November 24, 2010

the application of pure water.

The ultimate goal for quality control in industries is to produce a product water which cotains nothing but water. we use resistivity to determine the quality of the product water. pure water is not a good conductor of electricity.
for expmale: 
In Semiconductors the chip have to be rinsed to remove any particulates and also remove the last traces of the acid used for etching. and the electrode patterns have a width of approximately 0.1 micron. if the rinse water contains any particulates or dissolved substances they would on evaporation of the water leave such substances to alter the desired behavior of the device.  


November 17, 2010

what is ppm??

ppm is a unit of concentration which are used in chemistry. briefly, ppm means parts per million or milligrams per liter.
 for example:
1 ppm = 1 pound of any substance in 1,000,000 pounds of water.


November 17, 2010

removing silica from water

in some of  sand areas, high silica water is a big problem for filtration. using demineralization techniques we can easily remove silica from water. normally, silica is present in a weak acidic form so anion can exchange it from water. usually, silica in deionized water will be reduced to around 20-50 ppb. if you like to get water with more lower silica, you can use reverse osmosis to remove more silica. normally,  RO system will also remove silica by 90-98%.  but the two methods are non-specific for silica. if silica is below 15-20 ppm in raw water. RO and demineralization are available and work well.  in some of cases you can use lime softener or high temperature softner to remove silica from water. in lime softener, silica coagulated with Mg. and high temperature softner can improve silica removal. if silica is present non-ionic colloidal silica. you must use ultrafiltration to remove it. colloidal silica will foul your RO membrane.  



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