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GB2157322A - Removal of iron oxide deposits - Google Patents

Removal of iron oxide deposits Download PDF

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Publication number
GB2157322A
GB2157322A GB08408144A GB8408144A GB2157322A GB 2157322 A GB2157322 A GB 2157322A GB 08408144 A GB08408144 A GB 08408144A GB 8408144 A GB8408144 A GB 8408144A GB 2157322 A GB2157322 A GB 2157322A
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GB
United Kingdom
Prior art keywords
composition
sequestering agent
ferrous ions
removal
iron oxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08408144A
Other versions
GB2157322B (en
GB8408144D0 (en
Inventor
John Raymond Sutton
Samuel James Taylor
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Diversey Ltd
Original Assignee
Diversey Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Diversey Ltd filed Critical Diversey Ltd
Priority to GB08408144A priority Critical patent/GB2157322B/en
Publication of GB8408144D0 publication Critical patent/GB8408144D0/en
Publication of GB2157322A publication Critical patent/GB2157322A/en
Application granted granted Critical
Publication of GB2157322B publication Critical patent/GB2157322B/en
Expired legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23GCLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/24Cleaning or pickling metallic material with solutions or molten salts with neutral solutions
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23GCLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02Cleaning or pickling metallic material with solutions or molten salts with acid solutions

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Detergent Compositions (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

The invention provides a process for the removal of iron oxide deposits from a surface which comprises treating the surface with an aqueous solution of a sequestering agent at a pH of from 1 to 7.5 in the presence of at least a catalytic amount of ferrous ions. The process can be operated under relatively mild conditions and is suitable for use on mild steel, cast iron, aluminium, stainless steel, painted metals, plastics or fabrics. The invention also provides a composition for use in the process comprising a sequestering agent and a source of ferrous ions, which composition may optionally be presented in two parts with the sequestering agent and the source of ferrous ions separated.

