Nalco Chemical Company

Cynthia A Soderquist

Claudia C Pierce

John A Kelly

E H Zeiher

Mei-Jan L Lin

Frederick S Mandel

Kenneth P Fivizzani

Scott R Harder

Scott R Haraer

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 dispersant 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, an N-substituted acrylamide polymer, caustic and water.

Method for inhibiting scale formation and/or dispersing iron in reverse

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.

New oxygen scavengers for boiler waters have been discovered, which oxygen scavengers are based upon N,N,N',N'-tetra substituted phenylenediamines. These compounds provide oxygen scavenging capabilities, metal passivating capabilities, volatility such that condensate systems in an operating boiler are protected, and may be formulated with other oxygen scavengers and other common treatment agents used in boiler waters. The preferred tetra substituted phenylenediamines are N,N,N',N'-tetramethyl-1,4-phenylenediamines, or its precursors.

Method of retarding corrosion of metal surfaces in contact with boiler

A combination product containing (a) dihydroxyacetone, (b) hydroquinone, and (c) a volatile amine that is capable of removing oxygen and neutralizing carbon dioxide in industrial waters, particularly boiler waters, including boiler feed waters, internal boiling waters, condensate waters, and return waters. The combination product preferably contains weight ratios of ingredients (a):(b):(c) ranging from 1:0.01:0.1 to about 1:1:100, and may additionally contain a filming amine.

All-volatile multi-functional oxygen and carbon dioxide corrosion

New oxygen scavengers for boiler waters have been discovered, which oxygen scavengers are based upon N,N,N',N'-tetra substituted phenylenediamines. These compounds provide oxygen scavenging capabilities, metal passivating capabilities, volatility such that condensate systems in an operating boilder are protected, and may be formulated with other oxygen scavengers and other common treatment agents used in boiler waters. The preferred tetra substituted phenylenediamines are N,N,N', N'-tetramethyl-1,4-phenylenediamines, or its precursors.

An improved method for scavenging dissolved oxygen from waters used to generate steam which comprises treating said waters with at least 0.3 mole of gallic acid per mole of oxygen contained in said bioler waters. An aqueous concentrate useful for treating boiler waters to scavenge oxygen therefrom which contains at least 0.3% by weight of gallic acid. This aqueous concentrate has a pH adjusted to at least 8.5.

Gallic acid as an oxygen scavenger

A method of scavenging oxygen and passivating metal surfaces in steam generating equipment by treating feedwater with an ammonia or amine neutralized erythorbate form thereof.

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Bolingbrook, IL, United States of America

Cynthia A Soderquist