A cost-effective production of hydrogen peroxide via improved mass transfer of oxygen for electro-Fenton process using the vertical flow reactor

Abstract

This study has investigated a novel jet-type reactor (vertical flow reactor) in order to improve the oxygen utilization for enhanced production of hydrogen peroxide (H2O2). In vertical flow electro-Fenton (EF) system, the effects of current density, water flow rate, Fe2+ concentration and initial pH were investigated for the removal of tetracycline hydrochloride. The efficient removal of tetracycline hydrochloride could reach 100% within 60 min under the current density of 24 mA cm−2, water flow rate of 10 L h−1 and pH of 3. The vertical flow reactor was relatively stable and reusable for the removal of pollutants. The removal rates of tetracycline hydrochloride and total organic carbon (TOC) were maintained at about 95% and 80%, respectively in a 5-time continuous runs. Moreover, the vertical flow reactor could efficiently remove a wide type of organic pollutants, and the TOC removals of acid magenta, rhodamine B, alizarin yellow R, orange Ⅳ and diclofenacdium were 75.96, 77.90, 61.27, 72.11 and 82.89%, respectively after 3 h of reaction time. Cathodic adsorption, anodization, and H2O2 oxidation played minor roles in the removal of tetracycline hydrochloride, while the OH radicals are the most pivotal oxidizing substance in the system. As compared with the traditional aeration, the vertical flow reactor has a high-speed jet flow state, which makes the liquid-gas mixture homogeneous, and renders it high oxygen absorption rate, cost effectiveness and high power efficiency for the degradation of pollutants.