3. Theory of Osmosis Fresh Water Sea Water H 2 O Initial Condition Fresh Water Sea Water (diluted) H 2 O Equilibrium H 2 O π Semipermeable Membrane Fresh Water Sea Water H 2 O Pressure Reverse Osmosis The Osmotic Pressure, π, is defined as: π = MRT For sea water at 35 ppt, π is about 350 psi.
9. Strong Acid Cationic Resin Polymeric Resin R-SO 3 -H R-SO 3 -Na R-SO 3 - R-SO 3 -H R-SO 3 - Na + K + Cu 2+ Mg 2+ Ca 2+ H + Ca 2+ H + H + Typical Cations Metals Fe 2+ Zn 2+
10.
11. Mixed bed ion exchange capacity = 353,357 grains per m 3 10,000 grains per ft 3 Design Engineering of DI Systems Example: Your source water is potable city water and you require up to 400 liters per day of DI water. Source water TDS: 200 ppm Equivalent grains per gallon = 11.7 gpg (divide TDS by 17.1) Planned DI resin exchange frequency = 30 days Minimum required amount of mixed bed resin = 0.105 m 3 3.71 ft 3
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