Se-doped CuO NPs/H2O2/UV as a highly efficient and sustainable photo-Fenton catalytic system for enhanced degradation of 4-bromophenol

Brominated aromatic compounds including bromophenols are hazardous and are being fast recognized as priority pollutants. We present here a novel photo-Fenton based degradation system using selenium doped copper oxide nanoparticles (Se-doped CuO NPs)/H2O2/UV, which facilitated 99.5% degradation of 4-bromophenol in 90 min at a rate of 0,057 min(-1). The Se-doped CuO NPs are prepared by precipitation method, and their structural, morphological and optical properties are characterized. The selenium doping is chosen owing to its favorable photo-absorption property and its doping in CuO NPs improved charge transfer properties and resulted in enhanced in-situ generation of hydroxyl radicals. The selenium doping also restricted the growth of CuO crystals, due to which the surface area of the nanoparticles increased and led to higher rate of photochemical reaction. The degradation profile is measured by high performance liquid chromatography method. The photo-Fenton process is initiated by extraneous H2O2 and the reaction is sustained by the in-situ generation of hydroxyl radicals, as demonstrated from the ROS scavenger studies. The de-bromination, formation of 4-benozoquinone as an intermediate degradation product and production of anionic species in residual solution after degradation due to cleavage of the molecular structure of 4-bromophenol are the key events confirmed by ion chromatography and gas chromatography coupled with mass spectrometry studies. The robustness of the Se-doped CuO NPs as catalyst has been confirmed from the re-usability studies for seven cycles. (C) 2018 Elsevier Ltd. All rights reserved.