EP3772923A1

EP3772923A1 - Method and plant for purifying wax of animal origin from undesired chemicals

Info

Publication number: EP3772923A1
Application number: EP19721111.3A
Authority: EP
Inventors: Michela BOI; Massimo CAPOBIANCO; Roberto Colombo; Maria Luisa NAVACCHIA
Original assignee: Consiglio Per La Ricerca In Agricoltura E L'analisi Dell'economia Agraria; Consiglio Nazionale delle Richerche CNR
Current assignee: Consiglio Per La Ricerca In Agricoltura E L'analisi Dell'economia Agraria; Consiglio Nazionale delle Richerche CNR
Priority date: 2018-03-30
Filing date: 2019-03-29
Publication date: 2021-02-17
Also published as: WO2019186487A1; IT201800004155A1

Abstract

A method of purifying wax of animal origin from undesired chemicals, comprising the steps of: providing a certain amount of wax of animal origin to be purified; mixing the wax of animal origin with water and optionally air or gas or a mixture of gases, in a ratio from 10 to 40% w/w of wax, thus obtaining a multi-phase mixture of water, wax of animal origin and optionally air or gas(es); heating said multi-phase mixture until a temperature between about 80 °C and 100 °C is reached and maintaining said mixture under continuous stirring conditions; causing degradation of the undesired chemical contained in the wax by UV irradiation possibly catalyzed (TiO2 et al.) or caused by addition of reagents such as H2O2 or ozone; removing the degraded undesired chemical from the multi-phase mixture by applying a compressed air or gas flow, or by phase separation of the multi-phase mixture; separating the purified wax of animal origin from the multi-phase mixture.

Description

METHOD AND PLANT FOR PURIFYING WAX OF ANIMAL

ORIGIN FROM UNDESIRED CHEMICALS

Technical Field

The present invention relates to a method and a plant for purifying wax of animal origin from undesired chemicals. More precisely, the present invention relates to a method and a plant for removing contaminants or undesired organic compounds, such as plant treatment chemicals, pesticides or pollutants from beeswax and other waxes of animal origin. By the term“other waxes of animal origin” it is preferably meant lanolin, however, other waxes of animal origin can be, for example, Chinese wax and spermaceti. The following description refers to beeswax, however, the present invention is not limited to this kind of product, being also applicable to waxes produced by other animal organisms.

Prior Art

Beeswax is a wax of animal origin that is widely used in many fields exploiting beehive products. Artisan and industrial production of natural honey is, indeed, a well- established and economically important field in Italy and worldwide. In order ensure a good production of honey, good maintenance of beehives is necessary, to allow the bees to develop in good health and take care of pollen collection and honey production and storage within honey supers. For the purpose of promoting this process, it is a widespread practice to insert, inside the beehives, pre-formed honey supers, usually comprising wax sheets fitted on frames and intended to collect the honey produced by the bees. It is deemed that the bees, freed from the need to build honeycombs, can spend more time in collecting nectar and are therefore more productive, with a yield typically comprised between about 6 and 12 kg of honey pro kg of provided wax.

Many of these wax sheets are, however, damaged during the step of honey recovery. Others must in any case be replaced in order to ensure proper hygiene inside the beehives. For these reasons, the beekeeper must replace the wax sheets every two/three years.

These pre-formed wax sheets are made industrially by molding the wax recovered from old frames. The wax recovered from old frames, before being suitable for re-use, must be cleaned from debris and contaminants that have accumulated over time. This process is carried out by simple melting and resolidification of wax inside hot water vessels. The wax, after melting in water, is used for preparing fresh wax sheets by solidifying it in suitable molds, by means of several techniques. This process allows to remove plant residues (leaves, branches, pollens) and soil, and it allows sterilization of the spores of paenibacillus larvae (a bacterium responsible for American foulbrood) which is by now endemic in several regions in the world, including Italy.

Another problem is the varroa destructor, an external parasitic mite that attacks the honey bees apis mellifera and apis cerana. Although the varroa mite cannot reproduce on such insects, these are a means for diffusing the mite within a short distance range, especially by means of foraging bees. The varroa mite, in fact, is capable of reproducing only inside a colony of honey bees and it is deemed that an extensive mite infestation brings the colony itself to death. The varroa mite is, therefore, the mite with the strongest economic impact in the beekeeping industry.

