本文選題：施氏礦物　切入點：二氧化鈦　出處：《湘潭大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：施氏礦物是一種亞穩(wěn)態(tài)羥基硫酸高鐵礦物,主要分布于酸性礦山廢水和酸性硫酸鹽土壤中,也可通過人工簡單合成。施氏礦物廉價易得、環(huán)境友好、反應(yīng)活性強,可高效吸附重金屬、含氧酸根等污染物,是一種極具應(yīng)用前景的環(huán)境污染控制材料。近年來,施氏礦物在異相芬頓降解有機污染物的應(yīng)用開始受到關(guān)注。本文首先研究了施氏礦物光芬頓降解有機污染物活性;在此基礎(chǔ)上,分別選取了不同禁帶寬度和導(dǎo)帶價帶位置的兩種半導(dǎo)體(TiO_2和g-C_3N_4)與施氏礦物復(fù)合,旨在有效解決傳統(tǒng)光芬頓過程存在的反應(yīng)速率慢、反應(yīng)不夠徹底、溶解鐵較多等問題,并探討了兩種催化劑光芬頓降解污染物的催化機理,為研制高效、綠色的施氏礦物基光催化材料提供理論依據(jù)。本研究獲得以下結(jié)果:(1)發(fā)現(xiàn)施氏礦物可通過光芬頓反應(yīng)降解有機污染物羅丹明B。將施氏礦物分別在芬頓反應(yīng)、光反應(yīng)、光芬頓反應(yīng)條件下降解羅丹明B,發(fā)現(xiàn)只有在光芬頓條件下,施氏礦物才能使羅丹明B在120 min內(nèi)脫色,但其礦化率不足10%。(2)利用機械研磨將半導(dǎo)體TiO_2與施氏礦物(Sh)復(fù)合,制備了催化活性強、穩(wěn)定性良好的TiO_2/Sh催化劑,可高效降解羅丹明B。TiO_2/Sh催化性能受TiO_2含量、pH等影響;隨TiO_2含量增加,TiO_2/Sh反應(yīng)速率常數(shù)呈先增加后降低趨勢,TiO_2含量在20%為最佳,其反應(yīng)速率常數(shù)達0.157 min-1,僅需20 min可使羅丹明B完全脫色;在實驗pH條件下(3-6),pH越低TiO_2/Sh催化性能越強,pH為3時20%TiO_2/Sh的反應(yīng)速率為M-Sh的2.1倍。TiO_2/Sh催化劑能高效降解羅丹明B的主要原因是TiO_2上光生電子向Sh轉(zhuǎn)移,一方面有利于TiO_2上光生電子-空穴的分離,另一方面促進了Sh上Fe3+還原為Fe2+,從而實現(xiàn)了半導(dǎo)體光催化與異相光芬頓反應(yīng)的耦合。(3)研制了新型Sh/C_3N_4光芬頓催化材料,能高效降解咖啡因和羅丹明B,并且具有良好的穩(wěn)定性。通過原位合成法將施氏礦物與具有可見光響應(yīng)的半導(dǎo)體g-C_3N_4復(fù)合,制得新型Sh/C_3N_4光芬頓催化劑,二者復(fù)合后協(xié)同效應(yīng)顯著,且當(dāng)Sh含量為42%時,催化降解咖啡因活性最高,其反應(yīng)速率分別是Sh和g-C_3N_4的12.4倍和23.2倍;不同反應(yīng)體系pH下,42%S/C反應(yīng)速率均快于Sh。Sh/C_3N_4芬頓催化降解過程主要活性物種為·OH、O_2·-等,g-C_3N_4上的光生電子一方面可以將O_2還原成O_2·-,另一方面也會傳遞到Sh上,加速Fe2+的再生,加快芬頓反應(yīng)速率,同時電子轉(zhuǎn)移也會促進光生電子-空穴分離,進一步提高催化活性。
[Abstract]:Schneider mineral is a metastable hydroxy ferric sulfate mineral, mainly distributed in acid mine wastewater and acid sulphate soil, and can also be synthesized by artificial simple synthesis, which is cheap and easy to obtain, environmentally friendly and highly reactive. It can efficiently adsorb heavy metals, oxygenates and other pollutants, so it is a kind of environmental pollution control material with great application prospect in recent years. The application of Schneider minerals in the degradation of organic pollutants by heterogeneous Fenton has attracted much attention. In this paper, the photodegradation of organic pollutants by Scheffenton minerals has been studied. Two kinds of semiconductors, TiO2 and g-C3N _ 4, with different gap width and valence band position were selected respectively, which were combined with Schneider Minerals to effectively solve the problems of slow reaction rate, incomplete reaction and more dissolved iron in the traditional optical Fenton process. The catalytic mechanism of photodegradation of pollutants by two kinds of catalysts was discussed. In this study, the following results were obtained: 1) it was found that Schneider minerals can degrade organic pollutant Rhodamine B by photo-Fenton reaction. Rhodamine B was degraded under the condition of light Fenton reaction, and it was found that only under the condition of light and Fenton could the Rhodamine B be decolorized within 120 min, but the mineralization rate of Rhodamine B was less than 10%. TiO_2/Sh catalyst with strong catalytic activity and good stability was prepared, and the catalytic performance of Rhodamine B.TiO-2 / Sh was influenced by TiO_2 content and pH value, and the reaction rate constant of TiO-2 / Sh increased first and then decreased with the increase of TiO_2 content, and the content of TiO2 was the best, and the content of TiO2 was 20%. The reaction rate constant was 0.157 min-1, and Rhodamine B could be decolorized completely in 20 min. Under the experimental pH condition, the lower the pH value of TiO_2/Sh, the stronger the catalytic activity of TiO_2/Sh. The reaction rate of TiO2 / Sh is 2. 1 times that of M-Sh. The main reason why the catalyst can efficiently degrade Rhodamine B is the transfer of photogenerated electrons from TiO_2 to Sh, and the reaction rate of TiO2 / Sh is 2. 1 times of that of M-Sh, and the main reason for the degradation of Rhodamine B is the photoelectron transfer from TiO_2 to Sh. On the one hand, it is advantageous to the separation of photogenerated electrons and holes on TiO_2, and on the other hand, it promotes the reduction of Fe3 on Sh to Fe2, thus realizing the coupling of semiconductor photocatalysis and heterogeneous light Fenton reaction. It can efficiently degrade caffeine and Rhodamine B, and has good stability. A new type of Sh/C_3N_4 photo-Fenton catalyst was prepared by in situ synthesis, which was combined with the semiconductor g-C _ 3N _ 4 with visible light response, and the synergistic effect between them was remarkable. When the content of Sh is 42, the catalytic degradation activity of caffeine is the highest, and the reaction rate is 12.4 times and 23.2 times of that of Sh and g-C _ 3N _ 4, respectively. The reaction rate of 42S / C in different reaction system was faster than that in Sh.Sh/C_3N_4 Fenton catalytic degradation process. The main active species was 路OHH _ 2O _ 2 路-. The photogenerated electrons on the number of ohh and C _ 3N _ 4 could reduce O _ 2 to O _ 2 路-, on the other hand, they would be transferred to Sh to accelerate the regeneration of Fe2. The acceleration of Fenton reaction rate and electron transfer will promote photoelectron-hole separation and further improve catalytic activity.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703;TQ426

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本文編號：1586544