PURIFYING YOUR WATER
burst from so much water flowing in. On the other hand, if
red blood cells are placed in a highly concentrated salt solution, water will flow out of the cells into the salt solution and
the cells will shrivel.
Osmosis works the same with plant cells, but since plants
have cell walls, they don’t burst when placed in pure water
and their membranes get pulled away from the cell wall as
they shrivel if placed in a highly concentrated solution. This
is why plants wilt if the nutrient solution concentration is too
high. So, what about reverse osmosis? In reverse osmosis, we
are interested in making water as pure as possible by removing solutes and keeping the purified water. The universe
doesn’t really approve of this happening naturally, so we
have to come up with a way of reversing osmosis so that water
moves across a selectively permeable membrane toward a
lower solute concentration rather than a higher one.
Reverse Osmosis
Water flows across a membrane because of a difference in
osmotic potential. This potential is a pressure difference that
is a function of the different solute concentrations on either
side of the membrane. If we apply an external pressure in a
“
Water flows across a membrane
because of a difference in
osmotic potential. This potential
is a pressure difference that is a
function of the different solute
concentrations on either side of
the membrane.
Reverse osmosis uses a membrane as an extremely fine filter.
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Maximum Yield USA | June 2016