In daily life, household water softeners use more Cationic Resins. However, the resin in the industrial mixed bed is divided into anions and cations, and the main purpose is to replace and remove salt. The process is underdeveloped and before RO reverse osmosis membrane treatment, salt is removed by mixed bed. However, as the industry's demand for precision is getting higher and higher, and it needs to meet the requirements of pure water or even ultra-pure water, it needs RO reverse osmosis membrane treatment + mixed bed, RO + EDI to achieve together.

In the process of purchasing and using the water softener, how do we distinguish whether the water softener uses an anion or cation exchange resin? The simple judgment method I give is as follows:

In the first step, take 2ml of the resin sample, place it in a 30ml test tube, and remove the water on the top of the resin layer by pouring.

In the second step, add 5ml of 1ml/L HcL solution, shake for 1~2min, remove the upper solution, and repeat the operation 2~3 times. After operation, the cation resin is transformed into H type and the anion resin is transformed into cL type.

The third step is to add pure water to wash, and after shaking to remove the upper clear liquid, repeat the operation 2 to 3 times to remove excess hydrochloric acid.

In the fourth step, add 5 mL of acidified 10% CuSO4 solution (containing 1% H2S04), shake for 1 min, and place for 5 min. If the resin is light green, it is a cation resin, if it does not change color, it is an anion resin.

So how do we judge the quality of Ion Exchange Resin in daily purchases?

First of all, from intuitive judgment: if its color is yellow or light yellow, it is a good resin. The shape is spherical. It can also be judged by measurement that the resin diameter in our country is between 0.3-1.2mm.

Of course, we can also make some physical judgments: 1. Judge its pros and cons by its density. The true wet density is generally about 1.04 to 1.3. Generally, the density of cations is higher than that of anions, but the minimum wet true density of any resin must also be greater than 1. The moisture content of the resin is closely related to the degree of cross-linking. The smaller the degree of cross-linking, the greater the internal porosity and the greater the water content. Generally, the crosslinking degree of resin is about 7%, so the moisture content is only 45%-55%. 2. Judge its pros and cons by its swelling property. The size of the swelling property is expressed by the swelling rate. The swelling property is also affected by these factors: 1) The smaller the degree of cross-linking, the greater the swelling rate. 2) The more easily the active groups in the resin ionize, the greater the swelling rate. 3) The greater the electrolyte concentration in the solution, the smaller the swelling rate. 4) The greater the degree of hydration of the exchangeable ion, the greater the swelling rate. Not evaluated by specific data. 3. Abrasion resistance is an indicator of the mechanical strength of the resin, which is mainly manifested in the annual loss, which does not exceed 3% to 7%. 4. The maximum temperature that different resins can withstand is different. Generally, the cation resin can withstand 100 degrees Celsius or higher, about 120 degrees Celsius; while the anion resin can withstand 60 degrees Celsius for strong alkaline, and can withstand more than 80 degrees Celsius for weak alkaline

In the case of better conditions, we can also judge by some chemical methods: 1. The crosslinkability of general resin is between 4-14%, and the performance of about 7% is ideal. 2. Ion exchange resin is an insoluble polymer compound. Therefore, the assessment is not based on specific data.