纳米镍/铁去除四氯乙烯的影响因素

氯代烃是地下水中最常检出的有机污染物之一,传统的处理方法需要很长时间与经费。近年来随着铁还原技术的发展,纳米铁和纳米双金属也是一个活跃的研究领域。本文利用批实验的研究方法以四氯乙烯(PCE)为目标污染物,研究纳米镍/铁在去除PCE过程中的影响因素。实验结果表明,暴露后的纳米Ni/Fe脱氯速率比不暴露时速率降低约4倍;反应温度是影响反应速率的一个重要因素之一,每升高10℃,反应速率常数kSA提高2~3倍;在一定范围内,Ni/Fe质量比越高,越利于脱氯反应的快速进行,当Ni/Fe的质量百分比为8%左右时,对氯代烃脱氯速率最快;反应液中的溶解…     

纳米镍/铁去除氯代烃影响因素的探讨

氯代烃是地下水中最常检出的有机污染物之一,传统的处理方法去除率很低。近年来随着铁还原技术的发展,纳米铁和纳米双金属也成为一个活跃的研究领域。利用批实验的研究方法以四氯乙烯(PCE)和四氯化碳(CT)为目标污染物,研究纳米镍/铁在去除PCE过程中的影响因素。实验结果表明,在碱性条件下,纳米Ni/Fe对PCE脱氯速率比在酸性和中性条件下脱氯速率更快;纳米Ni/Fe对初始浓度为6·51mg/L的PCE溶液脱氯速率是对初始浓度为20·56mg/L的PCE溶液脱氯速率的1·8倍;对于氯代程度相同的CT和PCE,对CT的脱氯速率明显快于对PCE。     

零价铁降解水中氯代烃的实验室研究

由于氯代有机溶剂的大量使用和使用氯气对饮用水消毒 ,致使四氯化碳 (CT)和四氯乙烯 (PCE)成为地下水和饮用水中常见的污染物 .利用廉价铁屑对CT和PCE进行还原性脱氯 ,对其动力学过程进行初步研究 ,并对影响反应速率的因素进行探讨 .结果表明 ,零价铁对氯代烃有明显的脱氯作用 ,相同氯代程度的烷烃和烯烃 ,烷烃的脱氯速度快 ,反应符合一级反应动力学方程 ,反应是准一级反应 ,反应速率受到传质速率即零价铁比表面积的影响 .     

零价铁降解水中氢代烃的实验室研究

由于氯代有机溶剂的大量使用的使用氯气对饮用水消毒，致使四氯化碳（CT）和四氯乙烯（PCE）成为地下水和饮用水中常见的污染物，利用廉价铁屑对CT和PCE进行还原性脱氯，对其动力学过程进步初步研究，并对影响反应速率的因素进行探讨。结果表明，零价铁对氯代烃有明显的脱氯作用，相同氯代程度的烷烃和烯烃，烷烃的脱氯速度快，反应符合一级反应动力学方程，反应是准一级反应，反应速率受到传质速率即零价铁比表面积的影响。     

与铁相关的几种渗透反应格栅材料性能的比较

挥发性氯代有机化合物为地下水和饮用水中最常见的挥发性有机污染之一。文中对日益引人注意的渗透反应格栅(PRB:permeable reactive barrier)材料进行了研究。主要在实验室条件下,利用中国现有的实用性材料———铸铁的铁屑、实验室合成双金属和纳米双金属作为反应介质,对反应的脱氯效果和机理、还原性脱氯的反应动力学和影响因素进行初步的研究,以寻求一种可以大量得到的廉价而高效的材料,研究它对氯代烃的降解效率。在研究中选择最有代表性的CT和PCE作为目标污染物,讨论粒状铁、双金属以及纳米双金属对氯代有机物的降解速率,确定气相色谱法测定水溶液中的氯代有机物浓度的最佳实验条件,比较3 类反应介质的特点和应用范围。     

基于砂槽电化学-水动力学循环系统氯代烃反应迁移实验与模拟研究

在室内砂槽实验尺度,建立了潜水-微承压含水层中电化学-水动力循环系统下混合氯代烃生物降解的反应迁移模型,求取了混合氯代烃体系中各组分的反应动力学参数,并基于模型探究了含水层性质及工艺参数对该修复过程的影响机制.研究结果表明:（1）增大抽水流量可加快反应速率常数大的污染物降解,同时也会抑制反应速率常数较小的污染物去除.（2）增大电流强度和井内电极对氯代烃的好氧降解和厌氧脱氯过程分别具有促进和抑制作用.（3）含水层非均质性越强,氯代烃降解速率越小,这尤其体现在低渗区,且含水层非均质性对易降解污染物修复效果的影响较小.      

