1,4-dioxane degradation using a pulsed switching peroxi-coagulation process

Yaobin Lu,Renduo Zhang,Jialiang Yao,Haiping Luo,Hualei Shi,Guangli Liu

doi:10.2166/wrd.2021.092

Abstract

Abstract Widely used in chemical product manufacture, 1,4-dioxane is one of the emerging contaminants, and it poses great risk to human health and the ecosystem. The aim of this study was to degrade 1,4-dioxiane using a pulsed switching peroxi-coagulation (PSPC) process. The electrosynthesis of H2O2 on cathode and Fe2+ production on iron sacrifice anode were optimized to enhance the 1,4-dioxane degradation. Under current densities of 5 mA/cm2 (H2O2) and 1 mA/cm2 (Fe2+), 95.3 ± 2.2% of 200 mg/L 1,4-dioxane was removed at the end of 120 min operation with the optimal pulsed switching frequency of 1.43 Hz and pH of 5.0. The low residual H2O2 and Fe2+ concentrations were attributed to the high pulsed switching frequency in the PSPC process, resulting in effectively inhibiting the side reaction during the ·OH production and improving the 1,4-dioxane removal with low energy consumption. At 120 min, the minimum energy consumption in the PSPC process was less than 20% of that in the conventional electro-Fenton process (7.8 ± 0.1 vs. 47.0 ± 0.6 kWh/kg). The PSPC should be a promising alternative for enhancing 1,4-dioxane removal in the real wastewater treatment.

Highlights

As an important solvent stabilizer, reaction agent, and reaction media, 1,4-dioxane (C4H8O2) has been widely used in the manufacturing processes of chemical products such as paints, varnishes, lacquers, cosmetics, resins, and deodorants (Clercq et al ; Barndõk et al a)
In the pulsed switching peroxi-coagulation (PSPC) process, the molar ratio of H2O2 and Fe2þ concentrations were determined by the pulsed switching ratio of H2O2 and Fe2þ production
The residually soluble Fe3þ was During the hydroxyl radical production, many secondary reactions can occur in the Fenton process as follows: Fe2þ þ H2O2 þ Hþ ! Fe3þ þ H2O þ ÁOH

Summary

Introduction

As an important solvent stabilizer, reaction agent, and reaction media, 1,4-dioxane (C4H8O2) has been widely used in the manufacturing processes of chemical products such as paints, varnishes, lacquers, cosmetics, resins, and deodorants (Clercq et al ; Barndõk et al a). Since 1,4-dioxane is bio-refractory, indicated by the low ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) (i.e. 0.06), non-volatility, and its miscibility with water (Nakagawa et al ; Radcliffe & Page ; Rossum ; Somda et al ), it is difficult to effectively remove it in typical biological wastewater treatments (Mahendra et al ; Huang et al ; Xu et al ). Complete decomposition of 100 mg/L 1,4-dioxane in the activated sludge processes required 7 days (Sei et al ). The biological co-metabolism can be used to enhance the 1,4-dioxane degradation. Additional nutrients, such as tetrahydrofuran and lactate (Sekar & DiChristina ), may increase the treatment cost (Hand et al ; Zhang et al ; Chen et al ; Fan et al ; Lin et al ). It is necessary to develop an efficient method for 1,4-dioxane degradation

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