發(fā)布時(shí)間：2018-01-03 18:35

  本文關(guān)鍵詞：水溶液中有機(jī)砷的光化學(xué)降解轉(zhuǎn)化研究　出處：《合肥工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 有機(jī)砷 光降解 動(dòng)力學(xué) 砷形態(tài) 降解途徑

【摘要】：有機(jī)砷制劑作為飼料添加劑被廣泛的應(yīng)用于家禽養(yǎng)殖業(yè)中,常見的有機(jī)砷制劑有洛克沙胂(ROX)和阿散酸(ASA)。添加的有機(jī)砷大部分會(huì)隨著家禽糞便排出,引起環(huán)境的砷污染,并可能對人類健康產(chǎn)生危害。光化學(xué)降解是環(huán)境中有機(jī)污染物重要的降解方式,可以使污染物發(fā)生分解和礦化。因此,本論文選取ROX等幾種有機(jī)砷為研究對象,研究其在不同光降解過程中的降解,考察了環(huán)境因素(pH,無機(jī)陰離子和腐殖酸等)對其光降解的影響,并探討了有機(jī)砷的光化學(xué)降解轉(zhuǎn)化機(jī)制,旨在深入了解有機(jī)砷在環(huán)境中的光化學(xué)降解行為。(1)首先,本論文系統(tǒng)研究了ROX厭氧還原產(chǎn)物3-氨基-4-羥基苯胂酸(HAPA)在模擬自然環(huán)境下的光化學(xué)降解。研究結(jié)果表明,環(huán)境中短波紫外光(UVC)是導(dǎo)致HAPA的降解的主要原因,而溶解氧的單獨(dú)存在短期內(nèi)對HAPA的降解沒有影響。并進(jìn)一步研究HAPA在UVC254下的光化學(xué)降解動(dòng)力學(xué)及其影響因素。在UVC254光照下,HAPA的光降解符合偽一級(jí)動(dòng)力學(xué)模型。當(dāng)pH為堿性時(shí),HAPA的降解受到顯著的促進(jìn)。環(huán)境中存在的SO42-和Cl-會(huì)輕微抑制HAPA的降解,而HCO3-的存在對HAPA的降解有輕微的促進(jìn)作用。HAPA的光降解主要是由于直接光解,反應(yīng)過程中生成的1O2對HAPA的降解沒有明顯影響,但可以促進(jìn)降解生成的三價(jià)砷向五價(jià)砷轉(zhuǎn)化。根據(jù)反應(yīng)中離子和中間產(chǎn)物的測定,推導(dǎo)出HAPA可能的降解途徑,揭示出了HAPA在光照環(huán)境下降解轉(zhuǎn)化機(jī)制。(2)其次,系統(tǒng)研究了硝酸根光敏化降解體系中,ROX和ASA的降解轉(zhuǎn)化行為。研究結(jié)果表明,模擬太陽光下硝酸根的存在可以有效促進(jìn)ROX的降解,其降解遵循偽一級(jí)動(dòng)力學(xué)。溶液pH會(huì)顯著影響ROX的降解,尤其在強(qiáng)酸溶液中,ROX降解速率顯著增加。該體系中硝酸根吸收光子后可以產(chǎn)生強(qiáng)氧化性的·OH,·OH可以氧化降解ROX。ROX在降解過程中,生成了三價(jià)砷和五價(jià)砷,且五價(jià)砷為最終產(chǎn)物。通過研究太陽光下ROX在實(shí)際水體中的降解情況以及砷的形態(tài)分布情況,提出了ROX在有硝酸根的自然水體中的轉(zhuǎn)化機(jī)制。(3)最后,研究了ROX在UV/PDS體系中的光化學(xué)催化降解。研究結(jié)果表明,UV和PDS耦合作用可以有效的降解ROX,降解符合二級(jí)反應(yīng)動(dòng)力學(xué)模型,其速率常數(shù)為kapp=2.543 s-1 M-1(R2=0.998)。環(huán)境因素如pH,無機(jī)陰離子,腐殖酸對ROX的降解有很大影響。中性條件下ROX降解最快,酸性和堿性條件都不利于ROX的降解。Cl-對ROX的降解有明顯促進(jìn)作用,而腐殖酸會(huì)顯著抑制ROX的降解,當(dāng)腐殖酸濃度為20 mg/L時(shí),約62.5%的ROX降解被抑制。實(shí)際水體中ROX的降解受到明顯抑制,尤其是污水處理廠出水中。UV/PDS體系中起主要作用的氧化活性物種是SO4-.。在降解過程中,NO3-和五價(jià)砷是主要的降解產(chǎn)物。ROX在UV/PDS體系中可以完全礦化,生成對環(huán)境無害的CO2,H2O和無機(jī)鹽。
[Abstract]:As a feed additive, organic arsenic is widely used in poultry industry. The common organic arsenic preparations are roxarsone (Rox) and asalic acid (ASAA). Most of the organic arsenic added will be excreted with poultry feces, causing arsenic pollution in the environment. Photochemical degradation is an important degradation method of organic pollutants in the environment, which can decompose and mineralize pollutants. In this paper, ROX and other organic arsenic were selected as research objects to study their degradation in different photodegradation processes, and the effects of environmental factors such as pH, inorganic anions and humic acid on their photodegradation were investigated. The photochemical degradation mechanism of organic arsenic was discussed in order to understand the photochemical degradation behavior of organic arsenic in the environment. The photochemical degradation of 3-amino-4-hydroxyphenylarsonic acid (3-amino-4-hydroxyphenylarsonic acid), a product of ROX anaerobic reduction, was systematically studied in this paper. The degradation of HAPA is mainly caused by short wave ultraviolet light (UV) in the environment. However, the