Beekeepers, in an attempt to fight the proliferation of this mite, generally use chemicals and particularly acaricides, which, over time, deposit within the wax in the frames, and said wax will thus be contaminated by these undesired chemicals. It is therefore evident that it is necessary to remove these contaminants, introduced in the beehives by foraging bees, from the wax of old frames, before it can be re-used for building fresh frames.

Unfortunately, the simple treatment, as described above, of melting and resolidification of wax inside hot water vessels is not sufficient in order to remove residues of undesired chemicals, which, due to their lipophilic nature, are poorly water-soluble. This brings about an inevitable, progressive accumulation of undesired chemicals (contaminants) inside the wax, with consequent reduction of the well-being and activity of the honey bees and possible contamination of the produced honey, with predictable consequences on the consumer’s health.

Like beeswax, lanolin is a wax of animal origin which is formed by long-chain fatty acid esters and alcohols and derives from the secretion of the sebaceous glands of sheep and accumulates on their wool fleece. It is obtained by extraction and purification from wool. Lanolin melts at 35-40 °C and has good miscibility with water, whereby it is widely used in preparing waxes for protecting wood and hides, but, in particular, it is widely used as emollient in cosmetics (and also as food additive E913). Sheep spend most of their time grazing on fields, and all the pollutants present in the environment (plant treatment chemicals and atmospheric pollutants) accumulate on their fleece; in addition to these, there are also the veterinary drugs that are used by breeders in order to prevent infections by mites such as ticks and louses. As these pollutants are of lipophilic nature, they inevitably accumulate in lanolin, and conventional techniques, based on centrifugation, filtration and fractioning with solvents, for purifying this product are not always sufficient to guarantee removal of these pollutants from lanolin. In order to safeguard public health, the official pharmacopeia (9.0 edition) requires that the residues of organic pollutants in lanolin be particularly low: <0,05 ppm (parts per million) for each organochlorinated pesticide, <0,5 ppm for any other pesticide, and < 1 ppm as a sum of all pesticides.

The need to find a method capable of removing the aforementioned undesired chemicals from beeswax, lanolin and other waxes of animal origin is therefore obvious.

Documents W0200200038, CN103181504 and CN103181735 describe methods for removing pesticides present on the external surface of vegetables and fruit. These methods consist of steps that provide for washing the food to be treated (vegetables and fruit), in aqueous solutions under ultraviolet (UV) irradiation, in order to generate hydroxyl radicals ( OH), which will degrade the pesticides present on the outer surface of the treated foods.

However, the aforementioned methods have the disadvantage of not being effectively applicable to animal waxes.

The simple washing of the wax in aqueous solutions under UV irradiation, with the generation of hydroxyl radicals, does not lead to the degradation of the contaminants present inside the wax, but only of those present on the external surface thereof. This is mainly due to the opacity of the wax to UV radiation, which opacity, in fact, shields the most internal contaminants from photodegradation.

An object of the present invention is therefore to provide a solution to the problem of how to purify animal waxes from undesired chemicals which does not have the disadvantages of prior art.

A further object of the invention is to provide a solution which allows to reduce the concentration of contaminants inside beeswax and lanolin in a simple and economical way, with obvious advantages for the health of operators and consumers for whom beehive products and lanolin-derived products are intended.

A not least object of the invention is to provide a method and a plant for removing undesired chemicals from waxes of animal origin, which can be industrially produced at low costs.

These and other objects are achieved by the method and the plant as claimed in the appended claims.

Disclosure of the Invention

The purifying method according to the present invention allows to remove undesired chemicals, or contaminants, in particular plant treatment chemicals, pesticides and environmental pollutants, from wax of animal origin, preferably beeswax or lanolin, and mainly comprises a step of photodegrading, either directly or through hydroxyl radicals (ΌH), a multi-phase mixture of wax of animal origin and water or another suitable fluid preferably having a melting temperature lower than that of the wax.

Preferably, according to the invention, the photodegradation takes place by irradiating with UV rays a biphasic system comprising water and wax of animal origin. According to a preferred embodiment of the invention, the irradiation of the biphasic system takes place in the presence of reagents or catalysts. Specific, but not exclusive, examples of reagents or catalysts suitable for this purpose are H2O2 and TiCk.

