饮用水中内分泌干扰物阿特拉津UV光氧化研究

采用单独紫外光氧化工艺去除饮用水中低浓度阿特拉津,研究了不同影响因素对阿特拉津降解效果的影响,并分析了阿特拉津的降解机理.结果表明:单独紫外光氧化对阿特拉津有很好的去除效果,在光强为205μW/cm²条件下,光解120min后,阿特拉津去除率为92.38%.阿特拉津的光解过程符合一级反应动力学模型.通过提高紫外照射光强,可以在短时间内提高阿特拉津的去除率.阿特拉津的初始浓度对光解反应基本没有影响.自来水中的有机物及多种离子的存在会降低阿特拉津的光解速率.紫外光氧化阿特拉津主要降解途径是脱氯反应,反应速率很快.羟基化产物(OHA)是主要的中间产物.OHA在紫外光作用下可以继续发生脱烷基反应,生成OHDIA和OHDEA,反应速率非常缓慢.反应液中pH值的变化与中间产物的形成过程有很好的相关性.     

γ-射线辐照-H2O2联合技术降解3-氯酚的研究

利用60Coγ-射线辐照3-氯酚(3-CP)水溶液,研究了其辐射降解特性.通过测量辐射后3-氯酚的去除率、紫外-可见光谱、脱氯率、总有机碳(TOC)去除率等,探讨了吸收剂量、氯酚初始浓度、H2O2加入对氯酚降解效果的影响,并初步探讨了氯酚降解动力学特性.结果表明,当3-氯酚浓度为10 mg.L-1,辐射剂量为2 kGy时,脱氯率可达100%,TOC去除率达53%;当辐射剂量提高到8 kGy时,3-氯酚可完全矿化,TOC去除率达100%.3-氯酚的辐照降解过程可用一级反应动力学方程拟合.氯酚单独γ-辐射以及辐照/H2O2联合处理的一级反应动力学常数k分别为0.279 h-1和0.542 h-1.     

O3/UV反应体系的有机物消解动力学模型

为了提高O₃/UV（臭氧协同紫外）反应体系对有机物的消解效率,降低能源消耗,基于O₃分解的SHB机理和O₃、有机物在紫外辐射下的光解机理,并考虑该反应体系中存在的3种可能的有机物消解途径和反应器出口处O₃气体浓度变化,建立了O₃/UV反应体系的动力学模型.将该模型用于消解过程中有机物消解率变化规律的研究,进一步优化消解工艺参数.结果表明:使用苯酚和乙酸作为目标有机物,以该模型进行仿真,从理论上验证了O₃气体浓度与紫外辐射间存在协同作用和不同工艺参数下所建立模型的灵敏性;将该模型与其他模型、试验测量值进行对比,验证了其优越性和准确性;对比不同pH下的3种消解途径各自贡献率的仿真结果,发现O₃/UV反应体系的pH对其消解有机物效率具有重要影响.研究显示:在O₃/UV反应体系中,紫外辐射强度和投加的O₃气体浓度二者间具有协同作用,同时调节可获得更好的消解效果;在酸性条件下有机物消解以O₃直接氧化为主,碱性条件下则以自由基间接氧化为主.      

天然日光辐照下河口区CDOM的光化学降解

2005年5月初和5月末,对经0.2μm滤膜过滤的九龙江口低盐度水样进行了2次每天6h、为期1周的天然日光辐照实验,研究有色溶解有机物(CDOM)的荧光与吸收性质的光化学降解特征.结果表明, CDOM的类腐殖质荧光(λEx/λEm = 350/450nm)、类色氨酸荧光(λEx/λEm = 225/350nm)以及吸收系数在初夏短期日光辐照下均发生明显的光化学降解,其降解过程符合一级动力学方程,相应计算出类腐殖质和类色氨酸荧光以及吸收系数a(280)的半衰期分别为3.5～5.1 d、3.0～4.5 d及6.3 d.吸收损失光谱研究表明,对CDOM光降解起主要作用的是太阳辐射的紫外波段.照射42h后,类腐殖质荧光的损失(70%)远高于吸收系数a(280)的损失(约40%),表明CDOM荧光团比发色团更易被光漂白,但两者之间仍保持良好的正相关性.与对照组相比, CDOM经日光辐照后其A250/A350比值增大,表明光化学降解可使其平均分子粒径变小.结果表明, CDOM在入海后可通过光降解作用在近海海域发生转化及清除,光降解是陆源 CDOM 入海后的一个重要归宿.     

