Things to note when using ion exchange resins

There are many varieties of  ion exchange resins which have different functions and characteristics due to different chemical compositions and structures, and are suitable for different purposes. The application of resins should select appropriate types and varieties according to process requirements and material properties. Generally speaking, there are several points to note during use:

1. Ion exchange resins contain a certain amount of water and should not be stored in the open air. They should be kept moist during storage and transportation to avoid air drying and dehydration, which may cause the resin to break. If the resin is dehydrated during storage, it should be soaked in concentrated salt water (10%) first, and then gradually diluted. It should not be directly placed in water to avoid rapid expansion and breakage of the resin.

2. During winter storage and transportation, the temperature should be kept at 5-40℃ to avoid overcooling or overheating, which may affect the quality. If there is no insulation equipment in winter, the resin can be stored in salt water, and the concentration of the salt water can be determined according to the temperature.

3. Industrial products of ion exchange resins often contain a small amount of low polymers and unreacted monomers, as well as inorganic impurities such as iron, lead, and copper. When the resin comes into contact with water, acid, alkali, or other solutions, the above substances will be transferred into the solution, affecting the quality of the effluent. Therefore, new resins must be pretreated before use. Generally, the resin is fully expanded with water. Then, the inorganic impurities (mainly iron compounds) can be removed with 4-5% dilute hydrochloric acid, and the organic impurities can be removed with 2-4% dilute sodium hydroxide solution. Wash until it is nearly neutral. If used in pharmaceutical preparation, it must be soaked in ethanol.

4. When using the resin, prevent it from contacting with metal (such as iron, copper, etc.) oil, organic molecular microorganisms, strong oxidants, etc., so as to avoid reducing the ion exchange capacity or even losing its function. Therefore, the resin must be activated irregularly according to the situation. The activation method can be determined according to the pollution situation and conditions. Generally, the cationic resin is easily contaminated by Fe during softening and can be soaked in hydrochloric acid and then gradually diluted. The anionic resin is easily contaminated by organic matter and can be soaked or rinsed with a mixed solution of 10% NaC1 + 2-5% NaOH. If necessary, it can be soaked in 1% hydrogen peroxide solution for several minutes. Other methods can also be used. Acid-base alternating treatment, bleaching treatment, alcohol treatment and various sterilization methods, etc.

5. Pretreatment of new resin: Industrial products of ion exchange resins often contain a small amount of oligomers and monomers that do not participate in the reaction, as well as inorganic impurities such as iron, lead, and copper. When the resin comes into contact with water, acid, alkali or other solutions, the above substances will be transferred into the solution, affecting the quality of the effluent. Therefore, new resin must be pretreated before use. Generally, the resin is first swelled with water, and then the inorganic impurities (mainly iron compounds) can be removed with 4-5% dilute hydrochloric acid, and the organic impurities can be removed with 2-4% dilute sodium hydroxide solution and washed to near neutrality.