Still according to the invention, preferably, the biphasic water-wax system is obtained at a temperature of at least about 80 °C or higher. Advantageously, the temperature of at least 80 °C guarantees the workability conditions of the wax in the liquid phase.

According to a particular aspect of the invention, the biphasic system is advantageously made more transparent, i.e. less opaque, to UV radiation. Preferably, this condition of lower opacity of the biphasic system to UV radiation is obtained by effective mixing of the phases. According to the invention, a preferred method for obtaining the desired mixing of the phases involves subjecting the biphasic system to vigorous stirring. Still according to the invention, said vigorous stirring is preferably obtained by insufflating air or gas or a mixture of gases under pressure into the system, in order to cause bubbling of the constituents of the biphasic system. Other suitable means for causing the aforementioned vigorous stirring are for example ultrasounds, which can be used either separately or in combination with the aforementioned insufflation and mechanical stirring.

Advantageously, thanks to the method according to the invention, it is possible to reduce the pollution level of animal wax in a drastic and environmentally friendly manner. Such irradiation can advantageously take place during the melting of the wax, before the molding of the wax sheets, in the case of beeswax.

In a particular embodiment of the invention, the system on which the irradiation is performed is a multi-phase system consisting of water, liquid wax and air or gas or a mixture of gases. The multi-phase mixture is advantageously maintained in a condition of fine dispersion of the melted wax, to reduce opacity thereof to UV rays and to promote mixing thereof. The dispersion, in fact, allows the UV radiation to reach all parts of the mixture subjected to the treatment. Advantageously, the described condition of fine dispersion promotes the degradation of the contaminating compounds which have proved to be more easily attacked by UV rays, compared to the hydrocarbon chains of the wax.

Advantageously, in accordance with a particular embodiment of the invention, it is possible to increase the effectiveness of photodegradation by inducing, in the mixture, the production of hydroxyl radicals (ΌH) by adding small amounts of hydrogen peroxide or using suitable catalysts, such as for example Ti0₂.

The products originating from the degradation of the contaminating compounds are advantageously removed from the biphasic or multi-phase mixture, both because they are more volatile and because they are more hydrophilic than the starting compounds. The first condition makes it possible to remove the degradation products by means of air flows, and the second condition determines the separation of the degradation products from the wax when the latter separates from the water in the wax -water mixture and solidifies.

Undesired chemicals that the invention intends to purify from animal wax are mainly contaminating organic compounds, such as those deriving from the use of plant treatment chemicals and pesticides. Non-limiting examples for the purposes of the present invention are N-(2,4-dimethylphenyl)formamide indicated as 2,4-DMF, cymiazole, chlorfenvinfos, acrinathrin, bromopropylate, coumaphos, fluvalinate and flumethrin.

The method according to the present invention provides for mixing a certain amount of wax of animal origin with water and optionally with air or gas, or a mixture of gas, thus obtaining a biphasic or triphasic mixture, which for convenience will be referred to below as multi-phase mixture. According to the invention, the biphasic mixture of water and wax, or alternatively the triphasic mixture of water, wax and gas or a mixture of gases, is obtained in a ratio ranging from 10 to 40% w/w of wax. The air, gas or mixture of gases possibly introduced into the biphasic mixture will also preferably be preheated.

In a step of the method according to the invention, it is preferably provided to heat the multi-phase mixture, until the mixture reaches a temperature ranging from about 80 °C to 100 °C. Even more preferably, the multi-phase mixture is brought to a temperature of about 100 °C, this being, inter alia, the temperature imposed by law in the presence of ascertained parasitosis, since it is suitable for the sterilization of paenibacillus spores present in the wax.

The method according to the invention provides for preferably maintaining the multi phase mixture under continuous stirring during heating. Preferably, the multi-phase mixture is maintained under continuous stirring conditions, by blowing compressed air or gas into the mixture (bubbling). As an alternative or in addition to bubbling, the multi-phase mixture is maintained under continuous stirring conditions by treating the mixture with ultrasounds or mechanical blades. Advantageously, the continuous stirring conditions and the maintaining of the mixture at a temperature from about 80 °C to about 100 °C allow the multi-phase mixture to be maintained with the wax in fine dispersion in the liquid phase and more transparent to UV radiation. Advantageously, the maintaining of the conditions of fine dispersion allows the UV radiation to reach all the parts of the wax mass, thus allowing the photodegradation of the existing contaminants not only on the external surface, but also in the entire mass of treated wax. Contaminants are, in fact, more susceptible to the effects of UV radiation than hydrocarbon chains in the wax.

