施氏矿物基催化材料制备及其光芬顿性能研究

发布时间：2018-03-09 02:12

本文选题：施氏矿物　切入点：二氧化钛　出处：《湘潭大学》2017年硕士论文　论文类型：学位论文

【摘要】：施氏矿物是一种亚稳态羟基硫酸高铁矿物,主要分布于酸性矿山废水和酸性硫酸盐土壤中,也可通过人工简单合成。施氏矿物廉价易得、环境友好、反应活性强,可高效吸附重金属、含氧酸根等污染物,是一种极具应用前景的环境污染控制材料。近年来,施氏矿物在异相芬顿降解有机污染物的应用开始受到关注。本文首先研究了施氏矿物光芬顿降解有机污染物活性;在此基础上,分别选取了不同禁带宽度和导带价带位置的两种半导体(TiO_2和g-C_3N_4)与施氏矿物复合,旨在有效解决传统光芬顿过程存在的反应速率慢、反应不够彻底、溶解铁较多等问题,并探讨了两种催化剂光芬顿降解污染物的催化机理,为研制高效、绿色的施氏矿物基光催化材料提供理论依据。本研究获得以下结果:(1)发现施氏矿物可通过光芬顿反应降解有机污染物罗丹明B。将施氏矿物分别在芬顿反应、光反应、光芬顿反应条件下降解罗丹明B,发现只有在光芬顿条件下,施氏矿物才能使罗丹明B在120 min内脱色,但其矿化率不足10%。(2)利用机械研磨将半导体TiO_2与施氏矿物(Sh)复合,制备了催化活性强、稳定性良好的TiO_2/Sh催化剂,可高效降解罗丹明B。TiO_2/Sh催化性能受TiO_2含量、pH等影响;随TiO_2含量增加,TiO_2/Sh反应速率常数呈先增加后降低趋势,TiO_2含量在20%为最佳,其反应速率常数达0.157 min-1,仅需20 min可使罗丹明B完全脱色;在实验pH条件下(3-6),pH越低TiO_2/Sh催化性能越强,pH为3时20%TiO_2/Sh的反应速率为M-Sh的2.1倍。TiO_2/Sh催化剂能高效降解罗丹明B的主要原因是TiO_2上光生电子向Sh转移,一方面有利于TiO_2上光生电子-空穴的分离,另一方面促进了Sh上Fe3+还原为Fe2+,从而实现了半导体光催化与异相光芬顿反应的耦合。(3)研制了新型Sh/C_3N_4光芬顿催化材料,能高效降解咖啡因和罗丹明B,并且具有良好的稳定性。通过原位合成法将施氏矿物与具有可见光响应的半导体g-C_3N_4复合,制得新型Sh/C_3N_4光芬顿催化剂,二者复合后协同效应显著,且当Sh含量为42%时,催化降解咖啡因活性最高,其反应速率分别是Sh和g-C_3N_4的12.4倍和23.2倍;不同反应体系pH下,42%S/C反应速率均快于Sh。Sh/C_3N_4芬顿催化降解过程主要活性物种为·OH、O_2·-等,g-C_3N_4上的光生电子一方面可以将O_2还原成O_2·-,另一方面也会传递到Sh上,加速Fe2+的再生,加快芬顿反应速率,同时电子转移也会促进光生电子-空穴分离,进一步提高催化活性。
[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.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;TQ426

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