Removal of Reactive Blue 19 dye from synthetic waste water using UV/H2O2 and UV/Cl advanced oxidation processes

The textile and dyeing industries are among the largest water-consuming and polluting industries in the world. The most important feature of the textile and dyeing industry wastewater is its color, due to the use of colored materials. Most of these dye compounds are resistant to conventional purification methods and their biodegradation is very low through secondary purification processes and they are not completely removed. Therefore, selecting the optimal method to remove these color compounds is essential. In this study, we studied the removal of an organic dye contaminant (Reactive Blue dye 19 [RB19]) using advanced oxidation processes (AOPs). For this purpose, ultraviolet (UV) mercury lamps with a wavelength of 254 nm and a voltage of W16 inside the reactor were used as an energy source. The experiments were performed in a collimated beam reactor inside a dark chamber. Two oxidizers of sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) were used to remove RB19 from the artificial sewage stream. Removal of RB19 with a concentration of 20 mg/L with variable pH (5, 7, and 9), oxidant concentrations (5, 10, and 20 mg/L), and time (5, 10, 15, and 30 min) were investigated during the processes of photolysis, chemical oxidation (by H2O2 and NaOCl), and UV/NaOCl and UV/H2O2 AOPs. The photolysis process did not remove the RB19. The highest removal efficiency of RB19 by chemical oxidation processes with NaOCl and H2O2, UV/NaOCl, and UV/H2O2 at optimal conditions (pH = 5, [oxidant] = 20 mg/L, RB19 = 20 mg/L, and radiation intensity of 1005 mJ/cm(2)) was 64.49%, 0.88%, 99.7%, and 13.31%, respectively. These results indicate that the hydroxyl radical was produced, under optimum conditions, more in the acidic medium; thus, the RB19 removal efficiency was high in the acidic medium. The combination of UV rays with oxidants resulted in the production of more hydroxyl radicals and increased removal efficiency.

Automated summary

The textile and dyeing industries are major water-consuming and polluting industries. The wastewater from these industries is characterized by its color. Conventional purification methods are not effective in removing the colored dye compounds present in the wastewater. This study investigated the use of advanced oxidation processes (AOPs) for the removal of Reactive Blue dye 19 (RB19) from wastewater. The results showed that UV/NaOCl AOP had the highest removal efficiency of RB19 at optimal conditions.