Electrochemical and Optical Sensors for Real-Time Detection of Nitrate in Water

Abstract

The health and integrity of our water sources are vital for the existence of all forms of life. However, with the growth in population and anthropogenic activities, the quality of water is being impacted globally, particularly due to a widespread problem of nitrate contamination that poses numerous health risks. To address this issue, investigations into various detection methods for the development of in situ real-time monitoring devices have attracted the attention of many researchers. Among the most prominent detection methods are chromatography, colorimetry, electrochemistry, and spectroscopy. While all these methods have their pros and cons, electrochemical and optical methods have emerged as robust and efficient techniques that offer cost-effective, accurate, sensitive, and reliable measurements. This review provides an overview of techniques that are ideal for field-deployable nitrate sensing applications, with an emphasis on electrochemical and optical detection methods. It discusses the underlying principles, recent advances, and various measurement techniques. Additionally, the review explores the current developments in real-time nitrate sensors and discusses the challenges of real-time implementation.

Phosphate and Nitrate Electrochemical Sensor Based on a Bifunctional Boron-Doped Diamond Electrode

“…Though these methods can detect nitrate and phosphate accurately, they require expensive, large-scale instruments, and specialized operators. In addition, the detection process is cumbersome, time-consuming, and prone to the generation of chemical waste, leading to secondary contamination . In recent years, various methods have been explored to achieve the efficient and economical on-site detection of nitrate and phosphate.…”

“…Over the past two decades, various materials have been studied for nitrate detection through electrochemical analysis. These materials include metals and metal oxides such as Ru, Rh, Ir, Pt, Pd, Cu, Ni, and Ag, − as well as graphene derivatives, carbon nanotubes, carbon fibers, conductive polymers, and enzymes . Among all these catalysts, Cu has been found to be the most promising electrocatalyst for nitrate reduction reactions .…”

“…These materials include metals and metal oxides such as Ru, Rh, Ir, Pt, Pd, Cu, Ni, and Ag, − as well as graphene derivatives, carbon nanotubes, carbon fibers, conductive polymers, and enzymes . Among all these catalysts, Cu has been found to be the most promising electrocatalyst for nitrate reduction reactions . Therefore, copper-based electrodes, such as copper microelectrode arrays, copper comodified carbon fiber electrodes, and nanowire-based copper electrodes, have been used for nitrate analysis.…”

“…In addition, the detection process is cumbersome, time-consuming, and prone to the generation of chemical waste, leading to secondary contamination. 9 In recent years, various methods have been explored to achieve the efficient and economical on-site detection of nitrate and phosphate. Electrochemical methods are known for their simple equipment, affordability, and user-friendliness.…”

“… 22 Among all these catalysts, Cu has been found to be the most promising electrocatalyst for nitrate reduction reactions. 9 Therefore, copper-based electrodes, such as copper microelectrode arrays, 23 copper comodified carbon fiber electrodes, 24 and nanowire-based copper electrodes, 18 have been used for nitrate analysis. Electrochemical detection methods for phosphates also involve a variety of electrode materials.…”