Temperature-Swing Adsorption Process of Au(III) Ions Using Poly(N-isopropylacrylamide) Hydrogel Beads Prepared by Sedimentation Polymerization Combined with Two-Fluid Atomization

The temperature-swing adsorption (TSA) process the control of the adsorption and desorption behavior of metal ions by changing the temperature improves metal separation to reduce the consumption of chemicals and save energy. The TSA of Au(III) ions onto the thermosensitive poly(N-isopropylacrylamide) hydrogel (NIPA hydrogel) was successfully conducted in our previous study. This study focuses on a continuous process for the TSA of Au(III) ions from a solution onto NIPA hydrogel beads using the fixed bed method. Monodisperse hydrogel beads, which were approximately 1 mm in diameter, were prepared using a production method combining sedimentation polymerization and two-fluid atomization. The Au(III) adsorption properties on hydrogel beads, such as its isotherms and kinetics, were evaluated and analyzed. The continuous TSA featuring adsorption at 34 degrees C and desorption at 10 degrees C was demonstrated, and the associated breakthrough curve was successfully predicted by a mathematical analysis.