Effect of magnetic fields on the efficiency of the photocatalytic degradation of methylene blue in a dynamic fluid system

Abstract

Methylene blue dye can induce negative effects to aquatic life and the environmental system. So, it is important to remove it from water. Although, the photocatalytic degradation of dye solution during magnetic treatment (or static water process) can increase the dye degradation, but it cannot apply for a large wastewater. Therefore, the dynamic fluid system is required. This paper investigated the effect of magnetic fields (MFs) through dynamic fluid magnetization system on the degradation of dye solution. Ultraviolet (UV) irradiation experiments were carried out in the presence of zinc oxide (ZnO) catalyst. The experiment was divided into two parts. First, the dye solution was exposed to MFs multiple times. In the second part, the dye solution was exposed to MFs continuously using a dynamic fluid system. The results indicated that the dye solution degraded faster when the exposure time to MFs under dynamic fluid system was long. At least 60% of the dye solution degraded within 3 min when the MF of strength 600 mT was applied. On the other hand, the dye solution degraded by only 24% in the absence of MFs. The degradation mechanism was observed to fit the pseudo-first-order kinetic reaction. The rate constant of the reaction was higher in the presence of MFs than that in the absence of MFs. This resulted in better degradation performance. Therefore, it can be concluded that the photocatalytic degradation of the dye solution was enhanced when external MFs were applied to magnetize dye solution using dynamic fluid system.