AU720321B2 - The removal of pesticides from natural oil/grease products e.g., wool grease - Google Patents

Description

WO 98/10046 PCT/AU97/00572 THE REMOVAL OF PESTICIDES FROM NATURAL OIL/GREASE PRODUCTS WOOL

GREASE

Technical Field The present invention relates to the removal of pesticides from natural oil/grease products, particularly from wool grease.

Backeround-AMt There are many natural oil/grease products derived from plants. fish and animals in use today. Examples include natural and essential oils from plants. fish oils. and tallow and wool grease from animals. Due to the prevalence of the use of pesticides in agriculture and their presence in aquaculture. many of these products can contain unwanted levels of contaminating pesticides. Often. there is a requirement to remove any pesticide contaminants prior to further use or processing into products for animal and human use. The removal processes used at present can be expensive, adversely effect the quality of the oil/grease, produce harmful byproducts. or be ineffective.

One of the products from wool scouring is wool grease which often will include many of the contaminants removed from the wool. The contaminants are mainly grease, dirt. suint, detergents, and protein material.

Wool grease may be processed further to obtain other useful products. An important product obtained from wool grease is lanolin. To produce lanolin.

wool grease is refined to lighten its colour, remove unwanted contaminants.

reduce its odour, and remove free fatty acids. Another product obtainable from wool grease is wool wax which is the pure lipid material of the fleece that is extracted with common fat solvents such as diethvlether and chloroform.

The refining process most commonly used to produce lanolin from wool grease involves treatment with hot aqueous alkali to convert free fatty acids to soaps followed by bleaching, usually with hydrogen peroxide, although. sodium chlorite, sodium hypochlorite and ozone have also been used. Other refining processes include distillation, steam stripping, neutralisation by alkali, liquid thermal diffusion. and the use of active absorbents for example charcoal and bentonite and solvent fractionation.

The uses of wool grease, lanolin and lanolin derivativesare varied, ranging from pharmaceuticals and cosmetics to printing inks. anti-rust agents. and lubricants.

WO 98/10046 PCT/AU97/00572 2 A major problem faced by wool grease refiners is the need to safely remove pesticides that have been absorbed to the wool grease. The fleece of animals tends to accumulate pesticides that have been applied to the animals to control insect and parasite pests. Furthermore, grazing of animals on open pastures also results in the accumulation of pesticides that have been applied to the pasture to control weeds. During scouring, the pesticides are often concentrated in the wool grease due to their solubility in fats. Because concentrated pesticides may be toxic, there is a need to ensure that any product derived from wool grease is free from pesticide contamination.

In order to remove pesticides, specific removal and destruction steps are required during the refining process. The most common means of pesticide removal and destruction by wool refiners is steam stripping followed by extreme heat treatment (up to 1200 0 One seriousi oblem in the removal and destruction of pesticides from wool grease by this process is the formation of extremely toxic products if the pesticides are not broken down completely. The most serious problem is the formation of dioxins during the removal and destruction steps.

The present inventors have developed a new means of safely removing pesticides from natural oil/grease products, particularly wool grease, with reduced production of harmful products such as dioxins.

Disclosure of the Invention In a first aspect, the present invention consists in a method of removing pesticides from a natural oil/grease product containing pesticides comprising treating the natural oil/grease product with microwave energy such that the natural oil/grease product is heated to a temperature greater than about 120'C for sufficient time to cause at least some of the pesticides to be substantially removed.

Preferably, the natural oil/grease product is heated to a temperature between 140 0 C and 300'C, more preferably between 160 0 C and 250'C, even more preferably between 180 0 C and 240'C, and most preferably between 200'C and 220'C. It will be appreciated that the required temperatures may differ from those outlined above if the treatment is carried out under pressure or under vacuum.

The natural oil/grease product may be irradiated in any container or vessel. It will be appreciated that the natural oil/grease product is preferably irradiated such that substantially all pesticides present in the grease are WO 98/10046 PCT/AU97/00572 3 irradiated to assist in their removal. Furthermore, it is preferable that during irradiation there is relatively even distribution of heat through out the natural oil/grease product. In order to assist in the removal of pesticide contaminants from the natural oil/grease product, stirring or tumbling of the natural oil/grease product during irradiation can be carried out.

