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首页> 外文期刊>Ozone News >Interference-Free Measurements of Dissolved Ozone in Dirty Water Using a New MicroSparge? Technology
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Interference-Free Measurements of Dissolved Ozone in Dirty Water Using a New MicroSparge? Technology

机译：使用新型MicroSparge进行无干扰的脏水中臭氧的测量技术

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From its beginning in 1906 with the installation of the first drinking water treatment plant, the now rapidly growing industrial ozone industry has been impeded by the lack of an adequate method to measure dissolved ozone in "dirty" (e.g., untreated stream, lake, well or waste) water. It is necessary to measure dissolved ozone during the course of treatment in order to assure that an adequate dose has been delivered to make the water potable. However, natural waters contain both particulate matter and UV-absorbing inorganic and organic compounds, making direct measurement of ozone by UV absorbance impossible. The most common method of measuring dissolved ozone during the treatment process is the electrochemical method of amperometry where the electrodes are separated from the water sample by an ozone-permeable membrane. However, redox species may interfere with the amperometric method, the time response is slow due to diffusion through the membrane, and frequent maintenance is required due to accumulation on the filter of contaminants. Previously, other instruments have been developed that use a sparging method in which air is equilibrated with the water sample. Ozone is then measured in the equilibrated air and Henry's Law is used to relate the gas-phase concentration back to the concentration in the original solution. The idea is that particulate matter and dissolved species remain in the water and thus don't interfere with the measurement. This method never became popular because 1) the instrument is very large and bulky and 2) the results tend to be irreproducible due to the dependence of the Henry's Law constant on temperature, pH and ionic strength. In order to improve on this method, we miniaturized the sample volume to ~2 mL and developed a method to sparge nearly all of the ozone out of solution within ~5 seconds. A correction is made for the few percent of ozone remaining in solution by fitting the exponential decay curve and integrating to infinite time. The result is a relatively small instrument that does not rely on Henry's Law, and most importantly, the measurement is free of interferences arising from UV-absorbing compounds and particulate matter. Of course, the instrument can be used for high purity water as well. Since the instrument is based on an absolute measurement of ozone in the gas phase, it only requires annual calibration. Consuming only ~2 mL per ten second sample (~12 mL/min), the amount of process water used by this instrument is minimal, thereby reducing waste. Here we describe this new approach to dissolved ozone measurements and provide an example of its use in monitoring ozone during treatment of tertiary wastewater.
机译：从1906年开始安装第一座饮用水处理厂起，由于缺乏足够的方法来测量“脏”中的溶解臭氧（例如未经处理的溪流，湖泊，或浪费）的水。有必要在处理过程中测量溶解的臭氧，以确保已交付足够的剂量使饮用水。但是，天然水既包含颗粒物，又包含吸收紫外线的无机和有机化合物，因此无法通过吸收紫外线直接测量臭氧。在处理过程中最常用的测量溶解臭氧的方法是安培法的电化学方法，其中电极通过可渗透臭氧的膜与水样分开。但是，氧化还原物质可能会干扰安培法，由于通过膜的扩散，时间响应很慢，并且由于污染物在过滤器上的积聚而需要频繁维护。以前，已经开发出了其他使用喷射方法的仪器，在该方法中，空气和水样得以平衡。然后在平衡的空气中测量臭氧，然后使用亨利定律将气相浓度与原始溶液中的浓度联系起来。这个想法是，颗粒物和溶解的物质保留在水中，因此不会干扰测量。该方法从未普及，因为1）仪器非常大且笨重，并且2）由于亨利定律常数对温度，pH和离子强度的依赖性，结果往往无法重现。为了改进此方法，我们将样品体积最小化为〜2 mL，并开发了一种在约5秒内将几乎所有臭氧从溶液中喷出的方法。通过拟合指数衰减曲线并积分到无限时间，可以校正溶液中残留的少量臭氧。结果是一个相对较小的仪器，不依赖亨利定律，最重要的是，该测量不受紫外线吸收化合物和颗粒物产生的干扰。当然，该仪器也可以用于高纯水。由于该仪器基于气相中臭氧的绝对测量值，因此仅需进行年度校准。每十秒钟样品仅消耗约2 mL（约12 mL / min）的水，因此该仪器使用的工艺用水量极少，从而减少了浪费。在这里，我们描述了这种用于溶解臭氧测量的新方法，并提供了其在三次废水处理过程中用于监测臭氧的示例。

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