When the surface of the Polite ion exchange resin is covered with iron compounds or the exchange channels inside the resin are blocked by iron impurities, etc., the working exchange capacity and regeneration exchange capacity of the resin are significantly reduced, but the structure of the resin remains unchanged. This phenomenon is called iron in the resin"Poisoning".

It causes perlite resin iron"Poisoning"The main reasons are as follows4Aspect:

1The water source is groundwater with a high iron content or surface water contaminated by iron.

2Iron compounds have been produced due to corrosion inside the inlet pipe or exchanger.

3The regenerant contains iron impurities.

4The water contains large-molecule organic substances.

The iron of Pellett cation exchange resin"Poisoning"It generally only occurs in the water softening process using table salt as the regenerant. There are mainly two situations. One is that when iron enters the sodium ion exchanger in the form of colloidal or suspended iron compounds, it is adsorbed by the resin and forms a layer of iron compound covering on the resin surface, preventing the ions in the water from effectively contacting the resin. The other is that ironFe2+The form enters the exchanger and undergoes an exchange reaction with the resin, therebyFe2+Occupying the exchange position, becauseFe2+It is very easy to be oxidized into high-valent iron compounds, which deposit inside the resin and clog the exchange channels.

　　Iron is produced in the Perlite anion resin"Poisoning"The main reasons are as follows: First, the purity of the alkali in the regenerated anion resin does not meet the prescribed standards. Especially when the liquid alkali contains a large amount of iron compounds, it is more likely to cause poisoning of the anion resin. Second, when the water contains large-molecule organic substances, it is easy to form chelates with iron(That is organic iron)It can undergo exchange reactions with strongly basic anion resins, accumulate at the positions of exchange groups, block the exchange channels of the resin, reduce the exchange capacity and regeneration capacity, lower the regeneration efficiency, increase the consumption of regenerant and cleaning water, and further lead to iron in the resin"Poisoning".

Identification methods for contamination of Polite cation and anion exchange resins

　　1Appearance color identification

　　Iron formation"Poisoning"The Polite resin, in terms of appearance, has a color that is transparent yellow(Cationic resin)Or milky white(Anion resin)It becomes significantly darker, and in severe cases, it even turns black.

　　2Experimental identification

　　The iron content of Perlite resin is determined by measuring the iron content in water"Poisoning"To a certain extent, this is a relatively accurate method.

　　The method is as follows:

　　will"Poisoning"Wash the Perlite resin with clean water and soak it in10%Regenerate approximately in the brine30minPour out the salt water and then use distilled water(Or demineralized water)Wash2～3Next, take out a portion of the resin and put it into a test tube or glass bottle, then add it6mol/LHydrochloric acid(The volume is approximately that of resin2times)Seal off the oscillation15minThen, take out the acid solution and inject it into another clean test tube, and drop in the saturated potassium ferrocyanide solution to form a Prussian blue color of varying shades from the test solution(Light blue, brown and black)Resin iron can be identified"Poisoning"The degree.

　　It should be noted that only the method of measuring the exchange capacity of the Perlite anion and cation exchange resin is used to determine whether the resin is iron"Poisoning"It is one-sided. This result is inaccurate because of iron"Poisoning"It merely reduces the working exchange capacity of the resin, but has almost no impact on the total exchange capacity.