Kirby Thomas, Akbar Md Ali, Tavakkoli Gilavan Mehraneh, Selvaganapathy P Ravi, Kruse Peter
Department of Chemistry and Chemical Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4M1, Canada.
School of Biomedical Engineering, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4L7, Canada.
ACS Omega. 2024 Nov 11;9(47):46986-46996. doi: 10.1021/acsomega.4c06812. eCollection 2024 Nov 26.
Dissolved gases such as oxygen (DO) and ammonia (dNH) are among the most consequential parameters for the assessment of water quality. Since the concentrations of DO and dNH are interdependent through the nitrogen cycle, simultaneous monitoring can be useful in many applications. For example, in wastewater treatment, aeration baths are used to adjust the rate of removal of ammonia by the bioactive sludge. Here, we have developed a sensing array which can monitor dissolved molecular oxygen (DO) and dissolved un-ionized ammonia (dNH) continuously and simultaneously. This was achieved by functionalizing two sensors made from single-walled carbon nanotube (SWCNT) films with two different molecules: phenyl-capped aniline tetramer (PCAT) and iron phthalocyanine (II) (FePc). It was found that the FePc-doped SWCNT (FePc@SWCNT) sensors demonstrated good sensitivity and selectivity to DO, compared to dNH. Conversely, we found that the PCAT-doped SWCNT (PCAT@SWCNT) sensors demonstrate greater sensitivity to ammonia. Investigating the effect of different PCAT salts as a dopant, we describe the following series of sensor responses to ammonia: chloride < crotonate < fumarate. Additionally, we coated our sensors with thin PDMS membranes, which are selectively permeable to gases, over ionic species. Finally, using principal component analysis (PCA) and partial least-squares discriminant analysis, it was possible to discriminate between responses to DO and dNH, with 100% accuracy. As a result, here, we have developed a compelling proof-of-concept for the use of a single sensing substrate, doped with molecules with distinct mechanisms of interaction with two different analytes, to simultaneously monitor concentrations of two dissolved gases, in this example, DO and dNH.
溶解气体，如氧气（DO）和氨（dNH），是评估水质的最重要参数之一。由于DO和dNH的浓度通过氮循环相互依存，同时监测在许多应用中可能会很有用。例如，在废水处理中，曝气池用于调节生物活性污泥去除氨的速率。在这里，我们开发了一种传感阵列，它可以连续同时监测溶解分子氧（DO）和溶解未电离氨（dNH）。这是通过用两种不同的分子对由单壁碳纳米管（SWCNT）薄膜制成的两个传感器进行功能化实现的：苯基封端的苯胺四聚体（PCAT）和铁酞菁（II）（FePc）。结果发现，与dNH相比，FePc掺杂的SWCNT（FePc@SWCNT）传感器对DO表现出良好的灵敏度和选择性。相反，我们发现PCAT掺杂的SWCNT（PCAT@SWCNT）传感器对氨表现出更高的灵敏度。研究不同PCAT盐作为掺杂剂的影响，我们描述了以下一系列传感器对氨的响应：氯化物<巴豆酸盐<富马酸盐。此外，我们用对气体有选择性渗透性、对离子物种无渗透性的薄PDMS膜覆盖我们的传感器。最后，使用主成分分析（PCA）和偏最小二乘判别分析，可以100%准确地区分对DO和dNH的响应。因此，在这里，我们已经为使用单一传感基板开发了一个令人信服的概念验证，该基板掺杂有与两种不同分析物具有不同相互作用机制的分子，以同时监测两种溶解气体的浓度，在这个例子中是DO和dNH。
