On-site H2O2 electro-generation process combined with ultraviolet: A promising approach for odorous compounds purification in drinking water system

Abstract

The on-site generation of hydrogen peroxide (H2O2) attracts much attention for advanced oxidation processes (AOPs) in water treatment. In this work, we reported a novel on-site H2O2 generation reactor combined with ultraviolet (UV) for taste and odor (T&O) compounds removal in drinking water purification systems. The reactor is equipped with a gas diffusion electrode (GDE) accompanied by a proton-conducting solid electrolyte. In this reactor, GDE is used to improve the oxygen transfer efficiency. The porous solid electrolyte is selected for the proton and electron conduction instead of an electrolyte solution, which is crucial for producing pure H2O2 solution. The production rate and concentration of H2O2 can be controlled through adjusting the applied current efficiency and the flow rate of deionized water in a solid chamber. Meanwhile, this system exhibits long-term stability during a continuous operation for 96 h. For the application of the system, the single-cell was assembled into cell stacks, which improved the H2O2 concentration from 780.9 to 2301.3 mg·L−1, along with the energy consumption reduced from 23.81 to 6.67 kWh·kg−1 under the applied current density of 30 mA·cm−2. To evaluate the water purification performance of this system, the oxidation degradation of 2,4,6-trichloroanisoles (TCA) was conducted using the on-site H2O2 generation process under both static and dynamic flow conditions combined with UV light. The degradation rate of TCA was >95% with its initial concentration of 1 μg·L−1 under the hydraulic retention time from 10 to 40 min−1 and H2O2 dosage from 10 to 100 mg·L−1. Meanwhile, almost no residual H2O2 was detected after the degradation process. This study proposed a promising device for drinking water purification.