GB1596752A - Method for reducing malodours of carboxylic acids - Google Patents

Description

(54) A METHOD FOR REDUCING MALODOURS OF CARBOXYLIC ACIDS (71) We, CONTEMPORARY PER FUMERS LIMITED, a British Company of 20 Witham Industrial Estate, Critall Road, Witham, Essex, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method for removing unpleasant odours caused by certain carboxylic acids.

It is an unfortunate feature of some important chemical manufacturing processes that they are the source of unpleasant odours. One example is the animal feed industry where animal products such as offal, skin and feathers are processed in bulk. Such processing is the source of many malodours including fatty acids. In industries of this type amounts of malodorous compounds escape from the production plant into the surrounding factory space where they settle on surrounding surfaces such as floors, walls, handrails, etc. or pass into air conditioning ducts, whence they are expelled into the surrounding atmosphere and may cause an odour nuisance in the surrounding area.

The malodorous principles which settle within the factory area are remarkably tenacious and cannot be removed even after prolonged washing with detergents.

The odour is also transferred to the clothes, shoes and skin of the factory workers whence it is also extremely difficult to remove. Attempts to control these odours with standard industrial deodorants have not been entirely successful.

We have now found that certain alkanolamines form stable substantially nonvolatile complexes with carboxylic acids and can be used to reduce considerably or remove malodours caused by such compounds.

Accordingly this invention provides a method for reducing a malodour caused by one or more malodorous C2 to C10 saturated or unsaturated carboxylic acid contaminants which comprises intermixing a contaminated gas phase or washing a contaminated area with a mono-, di-, or tri (C2 to C6 alkanol) amine.

A method for reducing a malodour caused by butyric valeric and phenylacetic acids is disclosed in our co-pending British Patent Application No. 15107/78, Serial No.

1596753.

Examples of malodours which may be removed by the method of this invention include odours caused by acetic, propionic and caproic acids.

Examples of alkanolamines useful in the method of this invention are mono-, di-, and tri-ethanolamine; mono-, di- and tri-npropanolamine, mono-, di-, and triisopropanolamine, mono-, di-, and tripentanolamine and 2-amino-2methylpropan-l-ol, of which mono-, di-, and tri-ethanolamine, and 2-amino-2methyl-propan-l-ol, are most suitable and triethanolamine is particularly preferred.

A contaminating odour may be removed in one of two ways. Either a gaseous phase bearing the odour may be treated, with the alkanolamine or the origin of the odour may be found and the contaminant treated at source. However, in order to remove the odour completely, the contaminants must be intimately intermixed or washed with at least a stoichiometric equivalent of the alkanolamine, but in general it is preferred to use an excess.

The alkanolamines used in the present invention are substantially non-volatile and therefore a contaminated gas phase must be intermixed with the alkanolamine in a liquid phase. Methods for intermixing liquids and gases with greater or lesser degrees of intimacy are well known. One way in which this intermixing can be carried out is to bubble the contaminated gas through the liquid. Conventional apparatus for achieving this is a bubble cap column.

Alternatively the liquid may be dispersed through the gas phase by using standard gas scrubbing apparatus. Generally such apparatus consists of a tower up which the gas is passed and down which the alkanolamine passes as a spray. Such conventional scrubbing towers are often packed with a solid porous matrix, such as Raschig Rings, or contain a series of baffles.

However it is preferred, particularly where the method of this invention is used to decontaminate air, for example in an air conditioning duct, to carry out this contacting by spraying the liquid into the contaminated air as a mist, using a fine atomizer nozzle. It is preferred that the spray should have a particle size of less than 100 microns and most preferably less than 1 micron.

We have found that intermixing an alkanolamine and a contaminated gas is most effectively achieved when the alkanolamine is in solution. Suitable solvents for making up such solutions are polar and examples include water, ethanol, benzyl alcohol and diethylene glycol monoethyl ether.

Where it is desired to use the alkanolamine in spray form, the alkanolamine or solution thereof is preferably mixed with a surfactant and/or a fragrance. Suitable surfactants include fatty acid soaps, and salts of sulphonated lauryl alcohol or non-ionic detergents such as cetyl alcohoVethylene oxide condensate.

One convenient way of introducing a surfactant is to add a trace of C10 to C, saturated or unsaturated fatty acid which forms an alkanolamine soap in situ.

Particularly useful for this purpose are the liquid fatty acids such as oleic acid.

Examples of suitable fragrances include blends containing essential oils, and/or nitromusks, e.g. musk ambrette; and fragrant synthetic compounds such as coumarin.

Solution suitable for use in the method of this invention contain at least 1% wt./vol. of alkanolamine, but may contain up to 95% of this component. Where a surfactant is included in the solution, the amount employed will be not more than 1% wt./vol.

