微波無極紫外燈直接光降解去除水中抗生素恩諾沙星機理研究
發(fā)布時間：2018-08-10 22:05
【摘要】：微波無極燈光降解技術(shù)具備快速、高效、實用性強等優(yōu)點,已被成功用于去除水相中多種有機污染物。目前該方法研究主要集中在微波無極燈與氧化劑、催化劑聯(lián)用工藝去除污染物方面,而對微波無極紫外燈直接光降解有機物研究較少。當(dāng)前抗生素濫用問題嚴(yán)重,抗生素物質(zhì)已進入各類水體,引起一系列環(huán)境問題,危害人類健康,亟需開發(fā)出高效的工藝去除水中的抗生素類污染物。本論文提出利用新型紫外光源微波無極燈直接光降解去除水中氟喹諾酮類抗生素恩諾沙星(ENRO),利用光源發(fā)射的真空紫外光(185nm)和高強度遠紫外光(254nm)對ENRO進行光化學(xué)降解,研究從溶解氧(DO)和初始pH兩個影響因素入手,系統(tǒng)考察了低濃度(5 mg L-1)和高濃度(50 mg L-1)ENRO在不同微波無極燈光降解(MW/UV)體系中降解效能與反應(yīng)機理,通過對降解過程中間產(chǎn)物的檢測,提出了 ENRO在MW/UV過程中的降解歷程。同時研究了 ENRO與Fe(Ⅱ/Ⅲ)的螯合行為及其對MW/UV過程降解ENRO效能影響。研究結(jié)果如下:(1)在酸性(pH = 3.0)條件下,MW/UV體系能夠高效降解水相中高濃度(50 mg L-1)ENRO。在02,Air和N2氛圍下,ENRO光化學(xué)降解受DO影響較小,降解過程符合準(zhǔn)一級反應(yīng)動力學(xué)方程,其反應(yīng)速率常數(shù)k分別為0.095 min-1(02)、0.075 min-1(Air)和0.083 min-1(N2);而在三種氣體氛圍條件下DO對MW/UV礦化能力影響很大,在O2,Air和N2氛圍下的TOC去除率分別為70.3%,61.7%和46.6%,表明DO參與ENRO的礦化過程。MW/UV體系降解ENRO過程中檢測到14種芳環(huán)降解中間產(chǎn)物、4種有機酸(草酸、草氨酸、富馬酸及甲酸)以及無機產(chǎn)物(F-、NH4+、NO3-),氣體氛圍對ENRO降解中間產(chǎn)物的生成具有很大影響;在此基礎(chǔ)上提出ENRO在MW/UV體系中的三種主要降解途徑:(i)氟溶劑化(fluorine solvolysis),(ⅱ)輕基化(hydroxylated)和(iii)乙基哌嗪側(cè)鏈醛基化(piperazinyl aldehyde)。(2)在中性(pH = 7.0)條件下,MW/UV體系也能夠高效降解水相中高濃度(50 mg L-1)ENRO。溶液的DO及初始pH對MW/UV降解水相中ENRO效果有不同影響。在pH = 2.0-10.0區(qū)間,ENRO降解速率在pH = 2.0-5.0范圍內(nèi)呈現(xiàn)O2AirN2的規(guī)律;而在pH=6.0-10.0范圍內(nèi)呈現(xiàn)N2AirO2的規(guī)律,這與ENRO的兩性離子態(tài)有關(guān)。而在pH = 2.0-10.0區(qū)間,MW/UV的礦化能力均表現(xiàn)為02AirN2,在中性條件和O2氛圍條件下,TOC去除率最高可達到46.5%。MW/UV體系降解ENRO過程中也檢測到4種有機酸(草酸、草氨酸、富馬酸及甲酸)以及無機產(chǎn)物(F-、NH4+、NO3-),氣體氛圍對ENRO降解中間產(chǎn)物的生成具有很大影響。對低濃度(5 mg L-1)ENRO的降解研究發(fā)現(xiàn)不同氣體氛圍均能有效降解ENRO,在光解進行5 min后ENRO去除率均達到90%以上。低濃度條件下陰離子(NO3-、SO42-、Cl-、CO32-和HCO3-)對降解有不同影響,濃度為5mg L-1時,除Cr以外其余均對ENRO降解過程有一定的促進作用;濃度為10 mg L-1時,CO32和 HCO3-對ENRO降解過程有所促進,其余陰離子對ENRO的降解過程則表現(xiàn)出抑制作用;濃度為15 mg L-1時,Cl-與CO32-對ENRO降解過程幾乎無影響,SO42-和HCO3-表現(xiàn)為促進作用,NO3-表現(xiàn)出一定的抑制作用。(3)氣體氛圍與初始pH對微波無極燈光降解過程機理影響較大,通過分析各體系生成的H2O2情況發(fā)現(xiàn):溶液DO含量升高,H2O2生成濃度提高,酸性條件也有利于H2O2生成,在02氛圍和pH 3.00條件下H2O2生成濃度最高,達到41.3μM;中性條件下O2氛圍條件中H2O2生成濃度最高,達到38.3 μM;利用自由基捕獲劑手段的方式驗證MW/UV反應(yīng)機理,結(jié)果表明在不同DO條件下,MWUV光解純水過程在加入四種·OH捕獲劑后,在N2氛圍條件下生成H2O2濃度明顯降低,而O2和Air氛圍中H2O2含量則呈明顯升高。MWUV光降解ENRO過程中加入多種捕獲劑后,ENRO降解速率均有所減慢,速率常數(shù)由0.095 min-1變?yōu)?.057 min-1(叔丁醇 Tert-butanol),0.042 min-1(異丙醇 2-propanol),0.031 min-1(甲醇 Methanol)和0.019 min-1(正丁醇N-butanol),這表明MWUV降解ENRO過程中'OH起到很大作用。(4)ENRO與Fe(Ⅲ)發(fā)生螯合作用,螯合會抑制ENRO在MW/UV中光降解。ENRO濃度、Fe(Ⅲ)濃度及溶液pH值均會影響二者的螯合效果,確定最佳螯合比為[ENRO]:[Fe(Ⅲ)]= 1:1。在 0.mM[Fe(Ⅱ/Ⅲ)]條件下(O2,pH=3.0)ENRO溶液的降解速率無分別降低至0.056min-1(R2=0.996)和0.048 min-1(R2=0.990),并且在不同F(xiàn)e(Ⅱ/Ⅲ)濃度條件下,DO與初始pH對MW/UV體系降解ENRO速率均有所降低,即Fe(Ⅱ/Ⅲ)的存在會抑制ENRO降解;在未外加Fc(Ⅱ/Ⅲ)時,MW/UV(02,pH=3.0)反應(yīng)120 min后TOC去除率為70.1%,當(dāng)加入不同濃度的Fe(Ⅱ/Ⅲ)時,反應(yīng)中溶液的TOC去除率均有所降低,在最佳螯合比濃度時(約0.10 mM)降低最顯著,分別達到45.4%(Fe(Ⅱ)和45.8%(Fe(Ⅲ),結(jié)果表明Fe(Ⅱ/Ⅲ)的存在會對MW/UV過程中ENRO礦化也起到抑制作用。
[Abstract]:Microwave electrodeless lamp has been successfully used to remove many kinds of organic pollutants in aqueous phase due to its advantages of high speed, high efficiency and high practicability. Nowadays, antibiotic abuse is serious. Antibiotic substances have entered various kinds of water bodies, causing a series of environmental problems and endangering human health. It is urgent to develop efficient processes to remove antibiotic pollutants from water. In this paper, a new type of ultraviolet light source microwave electrodeless lamp is proposed to remove enroxa, a fluoroquinolone antibiotic in water by direct