Aqueous chloramine sensors based on molecules acting as switchable dopant sites on graphene-like carbon films

水对我们生活的大多数方面都至关重要。饮用水水质最重要的监测参数之一是消毒剂的水平。如果它们的水平太低，微生物会在水中生长，这对我们的健康有害。如果消毒剂水平太高，消毒剂本身可能是有害的，或者至少对人类是不愉快的。在水处理厂完成一级消毒后，必须在整个供水系统中保持消毒剂水平（二级消毒）。氯胺化越来越多地用于这一目的，而不是氯化。虽然它的持久性在分销过程中是一个好处，但一氯胺在消费者端更难检测（它是无味的）和去除（它是稳定的）。然而，对于医疗保健、水产养殖、游泳池以及食品和饮料行业的应用，必须通过过滤完全去除氯胺。过滤器寿命很难仅仅通过使用年限或水量来判断，因为它更直接地取决于过滤器容量和污染物负荷。理想情况下，紧接在过滤器之后的传感器可以警告由于缺陷或耗尽容量而导致的破坏。在这里，我们专注于氯胺传感器的使用点的水过滤器的发展。这项工作将建立在一种新型传感器设计的基础上，我们的研究团队最近已经证明这种设计可以有效地检测饮用水中的游离氯。该设计基于我们的发现，即苯胺低聚物能够被水中的游离氯氧化，从而开启它们作为碳纳米管膜的p型掺杂剂的能力。一个简单的化学电阻器配置可以定量检测由于掺杂剂切换的纳米碳膜的显著电导率变化，因此作为一个定量的氧化还原传感器在整个相关范围。初步数据表明，这些传感器也可用于检测和区分各种氧化还原活性物质。通过使用不同的可选择性切换的掺杂剂分子，相同的感测原理可以应用于pH或其他分析物。 因此，我们建议开发一种传感阵列，能够定量检测氯胺在相关应用中为我们的工业合作伙伴，3M加拿大。

Water is fundamentally important to most aspects of our existence. One of the most important monitoring parameters of drinking water quality is the level of disinfectants. If their levels are too low, microorganisms can grow in the water, which are harmful to our health. If the disinfectant levels are too high, the disinfectants themselves may be harmful, or at least unpleasant to humans. After primary disinfection at the water treatment plant is complete, disinfectant levels have to be maintained throughout the water distribution system (secondary disinfection). Chloramination is increasingly used for this purpose instead of chlorination. While its persistence is a benefit during distribution, monochloramine is harder to detect (it is odorless) and remove (it is stable) at the consumer end. For applications in health care, aqua culture, swimming pools, and in the food and beverage industry, however, complete removal of chloramines by filtration is imperative. Filter lifetime is difficult to judge just by age or water volume since it is more directly a function of filter capacity and contaminant load. Ideally, a sensor immediately after the filter could warn of breaches due to defects or exhausted capacity. Here we focus on the development of a chloramine sensor for point-of-use water filters. This work will build on a novel sensor design that our research team has recently demonstrated as effective for detecting free chlorine in drinking water. The design is based on our finding that aniline oligomers are capable of being oxidized by the free chlorine in water, thus switching on their ability to act as p-dopants for carbon nanotube films. A simple chemiresistor configuration can quantitatively detect the significant conductivity change of the nanocarbon film due to the dopant switching, and hence serve as a quantitative redox sensor across the entire relevant range. Preliminary data indicates that these sensors can also be used to detect and distinguish a variety of redox-active species. The same sensing principle can be applied to pH or other analytes by using different selectively switchable dopant molecules. Hence, we propose to develop a sensing array capable of quantitatively detecting chloramines in relevant applications for our industrial partner, 3M Canada.