Photodegradation of commercial dye, Procion Blue HERD from real textile wastewater using nanocatalysts

The aim of the study is to degrade reactive dye, Procion Blue HERD (PBH) in the presence of artificial UV light and nanophotocatalyst and to investigate the effectiveness of semiconductor photocatalytic treatment of real textile wastewater. For degradation of PBH, batch experiments were carried out by irradiating the aqueous solution of dye, in the presence of different semiconductors such as titanium dioxide (TiO2) and zinc oxide (ZnO) in the presence of UV light. The rate of decolorization was estimated from residual concentration spectrophotometrically. The effect of process parameters viz. pH (2–10), initial concentration of dye (10-100 ppm), and photocatalyst loading (0.5–2 g/l) on decolorization of dye has also been assessed. The experimental results indicated that 100% decolorization of dye occurred with ZnO at pH 7 and with TiO2 at pH 4. Optimum value of photocatalyst dose was found to be 1 g L− 1 for ZnO and 1.5 g L− 1 for TiO2. The rate constants for degradation of PBH using ZnO and TiO2 were calculated to be 0.077 and0 .075 min− 1, respectively. The performance of the photocatalytic system indicated that zinc oxide appears to be a suitable alternative to TiO2 in the presence of UV light at neutral pH. Finally, experiments using real textile wastewater were also carried out in order to examine the effectiveness of the method to a more complex substrate.

Research Highlights
► ZnO is more efficient photocatalyst for decolorization of Procion Blue HERD (PBH).
► Degree of decolorization is higher than degree of mineralization.
► GC analysis shows formation of several smaller organic intermediates.
► Significant decrease in the COD values of real textile effluents containing PBH.
► ZnO photocatalytic method is efficient in decolorizing textile mill effluents.