Description

SPECIFICATION Removal of iron oxide deposits This invention relates to the removal of iron oxide deposits.
The present invention provides a process for the removal of iron oxide deposits from a surface which comprises treating the surface with an aqueous solution of a sequestering agent at a pH of from 1 to 7.5 in the presence of at least a catalytic amount of ferrous ions.
The process of the invention is suitable, for example, for the removal of rust deposits on mild steel or cast iron, or of other iron oxide deposits on aluminium, stainless steel, painted metals, plastics or fabrics. The process has the advantage that it can be operated under relatively mild conditions, e.g. a pH around neutral and ambient temperature. The reagents used are not aggressive, do not significantly attack the substrate, are innocuous to personnel and equipment and do not present effluent disposal problems.
The sequestering agent is preferably one of the following or a mixture thereof: a condensed phosphate such as a pyrophosphate, e.g. Na4P2O7 or a tripolyphosphate e.g.
sodium tripolyphosphate, Na5P30,0 an organic phosphonate, e.g. amino tri(methylenephosphonic acid) otherwise known as ATMP an aminopolycarboxylic acid, e.g. ethylene diamine tetraacetic acid (EDTA) a phosphonocarboxylic acid, e.g. 2-phosphonobutane-1 ,2,4-tricarboxylic acid.
Examples of suitable concentration ranges for various classes of sequestrants are as follows: Sequestrant % w/w Moles per litre condensed phosphate 0.5 to 40 0.025 to 2 organic phosphonate 0.5 to 30 0.025 to 2 phosphono carboxylic acid 0.5 to 40 0.025 to 2 amino polycarboxylic acid 0.5 to 30 0.025 to 1 The source of ferrous ions will usually be a ferrous salt and any water soluble ferrous salt can be used for this purpose. Ferrous sulphate is preferred since this is readily available commercially. Ferrous ions must be present in at least a catalytic amount, for example 5 ppm (10-4 M) or more. However, it is preferred to operate above this minimum level since the process is more effective and this also allows for any losses which may occur as a result of oxidation of ferrous ions by the air. A typical operating level is about 560 ppm (about 0.01 M).In some systems it may be possible to use concentrations up to 1 M (56 g/l) or higher.
The preferred pH for the process is in the range 3.5 to 7.5 although if desired the process can be operated at a lower pH down to about 1. The optimum pH depends on the sequestering agent. For example, the optimum pH for ATMP is about 4.5 and that for sodium pyrophosphate is about 7.
The invention also extends to compositions intended for the production of solutions suitable for use according to the invention. Such compositions contain as essential components a sequestering agent as described above and a source of ferrous ions. The composition may be a single part composition or may be presented as a two part composition with the two parts intended to be mixed immediately before use. In a two part composition the sequestering agent and the source of ferrous ions are separated. A single part composition or in the case of a two part composition the parts thereof are preferably presented in the form of concentrated aqueous solutions although solid compositions may be used in some cases. Use of a two part composition provides greater flexibility in terms of formulation and can also reduce the tendency to air oxidation of the ferrous component.In addition, the ferrous component of a two part composition can be used on its own for addition to a working bath which has become deactivated on standing due to air oxidation.
The compositions according to the invention may contain any other components as necessary or desirable. The sequestering agents and ferrous salts may both be acidic in nature and since it is preferred that the composition or the parts thereof should have a pH about neutral, a neutralising agent such as potassium hydroxide will often be added. A single part composition or either or both parts of a two part composition may also contain a surfactant as a wetting agent and/or a thickener. When the composition or a part thereof is in the form of a concentrated aqueous solution, the water content can be in the range 40 to 60%, preferably 40 to 45%, more preferably 40%. Such a concentrated aqueous solution is diluted with water to form the treatment solution immediately before use.
The invention is illustrated by the following Examples.
EXAMPLE 1 This Example illustrates a concentrated one-pack product which is stable in a closed container with respect to ferrous content for several months at ambient temperature.
% w/w ADPA (1 -hydroxy ethylidene-l,l -diphosphonic acid, 60% active) 51.7 Potassium hydroxide liquor (50% w/w active) 38.4 Water 8.9 Ferrous sulphate 1.0 The ADPA and potassium hydroxide liquor are first mixed together carefully with cooling. The ferrous sulphate is dissolved in the water and a trace of ADPA added to give a clear solution which is then added to the neutralised ADPA.
EXAMPLE 2 This Example illustrates a two-part composition in which the ferrous component and the sequestrant are intended to be mixed immediately prior to use. In addition the ferrous component alone can be used to add to a working bath which has become deactivated on standing due to air oxidation (i) Sequestrant pack % w/w 4KP (Tetrapotassium pyrophosphate K4P207) 41.6 Water 41.7 ADPA (1 -hydroxyethylidene-1 , 1 diphosphonic acid) 16.7 The 4KP is dissolved in water and the ADPA is then carefully added to adjust the pH to about 7.
(ii) Activator pack % w/w Ferrous sulphate (FeSO4.7H2O) 10.0 Ethylan CD916 (Cg-C,1 alcohol + 6.5 moles ethylene oxide) 1.0 Water 88.9 Sulphuric acid 0.1 The ferrous sulphate is dissolved in water and the sulphuric acid added to give a clear solution in which the Cud916 surfactant is then dissolved.
EXAMPLE 3 This Example illustrates the cleaning of iron oxide from a mild steel surface. 6" by 4" Pyrene test panels were degreased and then rusted in a hot (60 C) salt water spray (4% solution) in one hour using a small domestic dish washer.
A derusting bath (pH 6.9) was prepared having the following composition.
grams per litre tetrapotassium pyrophosphate 63 polyphosphoric acid 14 ferrous sulphate 2.5 wetting agent (Dowfax 3B2) 2.5 Immersion of the above prepared mild steel panels gave complete rust removal at 1 0 C in 60 minutes. Subsequent derustings in the same bath gave complete removal in 21 minutes at 31"C or 10 minutes at 48"C.
EXAMPLE 4 This Example illustrates the derusting of cast iron. A new car engine cylinder head which had become very rusty from storage in a damp environment was treated in the following way. A solution containing 43 grams per litre ADPA, adjusted to pH 7 with sodium hydroxide and 280 ppm (0.0005 M) ferrous ion as ferrous sulphate was prepared at room temperature (20 C). The cylinder head was immersed in this solution and after 2 hours the rust deposit was almost completely removed leaving the iron surface with a dull grey metallic appearance. In order to complete the rust removal the cylinder head was left immersed over night for a further 1 6 hours and after this period the apperance of the iron was still excellent with no signs of corrosive attack on the machined surfaces or brass inserts.
EXAMPLE 5 This Example illustrates the improvement which can be obtained by adding ferrous ions over the use of sequestrant alone. Identical lightly rusted (artificially prepared as described in Example 3) mild steel panels were immersed in solutions at 20"C having the following compositions: A) 26 grams per litre active ADPA, pH 7.05 B) 26 grams per litre active ADPA, 500 ppm ferrous ion as ferrous sulphate, pH 7.05.
The panel from solution B was derusted completely in 1 5 minutes whereas that from solution A was only very slightly derusted in this time. Similar results were obtained with tetrapotassium pyrophosphate solutions (100 grams per litre). The panel from the solution containing 500 ppm ferrous ion was completely derusted whereas the solution without ferrous ion gave hardly any rust removal.
EXAMPLE 6 Aluminium (Pyrene) test panels were degreased and coated with a thin slurry of ferric oxide (B.D.H. precipitated, red) by painting on with a brush. After drying, the panels were immersed at ambient temperature in a solution containing 10% active (0.33 M) amino trimethylene phosphonic acid (Dequest 2000-Monsanto) and 0.14% (0.025 M) ferrous ion as ferrous sulphate at a pH of 4.5. Complete cleaning of the panels was achieved in 3 hours. In the absence of the ferrous ion the rate of cleaning was much slower, taking well in excess of 1 8 hours.
EXAMPLE 7 This Example illustrates the removal of a rust stain from a white cotton table cloth. The cloth was stained by immersion in a 1 % ferrous sulphate solution (containing a small amount of wetting agent), the excess liquid was squeezed out and the cloth was then transferred to a 1 % solution of 0.880 ammonia. The cloth was then rinsed and allowed to dry. Stain removal was then effected by immersion in a solution containing ADPA (43 grams per litre = 0.21 M) and ferrous sulphate (Fe+ + = 280 ppm = 0.005 M) at pH 6.5 and 65do. The iron stain was completely removed in about 5 minutes after which the fabric was rinsed and dried.