photodegradation. Star (ENRO) was photochemical degraded by vacuum ultraviolet light (185 nm) and high intensity far ultraviolet light (254 nm). The degradation efficiency and anti-degradation of low concentration (5 mg L-1) and high concentration (50 mg L-1) ENRO in different microwave electrodeless lamp degradation (MW/UV) systems were systematically investigated from two factors of dissolved oxygen (DO) and initial pH. The chelating behavior of ENRO with Fe (II/III) and its effect on the degradation efficiency of ENRO in MW/UV process were studied. The results were as follows: (1) MW/UV system could degrade high concentration (50 mg L-3.0) in aqueous phase efficiently under acidic condition. 1) The photochemical degradation of ENRO was less affected by DO in the atmosphere of 02, Air and N2, and the degradation process accorded with the Quasi-First-Order reaction kinetics equation. The reaction rate constants K were 0.095 min-1 (02), 0.075 min-1 (Air) and 0.083 min-1 (N2), respectively. DO had a great influence on the mineralization ability of MW/UV in the atmosphere of O2, Air and N2. The removal rates of DO were 70.3%, 61.7% and 46.6% respectively, indicating that DO was involved in the mineralization of ENRO. Three main degradation pathways of ENRO in MW / UV system were proposed: (i) fluorine solvolysis, (i i) hydroxylated and (i I i) piperazinyl aldehyde. (2) MW / UV system can also degrade DO and initial concentration of ENRO. solution in water phase efficiently under neutral (pH = 7.0). In the range of pH=2.0-10.0, the degradation rate of ENRO showed the regularity of O2 AirN2, while in the range of pH=6.0-10.0, the regularity of N2AirO2 was related to the amphoteric ionic state of ENRO. The removal rate of TOC was up to 46.5% under the condition of parts and O2. Four organic acids (oxalic acid, oxalic acid, fumaric acid and formic acid) and inorganic products (F-, NH4+, NO3-) were also detected during the degradation of ENRO in MW/UV system. Gas atmosphere had a great influence on the formation of intermediate products in ENRO degradation. ENRO can be effectively degraded in the same gas atmosphere, and the removal rate of ENRO can reach above 90% after 5 minutes of photolysis. The anions (NO3-, SO42-, Cl-, CO32-and HCO3-) have different effects on the degradation at low concentration. When the concentration of Cr is 5 mg L-1, the degradation process of ENRO can be promoted by CO32 and HCO3-except Cr. The degradation process of ENRO was promoted by Cl-and CO32-at 15 mg L-1, SO42-and HCO3-at 15 mg L-1, and NO3-at 15 mg L-1. (3) The effect of gas atmosphere and initial pH on the degradation mechanism of ENRO was studied. It was found that the concentration of H2O2 in the solution increased with the increase of DO content and the formation of H2O2, and the formation of H2O2 was facilitated by acidic conditions. The highest concentration of H2O2 was 41.3 mu M under the condition of 02 and pH 3.00, and the highest concentration of H2O2 was 38.3 mu M under the condition of neutral O2. The results show that under different DO conditions, the concentration of H2O2 produced by MWUV photolysis of pure water in N2 atmosphere decreases significantly, while the content of H2O2 in O2 and AIR atmosphere increases significantly. The degradation rate of ENRO is improved by adding various trapping agents in the process of MWUV photolysis of ENRO. The rate constants changed from 