December 2, 2008 
This entry was posted on Tuesday, December 2nd, 2008 at 3:37 pm and is filed under Reverse Osmosis Water Filters. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
Reverse osmosis is based on the natural process of osmosis which involves the selective movement of water from one side of a membrane to the other. Reverse osmosis ( also known as hyper filtration ) is the same process used by a human body to filter out contaminants. Particles or impurities can be removed from a solution through the process of reverse osmosis when the solution is forced through a semi-permeable membrane which allows the passage of water but rejects ions like sodium and calcium or contaminants like bacteria or urea. Gore-tex is a common semi permeable membrane. Gore-tex fabric contains an extremely thin plastic film into which billions of small pores have been cut. The pores are big enough to let water vapor through, but small enough to prevent liquid water from passing through.
Reverse osmosis also involves a process known as crossflow, which allows the membrane to clean itself. As fluid passes through the membrane some of the fluid continues downstream, sweeping the contaminants away from the membrane. For reverse osmosis to occur, pressure must be applied to the fluid. The most common method of applying pressure is the use of a pump. The higher the pressure applied, the greater the force created. As the concentration of the fluid being rejected increases, the force required to continue concentrating the fluid increases. Pressure is exerted on the area containing the concentrated solution, which forces the water molecules across the membrane to the area of the fresh water.
Reverse osmosis has become very popular in recent years because it not only filters water but also rejects bacteria, salts, sugars, proteins and other elements that have a molecular weight of greater than 150-250 Daltons; a unit of measurement so small it can only be seen with a microscope.
The process of reverse osmosis is of immense benefit to mankind. Its applications are wide ranging with the most common use being for purifying water in both commercial and residential water filtration systems. It is also used to desalinate seawater as well as to purify liquids in which water is an undesirable impurity, for instance in glucose or ethanol.
An Ezine article