Computational Modelling of the Hydride Generation Reaction in a Tubular Reactor and Atomization in a Quartz Cell Atomizer
Computational Modelling of the Hydride Generation Reaction in a Tubular Reactor and Atomization in a Quartz Cell Atomizer
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DOI：
10.4236/jasmi.2012.23022
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发表时间：
2012-09
期刊：
影响因子：
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通讯作者：
Wameath S. Abdul‐Majeed;W. Zimmerman
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文献类型：
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作者：
Wameath S. Abdul‐Majeed;W. Zimmerman
在这项研究中，我们提出了一个模型，其中的原子化通道的中心被证明是最佳位置的光谱数据采集在石英池原子化器。本研究旨在探索通常与高效热源相结合的氢化物发生技术，通过光谱分析来测定水样中的重金属。作为模型案例研究，对氢化砷发生过程和氢化物在石英原子化器中的原子化过程进行了解析研究。氢化物发生（HG）的过程进行了分析，采用两个假设，初生氢和形成的中间硼氢化物物种，其中基于第二个假设的结果被发现是更现实的设计目的。此外，所产生的氢化物从液相中的释放和它们的运输到气相中的螺旋管段中进行了模拟，其中推导出分离所需的实际管段长度。分析结果已被实验验证，通过测量信号强度的自由砷原子对几个反应管的长度，其中增加的管段长度从12厘米到100厘米的结果在信号改善不超过6.6%。此外，推导了两种结构的管状石英原子化器中氢化物的原子化过程和自由原子的分布。从两种研究情况获得的结果表明，在雾化通道的第一部分中产生高浓度的游离分析物原子，在雾化器中心的位置处饱和到最大值，并且在到达雾化器出口边缘之前在管状雾化器的内壁处消散，这与目前对管式雾化器雾化机理的认识完全一致，并强调了石英管雾化器的中心是最佳位置用于光谱数据采集。
In this study, we present a model whereby the centre of the atomization channel is shown to be the optimal location for the spectrometric data acquisition in a quartz cell atomizer. The study aims to explore the hydride generation technique which is normally coupled with efficient thermal source to apply determination of heavy metals in water samples via spectrometric analysis. The arsenic hydride generation process and the atomization of the generated hydride in a quartz cell atomizer were studied analytically as model case studies. The hydride generation (HG) process was analyzed by adopting two hypotheses, the nascent hydrogen and formation of intermediate hydroboron species, where the results based on the second hypothesis are found to be more realistic for design purposes. Moreover, the release of the generated hydride from the liquid phase and their transport to the gas phase is simulated in a helical tubular section, in which the actual tubular section length required for separation is deduced. The analytical results have been verified experimentally by measuring the signal intensity for the free arsenic atoms against several reaction tube lengths, in which increasing the tubular section length from 12 cm to 100 cm results in signal amelioration by no more than 6.6%. Furthermore, the atomization of the hydride and the distribution of the generated free atoms are deduced in two configurations of tubular quartz atomizers. The results obtained from both studied cases illustrate that a high concentration of the free analyte atoms is generated in the first part of the atomization channel, saturates to a maximum in a position at the atomizer centre, and dissipates at the inside wall of the tubular atomizer before reaching the atomizer outlet edge, which is found to be in total agreement with the current understanding of atomization mechanism in tubular atomizer and emphasizes the fact that the centre of the quartz cell atomizer is the best location for the spectrometric data acquisition.