LED Light Integrated Reactors: Study of the Methylene Blue Chemical Oxidation Process

Abstract

The contamination of water by organic dyes, such as methylene blue, is a risk factor for the environment, since all aquatic fauna and flora are immensely affected due to the reduction of the amount of dissolved oxygen and the passage of light, affecting the photosynthesis. The main source of contamination comes from the textile industry, so it is necessary to study efficient techniques for treating effluent without the cogeneration impact. In the present work, a study was developed to evaluate the best combination of factors of a batch treatment to be applied in a continuous treatment system. The removal of methylene blue by chemical oxidation was evaluated using sodium persulfate as an oxidizing agent. A complete experimental design 2³ was devised to evaluate the effects of the activation of the oxidizing agent by iron sulfate (II) and visible light (LED), these being the factors. After this batch step, the tests that were efficient in degrading the contaminant were carried out in the continuous reactor. The degradation results showed that, in batch, the oxidation with activation of sodium persulfate by iron sulfate (II) is more efficient, removing 91.2% of the dye in 20 minutes. In the continuous reactor, activation with a visible light source showed greater conversion due to its greater contact surface with water contaminated with dye, removing 59.2% over 15 meters from the reactor and residence time of 109 seconds.