MECHANISM OF THE DEGRADATION OF 1,4-DIOXANE IN DILUTE AQUEOUS-SOLUTION USING THE UV HYDROGEN-PEROXIDE PROCESS

1,4-Dioxane is an EPA priority pollutant often found in contaminated g roundwaters and industrial effluents. The common techniques used for w ater purification are not applicable to 1,4-dioxane, and the currently used method (distillation) is laborious and expensive. This study aim s to understand the degradation mechanism of 1,4-dioxane and its bypro ducts in dilute aqueous solution toward complete mineralization, by us ing the UV/H2O2 process in a UV semibatch reactor. The decay of 1,4-di oxane generated several intermediates identified and quantified as ald ehydes (formaldehyde, acetaldehyde, and glyoxal), organic acids (formi c, methoxyacetic, acetic, glycolic, glyoxylic, and oxalic) and the mon o-and diformate esters of 1,2-ethanediol. Measurement of the total org anic carbon (TOC) during the treatment indicated a good agreement betw een the experimentally determined TOC values and those calculated from the quantified reaction intermediates, ending in complete mineralizat ion. A reaction mechanism, which accounts for the observed intermediat e products and their time profiles during the treatment, is proposed. Considering the efficacy of the 1,4-dioxane removal from dilute aqueou s solutions, as shown in this work,the present study can be regarded a s a model for industrially affordable Advanced Oxidation Technologies.