Removal of 1,4-dioxane from industrial wastewaters: routes of decomposition under different operational conditions to determine the ozone oxidation capacity.

This paper denotes the importance of operational parameters for the feasibility of ozone (O3) oxidation for the treatment of wastewaters containing 1,4-dioxane. Results show that O3 process, which has formerly been considered insufficient as a sole treatment for such wastewaters, could be a viable treatment for the degradation of 1,4-dioxane at the adequate operation conditions. The treatment of both synthetic solution of 1,4-dioxane and industrial wastewaters, containing 1,4-dioxane and 2-methyl-1,3-dioxolane (MDO), showed that about 90% of chemical oxygen demand can be removed and almost a total removal of 1,4-dioxane and MDO is reached by O3 at optimal process conditions. Data from on-line Fourier transform infrared spectroscopy provides a good insight to its different decomposition routes that eventually determine the viability of degrading this toxic and hazardous compound from industrial waters. The degradation at pH>9 occurs faster through the formation of ethylene glycol as a primary intermediate; whereas the decomposition in acidic conditions (pH<5.7) consists in the formation and slower degradation of ethylene glycol diformate.