Improved degradation of textile effluents via the synergetic effects of Cu-CeO2 catalysis and non-thermal atmospheric pressure plasma treatment

Abstract The direct discharge of industrial textile effluents is increasingly constituting a major burden on the environment. The development of an effective treatment for the degradation of hazardous organic pollutants in effluents is therefore highly needed. In this paper, the synergetic effects of copper-doped cerium oxide (Cu-CeO2) nanoparticles (NPs) and non-thermal atmospheric pressure plasma (NTAPP) treatment were thoroughly examined on the degradation efficiency of reactive black-5 (RB-5) dye in aqueous solution and textile effluent. Initially, Cu-CeO2 NPs were synthesized by a hydrothermal method and further characterized by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The degradation efficiency of the combined plasma/Cu-CeO2 catalysis treatment was examined by UV–Vis spectroscopy as a function of the treatment time. Optical emission spectrometry (OES) was used to identify the generated primary and secondary reactive species such as OH●, O, H and N2* in the plasma jet. The presence of OH● radicals and H2O2 in treated RB-5 aqueous solution was also quantified spectroscopically. Furthermore, the variation in the pH, electrical conductivity and total organic carbon (TOC) was also studied. All combined results revealed that plasma advanced oxidation processes together with the Cu-CeO2 catalytic performance have triggered the formation of higher concentrations of various reactive species which in turn improved the RB-5 and effluent degradation efficiency and suppressed the formation of harmful intermediates. This was further corroborated by the non-toxicity of the treated solutions when in contact S. aureus and E. coli bacteria. Overall, it can be concluded that the distinctive combination of Cu-CeO2 and plasma-assisted processes is ideally required in different textile industries as a highly effective treatment of effluents before discharging.