Co-Free High-Entropy Alloys Powders Immobilized by Electrospray and Microfluidics for Decolorization of Azo Dye

In recent years, high-entropy alloys (HEAs) have received more and more attention due to their unique microstructure and properties. Several researchers have reported that some ball-milled (BM) HEAs powders possess prominent decolorization performance for azo dyes. Three kinds of Co-free HEA powders (AlCrFeMn, AlCrFeNi and FeCrNiMn) have been synthesized by ball milling in this work, of which AlCrFeMn shows the best decolorization efficiency for DB6 aqueous solution. However, at this time, the BM HEAs are in powder state and not easy to be reused, so the loss rate of the powders is high during the reaction. Sometimes, the reaction between reacted the powders and the dye solution is too fast to control. While, in order to solve these problems, this work proposes to immobilize bare BM AlCrFeMn HEA powders in calcium alginate beads (CABs) by electrospray and microfluidics. Through four cycles of reaction, the loss rate of the AlCrFeMn powders can be reduced from 40 to 5 wt% if the powders are immobilized by CABs with an average diameter of 0.55 mm obtained at the DC voltage of 30 kV. In addition, in the four cycles of experiment, the AlCrFeMn HEA-CABs with an average diameter of 0.55 mm shows better stability and easier separation than that of the bare AlCrFeMn powders. These findings provide new ideas for HEAs to decolorize azo dyes and are of great significance for protecting freshwater resources.