Advancements in electrochemistry for the sensing of aqueous compounds and persistent compound destruction

A significant research question to address is if existing electrochemical methods can be used to advance the sensing of biological compounds and toxic heavy metals, and to destroy persistent toxic pollutants to benefit the planet and humankind. Using the methods of cyclic voltammetry (CV), square wave voltammetry (SWV), square wave stripping voltammetry (SWSV), and electrochemical oxidation (EO), the sensing of isatin and manganese, and the destruction of perfluoroalkyl compounds was investigated. Each task had the main focus of advancing our understanding of the process and making significant process improvements.Isatin is an endogenous indole that has potential pharmaceutical applications based on its anticonvulsant abilities through reaction pathways in the human body. Due to its low concentrations in blood, serum, and tissues, it is typically detected using gas chromatography mass spectroscopy (GC/MS) which requires a specialized individual and lengthy measurement times. In order to combat this, researchers have begun investigating electrochemical detection methods for this compound. Here, the investigation of isatin detection on a 3-in-1 boron-doped diamond (BDD) sensor was studied to simplify the electrochemical system requirements and set the ground work for a potential plug and play sensor for isatin. Both sensor configurations tested showed applicability to this application with the lowest limit of detection obtained to be 0.04 μM. Not only was isatin able to be detected in a complex sample matrix in a short measurement time with this simplified technical approach, it was done so with the elimination of extensive electrode pretreatment processes that have been required for other electrode materials in the past. This study paves the way for a fully developed BDD sensor that can expand the understanding of isatin reaction pathways and advance its ability to be used in pharmaceuticals.Manganese is an important nutrient but has toxic effects in humans making it imperative to be able to detect it in human blood, urine, and serum as well as drinking water. Indium tin oxide (ITO) has been a typical electrode material for spectroelectrochemical measurements and metal detection experiments on transparent substrates. This study goes through a few process parameters for an ITO film on a non-transparent silicon substrate. It was found that heating and annealing the film created the best film structure for an electrochemical sensing application towards manganese with a limit of detection of 0.1 parts per billion (ppb). This obtained lower detection limit allows for improved accuracy in human serum measurements with no added membranes to the electrode’s surface and uses an electrode material that already has the capabilities to be mass produced with good repeatability. This makes ITO an economical sensing solution.Per- and polyfluoroalkyl substances (PFAS) are toxic to human health and are wide spread in the environment due to their numerous consumer and industrial applications. Most current remediation techniques take advantage of filtration or adsorption technologies to remove these compounds from a water source. However, since they do not destroy the compounds, these remediation techniques yield waste products. This study, utilizing electrochemical oxidation for the destruction of PFAS, looks at tackling waste products from an ion exchange process. By utilizing BDD, a laboratory study showed that PFAS completely mineralize in these complex solutions. Overall, it was foundthat ammonia based solutions allow for the best mineralization of the most common PFAS using electrochemical oxidation for an ion exchange regenerate solution. This study provides valuable knowledge to ion exchange manufacturers who are looking to solve their residual PFAS waste problem.All three studies have shown that existing electrochemical techniques can be used to further sensing and remediation knowledge in today’s world and provide safer, cleaner technology options for the betterment of human health and the environment.