O3/UV降解水中的乙酸和硝基苯

利用O3 /UV和O3/H2O2降解了水中的乙酸,结果表明,在相同条件下处理60min后,O3/UV对乙酸的去除率仅比单独臭氧化处理提高了3%,而O3/H2O2在此条件下完全降解乙酸.O3/UV在处理硝基苯过程中却显示较好的氧化降解能力,通过分析表明,硝基苯降解过程中所产生的副产物H2O2对有机物的去除具有很重要的作用.因此,O3/UV氧化降解能力的提高可能有2方面的原因,紫外光对有机物的活化作用;中间产物H2O2催化臭氧分解产生了高活性的羟基自由基. 单独紫外光催化臭氧分解产生羟基自由基的效率极低.     

Determination of nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia

Within a collaborative project between Slovenian Environment Agency （ARSO） and Research Center Jfilich （FZJ）, nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia were assessed. For this purpose the hydrological model GROWA- DENUZ was coupled with agricultural N balances and applied consistently to the whole territory of Slovenia in a spatial resolution of 100 x 100 m. GROWA was used to determine the water balance in Slovenia for the hydrologic period 1971-2000. Simultaneously, the displaceable N load in soft was assessed from agricultural Slovenian N surpluses for 2011 and the atmospheric N deposition. Subsequently, the DENUZ model was used to assess the nitrate degradation in soil and, in combination with the percolation water rates from the GROWA model, to determine nitrate concentration in the leachate. The areas showing predicted nitrate concentrations in the leachate above the EU groundwater quality standard of 50 mg NO3/L have been identified as priority areas for implementing nitrogen reduction measures. For these ＂hot spot＂ areas DENUZ was used in a backward mode to quantify the maximal permissible nitrogen surplus levels in agriculture to guarantee a nitrate concentration in percolation water below 50 mg NO3/L. Model results indicate that additional N reduction measures should be implemented in priority areas rather than area-covering. Research work will directly support the implementation of the European Union Water Framework Directive in Slovenia, e.g., by using the maximal permissible nitrogen surplus levels as a framework for the derivation of regionally adapted and hence effective nitrogen reduction measures.     

造纸废水的电离辐射预处理工艺研究

造纸废水是我国污染最为严重的难降解工业废水之一,研究了电离辐射处理造纸废水的可行性,探讨了混凝、辐照以及混凝-辐照组合工艺对废纸造纸废水的COD、BOD<,5>、吸光度、DOC以及有机物相对分子质量分布的影响.实验发现,造纸废水的COD主要是由相对分子质量<3 000的有机物构成,相对分子质量为1 000～3 000的...     

Ru(III) catalyzed permanganate oxidation of aniline at environmentally relevant pH

Ru（Ⅲ） was employed as catalyst for aniline oxidation by permanganate at environmentally relevant pH for the first time. Ru（Ⅲ） could significantly improve the oxidation rate of aniline by 5-24 times with its concentration increasing from 2.5 to 15 μmol/L. The reaction of Ru（Ⅲ） catalyzed permanganate oxidation of aniline was first-order with respect to aniline, permanganate and Ru（Ⅲ）, respectively. Thus the oxidation kinetics can be described by a third-order rate law. Aniline degradation by Ru（Ⅲ） catalyzed permanganate oxidation was markedly influenced by pH, and the second-order rate constant （ktapp） decreased from 643.20 to 2.67 （mol/L）^-1 sec^-1 with increasing pH from 4.0 to 9.0, which was possibly due to the decrease of permanganate oxidation potential with increasing pH. In both the uncatalytic and catalytic permanganate oxidation, six byproducts of aniline were identified in UPLC-MS/MS analysis. Ru（Ⅲ）, as an electron shuttle, was oxidized by permanganate to Ru（Ⅵ） and Ru（Ⅶ）, which acted the co-oxidants for decomposition of aniline. Although Ru（Ⅲ） could catalyze permanganate oxidation of aniline effectively, dosing homogeneous Ru（Ⅲ） into water would lead to a second pollution. Therefore, efforts would be made to investigate the catalytic performance of supported Ru（Ⅲ） toward permanganate oxidation in our future study.     

