Comparison of various oxidative treatments for removal of reactive black CNN

Abstract

Decolorization of reactive black CNN by chemical oxidation and reduction using KMnO₄, H₂O₂ and Ferrioxalate as oxidizing agents and Na₂SO₃ as reducing agent individually as well as in combination was studied on batch scale using UV-visible spectroscopy. Degradation of dye occurred in acidic medium with KMnO₄ and in alkaline medium with H₂O₂ and ferrioxalate. The most efficient methods for decolorization of reactive black CNN is oxidation using KMnO₄ as an oxidizing agent which removed 97.64% of dye. Maximum decolorization was obtained at 60 min of treatment under static conditions. H₂O₂ and ferrioxalate could remove only 50.71 and 44.21% dye, respectively. Sequential treatment was more successful with H2O2 and ferrioxalate when compared with KMnO₄. Chemical oxygen demand (COD) and total organic carbon (TOC) contents of treated wastewater decreased appreciably from 83.6 to 63.7 mg/L and 86.8 to 72.8 mg/L, respectively. Additionally, Fourier Transform Infrared Spectroscopy (FTIR) study revealed the degradation of reactive black CNN after treatment into non toxic products.

Keywords: Reactive black CNN, KMnO₄, ferrioxalate, sodium sulphite, chemical oxygen demand (COD).