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题名: 真空紫外/紫外在小规模水处理中去除磺胺类抗生素的研究
作者: 王琛
学位类别: 硕士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 强志民
关键词: 紫外 ; 真空紫外 ; 磺胺类抗生素 ; 降解 ; 饮用水处理,UV,VUV,Sulfonamide antibiotics,Removal,Drinking water treatment
其他题名: Removal of micro-pollutants under vacuum-UV/UV irradiation in small-scale water treatment
学位专业: 环境工程
中文摘要:       近年来,微量污染物在地表水、地下水甚至是饮用水中被频繁检出,表明人类的用水安全正受到威胁。产臭氧的低压汞灯发射的真空紫外/紫外(VUV/UV)在 不添加任何化学试剂的条件下就能与水反应生成羟基自由基(?OH),进而对水中微量有机污染物起到高效的去除作用,是紫外高级氧化技术的一个很好选择。然 而,VUV的低辐射功率和低穿透能力大大限制了其在大规模水处理中的应用。因此,了解典型有机污染物在VUV/UV辐照下的降解特性,合理优化的设计 VUV/UV反应器能够为其在小规模水处理中的应用提供理论和技术指导。
      首先,研究开发了一种新型VUV/UV细管流反应装置,其可以在不改变UV辐照强度的情况下,实现VUV/UV辐照和UV辐照两种反应模式的切换,通过二 者之间的对比探讨VUV的反应效果。实验利用化学剂量法测定了UV和VUV的辐射光强,分别为5.76和0.586 mW cm?2。以亚甲基蓝作为目标反应物初步探讨了VUV/UV细管流反应装置在紫外光解及紫外高级氧化技术降解污染物的效果。结果表明,VUV/UV由于产 生大量的?OH比UV/H2O2和UV有着更高效的去除能力;添加叔丁醇能够明显抑制其降解速率,体现了?OH氧化在VUV/UV过程中的主导地位。同 时,本文还研究了不同影响因素包括VUV透射气体介质、流速、pH和初始浓度对细管流反应器装置中VUV/UV降解速率的影响。
      其次,研究对比了UV、UV/H2O2、VUV/UV和VUV/UV/H2O2四种处理方式对八种磺胺类抗生素的降解效果。结果表明VUV/UV对各磺胺 的去除能力较UV/H2O2和UV有着明显增强,在180 mJ cm?2的UV剂量下各磺胺去除率均在99%以上,在VUV/UV基础上添加H2O2后降解速率保持不变。从中选择磺胺二甲基嘧啶(SMN)深入研究其在 VUV/UV辐照下的降解动力学与机理。结果表明,SMN难以被UV直接光解,其在VUV/UV辐照下主要受到?OH的氧化作用而快速降解;SMN在pH 6.0到9.0的范围内降解速率最快,而在其它pH条件下由于SMN的形态变化导致反应速率减慢。通过UPLC-Q-TOF,检测出了SMN在 VUV/UV降解过程中的6种产物,并推测了包括羟基化和脱硫等反应的降解途径。此外,通过测定大肠杆菌的生长抑制率评价了SMN的抗菌性,结果显示其在 接受VUV/UV处理20 min后能降低80%左右。
      在以上实验的基础上,本文设计了三种不同管径的VUV/UV管式中试反应器,以探讨VUV/UV处理微量污染物的实际应用。首先以亚甲基蓝为目标污染物对 比了不同管径反应器的去除效果,结果表明相同流量下反应器内径越小去除率越高。之后,选择降解效果最佳的反应器(内径35 mm),对比了UV和VUV/UV两种处理方式对七种磺胺类抗生素混合溶液的处理效果,并考察了磺胺初始浓度、天然有机物和处理流量对VUV/UV去除效 果的影响。结果表明,当每种磺胺初始浓度为20 μg L?1、处理流量为0.18 m3 h?1、灯管输入功率为120W时,VUV/UV对七种磺胺的去除率均接近100%,且处理各磺胺的单位电能消耗(EEO)值在0.55~0.80范围 间,远小于UV处理的EEO值(1.02~5.09),体现了VUV/UV比UV在达到相同的处理效果时能耗更低。
英文摘要:
      In recent years, the frequent detection of micro-pollutants in surface, ground and even drinking water posed a serious risk to human health. Vacuum-UV/UV (VUV/UV) emitted by ozone-generating low pressure Hg lamps can be an effective and convenient treatment for the degradation of trace organic contaminants in water without additional chemical reagents. However, the low VUV emission efficiency of conventional UV lamps and the short transmission distance of VUV light in water greatly limited its practical application in a large extent. With optimized reactor design and understanding of degradation performance of typical organic contaminants, VUV/UV technology will be a good choice for small-scale water treatment.
      In this study, a novel mini-fluidic VUV/UV photo-reactor was built. The fluence rate of UV and VUV was determined by chemical actinometry as 5.76 and 0.586 mW cm?2 respectively. The performance of the photo-reactor was first examined by degrading a model compound, methylene blue (MB). The results showed that VUV/UV enhanced the degradation than UV and UV/H2O2 treatment due to the large amount of generated hydroxyl radical (?OH). The degradation of MB in the presence of tert-butanol under VUV/UV irradiation became much slower, which confirmed that ?OH oxidation was dominant in the VUV/UV process. In addition, the effects of VUV transmission gas media, flow rate, pH and initial concentration in the VUV/UV degradation were investigated in this study.
      The photo-degradation of eight sulfonamide (SA) antibiotics under UV, UV/H2O2, VUV, and VUV/UV/H2O2 treatment processes was studied using the specially designed VUV/UV photo-reactor. Results indicated that VUV/UV obviously enhanced the removal of target micro-pollutants without adding any chemical reagents than UV/H2O2 and UV. The removal rate of each SA could reach more than 99% with UV fluence of 180 mJ cm?2. The addition of H2O2 under VUV/UV irradiation did not enhanced the degradtaion compared to VUV/UV. The degradation kinetics and mechanisms of a representative SA, sulfamethazine (SMN), were studied in detail. SMN was found to be resistant to direct UV photolysis but readily degradable under VUV/UV irradiation. ?OH oxidation dominated in the VUV/UV treatment process. The degradation of SMN was the fastest in the pH range of 6.0?9.0, while other pH conditions would decrease the reaction rate by affecting SMN speciation and ?OH concentration. Six byproducts were identified using UPLC-Q-TOF-MS, and the potential degradation pathways of SMN including hydroxylation and SO2 extrusion were proposed. The antibacterial activity of the SMN solution, assessed by the growth inhibition of Escherichia coli, decreased by about 80% after VUV/UV treatment for 20 min.
       Three pilot VUV/UV reactors were designed and their degradation performance were examined by MB. Results indicated that the removal rate of MB was higher in a reactor with smaller inner diameter. The removal of seven SAs mixed in aqueous solution by UV and VUV/UV treatments was comparatively investigated in the reactor with the smallest inner diameter (35 mm). The results showed that under the experimental conditions of initial SA concentration = 20 μg L?1 (each), flow rate = 0.18 m3 h?1, and lamp input power = 120 W, VUV/UV treatment could achieve an almost complete removal of all studied SAs. Meanwhile, the electrical energy per order (EEO) values of VUV/UV under these conditions for all studied SAs ranged from 0.55 to 0.80, considerably less than those of UV treatment (1.02?5.09). The study demonstrates that VUV/UV requires less energy than UV to achieve the same treatment efficiency.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34513
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
王琛. 真空紫外/紫外在小规模水处理中去除磺胺类抗生素的研究[D]. 北京. 中国科学院研究生院. 2015.
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