AgCl-based selective laser melting photocatalytic module for degradation of azo dye and E. coli

Abstract

An innovative 3D printing procedure for producing a highly porous AgCl/Ag0 photocatalyst was developed and tested for its stability and degradability of azo dye (Orange II) and bacteria (Escherichia coli). The AgCl/Ag0 photocatalytic module was fabricated through selective laser melting (SLM), in which the AgCl powder was stacked in a thin layer (approximate average thickness of 30 μm) on a platform and melted by a high-power laser beam layer by layer until the 3D module was created. The melting process may cause AgCl to transform into other compounds, which may, in turn, reduce the activity of photocatalysts; for this reason, the optimal laser power and scanning speed for constructing an SLM module were investigated; they were determined to be 26 W and at 385 mm/s. This photocatalytic module effectively degraded azo dye and sterilized E. coli. The degradation of azo dye was performed under visible and UV light irradiation, and the degradation kinetics was first-order reactions. Furthermore, the azo dye degradability (95%) of this photocatalyst module persisted for five cycles in our experiment. The sterilization of E. coli was accomplished within a 135-min test, and the degradation kinetics was also first-order reactions. The photocatalytic module fabricated through SLM not only exhibited the ability to degrade contaminants in the water but also had durability and reliability after repeated use.