Claims (11)

1. A process for the removal of iron oxide deposits from a surface which comprises treating the surface with an aqueous solution of a sequestering agent at a pH of from 1 to 7.5 in the presence of at least a catalytic amount of ferrous ions.
2. A process as claimed in claim 1, wherein the pH is 3.5 to 7.5.
3. A process as claimed in claim 1, wherein ferrous ions are present in an amount of at least 5 ppm (10-4 M).
4. A process as claimed in claim 1, wherein ferrous ions are present in an amount of 5 ppm (10-4 M) to 56g/l (1M).
5. A process as claimed in any of claims 1 to 4, wherein the sequestering agent is one of the following or a mixture thereof: a condensed phosphate; an organic phosphonate; an aminopolycarboxylic acid: a phosphonocarboxylic acid.
6. A process as claimed in claim 5, wherein the sequestering agent is present in the following concentration ranges (expressed as moles per litre); condensed phosphate-0.025 to 2 organic phosphonateO.025 to 2 phosphono carboxylic acid--0.025 to 2 aminopolycarboxylic acid--0.025 to 1.
7. A composition for the production of an aqueous solution suitable for use in a process as claimed in any of claims 1 to 6 the composition comprising a sequestering agent together with a source of ferrous ions and being adapted to produce a solution as defined in any of claims 1 to 6 on dissolution in water.
8. A composition as claimed in claim 7 which is a two part composition with the sequestering agent and the source of ferrous ions in seperate parts the two parts being in association and intended to be mixed immediately before use.
9. A composition as claimed in claim 7 to 8 wherein the composition in the case of a one part composition or both parts of the composition in the case of a two part composition are in the form of concentrated aqueous solutions.
10. A composition as claimed in claim 9, wherein the concentration of the concentrated aqueous solution(s) is 40 to 60% water.
11. A process for the removal of iron oxide from a substrate substantially as hereinbefore described with particular reference to any of the examples.
1 2. A composition for use in a process for the removal of iron oxide from a substrate substantially as hereinbefore described with particular reference to example 1 or example 2.
GB08408144A 1984-03-29 1984-03-29 Removal of iron oxide deposits Expired GB2157322B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08408144A GB2157322B (en) 1984-03-29 1984-03-29 Removal of iron oxide deposits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08408144A GB2157322B (en) 1984-03-29 1984-03-29 Removal of iron oxide deposits

Publications (3)

Publication Number Publication Date
GB8408144D0 GB8408144D0 (en) 1984-05-10
GB2157322A true GB2157322A (en) 1985-10-23
GB2157322B GB2157322B (en) 1987-10-21

