城市河流中WWMPs的迁移转化试验

为研究城市河流中WWMPs（污水印记药物）的迁移转化行为,以13种典型WWMPs[AZM（阿奇霉素）、CLM（克拉霉素）、STZ（磺胺噻唑）、TMP（甲氧苄啶）、ATL（阿替洛尔）、PNL（普萘洛尔）、DCF（双氯芬酸）、CLF（氯贝酸）、IBU（布洛芬）、CBM（卡马西平）、CAF（咖啡因）、PRC（扑热息痛）和TCS（三氯生）]为目标物,通过生物降解试验、吸附试验及光降解试验分析目标物主要的迁移转化机理.结果表明,AZM、CLM、PRC的降解主要是生物作用,不灭菌且有氧条件下的降解率分别可达90%、95%、100%.沉积物对CBM的吸附作用明显,但其难以被水解和生物降解,而且其吸附和解吸是一个相对平衡的过程,导致CBM能够稳定存在.ATL、STZ、PRC和TMP这4种亲水性化合物不易被沉积物吸附,其余9种属疏水性化合物的吸附能力取决于其K_OW（辛醇-水分配系数）.此外,光降解试验表明,在实际环境中,很多目标物受颗粒物和光敏剂的影响,不易发生直接光降解,TMP、DCF、PNL、CAF和TCS容易发生光降解作用,其在光照和避光的条件下降解率分别为20%和10%、58%和25%、22%和5%、20%和2%、30%和5%.研究显示,城市河流中的WWMPs在生物降解、吸附和光降解共同作用下有明显的降解效果.      

水中萘普生的紫外光降解机制及其产物毒性研究

以120 W汞灯为紫外光光源,通过活性氧物种(ROS)的淬灭实验和溶解氧(DO)浓度实验和发光菌毒性实验,对水中萘普生(NPX)的降解机制、反应动力学及其产物毒性进行了研究.结果表明,NPX的紫外光降解过程包括了直接光解和ROS参与的自敏化光解两个过程,同时.OH、1O2、O.2-的自敏化光解贡献率分别为0.1%、80.2%、35.7%;溶解氧浓度实验表明,溶解氧对萘普生的降解具有抑制作用,而且浓度越大,抑制效果越明显;发光菌毒性实验表明,萘普生光降解生成了具有较萘普生更高风险的中间产物.本研究中萘普生的所有光解实验过程均符合准一级动力学方程.     

Photoreductive degradation of sulfur hexafluoride in the presence of styrene

Sulfur hexafluoride （SF6） is known as one of the most powerful greenhouse gases in the atmosphere. Reductive photodegradation of SF6 by styrene has been studied with the purpose of developing a novel remediation for sulfur hexafluoride pollution. Effects of reaction conditions on the destruction and removal efficiency （DRE） of SF6 are examined in this study. Both initial styrene-to-SF6 ratio and initial oxygen concentration exert a significant influence on DRE. SF6 removal efficiency reaches a maximum value at the initial styrene-to-SF6 ratio of 0.2. It is found that DRE increases with oxygen concentration over the range of 0 to 0.09 mol/m^3 and then decreases with increasing oxygen concentration. When water vapor is fed into the gas mixture, DRE is slightly enhanced over the whole studied time scale. The X-ray Photoelectron Spectroscopy （XPS） analysis, together with gas chromatography-mass spectrometry （GC-MS） and Fourier Transform Infrared spectroscopy （FT-IR） analysis, prove that nearly all the initial fluorine residing in the gas phase is in the form of SiF4, whereas, the initial sulfur is deposited in the form of elemental sulfur, after photodegradation. Free from toxic byproducts, photodegradation in the presence of styrene may serve as a promising technique for SF6 abatement.     

Aqueous oxytetracycline degradation and the toxicity change of degradation compounds in photoirradiation process

The extensive use of antibiotics has been a worldwide environmental issue.In this study the fate of oxytetracycline (OTC),under photoirradiation,was investigated.The results showed that OTC photolysis followed first order model kinetics.Direct photolysis rate was found to be dependent on the initial OTC concentration,with k value ranging from 0.0075 to 0.0141 min~(-1),in the OTC concentration from 40 to 10 mg/L.OTC photolysis was highly pH-dependent and strongly enhanced at a high pH value,with a k value...     

Effects of humic acid fractions with different polarities on photodegradation of 2, 4-D in aqueous environments

Four fractions (A, B, C, and D) of humic acids (HAs) were separated based on the polarity from weak to strong. UV-vis absorption and Fourier transform infrared spectroscopy (FTIR) analysis show that the fractions C and Dpossessedmore aromatic C=C content. The influences of HAs and their fractions on the photolysis were investigated by the photodegradation of 2,4-D solutions under simulated solar light irradiation. The degradation rate of 2,4-D was found to decrease in the presence of bulk HAs or their fractions especially at high HAs concentration. The fractions of strong polarity C and D retarded the degradation rate more than the fractions of weak polarity A and B. This could be attributed to the different absorption intensity of the four HAs fractions in the order of D ⩾ C > A > B, and the stronger π-π electron donor-acceptor interactions between the strong polar fractions and 2,4-D.     

