Degradation of Environmental Pollutants and Biochemical Components via Chlorine Dioxide or Ozone Treatment

Abstract

Chlorine dioxide (ClO2) can be used as a disinfectant in medical and food applications and for wastewater treatment. The susceptibility of contaminants in aqueous solution to breakdown by ClO2 directly generated in solution from its precursors or via fumigation with ClO2 gas were compared. The direct ClO2 treatment method is better suited to wastewater treatment, whereas the fumigation method would be helpful for sterilizing equipment and facilities. Fumigation is less effective than the direct ClO2 method; it has the added benefit of disinfecting hard-to-reach places, including crevices and porous materials. Tobacco-related chemicals such as nicotine, benzyl alcohol, and N-nitrosodimethylamine were treated with ClO2 gas for 1 to 2 hours via direct treatment and 6 hours using the fumigation treatment. GC-MS analysis of ClO2-treated samples showed that nicotine is the most susceptible to ClO2 degradation, whereas benzyl alcohol is the most resistant. When treated with ClO2 via the direct method for 2 hours, nicotine was degraded to below the minimum detection limit, N-nitrosodimethylamine was degraded by 57.2%, and benzyl alcohol by 27.1%. The reaction kinetics and rate order for the reaction between benzyl alcohol (BA) and ClO2 followed a rate law of r = - 0.113 · [ClO2]1 · [BA]1.5. It is the first order with respect to ClO2, but the presence of water complicates the reaction order for benzyl alcohol. The industrial pollutant 2-chlorophenol was also studied using the direct treatment method with ClO2. The direct analysis in real-time-mass spectrometry (DART-MS) and fluorescence spectroscopy were used to study the effects of ClO2 gas on tryptophan, tyrosine, and peptides as well as the trace levels of degradation by-products not amenable to GC-MS analysis. The degradation of chemicals by ozone was also studied, especially for those less susceptible to degradation with ClO2. The pros and cons of oxidative degradation of chemical constituents using ClO2 and ozone will be discussed.