Sono-photo activation of percarbonate for the degradation of organic dye: The effect of water matrix and identification of by-products

Abstract

Several efforts have been conducted to reach an efficient and safe process for degradation of organic pollutants in water environments. Percarbonate (PC) or solid hydrogen peroxide has gained great attention as an alternative for hydrogen peroxide in advanced oxidation processes. In current work, sono-photo activation method was used to PC activation for degradation of Acid Orange 7 (AO7). Ultrasound (US) and ultraviolet light emitted diode (UVC-LEDs) were prosperous in the generation of free radicals in presence of PC. Under optimum conditions (pH = 6.0, PC = 1.5 mM, 100 W US power and 90 reaction time), 93% of AO7 was eliminated while its rate constant was 0.0315 min−1. There was a promotional effect for chloride and nitrate ions at high concentration in PC/US/UVC-LEDs process. Nitrate ions photolysis and sonolysis could degrade AO7 indicating that hydroxyl radical are generated in absent of PC. A major role for hydroxyl radical and minor role for superoxide radical were determined by trapping experiments. PC/US/UVC-LEDs was also applied for an actual matrix which was not successful as well as synthetic solution. By-products of AO7 degradation was identified and proposed reaction was illustrated. This article conclusively states that PC/US/UVC-LEDs can be a new method for the degradation of organic pollutants in water.