紫外光强化Fe(Ⅱ)-EDTA活化过硫酸盐降解直接耐酸大红4BS

为探索硫酸根自由基对偶氮染料的降解能力,以直接耐酸大红4BS（下称大红4BS）为模拟污染物,通过UV/Fe（Ⅱ）-EDTA/PDS（PDS为过硫酸钠）体系,探讨了初始c（PDS）、Fe（Ⅱ）/EDTA（摩尔比）、无机盐阴离子等对大红4BS降解的影响.结果表明,大红4BS的脱色率随着初始c（PDS）的增加而增大,当c（PDS）超过15 mmol/L时无显著变化.Fe（Ⅱ）/EDTA比在5:1时效果最好,5 min时使0.038 0 mmol/L大红4BS的脱色率达到93.6%.反应符合二级动力学模型.HCO₃-、Cl-、NO₃-、SO₄2-等无机盐阴离子表现出明显抑制作用,c（无机盐阴离子）在100 mmol/L条件下,脱色率分别降低66.9%、13.2%、12.1%、9.43%.利用紫外可见光谱,依据其结构与特征吸收的关系,初步推测自由基离子对大红4BS降解的途径:苯环最先遭到破坏,随后偶氮键断裂、萘环开裂.研究显示,UV光可有效强化Fe（Ⅱ）-EDTA活化过硫酸盐形成SO₄-·自由基,对偶氮染料具有很好的脱色能力,最佳反应条件[PDS:Fe（Ⅱ）:EDTA（摩尔比）为15:5:1]下,大红4BS在10 min时脱色率高达98.1%.      

Polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls in surface soil from the Tibetan Plateau

Concentrations of Polychlorinated dibenzo-p-dioxins and dibenzofurans（PCDD/Fs） and polychlorinated biphenyls（PCBs） in soil samples from Tibetan Plateau were determined. The average concentration of total 2,3,7,8-PCDD/Fs was（2.30 ± 1.02） pg/g, and World Health Organization Toxicity Equivalency（WHO-TEQ） average concentration was（0.013 ± 0.010）pg WHO-TEQ/g. The average concentration of ∑PCBs（7 indicator PCB and 12 dioxin like-PCB congeners） was（16.2 ± 9.25） pg/g, and WHO-TEQ average concentration was 0.043 ±0.049 pg WHO-TEQ/g. Comparing to previous studies in similar environmental conditions,PCDD/Fs and PCBs in this study showed a relatively lower concentration. The altitude dependences of PCDD/Fs and PCBs were also studied. Total organic carbon（TOC） normalized concentrations presented a quadratic relation with the altitudes, and an inflection could be found on the parabola of the total concentrations and some congeners of high concentration.The concentrations decreased with altitudes below about 4500 m above sea level（a.s.l.）, while they increased with altitudes above it. These phenomena indicate that cold condensation of PCDD/Fs and PCBs would happen above 4500 m a.s.l, on the Tibetan Plateau.     

偶氮染料4BS光解动力学和总氮脱除的初步研究

采用单独紫外光氧化降解偶氮染料直接耐酸大红(4BS),研究了不同因素对4BS光解效果的影响,并初步考察了光解对4BS溶液总氮的去除效果. 结果表明,单独紫外光氧化法对4BS及溶液中的总氮有一定的去除效果. 在非强碱性条件下,4BS的光解过程符合准一级反应动力学模型. 速率常数随紫外光强的增强而增大,并且与初始ρ(4BS)呈负相关关系. 溶液pH是影响光解反应的重要因素,速率常数随pH升高而增加显著,强碱性条件下光解速率最快. 光解对溶液中总氮的去除分为三步,含氮结构的发色基团易吸收紫外光,在反应初期被降解而生成气态含氮物,生成的中间产物比较稳定,需要经过一段时间的能量积累才能继续降解,从而总氮的去除率再次升高.      

Gamma irradiation of 2-mercaptobenzothiazole aqueous solution in the presence of persulfate

Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole(MBT) is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate(S2O82-) on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals(SO4-U), greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of –SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation,indicating the improvement of biodegradability and reduction of toxicity.     

Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai

The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe （visibility 〈 2 km） and moderate （2 km 〈 visibility 〈 3 km） haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm3 in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1μm and 1-10 μm size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100 nm and 100-200 nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15 μm3/cm3 and 949, 649, 206 μm2/cm3, respectively. As haze events got more severe, the number concentration of particles smaller than 50 nm decreased, but the particles of 50-200 nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4, SO24- and NO3 increased great/y, followed by Na＋, IC, Ca2＋ and CI-. These ions were very different in size-resolved particles during haze and photochemical smog episodes.     

