Inhibtion of silica scale using hydrophobically-modified alkylene oxide urethane copolymer

Patent metadata

Field	Value
Publication number	US-10160682-B2
Application number	US-201515129003-A
Country	US
Kind code	B2
Filing date	Apr 7, 2015
Priority date	Apr 23, 2014
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

A method for inhibiting silica scale formation in an aqueous system by adding a hydrophobically-modified alkylene oxide urethane copolymer anti-scalant to the water used in the aqueous system.

First claim

The invention claimed is:

1. A method for inhibiting silica scale formation in an aqueous system, the method comprising:
adding an anti-scalant to water used in the aqueous system, the anti-scalant being added to a source of feed water containing silica, the aqueous system comprising a revere osmosis system including a reverse osmosis membrane; and
passing the resulting feed water through the reverse osmosis system such that a portion passes through the reverse osmosis member to produce a permeate stream having a reduced concentration of silica with the remaining portion of feed water forming a reject stream having a higher concentration of silica,
wherein the anti-scalant comprises a hydrophobically-modified ethoxylated urethane copolymer comprising both ethylene oxide and urethane groups and an hydrophobic end group incorporated by reacting a hydrophobic alcohol, amine, or acid with an isocyanate group.

2. The method of claim 1 wherein the hydrophobically modified ethylene oxide urethane copolymer is nonionic.

3. The method of claim 1 wherein the hydrophobically modified ethylene oxide urethane copolymer comprises at least 50 wt % of ethylene oxide groups.

4. The method of claim 1 wherein the anti-scalant has a Mw of 1,000 to 500,000 Daltons.

5. The method of claim 1 wherein the hydrophobically modified ethylene oxide urethane copolymer comprises a plurality of urethane groups.

6. The method of claim 5 wherein the urethane group links the ethylene oxide group and the hydrophobic end group.

7. The method of claim 1 wherein the water has a pH of less than 9.5.

8. The method of claim 1 wherein the feed water has a pH less than 9 and a silica content of at least 30 ppm, and wherein the reject stream has a silica content of at least 100 ppm.

9. The method of claim 1 wherein from 1 to 1000 ppm of the anti-scalant is added to the water of the aquenous system.

10. The method of claim 1 wherein the anti-scalant has Mw of 10,000 to 100,000 Daltons.

Assignees

• Dow Global Technologies Llc
• Rohm & Haas

Inventors

• Mehta Somil Chandrakant
• Dufour Alain

Classifications

• B01D2321/168

  Use of other chemical agents · CPC title

• C02F1/441

  by reverse osmosis · CPC title

• C02F1/442

  by nanofiltration · CPC title

• B01D2311/04

  Specific process operations in the feed stream; Feed pretreatment · CPC title

• B01D65/08

  Prevention of membrane fouling or of concentration polarisation · CPC title