ICP-AES测定南宁市大气颗粒物中重金属含量

采用石英滤纸和隔膜真空泵自制采样装置,对南宁市区的居民区、校园区、商业区和工业区进行连续10d的大气采样,所得样品经微波消解后,用电感耦合等离子体发射光谱法(ICP-AES)同时测定铬、铁、铜、锌、砷、镉和铅七种重金属元素含量以检测南宁市空气质量,同时考察了仪器工作参数对测定结果的影响。实验表明:在选定的实验条件下,各元素的检出限低,准确性和精密度良好。样品测定结果表明,大气环境中重金属污染物以Fe、Zn和Pb为主;工业区,商业区,居民区重金属含量高于校园区。重金属平均浓度最大值为:Cr(0.06027μg/m)3、Fe(1.8541μg/m)3、Cu(0.02214μg/m)3、Zn(0.3666μg/m)3、As(0.02272μg/m)3、Cd(0.004733μg/m)3、Pb(0.1843μg/m)3,低于我国(TJ36-96)《居住区大气中的有害物质最高容许量》中规定值,说明南宁市空气质量良好。     

氢化物发生原子荧光法测定地表水和饮用水中的痕量砷、汞、硒

文章研究了用SK-2002 AFS analyser氢化物发生原子荧光法测定地表水和饮用水中的砷、汞、硒的测定。在5％的酸度条件下加入5％硫脲＋5％抗坏血酸,20g／L的硼氢化钾为还原剂,调整仪器的空气和辅气流量及分析条件为文中条件,取水样中分别添加砷,汞,硒,使它们的浓度分别为2μg/L,0．4μg／L,4μg／L,连续测定12次,以砷,汞,硒的相对标准偏差分别为0．4％,1．1％,1．2％。取水样加入As,Hg,Se标准分别为2．0ng,0．6ng,4．0ng,测定的添加标准回收率分别为99．5％,97．5％,95．8％。研究结果表明,该方法操作简便,快速,灵敏,干扰少,检出限低等特点,适合于测定地表水和饮用水中砷,汞,硒的测定。     

冷原子荧光法测定水中汞不确定度评定

通过对冷原子荧光法测定水中汞的过程分析,分析该方法测量不确定的来源,给出相对不确定度分量,得出测量扩展不确定度结果。     

石墨炉原子吸收法测定电子废弃物处理场地附近植物中的钼

利用预烘干一湿法酸化消解方法处理植物并获得消解液,然后采用涂层石墨管,在探索不同原子化温度与灰化温度的多种优化试验条件基础上,对电子废弃物处理场地附近植物体内的钼进行了测定,样品进行平行试验,相对标准偏差（n=11）〈2．3％。     

原子荧光法测定医疗废弃物焚烧废气中的汞

采用王水消解-氢化物-原子荧光光谱法,对医疗垃圾焚烧炉所产生的废气进行采集所得到的滤筒进行消解分析,讨论并确定了实验的最佳条件,结果表明,汞的检出限为0．009μg/L,回收率为90．8％和94．3％,结果表明,该方法操作简便,灵敏度高,准确性好。     

气相色谱法分析环境空气中糠醛

采用活性炭采样管吸附环境空气中的糠醛,以CS2解析,用Rtx-WAX毛细管柱分离,氢火焰离子化检测器检测,气相色谱仪测定。方法最低检出质量浓度糠醛0.006mg/m3,加标回收率在90%以上,方法安全,简单灵敏,分离度好,检出限低。     

废水中铜的纳米金共振散射光谱分析

在HAc-NaAc介质中,二价铜被抗坏血酸还原成亚铜离子,并与新铜试剂生成黄色的络合物,该络合物对纳米金在580nm处的共振散射光有较强的吸收,导致其共振散射强度降低,其共振散射强度降低值ΔI与铜的浓度成线性关系,据此建立一种测定痕量铜的共振散射光谱分析方法。在选定条件下,铜含量在0.02～2.54μg/mL范围内与ΔI值呈良好的线性关系,其回归方程为ΔI580nm=87.2C+2.2,相关系数R为0.9983,检出限为0.001μg/mL,用于废水中铜的测定,结果满意。     

Measurements and predictions of harmful releases of the gathering station over the mountainous terrain

Having a risk analysis of harmful releases over mountainous terrains through wind tunnel experiment is a frontier problem in China. In this paper, a straight-flow wind tunnel is applied to simulate the atmospheric boundary layer and research the motion of high-sulfur gas released to atmosphere when accidental releases occur in a gathering station over the mountainous terrain. After an analysis of hourly concentration in the field accident for eight wind directions, experimental results reveal that nearby concentration fields are dominated by wind and far-field concentration distribution is dominated by topography, which leads to complete levels of consequence impact for the personnel risk inside and around the gathering station. Based on CFD techniques, a three-dimensional modelling was established in comparison with the wind tunnel experiment, which suggests that CFD prediction had underestimated the near-field gas concentration and the performance could not precisely match actual risks the gathering station causes to the mountainous terrain, which leads to a modified equation for numerical prediction. Instead of proposing a lower personnel risk evaluation obtained through the use of CFD techniques, the wind tunnel experiment offers a new choice for the consequence impact analysis for the petrochemical industry in China.     

Detonation flows in aluminium particle gas suspensions,inhomogeneous in concentrations

A physical and mathematical model of the reduced kinetics is presented describing heterogeneous detonation in suspensions non-uniform in particle concentration. The model is based on the heterogeneous media approaches, semi-empirical laws of ignition and combustion, and data on the dependence of the detonation velocity on particle concentration. Formation of suboxides and incomplete combustion of aluminum are taken into account integrally. The dependence of the heat release of chemical reactions and the fraction of unburnt particles on the initial composition is determined from the solution of the stationary problem of the structure of the detonation wave. In the calculations of unsteady detonation flows, it is supposed to solve an additional equation for the spatial distribution of initial concentrations. The problems of initiation and development of cellular detonation in flat channels in suspensions of micron-sized aluminum particles are studied. Dependences of the cell size on particle concentration in uniform suspensions are determined. The flow patterns of cellular structures, the forms of the leading front, and the propagation velocities in channels with longitudinal or transversal gradients of particle concentration are analyzed.     

A CFD-based empirical model for hazardous area extent prediction including wind effects

Hazardous extent predictions that ensure process safety while avoiding overestimation have been a challenge for hazardous area classification. Specific leak scenarios can be addressed to build rapid empirical models to accurately determine hazardous extent considering several factors that are not included in general approaches. In view of that, this work aims to propose a novel CFD-based empirical model for gas emissions in open and unobstructed areas. It considers a wide range of variables such as storage temperature and pressure, orifice diameter, molecular weight, gas concentration, and wind velocity. A sensitivity analysis was performed to evaluate each variable's contribution to the gas cloud extent. The linear regression model resulting from the combination of all variables contribution was coupled with Ewan and Moddie's model to minimize the prediction errors due to the non-monotonic wind effects. The suggested algorithm accurately calculates the hazardous extent with a coefficient of determination equals to 0.9842 and a RMSE of 0.0151 for a dataset of 600 cases of generic gases release. The proposed model was also validated for 60 cases of hydrogen releases under different storage conditions, giving a coefficient of determination equal to 0.9829 and a RMSE of 0.0680, indicating a good agreement with the data.