Oxidation and Biodegradability Enhancement of 1,4-Dioxane Using Hydrogen Peroxide and Ozone

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

“…The degradation intermediates were mainly EG and volatile fatty acids, which are more biodegradable, meaning they could be removed in a traditional biological process. However, the MDO was almost completely degraded, even being in much higher quantities, which proves that it is oxidized more readily than 1,4-dioxane, and thus, it is competing for the available oxidants [8]. However, the combination of O3/H2O2 allows a complete degradation of 1,4-dioxane as well as MDO from sample 3 at the same experimental time.…”

“…Nevertheless, in terms of OCC consumed to degrade 1 g of COD, the treatment of samples 2 and 3 by ozonation was more efficient (2 and 1 OCC, respectively), while sample 1 needed more than 4 OCC per g of COD. This is probably due to the high MDO content that was degraded more readily than 1,4-dioxane [8]. However, in the combined process of O3/H2O2, a similar amount of oxidants was consumed per COD for all three wastewaters ( Figure 5B).…”

“…On the contrary, in the experiments ran at pH 7.0±0.1, the 1,4-dioxane reduction was very low (<15%), in accordance with the COD removal rates. This explains why the use of O3 as the only oxidant was ruled out for the treatment of 1,4-dioxane when the experiments were conducted in a solution of distilled water at unmodified pH below 7 [8,19,30]. The lower pH does not favor the decomposition of O3 to OH• [14,24,28] that has a much greater reactivity with 1,4-dioxane than O3 [19].…”

Catalytic liquid phase oxidation of 1,4-dioxane over a Pt/CeO2-ZrO2-Bi2O3/SBA-16 catalyst

“…It exists in its liquid state at ordinary temperature, and its boiling point is 101 ℃ [1] which is almost equivalent to that of water (100 ℃). 1,4-dioxane has been used as a solvent for extraction, purification and chemical reaction [2][3][4], but it has been identified as a cancer-causing pollutant by animal testing [5]. Therefore, a stringent environmental quality standard for water pollution has been established for 1,4-dioxane: for example, it is 0.05 mg/L or below in Japan [6].…”

“…1 Catalyst preparation SBA-16 was prepared according to the hydrothermal method described in previous studies [10,14]. Pluronic F-127 (1.6 g) and 1,3,5-trimethylbenzene (1.1 cm 3 ) were dissolved into 0.2 mol/dm 3 hydrochloric acid (90 cm 3 ), and the mixture was stirred at 35 ℃ for 3 h. After stirring, tetraethyl orthosilicate (7.1 cm 3 ) was added to the solution, and the mixture was stirred again at 35 ℃ for 20 h. Then the mixture was poured into a Teflon bottle in a sealed brass vessel and heated at 140 ℃ for 24 h. The solid product was collected by filtration, washed and dried at room temperature for 12 h. Finally, the dried powder was calcined at 600 ℃ for 4 h in air to obtain SBA- 16 3 ) was added, and the mixture was stirred at room temperature for 6 h. The content of Ce 0.68 Zr 0.17 Bi 0.15 O 1.925 was adjusted to be 16 wt%, which was the optimum amount for toluene oxidation [15]. After stirring, the solvent was vaporized at 180 ℃.…”