Method for inhibiting scale formation and/or dispersing iron in reverse osmosis systems
US5256303A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 1992 |
| Grant date | Oct 26, 1993 |
| Priority date | — |
| Expiry date | Jul 20, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A20/131
- WIPO fieldChemical engineering
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.