The natural oil/grease product is irradiated with microwave energy for a sufficient time in order to cause the pesticides to be removed. As a consequence of the microwave treatment or irradiation the natural oil/grease product is heated to a desired temperature. For example, a treatment time of 15 minutes for 5 kg of natural oil/grease product was sufficient to substantially remove a common pesticide from the product. It will be appreciated that the time of treatment will depend on the amount of natural oil/grease product being treated, the microwave energy being used, and the type and degree of pesticide contamination. It has been found that prolonged treatment with microwave energy is not required to remove many common pesticides found in natural oil/grease products.

The action of the microwave energy at the required temperature can cause the pesticides to break down to harmless products. The broken down pesticides are removed either in vapour form or are removed during further processing of the natural oil/grease product. The present invention has the distinct advantage in that substantially no detectable toxic products, including dioxins, are produced during the removal process.

The microwave frequency used in the present invention may be in the order of 2.45 Ghz. This frequency is the one available for use in Australia but other frequencies may also be used in the present invention. One advantage of the use of microwave technology is that the amount of energy needed can be adjusted up to about 250 kW using microwave generators presently available. It will be appreciated that the amount of energy required will depend on the quantity of natural oil/grease product being treated at any particular time and the degree and type of pesticide contamination.

A further advantage of the present invention is that the treatment also provides a deodorising effect on the natural oil/grease product.

The present invention is suitable to remove most if not all pesticides commonly used in the grazing and wool industry including organophosphate and organochloride pesticides. Examples of organophosphate pesticides that can be removed by the present invention are Chlorpyrifos, Diazanon, Ethion, WO 98/10046 PCT/AU97/00572 4 Malathion, and Ronnel. Examples of organochloride pesticides that can be removed by the present invention are Aldrin, a-Endosulphan, a-HCH, 3-Endosulphan, 3-HCH, Dieldrin, Endrin, Heptachlor, HCB, Lindane, Methoxychlor, o,p' DDE, o,p'-DDT, p,p'-DDE, p,p'-DDT, and Heptachlor Epoxide.

It will be appreciated, however, that other pesticides may also be removed by the present invention.

The natural oil/grease product-can be any natural or essential oil from plants, fish oils, and animal oils and greases including tallow and wool grease. The present invention has been found to be particularly suitable for the removal of pesticides from wool grease. It will be appreciated that although working examples relate to the treatment of wool grease, the present invention is suitable for the treatment of other natural oils/greases.

The present invention maybe used to pre-treat wool grease to remove pesticides and the treated wool grease maybe processed or refined at a later date to produce lanolin and other products. Alternatively, the method of the present invention maybe incorporated in a refining process for the production of lanolin and lanolin derivatives. The method may be used prior to one of the standard refining processes, or during or between any of the refining steps presently used. Refining processes to form lanolin and its derivatives from wool grease are well known and the present invention is adaptable to be used in combination with these processes.

As used herein wool is defined as any animal fibre that contains a grease component that can be removed during processing of the fibre. In particular the present invention is suitable for wool grease obtained from sheep, goats, lamas, alpacas and other domestic fleece animals. Pesticides present in wool grease derived from sheep can be removed effectively by the present invention.

In a second aspect, the present invention consists in natural oil/grease product, particularly wool grease, treated by the method of the first aspect of the present invention, the natural oil/grease product being substantially free of pesticide contamination.

In a third aspect, the present invention consists in lanolin substantially free from pesticide contamination obtained from wool grease treated by the method of the first aspect of the present invention.

WO 98/10046 PCT/AU97/00572 In order that the present invention maybe more clearly understood, preferred forms will be described with reference to the figure and the following examples using treatment of wool grease as an example of a natural oil/grease product.

Brief Description of the Drawings Figure 1 is a flow diagram of a method of producing lanolin from wool grease where the method of the present invention is carried out at the beginning of the refining process.

Detailed Description of the Invention

METHODS

Acid Value Definition: The acid value is the number of milligrams of potassium hydroxide necessary to neutralise the free acids in Ig.-f sample.

Scope: Applicable to all neutral and synthetic drying oils.

