Removal of a reactive dye from simulated textile wastewater by environmentally friendly oxidant calcium peroxide

Abstract In the present study, calcium peroxide (CaO 2 ) was used separately for potential application as an environmentally friendly and low-cost oxidant for the removal of a textile dye ‘Reactive Black 5’ (RB5) from simulated textile wastewater containing auxiliary chemicals of textile production. The specific morphology, elemental analysis, particle size distribution, specific surface area, identification of crystalline phases and surface functional groups of the synthesized CaO 2 were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), laser diffraction (LD), Brunaure–Emmett–Teller method (BET), X-ray diffraction (XRD) and Fourier transmission infrared (FTIR), respectively. X-ray Diffraction analysis confirmed the synthesized oxidant as CaO 2 with the tetragonal crystalline structure. The signal corresponded to a bending vibration of O–Ca–O was detected in the fingerprint region of the FTIR spectroscopy. The effects of various independent parameters such as contact time, pH, initial RB5 concentration and CaO 2 dosage on decolorization were investigated. The results of the study showed that pH, initial dye concentration and the CaO 2 amounts have significant effects on removal of the RB5. The optimum pH was determined 7 for the removal of RB5 by CaO 2 . 2.0 g CaO 2 was found to be sufficient for the removal of 300 mg/L RB5 with 96.93% removal efficiency. Also 82.8% chemical oxygen demand (COD) removal efficiency from simulated textile wastewater (STW) was obtained by 2.0 g CaO 2 . The results of the present study showed that the CaO 2 can be used as an environmentally friendly and low-cost oxidant for effective removal of reactive textile dyes.