existence of dissolved oxygen alone had no effect on the degradation of HAPA for a short time. Furthermore, the photochemical degradation kinetics of HAPA under UVC254 and its influencing factors were studied. The photodegradation of HAPA accords with pseudo-first-order kinetic model. When pH is alkaline, the degradation of HAPA is significantly promoted. The presence of SO42- and Cl- in the environment can slightly inhibit the degradation of HAPA. The photodegradation of HCO3- was mainly due to direct photolysis, and the 1O2 produced during the reaction had no obvious effect on the degradation of HAPA. However, it can promote the conversion of trivalent arsenic to pentavalent arsenic. According to the determination of ions and intermediate products in the reaction, the possible degradation pathway of HAPA is deduced. The mechanism of degradation and transformation of HAPA in light environment was revealed. Secondly, the degradation and transformation behavior of HAPA and ASA in the system of nitrate Guang Min degradation were systematically studied. Simulation of the presence of nitrate in sunlight can effectively promote the degradation of ROX, its degradation follows pseudo-first-order kinetics. Solution pH will significantly affect the degradation of ROX, especially in strong acid solution. The degradation rate of ROX was significantly increased. After the nitrate absorbed the photons, the 路OH could produce strong oxidized 路OH, and 路OH could oxidize and degrade ROX.ROX in the process of degradation. Trivalent arsenic and pentavalent arsenic were formed, and pentavalent arsenic was the final product. The degradation of ROX in the real water and the distribution of arsenic species were studied. The conversion mechanism of ROX in natural water with nitrate was proposed. Finally, photochemical catalytic degradation of ROX in UV/PDS system was studied. The coupling of UV and PDS can effectively degrade Rox, and the degradation accords with the second-order reaction kinetics model. Its rate constant is kapp=2.543 s-1 M-1N R2O 0.9980.The environmental factors such as pH, inorganic anion. Humic acid has a great effect on the degradation of ROX. Under neutral conditions, ROX degradation is the fastest, acid and alkaline conditions are not conducive to the degradation of ROX. Cl- has a significant role in promoting the degradation of ROX. Humic acid significantly inhibited the degradation of ROX. When the concentration of humic acid was 20 mg/L, about 62.5% of ROX degradation was inhibited, and the degradation of ROX in the actual water was significantly inhibited. Especially in the effluent of wastewater treatment plant, the main oxidizing active species in the system of UV / PDS is so _ 4-..in the process of degradation. NO3- and pentavalent arsenic are the main degradation products. Rox can be completely mineralized in UV/PDS system to produce environmentally sound CO _ 2H _ 2O and inorganic salts.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X713

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