CAS OpenIR  > 中科院上海应用物理研究所2004-2010年
Alternative Titlethe Analysis of Platinum Group Elements and Contamination in Aerosol Particles from Ambient Air in Shanghai
Thesis Advisor李晓林
Degree Grantor中国科学院上海应用物理研究所
Place of Conferral上海应用物理研究所
Keyword微波消解 空气颗粒物 铂族元素 三元催化转换器 电感耦合等离子体质谱(icp-ms)
Abstract由于三元催化转化器的广泛使用导致的城市大气中铂族元素污染已经引起了人们的广泛关注,准确测定环境样品中的铂族元素含量进而评价其在环境中的污染水平和进一步研究其对生物体的危害具有十分重要的意义。本论文工作主要由铂族元素电感藕合等离子质谱分析(ICP-MS)方法和上海市大气颗粒物中铂族元素污染特征两部分组成。 首先,研究了大气颗粒物中铂族元素溶样方法。铂族元素化学性质稳定,常用试剂往往不能将其全部溶解。论文工作中对微波消解法、高压密闭消解法等不同样品溶解方法进行了尝试,对不同混合酸溶样体系进行了试验选择。 铂族元素ICP-MS测定方法建立。在Pt、Pd、Rh ICP-MS测定中,存在基体效应和质谱干扰。实验采用1 ng/mL多元素混合标准溶液对仪器的工作参数进行调节,通过调节雾化器流速、射频发生器RF的正向功率等仪器参数使9Be,59Co,115In,208Pb,238U的实时检测信号灵敏度和稳定性达到最佳状态,从而使仪器达到最佳状态。分别采用115In、191Ir两种元素溶液作为195Pt和105Pd、103Rh测定内标溶液,以克服样品的基体效应及测定过程中仪器的信号漂移。Pt的干扰比较单一,实验采用数学校正法进行干扰校正,分别用标准溶液模拟样和国内、国际两种标准物质GBW7290和BCR-723进行可靠性验证,结果令人满意。对于Pd、Rh两种元素,其干扰则相对复杂,实验采用Dowex50W-8阳离子交换树脂分离干扰元素后进行ICP-MS直接测定。 阳离子交换树脂操作流程的建立及优化。分别从上柱液酸度、树脂装柱高度、溶液流出速率、最佳洗脱体积等方面对阳离子交换树脂进行了最佳条件选择,采用国际标准物质BCR-723(Road Dust),对阳离子交换分离流程的可靠性进行检验,实验表明实验测定值与标准值吻合。 上海市大气环境中铂族元素浓度和来源研究。为了研究上海市大气颗粒物中铂族元素的含量,采集了2003年12月至2005年12月PM10样品,分析结果表明:上海市中心区人民广场铂、钯、铑的平均浓度为1.71±0.93, 0.71±0.67, 0.16±0.08pg/m3,两年间铂族元素的浓度增长趋势不明显,但是呈现季节性变化。富集因子(EF)表明,上海大气中铂族元素主要由人为因素造成。不同型号的汽车尾气样品的分析表明,尾气样品中铂族元素的含量远远高于颗粒物样品,由此说明汽车尾气是大气铂族元素的重要排放源之一。
Other AbstractPlatinum group elements (PGE) are widely used in many fields, more and more PGEs have been emitted into our ambient environment, chemical analysis of the PGEs has attracted considerable interest of researchers. Several platinum group elements and their complex salts (e.g. Pt-and Pd-chlorides) have been reported as potential health risks to human, causing asthma, allergy, rhino-conjunctivitis and other serious health problems, so it is necessary for us to determine the PGEs concentrations accurately in ambient environment for investigating their possible diverse effects. This thesis mainly have two parts: (1) the establishment of the reliable methods of PGE analysis by using inductively coupled plasma mass spectrometry (ICP-MS) ; (2) the characters of PGE concentrations in urban airborne particles from Shanghai, China. Firstly, in order to establish a best procedure to digest the environmental samples for PGE analysis, several sample preparation methods were tested and compared in this work, such as microwave digestion, high pressure digestion with mixed acids at different ratios. Secondly, approaches to control of interferences in the determination of Pt, Pd, and Rh by ICP-MS were established. Accurate determination of Pt, Pd and Rh by ICP-MS is complicated due to molecular ion and doubly charged ion interferences. The sensitivity and stability of the instrument were tested with tune solution every operation by performing a short-term stability test. 115In and 191Ir were used as internal standard elements in order to eliminate matrix effect of samples and signal drift of ICP-MS. Pt can be determined accurately by using mathematical correction for interference of 179Hf16O+ . While for Pd and Rh, the matrix of environment samples is so complex that such the mathematical correction isn’t reliable. In this work, DowexAG50W-X8 strong cation exchange resin was applied to do the separation of Pd and Rh from the sample. The separation efficiency of interference elements and the recoveries of PGEs for the cation exchange procedure were verified by references materials GBW07290 and BCR-723. The results agree quite well with their certified values. The optimal resin operation conditions such as solution acidity, height of resin in column, flow rate of solutions, volume of wash solution, etc. were selected. The results also evaluated by the BCR-723, indicating the results are reliable. In order to investigate the current platinum group elements contamination in the urban ambient air, PM10 airborne particle samples were collected at Shanghai from December 2003 to December 2005. They were analyzed by ICP-MS. The results show that the average Pt, Pd and Rh concentrations in the air at the center of Shanghai were 1.71±0.93, 0.71±0.67, 0.16±0.08pg/m3, respectively. There were no significant changes of the PGE concentrations in air of Shanghai from December 2003 to December 2005. But, seasonal variations of the PGEs were significant. The seasonal variations of the PGE concentrations over two years were possibly caused by the meteorological influences (i.e., wind and rain). However, the PGE contamination levels in urban air of Shanghai are very low when compare with the other cities’ in west countries.
Document Type学位论文
Recommended Citation
GB/T 7714
杨永兴. 大气颗粒物中铂族元素分析及其污染状况研究[D]. 上海应用物理研究所. 中国科学院上海应用物理研究所,2007.
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