Is an ion exchange resin a resin? What are its main features

Resin was originally a general term for the gel secreted by the crown wood similar to the turpentine secreted by the pine tree. Later, people also called some substances similar to resin "resin", such as epoxy resin, phenolic resin, ion exchange resin and so on. Ion exchange resin is a synthetic polymer, its performance depends on the manufacturing process, raw material formula, polymerization temperature, crosslinking agent and functional groups, the main performance can be from the physical and chemical two aspects:

1. Physical properties

1) Appearance. Resin is a transparent or translucent substance, but different varieties and different colors, under normal circumstances, raw material impurities or crosslinking agents more, the color of the resin is slightly darker. Resin in the process of operation, because of various reasons sometimes the color will change. The shape of the resin is spherical, and the ball rate is required to reach more than 90%.

2) Granularity. The size of resin particles will affect the exchange rate, pressure loss, backwash effect and so on. The particle size of ion exchange resin for water treatment should be 20-40 mesh. The particle size should not vary too much. Particle size is expressed in terms of effective particle size and non-uniformity coefficient.

3) Density. It is related to the water treatment process and the amount of resin filling. The density is expressed as follows: thousand true density (generally 1. About 6 g/cm ³), wet true density (generally 1. 04 to 1. Between 30), wet apparent density (generally 0. 60-0. Between 80).

4) Moisture content. The higher the moisture content of the resin, the larger the porosity and the smaller the crosslinking degree.

5) Swelling rate. When the resin is put into water, it will swell, which is related to the degree of crosslinking, the exchange capacity of active groups, the density of electrolytes in water, and the properties of exchangeable ions, etc., the phenomenon of swelling and contraction will occur in the process of exchange and regeneration of the resin, and multiple swelling and contraction will make the resin prone to brittle cracking.

6) Wear resistance. Reflecting the mechanical strength of the resin, it should ensure that the amount of loss due to mechanical wear does not exceed 7% per year.

7) Solubility. When the resin contains oligomers, it will dissolve during use and affect the water quality.

8) Heat resistance. A Prajna resin can withstand temperature of about 100℃, strong alkaline Yin resin can withstand 60℃, weak Yin resin can withstand temperature of 80℃. At below 0 ° C, it will be broken due to ice.

9) Electrical conductivity: dry resin does not conduct electricity, wet resin can conduct electricity.

Second, chemical properties

1) The exchange reaction of ion exchange resin is reversible, so it can be exchanged, can also be regenerated, and can be used repeatedly.

2) With acid, alkaline. The properties of H positive and OH negative ion-exchange resins are the same as those of electrolyte acids and bases, and H positive and OH negative can be ionized in water.

3) With neutralization and hydrolysis properties. Due to its electrolyte properties, it can be neutralized with acids or bases, and hydrolysis can also occur.

4) The ability of ion exchange resin to absorb various ions is different and has selectivity.

5) Exchange capacity. Indicates the amount of ions it can exchange, and is often used in design and operation management. It can be expressed as full exchange capacity, working exchange capacity, balanced exchange capacity, etc. The units are milliliters per liter or milliliters per gram.