August 20, 2013

Basics of Ion Exchange Resin - 1

Resins are generally used for Ion exchange reactions which is a powerful technology to not only treat water to extremely good quality but to process many industrial operations also today.

This ion exchange technology is now well proven for many chemical industry applications also.
It was developed initially in 1950s, and today, it is still the best to produce ultra-pure water, i.e. to remove all traces of contaminants. For example, it can be used for

• color removal from sugar syrups to make white sugar
• Purify of antibiotics and other pharmaceuticals
• Extract uranium from ores
• Separate metals
• Remove harmful substances from solutions
• Catalyse reactions

Let us start this post with basics only for understanding of ion exchange resins. So I will start with some terminology and types of resins and how do they work?

So first focus is what is ION?

Ion is nothing but small ionised substances present in water, which are electrically charged atoms or molecules. The positively charged ions are called cations, and the negatively charged ions are called anions. Because water is neutral electrically (Else it would give electric shock) the number of positive charges are same as the number of negative charges.

Ions can have one charge or more, the most usual range being 1 to 3. Ions can be made of one atom only (monoatomiic ions) , or several atoms linked permanently together, like molecules (polyatomic ions). For Example...

1. Monovalent - Monoatomic Ion - Such as Na+, K+
2. Divalent - Monoatomic Ion - Such as Mg2+, Ca2+
3. Trivalent - Monoatomic Ion - Such as Al3+, Cr3+
4. Monovalent - Polyatomic Ion - Such as NH4+, NO3-, NO2-
5. Divalent - Polyatomic Ion - Such as SO4--, CO32--

Now I am explaining the basics one by one. So What is an Ion Exchange Resin first of all. The resin as name suggests are basically small polymer molecule which you can visualize as small plastic beads or granule. Now these beads are made of one fixed component which is generally polymer part and longer in chain (not necessary but effective if it is) and the second part is mobile and can leave the structure with other similar type of ion only.

Now for the purpose of making it simple, the general ion exchange use is for softening of water in any process plant because hard water can not be used directly for many reasons. So simply the hardness means Ca++ ions are removed and replaced with Na+ ions thus calcium ion from water is removed. The equation can be represented as below.

2 RNa + Ca++ ---> R2Ca + 2 Na+

Now let us see how resin looks like. it is clear from the two pictures given below.

Once you are ready to study more you can go thru the following website

Learn to Do It Right the First Time: Guidelines for...
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John Tyler said...


Weak Cation Exchange offers you services and use of ions for daily use, now pollution is more and everyone is more serious about it. So getting fresh water is so valuable, thanks...

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