A Mechanistic Study of High-Temperature Oxidation of Organic Carbon in Carbon Analyzers

溶解有机物氧化的机理 高温燃烧（HTC）碳分析仪 大部分都是未知的。 例如，不知道02（g）是否是 需要氧化DOC，是否需要"催化剂"，或者 催化剂中的含碳杂质是否有助于 对系统空白的影响很大。 在形势发生变化之前，HTC 分析器将继续设计和使用的经验， 方式 这项研究将测试的假设，氧化的 HTC仪器中的DOC在很大程度上是由于，在机械意义上， DOC与羟基自由基（OH）和其它反应性 通过注入的H2O的热均解产生的物质。 这一假说经得起直接的实验研究。 将对商用HTC碳分析仪进行大量修改， 与几种专用仪器（如气体 色谱仪;气相色谱-质谱仪）， 为了量化可能形成的主要和次要气体物质， DOC样品的分析。 载气的组成和 催化剂将系统地变化，以清楚地解决 O2（g）和OH在氧化过程中的作用。 温度- 程序挥发/燃烧将作为一种手段进行评估， 测量无机碳、挥发性有机碳和非 挥发性有机碳 新一代的，基于机械的 HTC碳分析仪将被设计和测试。

The mechanistic aspects of the oxidation of dissolved organic carbon (DOC) in high temperature combustion (HTC) carbon analyzers are largely unknown. For example, it is not known whether 02(g) is needed to oxidize DOC, whether "catalysts" are needed at all, or whether carbonaceous impurities in catalysts contribute significantly to system blanks. Until the situation changes, HTC analyzers will continue to be designed and used in an empirical manner. This research will test the hypothesis that oxidation of DOC in HTC instruments is largely due, in a mechanistic sense, to the reaction of DOC with hydroxyl radicals (OH) and other reactive species that are generated by thermal homolysis of injected H20. This hypothesis is amenable to direct experimental investigation. A commercial HTC carbon analyzer will be modified extensively and interfaced with several specialized instruments (e.g. gas chromatograph; gas chromatograph-mass spectrometer) that are used to quantify major and minor gaseous species that may form during analysis of a DOC sample. The compositions of carrier gases and catalysts will be varied systematically to clearly resolve the roles of 02(g) and OH in the oxidation process. Temperature- programmed volatization/combustion will be evaluated as a means of measuring inorganic carbon, volatile organic carbon, and non- volatile organic carbon. A new generation, mechanistically based HTC carbon analyzer will be designed and tested.