Degradation of nitrobenzene in wastewater by γ-ray irradiation

The degradation of nitrobenzene(NB) by γ-ray irradiation was studied. The influences of dose rate and initial NB concentration were investigated in details. At a dose rate of 55 Gy/min, the degradation kinetics was pseudo-first-order at NB concentrations from 0.2 mmol/L to 4.0 mmol/L. At an initial NB concentration of 0.8 mmol/L, the degradation of NB at various dose rates also followed pseudo-first-order kinetics. Dissolved oxygen was found to have a positive effect on NB degradation. The degradation products were identified as nitrophenol, nitrosobenzene, and hydroquinone, and so on. Based on the product analysis, possible degradation pathways of nitrobenzene were proposed.     

Photocatalytic activity of Fe-doped CaTiO3 under UV-visible light

The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.     

Analysis of a laser process for permanently degrading a photo-activated adhesive joint

A pulsed, laser process has been developed to reduce the permanent strength of photo-activated adhesive joints prior to work-piece de-bonding. The objective of this investigation was to gain insight into the relationships between carbon black content of the adhesive, laser delivery mode, heat transfer, and adhesive degradation. To do so, a variety of experiments were performed to characterize process sensitivity, radiation absorption within the adhesive joint, and thermal decomposition of the adhesive. In addition, heat transfer analysis was conducted to predict adhesive temperatures during the process.The results of this investigation indicate that the strength diminishment of an adhesive joint occurs after it has absorbed a train of high power pulses in rapid succession. The vast majority of strength diminishment occurs over a very narrow time window and is highly correlated to the rapid emission of gray smoke/vapor from the adhesive joint. For this to occur, the adhesive must contain carbon black. It is also highly correlated to a rapid increase in temperatures throughout the adhesive matrix. Laser pulse parameters that do not lead to this rapid increase, will not initiate adhesive degradation.The inclusion of carbon black into the adhesive promotes heat absorption and increased temperatures in the adhesive joint. These temperatures are large enough to enable adhesive decomposition. But the time span over which this happens is too small for significant damage to occur. It is currently hypothesized that high temperatures local to the carbon black particles may be the source of adhesive degradation.     

磺化酞菁钴光催化降解甲基橙染料的试验研究

针对难降解的偶氮染料废水,在以磺化酞菁钴CoPcS为催化剂的情况下,实验研究了催化剂浓度、光照强度、温度、甲基橙初始浓度对降解效果的影响。结果表明:当催化剂CoPcS浓度0.2 g/L,光照强度250 W,温度40℃,pH=1,甲基橙10 mg/L时,在30 min内,甲基橙的降解率高达98.06%。最佳试验条件:pH值为1,催化剂浓度0.2 g/L,甲基橙初始浓度15 mg/L,温度40℃。影响因素主次为:pH值〉甲基橙初始浓度〉温度〉催化剂浓度,该反应符合零级反应动力学方程。     

Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.     

UV/H2O2工艺降解微囊藻毒素-LR

采用UV/H₂O₂联合工艺,研究了光强、初始浓度、H₂O₂投加量、pH及阴离子对微囊藻毒素-LR (MC-LR)去除率的影响.结果表明,单独H₂O₂对MC-LR基本无去除效果;单独UV工艺可以一定程度上降解MC-LR;而UV/H₂O₂联合工艺由于发生协同作用明显提高降解效率.试验发现,随着光强的增大,MC-LR的去除率不断提高;随着MC-LR初始浓度的增大,其去除率不断降低;随着H₂O₂投加量的增大,降解速率常数逐渐增大,当H₂O₂投加量由1 mmol/L增大到3 mmol/L时,降解速率常数由0.084 4上升到0.166 4;当pH为3.13时,在相同条件下MC-LR的去除效果最好;阴离子的投加不利于MC-LR的降解,其中CO^2-₃、NO^-₃影响最大.     

UV/H_2O_2工艺降解微囊藻毒素-LR

采用UV/H2O2联合工艺,研究了光强、初始浓度、H2O2投加量、pH及阴离子对微囊藻毒素-LR (MC-LR)去除率的影响.结果表明,单独H2O2对MC-LR基本无去除效果;单独UV工艺可以一定程度上降解MC-LR;而UV/H2O2联合工艺由于发生协同作用明显提高降解效率.试验发现,随着光强的增大,MC-LR的去除率不断提高;随着MC-LR初始浓度的增大,其去除率不断降低;随着H2O2投加量的增大,降解速率常数逐渐增大,当H2O2投加量由1 mmol/L增大到3 mmol/L时,降解速率常数由0.0844上升到0.1664;当pH为3.13时,在相同条件下MC-LR的去除效果最好;阴离子的投加不利于MC-LR的降解,其中CO2-3、NO-3影响最大.