Electrochemical Oxidation of Chlorination Byproducts in Swimming Pool Applications

Abstract

Potential health risks related to disinfection byproducts (DBPs) in swimming pools have lately raised public concern and stringent legislation. This thesis presents a novel route to degrade DBPs with the use of electrochemical methods. A number of electrodes with nano-scale thin film materials have been investigated for this aim. Cyclic voltammetry results suggest that the byproducts from urea-chlorine reaction vary with initial chlorine concentrations. Having a higher amount of free chlorine induces transformation of monochloramine, dichloramine, and chlorourea into volatile trichloramine, nitrogen, and nitrate. In this work, free chlorine has been successfully regenerated from chlorination byproducts via pulse electrolysis. The process can be either direct or indirect oxidation of urea and DBP. Direct oxidation is the direct electron transfer from urea or chloramines to electrode. Indirect oxidation is mainly the electron transfer from chloride and chloramines to electrode, forming free chlorine, which is then used to oxidize urea and chloramines. Continuous electrolysis is suspected to convert hypochlorite to chlorate, decreasing the free chlorine concentration. A reaction mechanism for electrochemical oxidation of DBPs has been proposed. These findings clarify the role of free chlorine concentration in byproducts generation and open up new possibilities for DBP removal for water treatment applications.