According to the invention, the multi-phase mixture, preferably heated and maintained under continuous stirring conditions as mentioned above, is subjected to a photodegradation step.

The photodegradation can take place either directly, mainly by directly irradiating the multi-phase mixture with UV rays, and/or indirectly, mainly by the formation of hydroxyl radicals (OH) in the multi-phase mixture.

These radicals are particularly reactive and attack organic molecules leading to mineralization thereof, i.e. to a degradation of the organic substances up to the transformation into simple inorganic compounds. Unlike the lipophilic chains of wax, the contaminants are more easily attacked by these radicals. Induction of hydroxyl radical production in the mixture does not exclude simultaneous direct photodegradation.

According to the invention, the formation of hydroxyl radicals (ΌH) in the multi phase mixture is obtained thanks to the addition of a reagent, selected for example from H2O2 and O3, or thanks to a photocatalyst selected, for example, from the group comprising: T1O2, ZnO, CdS, Fe(CN)₆, G, preferably selected from T1O2 and ZnO, and by irradiating the mixture thus obtained with UV radiation.

The duration of irradiation depends on the time required for the photodegradation of undesired chemicals, such as plant treatment chemicals and pesticides.

Preferably, according to the invention, the UV radiation is generated by at least one UV lamp with high efficiency Hg vapors or by at least one low-pressure amalgam UV lamp.

In the method according to the invention, the products of the degradation of the contaminants are removed from the wax, both because they are more volatile than the starting compounds, and therefore eliminable by the application of an air flow, and because they are more hydrophilic than the starting compounds, and therefore eliminable by phase separation: with the separation of the phases of the multi-phase wax/water mixture the degradation products of the contaminants remain inside the aqueous phase, thus separating from the wax.

Still according to the invention, it is provided that the wax of animal origin purified from the contaminants be separated from the multi-phase mixture. Preferably, the separation can be carried out by interrupting the introduction of gas(es) and/or the possible mechanical stirring, thus interrupting the conditions of continuous stirring, in order to allow the natural separation of phases due to the wax/water immiscibility. The still-melted or semi-solid separated wax can be either directly sent to molding of the wax sheets or poured into suitable molds in order to be cooled and stored. Alternatively, it will be possible to completely cool down the wax before removing it from the water. According to an alternative embodiment of the method according to the invention, the wax, separated from the liquid substance of the multi-phase mixture, is dried in an oven prior to being destined for final use. The duration of the drying step will preferably be between 16 and 140 hours, at a temperature ranging from room temperature to about 50 °C. In a variant of the method, it will be possible to carry out the separation of phases by melting in a water bath. In another variant, it will be possible to filter the multi-phase mixture on suitable filters permeable to water, but not to wax of animal origin, so as to separate the purified wax from the washing water.

The present invention also relates to a plant for purifying animal wax from undesired chemicals.

In a preferred embodiment of the invention, the plant mainly comprises a reactor, in which a reaction chamber is defined, and means for causing degradation of undesired chemical compounds present in a certain amount of wax of animal origin contained in the reaction chamber. According to the invention, the means for causing degradation of undesired chemical compounds preferably comprise at least one UV lamp, for example a mercury vapor or low-pressure amalgam UV lamp. Said at least one lamp is also preferably housed inside the reaction chamber. According to the invention, there are also preferably provided a number of UV lamps proportional to the volume of the reaction chamber, so that substantially the whole volume of the reaction chamber is covered by the flow of UV rays produced by the lamps. For example, for a cylindrical reactor equipped with a reaction chamber having a diameter of about 80 cm and a height of about 80 cm, between five and ten UV lamps are preferably provided, and even more preferably seven UV lamps.

