GB1596753A

GB1596753A - Method for reducing malodours of carboxylic acids

Info

Publication number: GB1596753A
Application number: GB1510778A
Authority: GB
Original assignee: CONTEMPORARY PERFUMERS Ltd
Current assignee: CONTEMPORARY PERFUMERS Ltd
Priority date: 1978-04-18
Filing date: 1978-04-18
Publication date: 1981-08-26

Description

(54) A METHOD FOR REDUCING MALODOURS OF CARBOXYLIC ACIDS (71) We, CONTEMPORARY PER FUMERS LIMITED, a British Company of 20 Witham Industrial Estate, Crital 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 and biological processes that they are the source of particularly unpleasant odours. One such process is the manufacture of 6-aminopenicillanic acid, a most important intermediate in the manufacture of semisynthetic penicillins. The most troublesome odour associated with this process is that of phenyl acetic acid. This malodorous compound escapes in small amounts from the production plant into the surrounding factory space where it settles on surrounding surfaces such as floors, walls and handrails and is transferred thence to the skin, clothes and shows of production workers, or passes into air conditioning ducts whence it is expelled into the atmosphere and may cause an odour nuisance in the surrounding area. This malodour is remarkably tenacious and cannot be completely removed from a contaminated area even after prolonged washing with detergent. Furthermore, attempts to control the odour with standard industrial deodorants have been largely unsuccessful, partly because of the ability of phenyl acetic acid to mask other odours and fragrances.

Examples of other processes which are also the source of unpleasant odours are sewage treatment and the animal feed industry where animal products such as offal, skin and feathers are processed in bulk.

Both of these processes are the source of butyric and valeric acids which like phenyl acetic acid are distinguished from other malodorous alkanoic acids in that they are particularly unpleasant. As with phenyl acetic acid these acids cause an odour nuisance in the neighbourhood of the factory as well as to factory workers.

In the past, attempts have been made to deal with odoriferous fatty acids by scrubbing contaminated air conditioning exhaust gas with aqueous solutions of an alkali such as sodium or potassium hydroxide. However this is unsatisfactory for two reasons, firstly the solutions are corrosive and can only be used in specialised resistant apparatus, and secondly because the spent liquid from such apparatus tends to release quantities of the absorbed odour as it is run to waste thereby causing a subsidiary odour problem.

We have now discovered that certain alkanolamines form stable substantially non-volatile complexes with the above carboxylic acids and can be used to reduce considerably or remove malodours caused by such compounds.

Accordingly, the present invention provides a method for reducing a malodour caused by one or more of the contaminants butyric acid, valeric acid and phenyl acetic acid, which method comprises intermixing a contaminated gas phase or washing a contaiminated area with a mono-, di- or tri (C2 to C6 alkanol)-amine.

The method of this invention is applicable to the removal of the odour caused by isobutyric and iso- and tert-valeric acids as well as n-butyric and valeric acids, and is particularly suitable for removing phenyl acetic acid odour.

Examples of alkanolamines useful in the method of this invention are mono-, di- and tri-ethanolamine; mono-, di-, and tri - n propanolamine, mono-, di- and tri isopropanolamine, mono-, di-, and tripentanolamine and 2 - amino - 2 methylpropan - 1 - ol, of which mono-, di-, and tri - ethanolamine, and 2 - amino - 2 methyl - propan - 1 - 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 the intermixing 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 are water, ethanol, benzyl alcohol and ethylene 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 alcohol/ethylene oxide condensate. One convenient way of introducing a surfactant is to add a trace of C10 to C20 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 fragrant synthetic compounds such as coumarin.

Solutions 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 store room, 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 suck as 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.

The following Examples illustrate the method of this invention and solutions which are useful in its performance.

Example 1 a) Butyric and Valeric Acids The ability of mono-, di- and tri-ethanolamine and 2 - amino . 2 - methypropan I-ol to erradicate the odour of butyric and valeric acids was determined by asking a test group of ten volunteers to smell a filter paper to which an aliquot of the acid had been applied before and after treatment with an aliquot of alkanolamine.

A 0.5 mg aliquot of butyric acid was applied to 12.5 cm Whatman No. 1 filter paper (Whatman is a Registered Trade Mark) fastened vertically to a smelling shelf in a ventilated smelling booth. Each one of the test group people was asked individually to smell the odour. A 2.5 ml aliquot of a 50% wt/vol. aqueous mono-ethanolamine solution was applied as a spray to the surface of the filter paper, and the same test group was asked to smell the odour again.

The test was carried out for each alkanolamine using a fresh filter paper dosed with a fresh aliquot of butyric acid and the procedure repeated in the same way with each alkanolamine and with valeric acid.

None of the volunteers could detect any of the original odour after alkanolamine had been applied to the filter paper.

