Color removal from synthetic textile wastewaters with calcium peroxide

In the present study, potential application of a environmentally friendly and low-cost oxidant calcium peroxide (CaO2) was investigated for the removal Reactive Black 5 (RB5) dye from simulated textile wastewater (STA) containing production auxiliary chemicals. The specific morphology, elemental analysis, particle size distribution, identification the crystalline phases and surface functional groups of synthesized CaO2 were investigated by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX), Laser Diffraction (LD), Brunaure–Emett–Teller method (BET), X-ray Diffraction (XRD) and Fourier Transmission Infrared (FTIR), respectively. X-ray Diffraction analysis confirmed the synthesized oxidant as CaO2 with the tetragonal crystalline structure. Signal corresponded to 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 amounts of CaO2 on decolorization were investigated. The results of the study showed that pH initial dye concentration and the CaO2 amounts have significant effects on degradation of the RB5. The optimum pH was determined 7 for the removal of RB5 by CaO2. 2.0 g CaO2 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 STA was obtained by 2.0 g CaO2. Experimental data were applied to pseudo first order model in order to understand the RB5 degradation kinetic. The results of the present study showed that the CaO2 can be used as an environmentally friendly and low-cost oxidant for effectively removal of reactive textile dyes.