It refers to an insoluble polymer compound with active groups that exchange ions, a network structure, and plays a role in removing various anions and cations in water treatment.
The performance of ion exchange resin in ion exchange reactions is reflected in its "ion exchange capacity", which is the number of milliequivalents of ions that can be exchanged per gram of dry resin or per milliliter of wet resin, meq/g (dry) or meq/mL (wet); when the ion is monovalent, the number of milliequivalents is the number of millimolecules (for divalent or polyvalent ions, the former is the latter times the ion valence).
The measurement of the exchange capacity of ion resins is generally carried out using inorganic ions. These ions are small in size and can freely diffuse into the resin body and react with all exchange groups inside it.
In practical applications, the solution often contains polymeric organic matter. Their size is large and it is difficult to enter the microscopic pores of the resin. Therefore, the actual exchange capacity will be lower than the value measured using inorganic ions. This situation is related to the type of resin, the structural size of the pores and the material being processed. Extended information
Physical properties
Ion exchange resin is usually made into small beads-shaped particles, and its size is also important. The ones with finer resin particles have a faster reaction speed, but the fine particles have a greater resistance to the passage of liquid and require higher working pressure; especially when the viscosity of concentrated sugar liquid is high, this effect is more significant.
Therefore, the size of the resin particles should be selected appropriately. If the resin particle size is below 0.2mm (approximately 70 mesh), it will significantly increase the resistance to fluid passage and reduce the flow rate and production capacity.
Resin particles undergo changes such as transfer, friction, expansion and contraction during use. There will be a small amount of loss and breakage after long-term use, so the resin must have high mechanical strength and wear resistance.
Resins with a low degree of cross-linking are easier to fragment, but the durability of the resin mainly depends on the uniformity and strength of the cross-linked structure. For example, macroporous resins with higher cross-linking degree have stable structure and can withstand repeated regeneration.
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