The ability of mono-, di- and triethanolamine and 2 - amino - 2 - methylpropan 1 - ol to erradicate the odour of phenylacetic acid was determined exactly as described in paragraph a) above, except that the contaminated filter paper was prepared by spraying a solution of phenylacetic acid (1% wt./vol. 50 ml) in ethanol and allowing the solvent to evaporate. Each alkanolamine qas supplied in a 50% wt./vol. ethanol solution.

None of the volunteers could detect any of the original odour after the alkanolamine had been applied to the filter paper.

Non Aqueous Solutions Example 2 Wt./Vol.

% Wt./Vol.

Triethanolamine 5 2 - amino - 2 - methyl- propan-l-ol 2.0 Monoethylether of diethylene glycol to 100% Example 3 Triethanolamine 5 2 - amino - 2 methylpropan - 1 - ol 2.0 Oleic acid 0.1 Monoethylether of diethylene glycol to 100% Example 4 Triethanolamine 35 2 - amino - 2 - methyl- propan - 1 - ol 15 Monoethylether of diethylene glycol to 100% Aqueous Solutions Example 5 % Wt./Vol Triethanolamine 5 2 - amino - 2 methylpropan - 1 - ol 2 Propylene glycol 5 Water to 100% Aerosol Spray Solution Example 6 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 of the contaminants, butyric acid, valeric acid and phenyl acetic acid, which method comprises inter-mixing a contaminated gas phase or washing a contaminated area with a mono-, di- or fri- (C2 to C6 alkanol) amine.

2. A method as claimed in claim 1 wherein the contaminant is phenylacetic acid.

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

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

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

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

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

8. A method as claimed in claim 6 wherein the alkanolamine is sprayed into the gaseous phase.

9. A method as claimed in any one of claims 6 to 8 wherein the alkanolamine is in solution.

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Claims

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

applied to 12.5 cm Whatman No. 1 filter paper (Whatman is a Registered Trade Mark) fastened vertically to a smelling shelf in a ventilated smelling booth. Each one of the test group people was asked individually to smell the odour. A 2.5 ml aliquot of a 50% wt/vol. aqueous mono-ethanolamine solution was applied as a spray to the surface of the filter paper, and the same test group was asked to smell the odour again.

The test was carried out for each alkanolamine using a fresh filter paper dosed with a fresh aliquot of butyric acid and the procedure repeated in the same way with each alkanolamine and with valeric acid.

None of the volunteers could detect any of the original odour after alkanolamine had been applied to the filter paper.

The ability of mono-, di- and triethanolamine and 2 - amino - 2 - methylpropan 1 - ol to erradicate the odour of phenylacetic acid was determined exactly as described in paragraph a) above, except that the contaminated filter paper was prepared by spraying a solution of phenylacetic acid (1% wt./vol. 50 ml) in ethanol and allowing the solvent to evaporate. Each alkanolamine qas supplied in a 50% wt./vol. ethanol solution.

None of the volunteers could detect any of the original odour after the alkanolamine had been applied to the filter paper.

Non Aqueous Solutions Example 2 Wt./Vol.

% Wt./Vol.

Triethanolamine 5 2 - amino - 2 - methyl- propan-l-ol 2.0 Monoethylether of diethylene glycol to 100% Example 3 Triethanolamine 5

2 - amino - 2 methylpropan - 1 - ol 2.0 Oleic acid 0.1 Monoethylether of diethylene glycol to 100% Example 4 Triethanolamine 35 2 - amino - 2 - methyl- propan - 1 - ol 15 Monoethylether of diethylene glycol to 100% Aqueous Solutions Example 5 % Wt./Vol Triethanolamine 5

2 - amino - 2 methylpropan - 1 - ol 2 Propylene glycol 5 Water to 100% Aerosol Spray Solution Example 6 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 of the contaminants, butyric acid, valeric acid and phenyl acetic acid, which method comprises inter-mixing a contaminated gas phase or washing a contaminated area with a mono-, di- or fri- (C2 to C6 alkanol) amine.
2. A method as claimed in claim 1 wherein the contaminant is phenylacetic acid.
3. A method as claimed in claim 1 or claim 2 wherein the alkanolamine is mono-, di- or tri-ethanolamine or 2-amino-2methylpropan-l-ol.
4. A method as claimed in claim 1 wherein the alkanolamine is triethanolamine.
5. A method as claimed in any one of the preceding claims wherein the contaminant is intimately intermixed or washed with at least a stoichiometric equivalent of the alkanolamine.
6. A method as claimed in any one of the preceding claims wherein the alkanolamine is intermixed with a gaseous phase bearing the odour.
7. A method as claimed in claim 6 wherein the contaminated gas is bubbled through the alkanolamine in a liquid phase.
8. A method as claimed in claim 6 wherein the alkanolamine is sprayed into the gaseous phase.
9. A method as claimed in any one of claims 6 to 8 wherein the alkanolamine is in solution.