本文關(guān)鍵詞： 光催化 分子篩 溴化銀 磷鎢酸銫 AR18 Cr(Ⅵ) 苯酚　出處：《西北大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：環(huán)境的日益惡化已成為人們的擔(dān)憂,工業(yè)廢水已經(jīng)嚴(yán)重影響了人類的生存與發(fā)展,太陽(yáng)能充足又清潔,已是人類所使用的一種重要的新能源,于是用光能,特別是太陽(yáng)能并借助光催化劑克服環(huán)境污染問(wèn)題是一種經(jīng)濟(jì)而又有效的新技術(shù),而光催化技術(shù)的核心之一就是光催化的研究和開(kāi)發(fā)。本論文以變價(jià)金屬Cr摻雜MCM41分子篩為載體,通過(guò)負(fù)載TiO2和AgBr,通過(guò)AgBr修飾雜多酸磷鎢酸銫,設(shè)計(jì)合成了 AgBr/TiO2/Cr-MCM-41和AgBr-CsxH3-xPW12O40(x=2.5)復(fù)合光催化劑。以AR18,六價(jià)鉻離子和苯酚為催化底物,評(píng)價(jià)合成的光催化劑的活性,優(yōu)化光催化去除水中有機(jī)、無(wú)機(jī)污染的反應(yīng)條件;研究復(fù)合光催化劑的穩(wěn)定性、光響應(yīng)范圍以及光催化降解水中典型污染物的機(jī)理,揭示高效、穩(wěn)定光催化反應(yīng)結(jié)構(gòu)和性能關(guān)系,主要內(nèi)容和研究結(jié)果如下:(1)使用水熱法合成金屬鉻摻雜的MCM41,通過(guò)鈦酸丁酯的水解在Cr-MCM41表面負(fù)載Ti02,得到Ti02-Cr-MCM41,最后用沉淀沉積法在催化劑的載體表面成功負(fù)載AgBr,得到AgBr-TiO2-Cr-MCM41多元復(fù)合光催化劑。使用多種表征方法對(duì)催化劑進(jìn)行了分析,XRD和BET表明多元復(fù)合摻雜的催化劑良好的保持了分子篩的中孔結(jié)構(gòu),UV-Vis表明,所得催化劑有了較載體范圍更寬的光吸收范圍。通過(guò)可見(jiàn)光(λ400nm)照射下降解偶氮染料酸性大紅AR181評(píng)價(jià)AgBr-Ti02-Cr-MCM41催化活性,探尋了最佳降解條件(pH=3.0,催化劑用量為5g/L)。通過(guò)一系列自由基抑制實(shí)驗(yàn),發(fā)現(xiàn)·O2-是AgBr-Ti02-Cr-MCM41可見(jiàn)光照射下催化降解AR18的主要活性物質(zhì)。另外通過(guò)循環(huán)實(shí)驗(yàn)和研究表明所得材料是能夠重復(fù)使用的,每次使用時(shí)30 min后催化降解率都達(dá)到90%以上,并且使用次數(shù)越多,催化效率有增大的趨勢(shì),這是由于所得催化劑中存在變價(jià)金屬Cr,六價(jià)鉻充當(dāng)電子受體,反應(yīng)過(guò)程中被還原為三價(jià)鉻,但當(dāng)使用后的催化劑經(jīng)過(guò)鼓風(fēng)加高溫煅燒之后,三價(jià)鉻又被氧化為六價(jià)鉻,接收電子的能力恢復(fù)。(2)通過(guò)簡(jiǎn)單的沉淀沉積法,以雜多酸鹽為載體和電子梭,通過(guò)AgBr復(fù)合構(gòu)筑了AgBr-Cs2.5H0.5PW12O40 異質(zhì)結(jié)復(fù)合光催化劑。通過(guò) XRD,BET,SEM,XPS,UV-vis 等多種表征方法對(duì)所得材料進(jìn)行了表征,將有機(jī)染料酸性大紅AR18作為催化底物,探討了關(guān)系催化劑催化性質(zhì)的幾種重要因素,如溶液初始酸堿度,反應(yīng)體系中催化劑的使用量,催化底物的初始濃度等。又通過(guò)在催化反應(yīng)過(guò)程中加入活性物質(zhì)抑制劑,探討了催化反應(yīng)中的活性物質(zhì)。5次循環(huán)實(shí)驗(yàn)后催化劑的催化活性仍然很高,說(shuō)明構(gòu)建的復(fù)合催化劑具有較高的穩(wěn)定性。(3)利用催化劑AgBr-Cs2.5H0.5PW12O40嘗試同時(shí)光催化降解水中無(wú)機(jī)污染物Cr(VI)和有機(jī)污染物苯酚,研究?jī)烧邊f(xié)同降解情況。討論了分別改變Cr(VI)和苯酚的量和溶液初始pH值對(duì)兩者催化降解的影響,結(jié)果表明,初始反應(yīng)液為酸性時(shí)Cr(VI)的降解速率較快,為堿性時(shí)苯酚降解速率較快。
[Abstract]:Environmental deterioration has become a concern for people, industrial wastewater has seriously affected the survival and development of human beings, solar energy is sufficient and clean, has been used as an important new energy, so use light energy. Especially solar energy and photocatalyst to overcome environmental pollution is an economical and effective new technology. One of the core of photocatalytic technology is the research and development of photocatalysis. In this thesis, the carrier of variable-value metal Cr doped MCM41 molecular sieve is used as the carrier, which is supported by TiO2 and AgBr. Caesium phosphotungstate was modified by AgBr. The composite photocatalysts of AgBr/TiO2/Cr-MCM-41 and AgBr-CsxH3-xPW12O40O40xA2.5) were designed and synthesized by AR18. Hexavalent chromium ion and phenol were used as the catalytic substrates to evaluate the activity of the synthesized photocatalyst and to optimize the reaction conditions of photocatalytic removal of organic and inorganic pollution in water. The stability, the range of photoresponse and the mechanism of photocatalytic degradation of typical pollutants in water were