A. Apparatus: 1. Erlenmeyer flasks, 250 or 300 ml.

B. Reagents: 1. Sodium hydroxide, approximately 0.1N in synthetic methyl alcohol Specification H 17-58), accurately standardised with potassium hydrogen phthalate, using 1% phenolphthalein as the indicator.

2. Isopropyl alcohol-toluene mixture, prepared by mixing equal volumes of 99% isopropyl alcohol Specification H 17-58) and industrial toluene Specification H 17-58). The mixture must be neutralised with 0.1N methanolic sodium hydroxide to a pink colour that persists for one minute, using 1% phenolphthalein as the indicator.

3. Phenolphthalein indicator solution, 1% in methyl alcohol.

WO 98/10046 PCT/AU97/00572 6 C. Procedure: 1. Determine the size of sample from the following table: Acid value Approx. weight of Accuracy of sample weighing (g) 0 to 5 20 +0.05 to 15 10 +0.05 to 30 5 +0.05 to 100 2.5 +0.001 100 and over 1.0 +0.001 2. Weigh the designated size of sample into an Erlenmeyer flask.

Add approximately 100 ml of neutralised solvent and 1 ml of indicator and mix until sample is completely dissolved. Warming may be necessary for bodied oils.

3. Titrate with the standard alkali solution, shaking vigorously to the appearance of the first permanent pink colour of the same intensity as that of the neutralised solvent before addition. The colour must persist for 1 minute.

D. Calculation: Acid value,mg KOH per g of sample Ml. of alkali x Nx 56.1 Wt. of sample N Normality of alkali

RESULTS

Effect of Time and Temperature Firstly, the effect of time of microwave irradiation and temperature was measured.

A study was initially performed with the pesticide Diazanon as the benchmark as it is considered by wool refiners to be the more serious of the pesticide residues found in wool grease. The first trial examined the effect of holding time whereby 15 minutes and 30 minutes were chosen as arbitrary time points. Five kilogram samples of wool grease were used in the process and the results are shown in Tables 1 and 2.

WO 98/10046 PCT/AU97/00572 7 Table 1. Trial A: 15 minutes holding at a given temperature Sample Temperature (OC) Diazanon level (ppm) 1 Untreated 8.9 2 100 8.8 3 120 8.4 4 140 8.6 -160 6 200 6.2 Table 2. Trial B: 30 minutes holding at a given temperature Sample Temperature (OC) Diazanon level (ppm) 1 Untreated 8.9 2 100 8.9 3 120 8.6 4 140 8.6 160 6.9 6 200 5.8 This series of experiments indicated that duration of heating had only a marginal effect on the removal of Diazanon.

A second series of tests examined the effect of temperature held at minutes with the results shown in Table 3.

Table 3.

Sample Temperature 0 C) Diazanon level (ppm) 1 Untreated 9.6 2 100 9.3 3 120 4 140 8.9 160 6 200 6.2 7 250 <0.4 WO 98/10046 PCT/AU97/00572 8 It can be seen from the results that treatment at temperatures of 140"C and above resulted in the removal of at least some of the pesticide from the wool grease. At 250 0 C, all detectable pesticide was removed from the wool grease.

A third series of experiments examined use of incremental temperatures between 200 and 220 0 C held at 15 minutes with the results shown in Table 4.

Table 4.

Sample Temperature Diazanon level (ppm) 1 200 5.8 2 210 4.9 3 220 <0.4 Treatment at a temperature of 2100C removed more than 50% of the pesticide and a temperature of 220 0 C removed all detectable pesticide from the wool grease. It will be appreciated that other pesticides may be treated with lower temperatures to obtain the same level of removal.

A fourth series of tests repeated the processing parameters for sample '3 in the third series and the method was tested for a range of organophosphate and organochloride pesticides which appear as part of the specification of the USP '93. To meet this US specification, lanolin must have less than 10 ppm of individual pesticides and have less than 40 ppm total pesticides. The methodology of the present test had a detection limit of 2 ppm of individual organophosphate pesticides and 0.5 ppm of individual organochloride pesticides. The results are shown in Table 5. No residuals were detected for any individual pesticide above these levels.

