The process of ion exchange can be summarized as: 1. Ions in water diffuse to the surface of resin in aqueous solution. 2. Ions in water enter the cross-linked mesh of resin particles and diffuse. 3. Ions in water contact with resin exchange groups to exchange ions. 4. The exchanged ions diffuse to the resin surface in the resin cross-linked mesh. 5. The main factors affecting the exchange are flow rate, concentration of raw material solution and temperature. Velocity The velocity of the feed liquid actually reflects the time to reach the reaction equilibrium. In the exchange process, ions go through a series of steps of diffusion-exchange-diffusion, so it is very important to control the speed effectively. Generally, when the flow rate of the exchange solution is high, the dialysis amount of ions will be high, and the amount lost through the resin layer will increase in the future. Therefore, the appropriate flow rate should be selected according to the exchange capacity. Exchangeable ions in the resin may exchange or repel with the same-sex ions in the solution with the concentration of the raw material solution. When the concentration of liquid ions is high, there are many opportunities for resin to contact and easily enter the resin net. When the liquid concentration is low and the resin exchange capacity is large, the opposite is true. However, if the ion concentration in the liquid phase is too high, it will lead to the shrinkage of the cross-linked grid on the surface and inside of the resin, and will also affect the ion entering the grid. Experiments show that when the flow rate is constant, the higher the solution concentration, the greater the solute loss. The higher the temperature, the more intense the thermal movement of ions. The reaction speed can be accelerated by increasing the number of collisions per unit time. However, if the temperature is too high, it will reduce the adsorption strength of ions and even affect the thermal stability of the resin, which is economically unfavorable. It is suitable to operate at room temperature in practical production.
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