0.095 min-1 to 0.057 min-1 (Tert-butanol), 0.042 min-1 (isopropanol 2-propanol), 0.031 min-1 (methanol methanol) and 0.019 min-1 (n-butanol), which indicated that'OH played an important role in the degradation of ENRO by MWUV. (4) ENRO chelated with Fe (III) and the chelation inhibited ENRO photodegradation in MWUV/UV. The concentration of ENRO, the concentration of Fe (III) and the pH value of the solution all affect the chelating effect of the two. The optimum chelating ratio is determined to be [ENRO]: [Fe (III)] = 1:1. Under the condition of 0.mM [Fe (II/III)], (O2, pH = 3.0) the degradation rate of ENRO solution is not reduced to 0.056 min-1 (R2 = 0.996) and 0.048 min-1 (R2 = 0.990) respectively, and DO and 0.048 min-1 (R2 = 0.990) at different concentrations of Fe (II/III). Initial pH decreased ENRO degradation rate of MW/UV system, that is, the presence of Fe (II/III) inhibited ENRO degradation; without Fc (II/III), the removal rate of TOC was 70.1% after 120 minutes of MW/UV (02, pH=3.0). When different concentrations of Fe (II/III) were added, the removal rate of TOC in the reaction solution was reduced, and at the optimum chelation ratio concentration (about 0.10 m). The results showed that the presence of Fe (II/III) also inhibited ENRO mineralization in MW/UV process.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703
本文編號：2176346
[Abstract]:Microwave electrodeless lamp has been successfully used to remove many kinds of organic pollutants in aqueous phase due to its advantages of high speed, high efficiency and high practicability. Nowadays, antibiotic abuse is serious. Antibiotic substances have entered various kinds of water bodies, causing a series of environmental problems and endangering human health. It is urgent to develop efficient processes to remove antibiotic pollutants from water. In this paper, a new type of ultraviolet light source microwave electrodeless lamp is proposed to remove enroxa, a fluoroquinolone antibiotic in water by direct photodegradation. Star (ENRO) was photochemical degraded by vacuum ultraviolet light (185 nm) and high intensity far ultraviolet light (254 nm). The degradation efficiency and anti-degradation of low concentration (5 mg L-1) and high concentration (50 mg L-1) ENRO in different microwave electrodeless lamp degradation (MW/UV) systems were systematically investigated from two factors of dissolved oxygen (DO) and initial pH. The chelating behavior of ENRO with Fe (II/III) and its effect on the degradation efficiency of ENRO in MW/UV process were studied. The results were as follows: (1) MW/UV system could degrade high concentration (50 mg L-3.0) in aqueous phase efficiently under acidic condition. 1) The photochemical degradation of ENRO was less affected by DO in the atmosphere of 02, Air and N2, and the degradation process accorded with the Quasi-First-Order reaction kinetics equation. The reaction rate constants K were 0.095 min-1 (02), 0.075 min-1 (Air) and 0.083 min-1 (N2), respectively. DO had a great influence on the mineralization ability of MW/UV in the atmosphere of O2, Air and N2. The removal rates of DO were 70.3%, 61.7% and 46.6% respectively, indicating that DO was involved in the mineralization of ENRO. Three main degradation pathways of ENRO in MW / UV system were proposed: (i) fluorine solvolysis, (i i) hydroxylated and (i I i) piperazinyl aldehyde. (2) MW / UV system can also degrade