In a preferred embodiment of the invention, the reaction chamber is associated with a heating device which has the purpose of keeping the substance contained in the chamber at the desired temperature, preferably between about 80 °C and about 100 °C. According to the invention, the heating device can consist, for example, of a thermostatic jacket surrounding the reaction chamber and in which a carrier fluid circulates through a hydraulic circuit functionally connected to a thermostat.

According to the invention, the reaction chamber comprises a wall preferably having a porous membrane. Preferably, the reaction chamber extends vertically and the wall provided with a porous membrane defines the lower base of the reaction chamber. Said wall provided with a porous membrane also separates the reaction chamber from a volume defined inside the reactor. The porous membrane is provided primarily for the entry of air, or gas, or a mixture of gases under pressure, into the reaction chamber to cause stirring, by bubbling, of the multi-phase mixture housed in the reaction chamber, in which the wax of animal origin that must be purified is dispersed. For this purpose, the volume defined inside the reactor is connected to a pressurized air transport line, preferably equipped with a shut off valve, for adjusting and possibly interrupting the flow of air or gas or mixture of gases directed to the reaction chamber through the porous membrane. Said volume is also preferably provided with an inclined bottom and comprises a discharge valve for evacuating the liquid possibly penetrated through the porous membrane.

The reactor is also preferably provided with a condenser element for condensing the vapors escaping from the reaction chamber and for letting out air and gas. The reaction chamber is also preferably provided with an openable or removable wall or lid and with possible openings for withdrawing and/or introducing substances from/into the reaction chamber. Examples of said substances are reagents such as H2O2 and O3, and catalysts such as T1O2, ZnO, CdS, Fe(CN)₆, G.

In a preferred embodiment of the invention, the lid is arranged on the opposite side with respect to the porous membrane in the reaction chamber and is fixed to the reactor for example by means of fixing clamps or it can be hinged to the reactor and closed by at least one clamp. The main function of the lid is to allow the substance to be degraded to be introduced into the reaction chamber and the purified wax to be removed at the end of the purification process. The reactor and the lid can be made of various materials, for example steel or other metal alloys. The cover can also be made of transparent material, for example transparent pyrex, in order to make the contents of the reaction chamber visible. Optionally, the reactor can also be equipped with an inspection window for checking the contents of the reaction chamber.

In a preferred embodiment of the invention, the at least one UV lamp is fixed under the lid, so that when the lid is removed, the lamp is simultaneously extracted from the reaction chamber. In addition, still with reference to this preferred embodiment of the invention, the lid is provided with at least one of said openings for the introduction of substances into the reaction chamber and comprises a connection for connecting the condenser element. Advantageously, in this preferred embodiment, the lid is provided with a plurality of through-connections, which can be used for fixing corresponding UV lamps, for fixing the condenser element and for defining said opening for the introduction of substances.

In a preferred embodiment of the invention, the reactor comprises a substantially cylindrical lateral surface comprising, in turn, a first end integral with said at least one porous base, and a second end closable with said closure element or lid. Under working conditions, the reactor is also preferably arranged with its longitudinal axis arranged vertically and with the porous base and the lid both substantially horizontal.

The reaction chamber is also possibly provided with at least one discharge valve for discharging the melted wax out of the reaction chamber. When more than one discharge valve is provided, the discharge valves are preferably located at different distances from the porous membrane which defines the lower base of the reaction chamber, for taking out portions of the substance contained in the reaction chamber which are at different distances from said porous membrane.

According to the invention, the at least one internal reaction chamber is capable of receiving a multi-phase mixture of wax of animal origin containing a certain amount of undesired chemical and water, having a ratio preferably ranging from 10 to 40% w/w of wax.

The plant and the method according to the present invention preferably require that the multi-phase mixture be continuously and vigorously stirred during the steps of treatment of the wax of animal origin. Maintaining the multi-phase mixture under conditions of continuous stirring guarantees, in fact, that the UV radiation can reach the whole mass of the treated wax of animal origin, not only the external surface thereof, thus determining a greater performance in the degradation, and in particular in the photodegradation, of the contaminants present inside said mixture. In order to further promote stirring, the reaction chamber may optionally be equipped with means for moving and stirring the multi-phase mixture. Said means may comprise, for example, mechanical means such as motorized mobile blades.

