Generating chlorine dioxide for third world water purification

Abstract

Chlorine dioxide has been proven to be more effective in deactivating viruses and holds a number of advantages over other disinfection methods such as preventing trihalomethane (carcinogenic) formation whilst eliminating harmful pathogens such as Giardia. There are 3.41 million deaths per year in less economically developed countries due to pathogenic diseases in their water supply. Therefore, a simple electrolysis setup was explored using readily available chemicals, with the aim of implementing this practical disinfection method in third world countries. This research proposes that chlorine dioxide can be economically produced by the electrolysis of sodium chloride solution. Attempts to stabilise chlorine dioxide, due to its sensitivity to disproportionate, were explored via the addition of sodium bicarbonate. From conducting a series of electrolysis experiments, the conditions that permit the production of chlorite/chlorate were identified to be: a maximum current density of 1 A/dm2, dissimilar electrode materials and a large amount of sodium chloride, ~30 wt%. It was also concluded that a higher oxidation potential was essential for producing the desired chlorine dioxide. Additions of sodium bicarbonate proved useful in controlling the pH but caused complications in analysis, further investigations are required into when and how much should be added. Optimisation of the variables identified in this research could unlock the operating conditions required to successfully produce chlorine dioxide via this inexpensive method.