The quantity of fragrance employed may be varied according to the level of new odour required. The solution is made up to 100% with solvent.

For use in small spaces such as a storeroom, the alkanolamine solution may be filled into a spray can with a conventional inert aerosol propellant.

Suitably the can will contain between 1 and 10 parts inclusive by weight of alkanolamine, between 5 and 50 parts by weight of solvent made up to 100 parts with propellant.

Preferred solvents for this mode of application are ethanol and glycol ethers.

When it is desired to treat the odour at source, if possible the alkanolamine should first be mixed with the contaminated mass.

If this is not possible, the odour may be contained by first overlaying an exposed area with alkanolamine.

Decontamination of a surface or a similar area such as a floor or wall to which the odour is adhering is conveniently effected by washing with an alkanolamine solution.

For this latter purpose the alkanolamine is advantageously used with a soap or detergent composition.

It is appreciated that certain soap and detergent compositions comprise anionic surfactants which have carboxylic and/or sulphonic acid groups. These acid groups are generally present in the form of a salt such as a sodium salt, but in some circumstances some of these groups may be unsalified. Such free acid groups can complex with the alkanolamines and therefore a stoichiometric excess of alkanolamine to free acid group must be present, when the area is washed to provide free alkanolamine to complex with acidic malodorous contaminants.

One convenient way to achieve this is to formulate a soap or detergent composition so as to include free alkanolamine.

Such compositions are prepared by standard methods, and the alkanolamine is added at any convenient stage in the preparation.

The following are examples of solutions useful for carrying out the method of this invention: Non-Aqueous Solutions Example 1 % W./Vo.

Triethanolamine 5 2-amino-2-methylpropan-1-ol 2.0 Monoethylether of diethylene glycol to 100% Example 2 % Wt./Vol.

Triethanolamine 5 2-amino-2-methylpropan- 1 ol 2.0 Oleic acid 0.1 Monoethylether of diethylene glycol to 100% Example 3 Triethanolamine 35 2-amino-2-methylpropan- 1 -ol 15 Monoethylether of diethylene glycol to 100% Aqueous Solutions Example 4 Triethanolamine 5 2-amino-2-methylpropan- l-ol 2 Propylene glycol 5 Water to 100% Aerosol Spray Solution Triethanolamine 5 Ethanol 45 Propellant 11/12 50/50 50 WHAT WE CLAIM IS: 1. A method for reducing a malodour caused by one or more malodorous C2 to C10 saturated or unsaturated carboxylic acid contaminants which comprises intermixing a contaminated gas phase or washing a contaminated area with a mono-, di-, or tri (C2 to C6 alkanol) amine.

2. A method as claimed in claim 1 wherein the alkanolamine is mono-, di or tri-ethanolamine or 2-amino-2methylpropan- 1 -ol.

3. A method as claimed in claim 1 wherein the alkanolamine is triethanolamine.

4. A method as claimed in any one of the preceeding claims wherein the contaminant is intimately intermixed or washed with at least a stoichiometric equivalent of the alkanolamine.

5. A method as claimed in any one of the preceeding claims wherein the alkanolamine is intermixed with a gaseous phase bearing the odour.

6. A method as claimed in claim 5 wherein the contaminated gas is bubbled through the alkanolamine in a liquid phase.

7. A method as claimed in claim 5 wherein the alkanolamine is sprayed into the gaseous phase.

8. A method as claimed in any one of claims 5 to 7 wherein the alkanolamine is in solution.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. Aqueous Solutions Example 4 Triethanolamine 5 2-amino-2-methylpropan- l-ol 2 Propylene glycol 5 Water to 100% Aerosol Spray Solution Triethanolamine 5 Ethanol 45 Propellant 11/12 50/50 50 WHAT WE CLAIM IS:

1. A method for reducing a malodour caused by one or more malodorous C2 to C10 saturated or unsaturated carboxylic acid contaminants which comprises intermixing a contaminated gas phase or washing a contaminated area with a mono-, di-, or tri (C2 to C6 alkanol) amine.

2. A method as claimed in claim 1 wherein the alkanolamine is mono-, di or tri-ethanolamine or 2-amino-2methylpropan- 1 -ol.

3. A method as claimed in claim 1 wherein the alkanolamine is triethanolamine.

4. A method as claimed in any one of the preceeding claims wherein the contaminant is intimately intermixed or washed with at least a stoichiometric equivalent of the alkanolamine.

5. A method as claimed in any one of the preceeding claims wherein the alkanolamine is intermixed with a gaseous phase bearing the odour.

6. A method as claimed in claim 5 wherein the contaminated gas is bubbled through the alkanolamine in a liquid phase.

7. A method as claimed in claim 5 wherein the alkanolamine is sprayed into the gaseous phase.

8. A method as claimed in any one of claims 5 to 7 wherein the alkanolamine is in solution.