Oxidation/mineralization of 2-Nitrophenol in aqueous medium by electrochemical advanced oxidation processes using Pt/carbon-felt and BDD/carbon-felt cells

Abstract

Electrochemical degradation of toxic and persistent organic pollutant 2-Nitrophenol (2-NP) in acidic medium of pH 3 has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation using BDD anode (AO-BDD), electro-Fenton (EF-Pt) and anodic oxidation coupled to electro-Fenton (EF-BDD) processes under galvanostatic electrolysis conditions. The effect of current density and 2-NP initial concentration on the degradation rate and solution TOC removal efficiency was studied. The oxidation power of these processes has been comparatively studied in a one compartment cell with platinum (Pt) or boron doped diamond (BDD) anode. Results obtained show that acidic solutions of 2-NP can be efficiently mineralized by all EAOPs under examination, with increasing oxidation/mineralization power in order AO-Pt<AO-BDD<EF-Pt<EF-BDD processes. Total mineralization is attained with EF using BDD electrode as anode. The poor decontamination achieved in anodic oxidation with Pt anode is explained by the small amount of chemisorbed OH formed from water oxidation on its surface. The current efficiency increases in the same sequence as the mineralization power of the methods: all EAOPs present a maximum efficiency at early stage (t<1h) of electrolysis and then the MCE decreases to reach a value about 20% for longer treatment times.