Difference between de-ionised / de-mineralised water 1

[RotaryG]

Ladies & Gentlemen,

Is there a difference between de-ionised water and de-mineralised water? Or are they both refer to the same quality water?

Regards,

Guru

http://www.americansanskrit.com/default.html

 

[quark]

In pharmaceutical usage, the term 'Purified Water' is used instead of DM or DI Water with a maximum conductivity of 5microsiemens/cm. There is no difference between DM and DI water. Where as the maximum conductivity of Distilled Water should be 1microsiemen/cm. So there is a clear difference between DI/DM and Distilled Water.

If distilled water is purified to take care of total viable count and bacteriological endotoxins, then it is called water for injection.

USP24 is the best reference to know different water qualities.

Regards,


Believe it or not : A cobweb with it's strands a pencil width, can catch hold of a concord. All questions directed to Discovery Channel.

 

[25362]

FWIW, pay a visit to

http://www.the-scientist.com/yr1998/june/profile1_980608.html

 

[Petro2]

In our company the deionized water is the water that has been treated through cationic/anionic resins with a conductivity of less than 5 microsiemens/cm and the demineralizaed water is the deionized water that has passed through a mixed bed and the conductivity is less than 0.2 microsiemens/cm to be used for very high pressure steam generation.

 

[saxon]

Rotaryguru, According to my understanding of your three classifications the following process hold:

1. de-mineralized: std. water softening process utilizing salts and resin beds.

2. de-ionized: processed through de-ionizing resin beds

3. distilled: processed through steam distillation and condensation

Hope this helps.
saxon

 

[moltenmetal]

Saxon has it, though I'm sure there is not such a clear distinction between demineralized and deionized water everywhere- sometimes they're used interchangeably to describe water that's been through either cation or both cation/anion exchange resins.

It would appear that the term "demineralized water" is sometimes used to indicate water which has at least been "softened" by cation exchange, where either sodium or protons have been substituted for calcium, magnesium and other cations which can tend to form "mineral" deposits.

Deionized water, by definition, has had all ions other than H+ and OH- removed by means of both anion and cation exchange. The degree to which this has happened is often measured by conductivity as mentioned by previous posts.

 

[25362]

While demineralization is defined as the removal of minerals, without specifying the used procedure, deionization is considered specifically an ion exchange process in which all charged or ionizable inorganic or organic species are removed from solution.

Distilled water (sometimes double- or triple-distilled) is obtained by "physical" means and this purifying method is considered the most energy-intensive of all. Deionized and/or demineralized water, are often produced by combinations of chemical (ion exchange), and physical (RO, filtration, etc.) means.

Depending on the purity desired demineralized waters may still contain traces of iron, silica, and even Ca hardness and organic material.

A water with more than 10 megohms resistivity (< 0.1 microsiemens conductivity) at 25^oC is classified as &quot;ultra pure&quot;. Sometimes degassing and sterilization by heat, UV irradiation, etc. are added.

 

[RotaryG]

Thanks 23562.

Regards,

Guru

http://www.americansanskrit.com/default.html

 

[quark]

23562 is right. DI water is processed by ion exchange resin columns and DM water can be either by IOR beds or RO or Ultrafiltration system. TOC (total organic carbon for purified water/WFI should not be greater than 500ppb)

If you want further reading about water sytems in various manufacuring setups, check this link for OsmonicsWater Purification Handbook. You can download it too.

http://www.osmonics.com/library/1154273- Lit- Pure Water Handbook.pdf

Regards,


Believe it or not : A cobweb with it's strands a pencil width, can catch hold of a concord. All questions directed to Discovery Channel.

 

[natsamura]

Although the relative degrees of purity can vary enormously even within the normal definition of each demineralised, de-ionised and distilled waters its probably simplest to think of this as a progression from impure to pure water;

demineralised water is &quot;softenned&quot; by replacing undesirable dissolved minerals with table salt (NaCl) and ussually uses a mixed-bed anion/cation exchange resin;

in de-ionised water the mineral salt is replaced with the H+ ion in a cation bed and an OH- ion in an anion bed to make mineral-free water H+ + OH- > H20).

The purest water available is first demineralised, then distilled and finally de-ionised immediately before use in order to eliminate dissolved gasses (CO2, etc.)