄膜液中制備膜型吸附劑,因?yàn)槟た梢赃M(jìn)行彎曲或纏繞等操作,適用于工業(yè)化應(yīng)用,因此可以克服粉末狀吸附劑的不足。首先,以水熱法合成了長(zhǎng)孔道SBA-15(L-SBA-15),將其添加到PVC鑄膜液中,通過相轉(zhuǎn)化法制備了L-SB A-15-PVC膜型吸附劑。實(shí)驗(yàn)結(jié)果表明,在PVC濃度為10%、L-SBA-15含量為5%、溶液pH=6的條件下,L-SBA-15-PVC膜的吸附容量為2014.0 mg/m2。其吸附行為符合準(zhǔn)二級(jí)動(dòng)力學(xué)模型與Langmuir吸附等溫模型,其經(jīng)3mol/L硝酸脫附后的循環(huán)吸附效果良好,吸附量幾乎沒有損失。對(duì)比了粉末狀L-SBA-15對(duì)鈾的吸附性能,發(fā)現(xiàn)成膜后的L-SBA-15的吸附容量?jī)H損失了10.9%,但吸附及脫附的操作步驟大為簡(jiǎn)化且易于重復(fù)利用。其次,合成了短孔道SBA-15(S-SBA-15),并將其添加到鑄膜液中制備S-SBA-15-PVC膜型吸附劑。結(jié)果表明,在PVC濃度為10%、S-SBA-15含量為5%、溶液pH=6的條件下,S-SBA-15-PVC膜的吸附容量可達(dá)2520.0 mg/m2,明顯高于L-SBA-15-PVC膜型吸附劑。以Langmuir和Freundlich兩種等溫吸附模型擬合吸附過程,結(jié)果表明鈾離子在S-SBA-15-PVC膜型吸附劑上的吸附過程更符合Langmuir吸附等溫模型。動(dòng)力學(xué)研究表明S-SBA-15-PVC膜對(duì)鈾的吸附過程用準(zhǔn)二級(jí)動(dòng)力學(xué)模型描述更為合適。進(jìn)行了九次吸附-解吸實(shí)驗(yàn),在后八次循環(huán)中吸附量幾乎保持不變。最后,將SBA-15進(jìn)行有機(jī)官能化改性,制備了氰基和偕胺肟基功能化的SBA-15,然后將其添加到PVC鑄膜液中,制備成膜型吸附劑并考察其對(duì)溶液中鈾的吸附效果。實(shí)驗(yàn)結(jié)果表明,改性后的SBA-15-PVC膜吸附容量明顯優(yōu)于未經(jīng)改性的SBA-15-PVC膜。通過該方法制備的膜型吸附劑的性能與相應(yīng)的粉末吸附劑呈正相關(guān),說明該制膜工藝比較成熟,吸附劑本身的性能決定了成膜后的吸附效果。因此,尋找吸附性能更加優(yōu)異的吸附劑將是后續(xù)研究的重點(diǎn)。
[Abstract]:With the rapid development of modern industry, energy issues become increasingly prominent. Uranium as an important raw material of new nuclear energy, is considered to be the most promising energy strategy. However, land limited uranium resources and facing excessive exploitation. The uranium from seawater volume reached 45 tons, about 1000 times the land reserves, so the extraction uranium has an important strategic significance from the sea. But the concentration of uranium in sea water is very low, only 3.3 g/L, so the separation and extraction technology is particularly important. In recent years, many methods have been applied to the extraction of uranium, such as ion exchange, adsorption, solvent extraction, chemical precipitation, ultrafiltration, nanofiltration and reverse infiltration. Adsorption due to the economic efficiency, environmental friendly, simple operation and other advantages, has become the main method of extracting uranium from sea water, so to find a suitable adsorbent is the key of the study. In recent years, mesoporous silica as a The new inorganic materials gradually attracted people's attention, because of its high specific surface area, pore size uniform and orderly, larger pore volume, morphology and structure controllable, adjustable pore size, surface hydroxyl rich advantages. Compared with other mesoporous materials, SBA-15 cell with large pore size, thick pore wall and higher hydrothermal stability and exhibit more excellent properties. The preparation of SBA-15 channel to parallel to the long axis of the traditional method, is not conducive to energy transfer channels and material transport, and easy to cause pore blockage. Compared with SBA-15 for short channel channel to parallel to the short axis for material transport energy transfer and wide application prospect. However, whether it is a pure silica based SBA-15 or functionalized SBA-15 were powder which is not easy to operate and difficult to recycle lack of reuse, it is difficult to be used in the industry Operation and business. Therefore, this paper will be added to the powder adsorbent in the casting solution preparation of membrane type adsorbents, because of bending or winding operation can be applied to film, industrial application, so it can overcome the shortage of powdered adsorbent. Firstly, by hydrothermal method with a long channel SBA-15 (L-SBA-15), PVC will be added to the casting solution, prepared by the method of phase inversion L-SB A-15-PVC membrane adsorbent. The experimental results show that the concentration of PVC was 10%, L-SBA-15 was 5%, pH=6 of the solution under the condition that the adsorption capacity of L-SBA-15-PVC film with quasi two level dynamic model and Langmuir adsorption isotherm the model is 2014 mg/m2. the adsorption behavior, the nitrate desorbed by 3mol/L cyclic adsorption effect is good, the adsorption capacity is almost no loss. The adsorption properties of L-SBA-15 powder of uranium by comparison, found that the adsorption capacity of the film L-SBA-15 only lost 10.9%, but the adsorption and removal steps of greatly simplified and easy to reuse. Secondly, the short channel SBA-15 synthesis (S-SBA-15), and add it to the casting solution preparation of S-SBA-15-PVC membrane type adsorbents. The results showed that the concentration of PVC was 10%, S-SBA-15 was 5%, pH =6 solution under the condition that the adsorption capacity of S-SBA-15-PVC film is 2520 mg/m2, significantly higher than that of L-SBA-15-PVC membrane adsorbent. The adsorption process using Langmuir and Freundlich model to fit the adsorption of two kinds of isothermal, the results show that the adsorption process of uranium ions in S-SBA-15-PVC membrane adsorbent conforms to Langmuir adsorption isotherm model. Kinetic studies showed that the adsorption process of S-SBA-15-PVC films on uranium with the quasi two level dynamic model description is more appropriate. The nine adsorption desorption experiment, adsorption capacity after eight cycles remains almost unchanged. Finally, the SBA-15 of organic functional modification, preparation Cyano and amidoxime functionalized SBA-15 were prepared, and then add it to the PVC casting solution, preparation of membrane adsorbents and study the adsorption of uranium. The experimental results show that the adsorption capacity of modified SBA-15-PVC membrane was obviously better than that without SBA-15-PVC film modified by the. The preparation methods of the properties of membrane type adsorbents and the corresponding powder adsorbent was positively related to the membrane preparation process is relatively mature, the performance of adsorption agent itself determines the adsorption effect of the film. Therefore, looking for more excellent adsorption properties will be the focus of future studies.

【學(xué)位授予單位】：中國(guó)海洋大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O647.33

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本文編號(hào)：1478050