Proof-of-concept for chemiresistive water quality sensors: free chlorine in drinking water; ammonia in wastewater

水对我们的生活是必不可少的。我们从环境中取水，为了各种目的消耗它，然后将它排放回环境中。始终保持水质是非常重要的。例如，我们的饮用水需要在整个分配系统中保持残留的消毒剂水平，以避免病原体。游离氯是一种常用的消毒剂，因为它可以有效地杀死病原体，尽管它不是很稳定，而且在饮用水分配过程中很容易耗尽。这就是为什么需要在配电系统的多个点上进行连续在线监测。对排放到环境中的废水进行监测也同样重要。虽然它不是直接供人类消费的，但它会严重影响排放地点或其下游的生态系统。在大多数情况下，废水最终将通过其他饮用水系统的取水点。废水中的氮含量，特别是以氨水形式存在的氮含量，尤其值得关注。因此，铵传感器通常部署在污水处理厂。游离氯和氨传感器由我们的工业合作伙伴ABB制造和销售，作为Aztec和Navigator系列连续水分析仪的一部分。这些装置主要依靠比色和电化学传感器。虽然ABB已经成功地减少了其比色传感器的试剂消耗，但它们仍然需要定期维护以重新填充。电化学传感器通常是无试剂的，但受其参考电极耐久性的限制。该提案旨在开发McMaster的化学电阻技术，用于ABB的在线分析仪。

Water is essential to our life. We take water from the environment, consume it for various purposes, and discharge it back into the environment. Maintaining water quality at all times is very important. Our drinking water, for example, needs to be kept free from pathogens throughout the distribution system by maintaining residual disinfectant levels. Free chlorine is a common disinfectant used for that purpose because it is effective at killing pathogens, even though it is not very stable and can easily deplete during drinking water distribution. This is why continuous online monitoring is desirable at multiple points along the distribution system. Monitoring of wastewater during its discharge into the environment is similarly important. While it is not destined for immediate human consumption, it can severely impact the ecosystem at the discharge site, or downstream of it. In most cases, wastewater will eventually pass by the intake sites of other drinking water systems. The nitrogen content of wastewater, in especially in the form of aqueous ammonia, is of particular concern. Thus, ammonium sensors are commonly deployed at wastewater plants. Both free chlorine and ammonia sensors are being manufactured and distributed by our industrial partner ABB as part of the Aztec and Navigator series of continuous water analyzers. These devices mainly rely on colorimetric and electrochemical sensors. While ABB has succeeded in reducing the reagent consumption of their colorimetric sensors, they nevertheless require periodic maintenance for refills. Electrochemical sensors are typically reagentless, but nevertheless limited by the durability of their reference electrodes. This proposal aims to develop McMaster's chemiresistive technology for use in ABB's online analyzers.