Characterization of electric arc furnace dust and its application in photocatalytic reactions to degrade organic contaminants in synthetic and real samples

In this study, waste from electric arc furnace dust (EAFD) was characterized and used as a photocatalyst for discoloration of the textile dye Remazol Black (RB) and an effluent sample collected at a textile industry. The results of X-ray fluorescence and EDS showed that the main oxides were ZnO (46.2 %), MgO (41.4 %) and Fe2O3 (6.4 %). Scanning electron microscopy and mapping images showed irregular particles with agglomerates of zinc and magnesium, in addition to spherical iron particles. The results of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that the waste contained organic matter in addition to the oxides already identified. The response surface and Pareto graphs showed that variations in photocatalyst mass and the power of UV radiation have a greater effect than RB solution pH on photocatalytic efficiency. The best result was obtained with 120 mg EAFD, a 51 W Hg lamp, and a pH of 10, which resulted in 84 % RB discoloration efficiency. The results of the reaction carried out with a real sample of textile effluent showed that EAFD removed 58 and 38 % of the color and chemical oxygen demand, respectively. The results of EAFD reuse tests showed that the photocatalyst presented no significant losses in efficiency over 40 h of reaction. The high potential of EAFD for application in photocatalytic processes adds value to waste that is usually destined for landfills.