Advantageously, moreover, the method and the plant according to the present invention not only allow the purification of animal wax from undesired chemicals, but also allow, by means of the degradation of the undesired chemical contained in the wax, to cause discoloration and/or deodorization of the treated wax of animal origin. This represents an advantage, as these are features that are required for some applications (such as those using beeswax as a food additive (E901) or for the preparation of cosmetics).

Brief Description of the Figures

A preferred embodiment of the invention is given by way of non-limiting example with reference to the annexed figures, in which:

Fig. 1 shows a front sectional view of a plant according to the present invention;

Fig. 2 shows a front sectional view of a component of the closing element of the plant of Fig. 1.

Description of a Preferred Embodiment

Referring to the annexed figures, the plant for purifying beeswax from undesired chemicals according to the invention has been indicated as a whole with reference 11.

The plant 11 comprises a reactor 13 having an air-permeable and/or gas-permeable porous base 15, functionally connected to a regulator 17 for the flow of a compressed air line l7a. The reactor 13 further comprises a lateral cylindrical surface 19 comprising, in turn, a first end 21 integral with the porous base 15, and a second end 23 that can be closed by means of a lid 25. The lid 25 and the second end 23, or upper end of the reactor 13, are firmly connected to each other by means of clamps 51 clamping corresponding peripheral flanges.

The porous base 15, the lateral surface 19 and the lid 25 define among them a reaction chamber 27 in fluid connection with a condenser or cooling column 30, for letting out air/gas from the chamber 27 and for recovering water by condensation. In the illustrated embodiment, the column 30 is attached outside the lid 25 by means of a corresponding threaded connection that passes through the lid 25.

The reactor 13 further comprises a thermostatic jacket 29 externally surrounding the lateral surface 19, and seven UV lamps 31 fed by an electric circuit provided with electric wires 45. In the shown embodiment, the lamps 31 are low-pressure amalgam UV lamps mounted inside the chamber on an inner component or insert 26 of the lid 25 by means of suitable threaded connections and protected by suitable jackets transparent to UV radiation.

When the lid 25 is closed against the upper end 23 of the lateral surface 19 of the reactor 13, the lamps 31 are therefore housed within the inner reaction chamber 27.

The reactor 13 further comprises a first valve 33a in flow connection with a collecting volume or chamber 44 arranged in the lower part of the reactor 13, under the porous base 15, and a second valve 33b in flow connection with the reaction chamber 27. Both valves 33a and 33b are provided laterally through the lateral surface 19 of the reactor 13.

The first discharge valve 33a is arranged adjacent to a transverse partition 43 closing the collecting chamber 44 in its lower part. The partition 43 is inclined by about 2-5° relative to a plane perpendicular to the longitudinal axis of the reactor and to the horizontal plane defined by the porous base 15. A volume 44, which also has the function of a collecting tank with an inclined bottom and in which the liquid that may have passed through the porous base by gravity is collected, is thus defined between the porous base 15 and the transverse partition 43.

Said first discharge valve 33a is located at the portion of the inclined partition 43 distal to the porous base 15 and diametrically opposite to the regulator 17 for the compressed air or gas line l7a through which the compressed air or gas is introduced into the collecting volume or tank 44. The second discharge valve 33b is instead located on the opposite side of the porous base 15 with respect to the discharge valve 33a at a certain distance from the porous base 15. Said discharge valve 33b is provided on the lateral surface 19 between the porous base 15 and the second upper end 23 of the lateral surface 19 and allows the melted wax to be discharged from the reaction chamber 27.

As better shown in Fig.2, the internal component 26 of the lid 25 has a convex shape facing outwards when the lid is closed, and comprises a set of connections 35 to allow the connection of the UV lamps 31 inside. The lid 25 further comprises a first connection 36a to allow connection of the condenser 30 arranged outside the lid 25. In addition, the lid 25 is provided with a second connection 36b which can be closed by a threaded plug or is provided with a tap and is used as a passage channel for introducing substances into the chamber 27, preferably with the aid of a funnel 41.