The holding time for processing at 220 0 C was negligible to obtain removal of the pesticides. The heating profile of the individual 5 kg samples took between 8 10 minutes to achieve the required temperature.

Only those pesticides which have a commercial significance in respect to USP '93 were tested in these trials. It will be appreciated that other pesticides may require a different temperature profile than outlined above.

Although not all the pesticides which are used in the wool industry were tested, it is expected that the present invention would be suitable for most other pesticides.

WO 98/10046 PCT/AU97/00572 Table Pesticide Type Pesticide Result Organophosphates Chlorpyrifos <10 ppm Diazanon <10 ppm Ethion <10 ppm PQL 2 ppm Malathion <10 ppm Ronnel <10 ppm No detectable levels Organochlorides Aldrin <10 ppm a-Endosulphan <10 ppm a-HCH <10 ppm PQL 0.5 ppm p-Endosulphan <10 ppmp-HCH 10 ppm No detectable limits in Dieldrin 10 ppm any pesticide Endrin <10 ppm Heptachlor 10 ppm HCB <10 ppm Lindane 10 ppm Methoxychlor 10 ppm o,p'-DDE <10 ppm o,p'-DDT 10 ppm p,p'-DDE <10 ppm p,p'-DDT 10 ppm Heptachlor Epoxide <10 ppm Tested in accordance to USP '93 specification which requires all individual pesticides must be <10 ppm and 40 ppm total pesticides.

Control studies of heating wool grease without using microwave energy failed to remove any pesticide contaminants. It would appear that the effectiveness of the present invention results from the action of the microwave energy on the pesticides to cause removal when the temperature has been elevated to greater than 140 0

C.

WO 98/10046 PCT/AU97/00572 Effect of Time and Temperature on a Range of Common Pesticides A fifth detailed study was carried out on wool grease containing eight common pesticides. The samples tested and the conditions of treatment are given in Table 6. Temperatures of 140, 160, 180, 200 220 and 240 0 C were tested at times 15, 30 and 60 minutes, under partial vacuum.

Table 6 Sample No Temp Time (min) Vacuum (atm) 1 140 15 2 140 30 3 140 60 4 160 15 160 30 6 160 60 7 180 15 8 180 30 9 180 60 200 15 11 200 30 12 200 60 13 220 15 14 220 30 220 60 16 240 15 17 240 30 18 240 60 The results of the different treatments set out in Table 6 are shown in Table 7.

Table 7 Concentration of pesticides iffn wool grease (mg/kg)0 Cyhalo- Cypr- Delta- Propetam Diazinon Chiorfen- Couma- Difinthrin methrin methrin phos vinplios phos benzuron Raw wool grease 0.9 22 0.7 3.2 53 173 2.2 2.7 Sample 1 1.4 22 1.0 2.7 35 117 3.4 0 Sample 2 5.1 21 1.3 3.7 63 176 2.5 0 Sample 3 0.7 21 0.8 4.0 64 179 5.2 0 Sample 4 1.0 21 1.2 3.9 61 163 1.9 0 Sample 5 1.0 22 1.1 3.4 49 130 3.7 0 Sample 6 0.8 21 0.7 3.6 .47 102 <0.1 0 Sample 7 1.0 20 0.8 3.2 34 40 <0.1 0 Sample 8 0.8 22 0.6 3.3 37 50 1.5 0 Sample 9 1.4 19 0.7 2.3 16 7 2.0 0 Sample 10 1.1 15 0.8 1.4 4.5 0.3 <0.1 0 Sample 11 1.1 17 0.5 1.5 5.6 <0.1 1.0 0 Sample 12 1.1 10 0.1 0.7 3.1 0.4 <0.1 0 Sample 13 1.4 18 0.6 1.7 6.8 2.1 1.1 0 Sample 14 1.2 13 0.6 1.1 3.0 <0.1 <0.1 0 Sample 15 1.3 8.7 0. 2 0.7 2.8 <0.1 <0.1 0 Sample 16 1.8 8.7 0.2 0.6 2.3 <0.1 0.9 0 Sample 17 0.4 2.4 0.4 <0.1 2.6 <0.1 <0.1 0 Sample 18 1 1.4 1 3.2 1 0.5 1 <0.1 1 2.9 1 <0.1 I <0.1 0 tU' 4tW WO 98/10046 PCT/AU97/00572 12 As can be seen from the results in Table 7, a significant reduction of the content of most pesticides in the wool grease was achieved in sample 7 (180"C for 15 minutes). Substantially all pesticides were removed in sample 2 2 0"C for 60 minutes).