环糊精对Fe(Ⅲ)引发双酚A光降解的影响

环糊精口α-CD、β-CD和γ-CD能分别与双酚A形成1:1主-客体包结物.在250W金属卤化物灯(λ≥365 nm)光照下,研究了在Fe(Ⅲ)-OH配合物体系中,不同环糊精对双酚A光降解的影响.结果表明,β-CD能较大地促进双酚A的光降解,α-CD次之,而γ-CD对双酚A的光降解存在一定的抑制;并且CDs浓度的变化对双酚A光降解的初始速率有明显的影响.双酚A光降解的初始速率随着β-CD和α-CD浓度增大而增加,当β-CD=60μmol/L时达到最大,然后随着浓度增大而降低,而BPA的光降解初始速率随γ-CD浓度的增加总的趋势是减小的.通过计算机软件Gaussian98,采用PM3方法模拟了环糊精与双酚A的包结行为,进一步说明3种环糊精与双酚A形成主-客体包结物对光降解的影响.     

含碳酸盐水溶液中扑热息痛的光解研究

采用动力学方法研究了环境浓度范围内的扑热息痛在含碳酸盐溶液中的光解,比较了碳酸盐自由基和羟基自由基对扑热息痛的光解效果,探讨了pH值、硝酸根离子、腐殖质、氯化钠、钙镁离子等因素对扑热息痛光解的影响.利用GC/MS技术鉴定了扑热息痛的光解产物,并探讨了扑热息痛在碳酸根体系中可能的光解途径.结果表明,扑热息痛与碳酸盐自由基反应的二级反应速率常数为 k.=5.0×107L·(mol·s)-1,低于与羟基自由基反应的二级反应速率常数kb=8.1×109L·(tool·s)-1,但是由于天然水体中碳酸盐自由基的稳态浓度较高,所以碳酸盐自由基对扑热息痛光解的影响和羟基自由基大致相当.提高体系pH值,加入硝酸根离子、氯化钠或者钙镁离子都会加快扑热息痛的光解速率;而加入Suwannee河富里酸则会降低光解速率.     

Factors influencing the photodegradation of N -nitrosodimethylamine in drinking water

In order to provide basic data for practical application, photodegradation experiment of N-nitrosodimethylamine (NDMA) in aqueous solution was carried out with a low-pressure Hg lamp. Effects of the initial concentration of NDMA, solution pH, dissolved oxygen, and the presence of humic acid on NDMA photodegradation were investigated. NDMA at various initial concentrations selected in this study was almost completely photodegraded by UV irradiation within 20 min, except that at 1.07 mmol/L, NDMA could be photodegraded almost completely in the acidic and neutral solutions, while the removal efficiency decreased remarkably in the alkaline solution. Dissolved oxygen enhanced the NDMA photodegradation, and the presence of humic acid inhibited the degradation of NDMA. Depending on the initial concentration of NDMA, NDMA photodegradation by UV obeyed the pseudo-first-order kinetics. Dimethylamine, nitrite, and nitrate were detected as the photodegradation products of NDMA. ¹O₂ was found to be the reactive oxygen species present in the NDMA photodegradation process by UV, based on the inhibiting experiments using tert-butanol and sodium azide.     

秋季南海珠江口和北部湾溶解有机物的光降解

利用三维荧光光谱分析手段,结合吸收光谱测定,分析了2007年10月中国珠江口及北部湾水体中4个典型有色溶解有机物(CDOM)样在太阳光辐照下的光降解特性.结果表明,珠江口及广西沿海CDOM样受陆源输入影响较大,而北部湾中部的HX样具有典型海洋CDOM特征,80m水深的HN样则受到北部湾环流的主要影响.这些CDOM样品中均观测到类腐殖质荧光峰A、C、M以及类色氨酸荧光峰R、T,它们的荧光峰强度及吸收系数a(280)在秋季短期日光辐照下发生了较明显的光化学降解,受陆源输入影响较大的珠江口及广西沿海样品的光降解程度高于北部湾的远岸样品,反映出它们含有更多的发色团.光降解未引起CDOM荧光峰位置的显著变化,类腐殖质荧光峰M和A、类蛋白质荧光峰R和T的强度变化趋势一致,表明这两对峰具有相似的性质.A峰区存在的双峰现象表明其为多个荧光组分的叠加.CDOM吸收光谱的光谱斜率S(270～350)随光辐射而逐渐增加,可用于指示光降解引起的CDOM分子量的减小趋势.研究表明,光降解在南海生源要素的生物地球化学循环中起重要作用.     

不同背景气体下非平衡等离子体去除NO实验

设计了一套高压电源和柱-筒反应器装置,在不同的背景气体下进行了介质阻挡放电脱硝的实验研究,主要探讨了放电电压、含氧量、停留时间和功率对NO去除率的影响.结果表明:不同背景气体下,放电电压在一定的范围内(氩气:5～7kV;氮气:9～11kV)对NO脱除率有较大影响;氧气的加入对不同背景气体下的脱硝率都有影响,对氩气背景下的NO去除率影响最大;停留时间的增加有利于NO的去除,当停留时间增加到某一个值(7s)后,NO的去除率变化逐渐平缓;达到相同的去除率,氩气背景下的功率远远小于氮气背景,功率的增加有利于NO的去除;合理选择背景气体有利于NO去除率的提高和能耗的降低.