In the illustrated embodiment, the reactor 13 comprises a control window 49 for controlling the internal reaction chamber 27 from the outside. Said window 49, in fact, passes through both the thermostatic jacket 29 and the lateral surface 19 in a radial direction, thus allowing the contents of the reaction chamber 27 to be controlled from the outside. In a preferred embodiment of the method according to the invention, the wax to be purified is placed in the inner reaction chamber 27. More precisely, the wax is placed in said chamber 27, on the porous base 15 of the reactor 13. Inside the reaction chamber 27, the wax is mixed with 120 ml of deionized water, thus obtaining a biphasic mixture of water and beeswax. The regulator 17 for the flow of the compressed air line l7a functionally connected to the porous base 15 is opened to cause the insufflation of compressed air into the multi phase mixture through the porous base 15, thus obtaining bubbling of the mixture. The multi phase mixture is kept under conditions of continuous stirring thanks to the insufflation of air. During this continuous stirring step, the thermostatic jacket 29 which externally surrounds the lateral surface 19 of the reactor 13 is brought to a temperature of 100 °C, thus maintaining the inner reaction chamber 27, and therefore the multi-phase mixture contained therein, at a temperature of about 100 °C. The continuous stirring conditions and the maintaining of the temperature at 100 °C allow to maintain said multi-phase mixture with the wax in a finely dispersed state.

The closure element 25 provided with seven low-pressure amalgam UV lamps 31 is connected to the second end 23 of the lateral surface 19 of the reactor 13, so as to house the seven UV lamps inside the inner reaction chamber 27 of the reactor 13 and thus close the inner reaction chamber 27.

The reactor 13 is equipped with a cooling column 30, in which a cooling fluid is circulated. The cooling column 30 allows, during purification, the escape of compressed air from the inner reaction chamber 27 and the recovery, by condensation, of water molecules that may have evaporated due to the temperature being maintained at 100 °C inside the chamber 27.

The seven low-pressure amalgam UV lamps 31 are activated, thus directly irradiating the multi-phase mixture with ultraviolet radiation for the necessary period of time (indicatively at least one hour, preferably for a period of time between one and sixteen hours, even more preferably for a period of time between one and four hours) to photodegrade the existing organic contaminants, thus making them more volatile or more water-soluble. The duration of irradiation depends on the grade of contamination of the beeswax, the nature of the contaminants, the power of the UV lamp, the geometry of the reactor and the grade of stirring.

The regulator 17 for the flow of the compressed air line l7a is kept open to blow compressed air into the multi-phase mixture, so as to remove the photodegraded contaminants from the multi-phase mixture. Those contaminants that are made more volatile by photodegradation will be removed from the multi-phase mixture by means of the flow or compressed air that is guided though the multi-phase mixture, whereas those that are made more water-soluble will remain in the water at the end of the treatment. The flow of compressed air, charged with photodegraded contaminants, exits the inner reaction chamber 27 through the cooling column 30, whereas the water vapor is recovered by condensation inside the cooling column 30.

After elapse of the necessary time (for example, about four hours) in which the multi phase mixture is subjected to irradiation with ultraviolet radiation, the regulator 17 for the flow of the compressed air line l7a is closed. The discharge valve 33b is opened to connect the reaction chamber 27 with the external environment and allow the purified multi-phase mixture to be evacuated. The separation of purified beeswax from the multi-phase mixture takes place by natural separation of phases due to wax/water immiscibility.

In accordance with another embodiment of the invention, the removal of contaminants from beeswax takes place by steps equivalent to those described with reference to the first embodiment, except that the following step is also provided: through the connection 35 provided on the closure element 25 of the reactor 13, before activating the seven low-pressure amalgam UV lamps 31, T1O2, or hydrogen peroxide or ozone, is added to the multi-phase reaction mixture contained in the chamber 27. Irradiating Ti0₂ with UV rays in water, being Ti0₂ a photocatalyst, catalyzes the generation of hydroxyl radicals ( OH), which, being particularly reactive, attack the molecules of the organic contaminants, thus degrading them. Hydrogen peroxide or ozone are instead chemical reagents (consumables) which react with UV radiation to generate hydroxyl radicals, or radical oxygen, which propagate through the multi-phase mixture and degrade organic pollutants.

At the end of the irradiation with UV rays, once the regulator 17 for the flow of the compressed air line l7a is closed, the reactor is cooled so as to bring the multi-phase mixture to about room temperature, so as to induce a phase separation between water and beeswax purified from contaminants. Ti0₂ precipitates to the bottom of the aqueous phase, thus separating from the wax. Once the phase separation is complete, the aqueous phase is evacuated from the reactor by means of the valve 33b and the purified beeswax can be extracted from the internal reaction chamber in a semi-solid state, with the aid of a scraper.

