Phenolic wastewater treatment by an electrocatalytic membrane reactor

• Electrocatalytic membrane reactor was built and used in phenolic wastewater treatment.
• Synergistic effect of reaction and separation in ECMR gives efficient phenol removal.
• Accurate control of the residence time realizes the phenol controllable oxidation in ECMR.

An electrocatalytic membrane reactor (ECMR) constituted by TiO2 loading carbon membrane named TiO2/carbon electrocatalytic membrane as an anode and a stainless steel mesh as a cathode has been employed to treat phenolic wastewater. A synthetic phenol wastewater as the feed was prepared by mixing phenol and electrolyte (Na2SO4) with the concentration of 15 g/L. FESEM, XPS, cyclic voltammetry (CV) and high-performance liquid chromatography (HPLC) were used to characterize and analyze the electrocatalytic membrane, phenol concentration and degraded intermediates. The results showed that the removal rate of phenol and TOC reached approximately 99.4 and 86.3% after 2 h treatment at 2.0 mM phenolic wastewater by ECMR, respectively. The main intermediate products of phenol degradation included benzoquinone and organic acids. The efficiency and the degraded intermediates could be controlled by the main parameters of ECMR such as residence time, current density, etc. During the ECMR operation under the conditions of 10.0 mM phenolic wastewater, pH of 6, current density of 0.3 mA/cm2 and residence time of 5.2 min, the achieved phenol removal rate and complete mineralization fraction were 99.96 and 72.4%, respectively. The high efficiency and phenol removal obtained are related to the synergistic effect of the electrochemical oxidation and separation in the reactor.

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