Effects of system parameters and inorganic salts on the photodecolourisation of textile dye Reactive Blue 19 by UV/H₂O₂ process

Abstract

The photodecolourisation of textile dye Reactive Blue 19 (RB 19), an anionic anthraquinone dye of the reactive class, was investigated using UV radiation in the presence of H₂O₂ in a batch photo-reactor with  low-pressure mercury lamps. The effects of the system parameters: initial pH, initial dye concentration, concentration of peroxide and radiation  intensity, as well as the presence of salts, (NaCl, Na₂SO₄, NaNO₃,  NaH₂PO₄) on dye decolourisation was examined. Increasing the initial pH resulted in an increase in decolourisation efficiency. Results showed that with an increase of dye concentration from 10 to 100 mg·l–1, the efficiency of the process decreases. The highest decolourisation rates were noted at H₂O₂ concentrations of approximately 30 mmol·l^–1. The increase of radiation intensity from 730 to 1 950 µW·cm^-2, linearly increases  decolourisation efficiency. The inorganic ions investigated have inhibiting effects on RB 19 decolourisation by the UV/H₂O₂ process with inhibition intensities in the following order: H₂PO₄– > NO3^- > SO₄2– > Cl^-. This study has shown that the UV/H₂O₂ process is a promising technology for degradation of RB 19 in water and wastewater.

Keywords: UV/H₂O₂ process, Reactive Blue 19, decolourisation, inorganic salts