Ni/Fe双金属对PCE脱氯影响因素研究

以四氯乙烯(PCE)为目标污染物, 利用批试验研究Ni/Fe双金属对氯代烃脱氯的影响因素.结果表明: (1)当参加反应的Ni/Fe双金属分别为10 g和20 g时, 反应速率常数k_obs分别为0.047 7 h-1和0.097 0 h-1, 说明增加参加反应的Ni/Fe双金属的质量可提高脱氯速率; (2)当粒度分别为20~ 40目、40~ 65目和80~ 100目时, k_obs分别为0.047 7 h-1, 0.059‥ 8 h-1和0.088 6 h-1, 说明选用Ni/Fe双金属颗粒越小脱氯速率越快; (3)当Ni/Fe质量比分别为0.024%, 0.048%和0.072%时, 所得k_obs分别为0.047 7 h-1, 0.066 2 h-1和0.073 4 h-1, 说明Ni/Fe双金属系统中Ni/Fe质量比越高脱氯效果越好, 但最优Ni/Fe质量比还有待于进一步研究.      

负载型纳米Pd/Fe对挥发性氯代烃的去除

氯代烃的污染治理已成为当今世界最热门的研究领域之一。以水体中最常见的氯代烃污染物1,1-二氯乙烯（1,1-DCE）、林丹（γ-HCH）为主要目标污染物,探讨了不同条件下负载型纳米Pd/Fe对氯代烃的去除效果。负载型纳米Pd/Fe采用浸渍→液相还原→还原沉淀的方法制备,透射电镜显示采用该方法制备的负载型金属钯和铁的平均粒径均在纳米级范围内。负载型纳米Pd/Fe具有较高的表面反应活性,当负载型纳米Pd/Fe 用量为40 g/L、反应时间达2 h时,1.1-二氯乙烯和林丹的去除率分别达到85%和100%。脱氯率与Pd/Fe投加量、钯含量、初始pH值、反应温度等因素有关,与溶液的初始浓度关系不大。负载型纳米Pd/Fe对11-DCE和γ-HCH去除均符合一级反应动力学方程,速率常数分别为0-528 3 h^-1及2-012 9 h^-1,反应的半衰期t1/2分别为1.31 h和0.34 h。推断在反应过程中,Fe腐蚀产生的H2为主要还原剂,Pd是良好的加氢催化剂,在金属颗粒表面形成高浓度反应相,使反应短时间内完成。     

浅层地下水氯代烃污染天然衰减速率的估算

天然衰减恢复技术是恢复和控制浅层地下水氯代烃污染的技术之一,如何简便获取可靠的氯代烃衰减速率常数是该技术应用的一个关键。趋势线分析方法是一种简便有效的方法,在污染羽状体稳定的条件下,通过地下水流向上至少3口监测井的资料,能够比较准确地估算出污染物的天然衰减速率常数和生物降解速率常数。某氯代烃污染典型区的应用实例研究表明,该区四氯乙烯(PCE)的天然衰减速率常数和生物降解速率常数分别为0·000925d-1和0·000537d-1,证实该区浅层地下水中的PCE存在天然生物降解,但降解速率比较缓慢。忽略吸附作用的天然衰减容量计算所得出的天然衰减速率常数明显小于实际结果,说明尽管典型区包气带及含水层介质的有机碳含量很少,但它们对PCE的吸附作用不容忽视。     

纳米镍／铁对四氯乙烯快速脱氯试验

实验室合成的纳米Ni/Fe(粒径20~60nm,比表面积为52. 61m2 /g),在固液比相对较低条件下(5. 4g/L),对四氯乙烯(PCE)能够快速并完全脱氯,在6h时,脱氯率为99. 70%,反应符合准一级反应动力学方程,标准化反应速率常数kSA为3. 04mL·m-2·h-1。反应过程中水样未检测到其他的氯代中间产物或最终产物,无毒的烃类乙烷(C2H6 )是主要产物,约占加入时PCE总碳质量的94% ~110%。试验结果说明加氢催化剂Ni的存在,通过原电池腐蚀作用提高了脱氯速率并同时增加了良性产     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861