Liquid purification or separation – Processes – Preventing – decreasing – or delaying precipitation,...
Patent
1992-07-20
1993-10-26
Sever, Frank
Liquid purification or separation
Processes
Preventing, decreasing, or delaying precipitation,...
210725, C02F 514
Patent
active
052563030
ABSTRACT:
A method for inhibiting calcium sulfate scale formation and deposition and/or dispersing iron from a feedstream passing through a reverse osmosis system which comprises the steps of: controlling the pH of the feedstream within the range between about 6.0 to about 7.0; controlling the temperature of the feedstream within the range between about 50.degree. to about 80.degree. F.; and adding a scale inhibitor and/or iron disperant to the feedstream in an amount between about 0.002 ppm per ppm hardness (as CaCO.sub.3) of the feedstream to about 0.005 ppm per ppm hardness (as CaCO.sub.3) of the feedstream, the scale inhibitor comprising a water-soluble organic phosphonate and an N-substituted acrylamide polymer containing an amide structure as follows: ##STR1## where R.sub.2 is hydrogen or methyl, R.sub.1 is a hydrogen or an alkyl, and R is alkylene or phenylene and X is sulfonate, (poly) hydroxyl, (poly) carboxyl or carbonyl, and combinations thereof, with the weight ratio of polymer to phosphonate being within the range of about 0.2:1 to about 2:1; provided that when X is sulfonated then R--X-- is selected from the group consisting of sulfomethyl and 2-sulfoethyl.
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Fivizzani Kenneth P.
Pierce Claudia C.
Soderquist Cynthia A.
Zeiher E. H. Kelle
Nalco Chemical Company
Sever Frank
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