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4810405A (en) * 1987-10-21 1989-03-07 Dearborn Chemical Company, Limited Rust removal and composition thereof
EP1652969A1 (en) * 2004-10-28 2006-05-03 Henkel Kommanditgesellschaft auf Aktien Deruster composition and method
WO2014111267A1 (en) 2013-01-17 2014-07-24 Archroma Ip Gmbh System for the removal of iron oxide from surfaces
EP2862973A1 (en) * 2013-05-23 2015-04-22 Washing Systems, LLC Method of laundering industrial garments

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB824275A (en) * 1955-01-20 1959-11-25 Dow Chemical Co Improvements in and relating to the recovery of complexing agents from spent solutions
GB1198693A (en) * 1966-08-02 1970-07-15 Beratherm A G Process for the Chemical Cleansing of Water and Steam Contacted Metal Surfaces.
GB1312423A (en) * 1970-04-13 1973-04-04 Monsanto Co Phosphorus-containing epoxy compounds
US3754990A (en) * 1968-02-09 1973-08-28 Dow Chemical Co Cleaning of ferrous metal surfaces
GB1347008A (en) * 1970-11-13 1974-02-13 Ciba Geigy Uk Ltd Detergent compositions
GB1354637A (en) * 1971-01-11 1974-06-05 Monsanto Co Isocyanuric acid derivatives
GB1438079A (en) * 1973-05-17 1976-06-03 Monsanto Co
GB1469160A (en) * 1973-05-22 1977-03-30 Henkel & Cie Gmbh Sequestering agent
GB1476840A (en) * 1974-12-27 1977-06-16 Hoechst Ag Rust-removing cleaning agents and their manufacture and uses
EP0086245A1 (en) * 1980-12-05 1983-08-24 Dowell Schlumberger Corporation Aqueous acid metal cleaning composition and method of use
EP0104012A2 (en) * 1982-09-21 1984-03-28 Halliburton Company Composition and method for simultaneously removing iron and copper scales from ferrous metal surfaces

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB824275A (en) * 1955-01-20 1959-11-25 Dow Chemical Co Improvements in and relating to the recovery of complexing agents from spent solutions
GB1198693A (en) * 1966-08-02 1970-07-15 Beratherm A G Process for the Chemical Cleansing of Water and Steam Contacted Metal Surfaces.
US3754990A (en) * 1968-02-09 1973-08-28 Dow Chemical Co Cleaning of ferrous metal surfaces
GB1312423A (en) * 1970-04-13 1973-04-04 Monsanto Co Phosphorus-containing epoxy compounds
GB1347008A (en) * 1970-11-13 1974-02-13 Ciba Geigy Uk Ltd Detergent compositions
GB1354637A (en) * 1971-01-11 1974-06-05 Monsanto Co Isocyanuric acid derivatives
GB1438079A (en) * 1973-05-17 1976-06-03 Monsanto Co
GB1469160A (en) * 1973-05-22 1977-03-30 Henkel & Cie Gmbh Sequestering agent
GB1476840A (en) * 1974-12-27 1977-06-16 Hoechst Ag Rust-removing cleaning agents and their manufacture and uses
EP0086245A1 (en) * 1980-12-05 1983-08-24 Dowell Schlumberger Corporation Aqueous acid metal cleaning composition and method of use
US4430128A (en) * 1980-12-05 1984-02-07 The Dow Chemical Company Aqueous acid composition and method of use
EP0104012A2 (en) * 1982-09-21 1984-03-28 Halliburton Company Composition and method for simultaneously removing iron and copper scales from ferrous metal surfaces

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4810405A (en) * 1987-10-21 1989-03-07 Dearborn Chemical Company, Limited Rust removal and composition thereof
EP1652969A1 (en) * 2004-10-28 2006-05-03 Henkel Kommanditgesellschaft auf Aktien Deruster composition and method
WO2014111267A1 (en) 2013-01-17 2014-07-24 Archroma Ip Gmbh System for the removal of iron oxide from surfaces
EP2862973A1 (en) * 2013-05-23 2015-04-22 Washing Systems, LLC Method of laundering industrial garments

Also Published As

Publication number Publication date
GB2157322B (en) 1987-10-21
GB8408144D0 (en) 1984-05-10

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19970329