Nuclear chemistry

Hydroxyl radical

Sodium

Quantum mechanics

Reaction rate constant

Engineering

Sodium carbonate

Telecommunications

Computer science

Inorganic chemistry

Chemical engineering

Nitrogen

Quenching (fluorescence)

Thermodynamics

Physics

Organic chemistry

Cavitation

Degradation (telecommunications)

Environmental chemistry

Fluorescence

Radical

Kinetics

Chemistry

Mineralization (soil science)

Ethylene glycol

Ozone

Chemical Engineering Journal

Hydrodynamic cavitation (HC) was employed to activate sodium percarbonate (SPC) and ozone (O3) to degrade recalcitrant 1,4-dioxane. The degradation efficiency > 99 % with a rate constant of 4.04 × 10−2 min−1 was achieved in 120 min under the optimal conditions of cavitation number (Cv) 0.27, pH 5, molar ratio of oxidant to pollutant (rox) 8, ozone dose of 0.86 g h−1 under 25 ± 2 °C with initial concentration of 1,4-dioxane 100 ppm. The application of HC with SPC/O3 increased the degradation efficiency by 43.32 % in 120 min, confirming a synergistic effect between the coupled processes. In addition, the degradation efficiency of 1,4-dioxane in HC/SPC/O3 was superior as compared to HC/H2O2/O3, suggesting that the presence of SPC has a significant role in degradation of 1,4-dioxane. Radical quenching experiment revealed highest contribution of hydroxyl (HO) radicals in the degradation of 1,4-dioxane among carbonate (CO3−) and superoxide (O2−) radicals. The presence of co-existing anions resulted in an inhibitory effect in the following order: SO42− > NO3− > Cl−. Based on GC–MS analysis, ethylene glycol diformate (EGDF) was detected as the main degradation product of 1,4-dioxane. The observed intermediate supports the radical route of 1,4-dioxane oxidation, which involves H-abstraction, ΔC-C splitting at the α-C position, subsequent dimerization, fragmentation and mineralization. Electric energy per order (EEO) for best process was 102.65 kWh·m−3·order−1. Total cost of treatment was estimated as approx. 12 USD/m3. These findings confirmed the SPC as an efficient, environmentally-friendly alternative to H2O2 and broadened the scope of HC-based AOPs for water and wastewater treatment.

Activated sodium percarbonate-ozone (SPC/O3) hybrid hydrodynamic cavitation system for advanced oxidation processes (AOPs) of 1,4-dioxane in water