Principle of diffusion dialysis

Multiple anion-exchange membranes are laminated into a stack, with spacers in between the membranes. One side of the laminated anion exchange membranes is fed with waste acid, and the opposite side with water as a counter-stream. Any concentration difference generated via the anion exchange membrane causes acids to diffuse and move from the waste acid side to the water side (the recovered acid side). Metal ions having large multivalent cations, however, cannot pass through the anion exchange membrane and remain on the dialysate side. Clean acids can thus be separated and recovered from metal ions.

Process flowchart of diffusion dialysis

Unlike electrodialysis, diffusion dialysis feeds the diffusion dialyzer from the head tank with solution by using the difference in solution level. This process separates metal ions from acids without circulating the solution.

Differences between electrolysis acid recovery and diffusion dialysis acid recovery

Advantages of electrodialysis acid recovery

• Concentrates and recovers clean acids.
• Reduces the volume of waste acid.

Advantages of diffusion dialysis acid recovery

• Requires no electricity, resulting in lower running costs.
• The system's simple process flow makes it easy to operate and maintain.