- #1
Enigman
- 640
- 312
Why is the cation exchange always carried out before anion exchange in softening of hard water by ion exchange resins?
Plz. Help:(
Plz. Help:(
In summary, the conversation discussed the order of cation and anion exchange in softening hard water using ion exchange resins. It was determined that cation exchange is carried out before anion exchange, with the products being acidic if cation exchange is done first and basic if anion exchange is done first. The compounds formed in the two processes are hydronium ions and hydroxyl ions, respectively, and their physical properties are dependent on the order of exchange. It was also mentioned that cation exchange resins are styrene-divinyl benzene copolymers and the products are completely ionizable. The solubility of the products is not a factor, but the sequence of exchange can affect the resin itself.
- #2
DrDu
Science Advisor
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- 972
What compounds are predominantly formed in the two alternative exchange processes?
What are their physical properties?
What are their physical properties?
- #3
Enigman
- 640
- 312
DrDu said:
Ummm... Hydronium ions in cathode exchange and hydroxyl ion in anode exchange...products after cathode exchange are acidic if carried out first (H2SO4,HCl...etc.) if anion exchange is carried out first products will be basic (Ca(OH)2, Mg(OH)2...etc.)
So it has some thing to do with pH.
Are cation exchange resins reactive?
Cation exchange resins are styrene-divinyl benzene copolymers maybe the benzene ring is attacked by hydroxyl ions? Could you please confirm the solution?
or
Thanks in advance.
- #4
DrDu
Science Advisor
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How soluble are the products?
- #5
Enigman
- 640
- 312
Don't think solubility has anything to do with it, the products are completely ionizable (all are bases, when anion exchange is carried out first.), so no ppt. should be formed. Unless if it is with the resin itself...
- #6
DrDu
Science Advisor
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Well, if you don't take a hint, you have to find a solution on your own.
- #7
Enigman
- 640
- 312
I did, a book I issued from the library confirms my theory that when the sequence is reversed the alkali formed in anion exchange will attack the cation exchange resin (the mechanism isn't mentioned 
) and thus degrade it. While in the usual sequence the acid formed in cation exchange passes harmlessly through anion exchange resin.
Thanks for your help.
P.S. I still didn't get what you were trying to point me towards...
) and thus degrade it. While in the usual sequence the acid formed in cation exchange passes harmlessly through anion exchange resin.Thanks for your help.
P.S. I still didn't get what you were trying to point me towards...
1. What are ion exchange resins?
Ion exchange resins are small, porous beads made from synthetic polymers. They contain functional groups that can exchange ions with the surrounding water, making them useful for softening hard water.
2. How do ion exchange resins soften water?
Ion exchange resins work by attracting and binding to positively charged ions, such as calcium and magnesium, which are responsible for making water hard. As the hard water passes through the resin, the calcium and magnesium ions are exchanged for sodium or potassium ions, resulting in softened water.
3. How long do ion exchange resins last?
The lifespan of ion exchange resins depends on various factors such as the quality of the water being treated, the type and amount of resin used, and the regeneration process. On average, they can last for 5-10 years before needing to be replaced.
4. Are there any health risks associated with using ion exchange resins?
Ion exchange resins are generally considered safe for use in water softening systems. However, some resins may contain trace amounts of chemicals that can leach into the water. It is important to choose high-quality resins and regularly maintain and monitor your system to minimize any potential health risks.
5. Can ion exchange resins remove all contaminants from water?
No, ion exchange resins are primarily designed to remove hardness-causing minerals from water. They may also be able to remove some other contaminants, such as iron and manganese, but they are not effective against all types of contaminants. It is important to have your water tested to determine the most appropriate treatment method for your specific needs.
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