DO and initial concentration of ENRO. solution in water phase efficiently under neutral (pH = 7.0). In the range of pH=2.0-10.0, the degradation rate of ENRO showed the regularity of O2 AirN2, while in the range of pH=6.0-10.0, the regularity of N2AirO2 was related to the amphoteric ionic state of ENRO. The removal rate of TOC was up to 46.5% under the condition of parts and O2. Four organic acids (oxalic acid, oxalic acid, fumaric acid and formic acid) and inorganic products (F-, NH4+, NO3-) were also detected during the degradation of ENRO in MW/UV system. Gas atmosphere had a great influence on the formation of intermediate products in ENRO degradation. ENRO can be effectively degraded in the same gas atmosphere, and the removal rate of ENRO can reach above 90% after 5 minutes of photolysis. The anions (NO3-, SO42-, Cl-, CO32-and HCO3-) have different effects on the degradation at low concentration. When the concentration of Cr is 5 mg L-1, the degradation process of ENRO can be promoted by CO32 and HCO3-except Cr. The degradation process of ENRO was promoted by Cl-and CO32-at 15 mg L-1, SO42-and HCO3-at 15 mg L-1, and NO3-at 15 mg L-1. (3) The effect of gas atmosphere and initial pH on the degradation mechanism of ENRO was studied. It was found that the concentration of H2O2 in the solution increased with the increase of DO content and the formation of H2O2, and the formation of H2O2 was facilitated by acidic conditions. The highest concentration of H2O2 was 41.3 mu M under the condition of 02 and pH 3.00, and the highest concentration of H2O2 was 38.3 mu M under the condition of neutral O2. The results show that under different DO conditions, the concentration of H2O2 produced by MWUV photolysis of pure water in N2 atmosphere decreases significantly, while the content of H2O2 in O2 and AIR atmosphere increases significantly. The degradation rate of ENRO is improved by adding various trapping agents in the process of MWUV photolysis of ENRO. The rate constants changed from 0.095 min-1 to 0.057 min-1 (Tert-butanol), 0.042 min-1 (isopropanol 2-propanol), 0.031 min-1 (methanol methanol) and 0.019 min-1 (n-butanol), which indicated that'OH played an important role in the degradation of ENRO by MWUV. (4) ENRO chelated with Fe (III) and the chelation inhibited ENRO photodegradation in MWUV/UV. The concentration of ENRO, the concentration of Fe (III) and the pH value of the solution all affect the chelating effect of the two. The optimum chelating ratio is determined to be [ENRO]: [Fe (III)] = 1:1. Under the condition of 0.mM [Fe (II/III)], (O2, pH = 3.0) the degradation rate of ENRO solution is not reduced to 0.056 min-1 (R2 = 0.996) and 0.048 min-1 (R2 = 0.990) respectively, and DO and 0.048 min-1 (R2 = 0.990) at different concentrations of Fe (II/III). Initial pH decreased ENRO degradation rate of MW/UV system, that is, the presence of Fe (II/III) inhibited ENRO degradation; without Fc (II/III), the removal rate of TOC was 70.1% after 120 minutes of MW/UV (02, pH=3.0). When different concentrations of Fe (II/III) were added, the removal rate of TOC in the reaction solution was reduced, and at the optimum chelation ratio concentration (about 0.10 m). The results showed that the presence of Fe (II/III) also inhibited ENRO mineralization in MW/UV process.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703
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