Mixed bed resins are divided into standard mixed bed resins and polishing resins.
The difference between the two is
1. Different definitions
Polishing resins are a mixture of [hydrogen type strong acid cation exchange resins] and [hydrogen type strong base anion exchange resins]. They are generally used at the end of ultrapure water treatment systems, i.e. a step or process of water treatment to ensure that the quality of the water leaving the system can meet the water usage standard. It is a single ion exchange resin with high specificity that can remove some difficult to remove ions in water, such as dissolved organic matter, heavy metal ions, etc. Polishing resin can bring water to very high purity requirements and its exchange capacity is relatively small.
Ordinary mixed-bed resin refers to a ready-to-use resin composed of [strong acid gel-type cation exchange resin] and [strong base anion exchange resin], which has been regenerated and pre-mixed. It is mainly used in the water purification industry to polish process water to achieve demineralised water quality. It has a high exchange capacity and a wider range of application and can remove more types of ions such as carbonates, nitrates, sulphates, ammonium salts, etc. Mixed bed resins are usually used in the first steps of water treatment to remove most of the ions, thereby reducing the load on subsequent treatment steps.
2. Different performance characteristics
Polishing resin is usually a separate ion exchange bed used to remove residual anions and cations from water. This resin bed can only remove one of the ions, so it is usually necessary to add a neutralisation bed between the two beds to ensure water quality is maintained. The advantage of polishing resin is that it can achieve good purification at a lower cost, but as it can only remove one of the ions it is not very practical in applications where high purity water is required.
3. Different application scenarios
Polishing resin generally produces water with a quality of more than 18 megohms, of very high quality, and has some control over TOC and SIO2. The ionic forms of polishing resins are H and OH types when they leave the factory and can be used after filling without regeneration. They are generally used in the semiconductor industry.
Ordinary mixed bed resins are generally suitable for water with more cations and anions, because mixed bed resins are highly transformed and specially purified, and mixed and compounded according to specific chemical equivalents, so they are suitable for various water treatment fields with high water requirements and no high regeneration conditions. It is also renewable. The main industrial fields include ultrapure water production, demineralisation, condensate polishing (boiler feed water), microelectronics cleaning, pharmaceuticals, etc.
Conventional ion exchange resins have only one of anion and cation resins that can effectively remove anions or cations from water. Due to different applications, the water quality resistance of general ion exchange resins will not be too high, and they are widely used in general industrial and living water treatment industries, such as industrial water treatment, pharmaceutical industry, pure water preparation, ultra pure water preparation, waste water treatment, drinking water softening, food industry water treatment, etc. For example, the water softening resin we commonly use is a weak acid cationic resin, which is mainly used to exchange calcium and magnesium ions in water and reduce the hardness of water.