纳米铁锰氧化物对钒的吸附特性研究

为寻求处理土壤和地下水钒污染的吸附剂,采用模拟实验,开展了纳米铁锰氧化物(MnFe_2O_4)对五价钒(V~(5+))的吸附特征研究,分析了纳米铁锰氧化物浓度、pH值、时间、温度和初始钒浓度等因素对MnFe_2O_4吸附V~(5+)的影响,以揭示纳米铁锰氧化物的吸附动力学及热力学等特征,并通过扫描电镜(SEM)和红外光谱(IR)等表征方法分析了纳米铁锰氧化物吸附V~(5+)的机理.结果表明,在初始钒溶液为100 mg·L~(-1),MnFe_2O_4加入量为0.1 g,pH=4,温度为25℃的条件下,吸附过程在24 h达到平衡,且此条件下有最大吸附值和吸附率,分别为15.14 mg·g~(-1)和60.54%.纳米铁锰氧化物吸附钒的动力学过程符合伪二级动力学模型,等温吸附线符合Langmuir模型.热力学研究表明,升高温度有利于吸附,吸附过程为吸热过程.由扫描电镜结果可知,纳米铁锰氧化物有较大的比表面积,可提供较多的活性位点.因此,纳米铁锰氧化物可作为一种吸附材料用于钒污染废水处理.     

Second german heavy-metal survey by means of mosses,and comparison of the first and second approach in germany and other european countries

This paper shows the geographic distribution in Germany of iron (Fe), nickel (Ni) and lead (Pb) analyzed in mosses in 1995/96 and compares it with the results of the 1990/91 pilot study within a European moss-monitoring programme. Other elements (As, Cd, Cr, Cu, Ti, V, Zn) are compared on basis of the overall element medians for Germany of the 1990/91 and 1995/96 survey. Samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens were taken at a total of 1026 sites. In the 1995/96 monitoring campaign, 95% of the original sites of the 1990/91 study were resampled. The results from 1995/96 display local elevated values and many cases of areas affected by known sources of heavy-metal emissions. The industrialized and urban regions of Germany are shown up clearly by the 1995/96 moss-monitoring results: the Ruhr area, parts of Saarland and Baden-Württemberg, as well as areas in eastern Germany. Relatively low values for many elements were found in large areas of Lower Saxony and Bavaria. A comparison of the results of the 1990/91 and 1995/96 moss-monitoring programmes shows a fall in the concentration of the presented elements (except cadmium, copper and zinc) over the relevant period. Especially in the former GDR, chromium (Cr), iron (Fe), titanium (Ti) and vanadium (V) decreased significantly. This is, firstly, a reflection of the closure of and/or technological improvements to large power plants; secondly it is due to the fact that lignite has given way to other fuels. Vanadium (V) and nickel (Ni), typical constituents of crude oil, also show a decrease in the western part and thus document changes in the type of fuel consumed. The significant fall in lead concentration in 1995/96 as compared to 1990/91 in what used to be East and West Germany probably results from the increasing use of lead-free petrol. A comparison of the median values for 1990/91 and 1995/96 in mosses to the rate of emission of heavy metals in Germany for 1990 and 1995 shows similar trends in the case of elements such as arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb). The comparison of the medians of the elements analyzed for 19 European countries indicates for most of the elements a general tendency to lower values in 1995, except for Lithuania, Netherlands, Portugal, Italy and United Kingdom.     

露天开采生态环境影响识别与修复技术的探讨——以崇阳露天石煤钒矿矿山开发环评为例

矿山开采活动在获得最大的经济利益的同时,势必给原有的生态环境带来严重破坏和影响.结合矾矿露天采矿特点,讨论矿山开采各个环节对生态因子的影响及强度,筛选主要影响因子,分析露天矿山开采可能引起的地形地貌、土地占用、土壤侵蚀、破坏野生动植物生境、地表水水质、景观格局等方面对环境的影响,并提出相应的优化施工方案、闭坑露天矿山土地、植被复垦等生态环境保护对策,对科学开发崇阳钒矿具有一定参考意义.     

钒镉复合污染对水稻吸收积累镉、钒和磷的影响

采用溶液培养法研究钒与镉复合污染对水稻生长及其吸收积累镉的影响,以便弄清在钒与镉复合污染条件下水稻的生长情况.试验结果表明,钒镉复合污染可影响水稻的生长发育.在培养液镉浓度(1 0mg·L-1)不变的情况下,随着溶液中钒浓度的增加,水稻根长、根系和茎叶的干重不断减少.当溶液中钒浓度达到1 6mg·L-1和3 2mg·L-1时,水稻茎叶和根系干重减少分别达到显著水平(p<0 05).钒镉复合污染也影响水稻植株对磷、钒和镉的吸收与积累.当培养液中镉浓度不变时,随着溶液中钒浓度的增加,水稻根系和茎叶中的磷浓度不断降低,而钒含量却不断提高,根系比茎叶积累更多的钒.此外,钒可抑制水稻植株对镉的吸收与积累.     

