Carbon-Based Electrochemical-Free Chlorine Sensors

Sodium hypochlorite is a widely used additive in water used to disinfect and remove any disease-causing bacteria that can be found in sources of water, and is used to wash contaminants from meats, fruits, and vegetables. Many free chlorine sensors exist which monitor free chlorine levels such as the use of colorimetric or electrochemical methods, ensuring that the free chlorine is within safe and regulated levels. However colorimetric sensing methods are irreversible and often use toxic compounds, and electrochemical sensors, although reversible, are made with materials which are not suitable to be used near drinking water or food products. By developing sensors which are made using alternative materials and methods, the sensors can be used in and around drinking water and food products. This review article discusses various electrochemical-free chlorine sensors made with various carbon-based materials and methods resulting in sensors that are biodegradable, relatively inert, and resilient in the presence of harsh chemicals, making them safe to use near and around food and still maintain competitive performance parameters. This review article showcases some of the recent progress, the importance, preconditions, and the various future needs and potentials of carbon-based electrochemical-free chlorine sensors.