In many industries such as food, beverage, pharmaceutical, automobile manufacturing, chemical, electronics, tanning, steel, textile, etc., the quality of water has a very important impact on the quality of products.

Softened water can effectively improve water quality, reduce the content of calcium and magnesium ions in the water, and avoid the formation of scale, thereby reducing the energy consumption of heating and cooling equipment, reducing equipment maintenance costs, greatly improving production efficiency and product quality, and reducing the use of chemicals. Use, reduce costs and environmental pollution.

It is well known that the hardness of water is mainly composed of calcium and magnesium ions. The softening water treatment usually adopts ion exchange technology and uses ion exchange resin to absorb calcium and magnesium plasma. When the raw water containing calcium and magnesium ions passes through the cation exchange resin, the calcium and magnesium ions in the water will be replaced with the sodium ions in the resin. After ion exchange, the calcium and magnesium ions will be adsorbed on the resin in the water softener, thus forming the softening water, ion exchange resins are therefore essential in softening water treatment.

The following small series of five commonly used knowledge points on softening resin, it is recommended to collect.

　　1. The difference between sodium type & hydrogen type cationic resin

Generally, ion exchange resins are divided into cation resins and anion resins.

Sodium cation resin internal ion is Na ion, has good anion exchange capacity, can be in the water anion adsorption and exchange, mainly used in hard water softening, often use sodium chloride regeneration.

The internal ion of hydrogen cation resin is H ion, which has stronger acidity and better anion exchange capacity. It is often used to remove chloride ion, nitrate ion and other anions in water, such as pure water preparation and ultra pure water preparation, using hydrochloric acid for regeneration.

　　2. The principle of sodium ion exchange resin softening water

In the process of softening, with the increase of calcium and magnesium ions in the resin, the efficiency of resin replacing calcium and magnesium ions gradually decreases. When the resin absorbs a certain amount of calcium and magnesium ions, it must be regenerated. The regeneration process is to wash the resin layer with salt water in the salt box to replace the hardness ions on the resin. With the waste liquid discharged from the tank, the resin resumes the softening exchange function.

The reaction principle of the exchange process is as follows:

　　2RNa Ca2 =R2Ca 2Na

　　2RNa Mg2 =R2Mg 2Na

That is, after the water passes through the sodium ion exchanger, the Ca and Mg in the water are replaced by Na.

　   3. Food soft water resin VS industrial soft water resin

Food soft water resin pays more attention to the safety problem, which has the characteristics of high regeneration efficiency, long service life, strong adsorption capacity, good anti-pollution, and low dissolved content;

Industrial soft water resin pays more attention to mechanical strength, with high mechanical strength, good physical and chemical stability, high exchange capacity, small density change, wide working temperature range, and can be reused many times.

　　4, high salt water in addition to calcium and magnesium should choose what resin

In practical applications, calcium and magnesium ions in water are often interfered by other factors, which affect the removal efficiency of calcium and magnesium ions, such as the removal of calcium and magnesium ions from high-salt wastewater.

In the treatment process of high brine, there will be the problem of high calcium and magnesium ions before the high brine enters the membrane system or the evaporator, resulting in the decrease of the water production rate of the membrane system. The structure of the evaporator heat exchange system affects the use effect. The macroporous weakly acidic cation exchange resin can be used to replace the calcium and magnesium ions in the water with sodium ions, thus avoiding the precipitation and adhesion of sexual ions on the membrane or tube wall after membrane concentration or evaporation, the formation of hard scale leads to problems such as reduced membrane and evaporation of water production efficiency.

　　5, High salt water in addition to calcium and magnesium resin application case

The new energy calcium and magnesium removal project has a treated water volume of 5mg/l and an incoming water content of 100mg/l. The two stages are operated in series to stabilize the outgoing water below 1mg/l.

Sodium gluconate solution to remove divalent calcium and magnesium is used in the front of the membrane process to avoid calcium and magnesium blocking the membrane. The treated water volume is 15 tons of water per day, the calcium and magnesium content in the incoming water is 30PPM, single-stage operation, and the effluent water is below 1mg/l.

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