The -acid values on the samples were also carried out and the results are shown in Table 8.

Table 8 Acid values on wool grease Acid value test 2 3 Sample Raw wool grease Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10 Sample 11 Sample 12 Sample 13 Sample 14 Sample 15 Sample 16 Sample 17 Sample 18 8.04 7.67 7.88 7.91 7.66 '7.70 7.23 7.59 7.56 7.39 8.65 8.06 9.27 9.08 9.59 9.76 10.55 10.61 10.62 8.08 7.81 7.91 7.84 7.70 7.52 7.45 7.56 7.23 7.32 8.42 8.02 9.03 9.17 9.71 9.66 10.50 10.61 10.73 0 7.61 7.65 7.34 10.58 An acid value is an indicator of the oil character of grease. The results shown in Table 8 indicate that the process according to the present invention does not adversely effect the characteristics of wool grease.

WO 98/10046 PCTIAU97/00572 13 Production of Lanolin from Wool Grease Figure 1 shows a flow chart of a wool grease refining process incorporating the method of the present invention. The steps of the refining process are labelled 1 to 10. The wool grease is irradiated with microwave energy and heated to about 200 0 C (step 1) such that the pesticides are substantially removed from the wool grease. The treated wool grease is cooled to 180'C (step 2) then mixed with hexane and water to form a mycelate (step The mixture is then treated with hot alkali in the form of sodium hydroxide to remove free fatty acids (step The partially treated wool grease is then acidified to pH 4 (step then bleached using sodium chlorate and hydrogen peroxide mixture (step After bleaching, sodium hydroxide is used to neutralise and wash the bleached wool grease (step 7).

The water is then removed by decanting (step 8) and the organic phase (hexane) containing the lanolin is retained. The hexane is removed by distillation using microwave energy to heat the hexane and lanolin mixture (step Finally, water is added and stirred vigorously (step 10) to form lanolin.

The final lanolin product contained no detectable levels of pesticides and met the regulatory requirements for lanolin.

It will be appreciated that the pesticide removal step could also be incorporated during- the wool grease refining process shown in Figure 1.

Furthermore, thile method of the present invention is suitable for use prior to or during other wool refining processes to replace the pesticide removal and destruction steps presently used by the industry.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (12)

1. A method of removing pesticides from a natural oil/grease product containing pesticides comprising treating the natural oil/grease product with microwave energy such that the natural oil/grease product is heated to a temperature greater than-about 120 0 C for sufficient time to cause at least some of the pesticides to be substantially removed.

2. The method according to claim 1 wherein the natural oil/grease product is heated to a temperature between 140°C and 300 0 C.

3. The method according to claim 2 wherein the natural oil/grease product is heated to a temperature between 160 0 C and 250 0 C.

4. The method according to claim 3 wherein the natural oil/grease product is heated to a temperature between 180°C and 240 0 C. The method according to claim 4 wherein the natural oil/grease product is heated to a temperature 200°C and 220°C.

6. The method according to any one of claims 1 to 5 wherein the time of treatment is from 5 to 60 minutes.

7. The method according to claim 6 wherein the time of treatment is from 15 to 30 minutes.

8. The method according to any one of claims 1 to 7 wherein the pesticide is an organophosphate and/or organochloride pesticide.

9. The method according to any one of claims 1 to 8 wherein the natural oil/grease product is selected from the group consisting of natural and essential oils from plants, fish oils, and animal oils and greases. The method according to claim 9 wherein the natural oil/grease product is wool grease.

11. The method according to claim 10 wherein the wool grease is obtained from sheep.

12. A natural oil/grease product treated by the method according to any one of claims 1 to 11 wherein the natural oil/grease product being substantially free of pesticide contamination.

13. The natural oil/grease product according to claim 12 being wool grease.

14. Lanolin substantially free from pesticide contamination obtained from treated wool grease according to claim 13. F