空气整段间隔流动注射-催化动力学光度法测定天然水中痕量钒

应用空气整段间隔流动注射法与改进的钒-溴酸钾-没食子酸催化动力学反应体系相结合,建立了测定天然水体中痕量钒的催化动力学光度FIA法。通过使用一个自制的进样阀,使样品带在反应管道中的留存时间得到延长,加热允许温度得到提高。在温度80℃,反应留存时间4.75min条件下,可测定0—10ppb的钒,检出限达0.1ppb。测定2ppb钒样品时,RSD为2.7％(n=10),测定频率达90次/h,方法的平均回收率在80—109％之间。     

陕西省石煤提钒行业存在的问题及对策研究

陕西的石煤主要分布在陕南秦岭南坡的商洛地区,但大部分石煤钒矿属于难处理矿,钒大部分以V（Ⅲ）和V（Ⅳ）存在,目前企业大多采用“焙烧＋稀酸浸出＋氨法沉钒”或者“强酸浸出＋氨法沉钒”工艺进行生产。存在的问题一是钒的综合回收率为65％左右,整体偏低;二是生产废水中含有大量氨使得废水闭路循环难度大;三是矿区大部分位于汉丹江水系的中上游地区或临近出省断面,选址较为敏感。针对以上存在的问题提出了解决建议．并对陕西省石煤提钒行业的发展做出了展望。     

Plant Uptake of Trace Metal Oxoions From Two Contrasting Acid Soils

Uptake of arsenic, molybdenum, uranium and vanadium by species of natural vegetation (Agrostis capillaris, Betula pendula, Calluna vulgaris, and Deschampsia flexuosa) on two contrasting, highly acid soils (pH of soil solution 4.2-4.3), differing in natural abundance of these elements, was compared. the soil developed from alum shale was rich in these elements, the soil from a gneiss moraine was poor in these elements. Leaf/ above ground biomass concentrations were positively related to soil concentrations of the elements, but least closely for uranium, and vanadium tended to be excluded by the plants, compared to arsenic, and especially to molybdenum. the relationships between soil and plant concentrations were broadly similar whether nitric acid-digestible or the much lower DTPA extractable soil fractions were considered. Leaf concentrations of plants from the shale and the gneiss soil, respectively, ranged 1.41-2.76 and 0.30-0.58 nmolg^-1 dry weight for arsenic, 14-140 and 0.5-9.6 for molybdenum, 0.031-0.069 and 0.013-0.030 for uranium, 2.3-6.4 and 0.75-3.3 for vanadium.     

BiVO4表面氧缺陷调控及其光催化氧化三价砷

以乙二醇为溶剂,采用溶剂热-煅烧法制备缺陷型BiVO₄光催化剂,通过控制溶剂热反应时间调控BiVO₄表面氧缺陷以增强对As （III）的光催化氧化性能.同时,借助各种表征手段如XRD、SEM和XPS等分析样品的晶型结构、形貌特征及化学组成等性质,考察其在可见光下对As（III）的光催化氧化性能,并研究其氧化机理.结果表明,溶剂热反应时间对BiVO₄的晶粒尺寸和光吸收性能没有影响,但能通过影响比表面积调控BiVO₄的表面氧缺陷浓度.经优化得到,反应时间为14 h时制备的BiVO₄光催化剂（BiVO-14）对As（III）（6 mg·L^-1）的氧化效率高达95.7%,并具有良好的光催化稳定性.BiVO₄氧化As （III）的主要途径是光生空穴（h⁺）的直接氧化作用.表面氧缺陷能增强导电性能,促进电荷分离和迁移,强化h⁺的氧化作用,从而提高BiVO₄的光催化氧化性能.BiVO-14能有效促使As（III）转化为低毒的As（V）,在饮用水源As污染去除方面具有广阔应用前景.     

The use of δ18O as an indicator of vanadium movement in a dormant stratovolcano region

The oxygen isotope (δ¹⁸O) stable water tracer can be a promising new tool for identifying trace metals in volcanoes and their sources. In the present study, the origin of vanadium in water from a spring at the base of Mt. Fuji is examined using δ¹⁸O, a dormant stratovolcano consisting of lava and basalt rock located on the North Pacific Coast of Japan. A comparison of water from the main springs at the foot of the Mt. Fuji volcano indicates that only V, Cr, Mn and Co enrichment could be related to volcanic events, whereas Ni, Cu, Cd and Pb originate from the dissolution of particles of anthropogenic origin from the industrial areas of Fuji and Fujinomiya. The average V concentrations at the mountain sites ranged from 50 to 110 µg L^?1 and from 18 to 47 µg L^?1 in the coastal areas. The δ¹⁸O became depleted at higher elevations and increased in coastal areas as well as in some NO₃^?-contaminated water. Therefore, variations in the dissolved V/δ¹⁸O ratio in springs of the study area occur due to the elevations of their catchments and the increased concentrations of δ¹⁸O from NO₃^? as a contaminant.     

油酸铵改性的高活性TiO2/V-TiO2复合光催化剂的制备及光催化降解甲基橙的研究

采用溶胶-凝胶法,将经过油酸铵改性的掺钒二氧化钛粉末投入到纯TiO2溶胶中,烘干、煅烧,制得带有n-n异质结半导体结构的复合型高活性掺钒二氧化钛光催化剂,并通过XRD、TEM、XPS等技术对样品进行了表征。通过对甲基橙溶液的光催化降解实验来考察TiO2/V-TiO2催化剂的光催化活性。结果表明：TiO2/V-TiO2复合催化剂拥有比纯TiO2更高的光催化活性。其中,V的掺杂摩尔分数为0.5%、TiO2：V-TiO2的质量比为10∶1的最佳复合催化剂,其光催化活性是纯TiO2的5.1倍。