studied, and the relationship between the structure and performance of high efficient and stable photocatalytic reaction was revealed. The main contents and results are as follows: (1) Metallic chromium doped MCM41was synthesized by hydrothermal method, and Ti02 was loaded on the surface of Cr-MCM41 by hydrolysis of butyl titanate. Ti02-Cr-MCM41 was obtained and AgBr was successfully supported on the surface of the catalyst by precipitation deposition method. AgBr-TiO2-Cr-MCM41 multicomponent composite photocatalyst was obtained and the catalyst was analyzed by various characterization methods. The results of XRD and BET showed that the multi-doped catalyst kept the mesoporous structure of molecular sieve well and UV-Vis showed. The resulting catalyst has a wider range of light absorption than the carrier. Through visible light (位 400nm). Degradation of azo dye acid scarlet AR181 under irradiation to evaluate the catalytic activity of AgBr-Ti02-Cr-MCM41. The optimum degradation conditions (pH = 3.0, catalyst dosage = 5 g / L ~ (-1)) were investigated, and a series of free radical inhibition experiments were carried out. It was found that O _ 2- was the main active substance for the catalytic degradation of AR18 under visible light irradiation by AgBr-Ti02-Cr-MCM41. In addition, the cycling experiments and studies showed that the obtained material was able to repeat the degradation of AR18. Yes. The catalytic degradation rate reached more than 90% after 30 min, and the higher the use times, the higher the catalytic efficiency, which was due to the existence of the metal Cr in the catalyst. Hexavalent chromium acts as an electron receptor and is reduced to trivalent chromium during the reaction, but after the catalyst is calcined by blast and high temperature, trivalent chromium is oxidized to hexavalent chromium. The recovery of the ability to receive electrons. 2) by a simple precipitation deposition method, using heteropolyacid as the carrier and electron shuttles. AgBr-Cs2.5H0.5PW12O40 heterojunction photocatalyst was synthesized by AgBr. The organic dye acid reddish AR18 was used as the catalyst substrate, and several important factors related to the catalytic properties of the catalyst were discussed. For example, the initial pH of the solution, the amount of catalyst used in the reaction system, the initial concentration of the catalyst substrate, etc. The catalytic activity of the catalyst is still very high after the experiment of the active substance in the catalytic reaction. The results show that the composite catalyst has high stability. The catalyst AgBr-Cs2.5H0.5PW12O40 is used to try to photocatalyze the degradation of inorganic pollutants in water at the same time. And organic pollutants, phenol. The effects of the amount of CrVI and phenol and the initial pH value of the solution on the catalytic degradation were discussed. The degradation rate of CrVI was faster when the initial reaction solution was acidic, and the degradation rate of phenol was higher when the reaction solution was alkaline.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;X52

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