Photochemical Removal of Methylene Blue from Aqueous Solutions Using Surface Morphology Techniques

Methylene blue (MB) is a synthetic dye widely used in textile industries. This work describes the application of solar radiation to direct degradation by photolysis of methylene blue in aqueous solution. Experiments were conducted at room temperature to study the effects of exposure time, solution volume and MB concentration on dye degradation rates. The results show that the maximum amount of methylene blue removed is 6.8 mg/L, representing a yield of 51.2%, obtained at an initial concentration of 10 mg/L, volume of 50 mL and exposure to solar radiation for 5 hours. These results also indicate an increased efficiency of direct photolysis of methylene blue as the concentration of the dye increases. The kinetic model analysis indicates that the absorption of methylene blue follows a first-order kinetics, with a constant velocity k=1,3.10-3 min-1. Direct solar photolysis is an effective method to degrade or even remove methylene blue in water.