Diffusion dialysis equipment
This equipment consists of a certain number of membrane groups formed by diaphragms and partitions. On both sides of the membrane groups, waste acid and pure water are introduced respectively. The concentration of free acid and metal salts on the waste acid side is higher than that on the pure water side. And the anion exchange membrane has positive charge groups. Due to the existence of the concentration difference, the anions on the waste acid side enter the pure water side through the channels on the ion exchange membrane. At the same time, according to the requirement of electrical neutrality, positive charged ions need to be carried into the pure water side. Since the valence state of hydrogen ions is low and water and radius are small, they are easier to pass through the ion exchange membrane and reach the pure water side to combine with anions. Thus, the acid in the waste acid can be separated.
Bipolar membrane electrodialysis equipment
The bipolar membrane is a type of ion-exchange membrane composed of an anion exchange layer and a cation exchange layer. The middle part between the anion and cation exchange layers is a hydrophilic interface layer, also known as the intermediate layer. On both sides of the membrane device, positive and negative electrodes are configured, with the anode membrane layer facing the negative electrode and the cathode membrane layer facing the positive electrode. Under the action of an electric field, water in the middle layer undergoes dissociation reactions to generate hydroxide ions and hydrogen ions. Hydroxide ions pass through the anion exchange layer and hydrogen ions pass through the cation exchange layer. The water molecules consumed during the dissociation process in the intermediate layer will be replenished by the diffusion of water molecules from the solution to the membrane intermediate layer.