The results of experiments carried out in the laboratory and obtained by applying the method of present invention to real samples of beeswax containing plant treatment chemicals are shown below. The experiments were conducted in a laboratory reactor having a volume of approximately 250 ml, equipped with a porous base for blowing air, and a quartz heating and comprising a 125 Watt mercury vapor UV lamp.

Experiments 1 to 6 refer to samples of commercial beeswax (contaminated due to acaricide treatments applied by beekeepers).

Experiment 1 : 5 g beeswax, 120 ml deionized water, 4-hour irradiation.

Experiment 2: 5 g beeswax, 120 ml deionized water, 100 mg T1O2 in the form of microbeads, 4-hour irradiation.

Experiment 3: 5 g beeswax, 120 ml deionized water, 2-hour irradiation.

Experiment 4: 5 g beeswax, 120 ml deionized water, l-hour irradiation.

Experiment 5: 5 g beeswax, 120 ml deionized water, 100 mg di Ti0₂ in the form of microbeads, 2-hour irradiation.

Experiment 6: 5 g beeswax, 120 ml deionized water, 100 mg di Ti0₂ in the form of microbeads, l-hour irradiation.

Table 1 summarizes the results obtained for Experiments 1 to 6.

Experiments 7 to 12 refer to samples of beeswax contaminated with 5 mg/kg of the main acaricides used in beekeeping.

Experiment 7: 5 g beeswax, 120 ml deionized water, 2-hour irradiation.

Experiment 8: 10 g beeswax, 120 ml deionized water, 2-hour irradiation.

Experiment 9: 18,2 g beeswax, 150 ml deionized water, 2-hour irradiation.

Experiment 10: 18,2 g beeswax, 200 mg di Ti0₂, 150 ml deionized water, 2-hour irradiation. Experiment 11 (blank): 18,13 g beeswax, 150 ml deionized water heated to 85°C for 3 hours without UV irradiation. (The recovered wax was again diluted in 50 ml deionized water and recovered after cooling overnight in order to allow optimal separation of the phases).

Experiment 12: 18,20 g beeswax, 4 x 3,75 mg di H₂0₂, 150 ml deionized water, 2-hour irradiation (100 mΐ H₂0₂ at 30% by weight were diluted with 900 mΐ water. At time t=0, t=30, t=60, t=90 minutes, 125 mΐ of 3% H₂0₂ solution diluted in 2-3 ml deionized water are added. At the end of the irradiation the multi-phase mixture was poured into a beaker for the solidification of the wax and the separation of the aqueous phase).

Table 2 summarizes the results obtained for Experiments 7 to 12. Table 1

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C/I

Experiments carried out in the laboratory and obtained by applying the method of the present invention to samples of lanolin containing plant treatment chemicals are instead reported below. The analyzed lanolin samples are samples of commercial anhydrous lanolin charged with plant treatment chemicals at a concentration of 5 ppm (mg/kg). The experiments were carried out in a laboratory reactor having the same features as the plant described with reference to Figs. 1 and 2, having a volume of about 250 ml, a porous base for blowing air and a quartz heating jacket and comprising a 125 Watt mercury vapor UV lamp.

Experiment L0: lanolin sample not charged with plant treatment chemicals.

Experiment Ll : lanolin sample charged with plant treatment chemicals at a concentration of 5 ppm.

Experiment L2: 20 g lanolin (charged with plant treatment chemicals at a concentration of 5 ppm) in 150 ml milli-Q water were irradiated for 3 hours in the above- described reactor at a temperature of 50°C under air-blowing. At the end of the irradiation the air-water mixture was separated while still hot and allowed to cool slowly in a beaker. The water (lower phase) was removed by simple discharging (lanolin remains adherent to the beaker). The recovered lanolin was dried in an oven at 50 °C for 16 hours. Lanolin recovery 20,25 g.

Experiment L3: 40 g lanolin (charged with plant treatment chemicals at a concentration of 5 ppm) in 130 ml milli-Q water, were irradiated for 3 hours in the above-described reactor at a temperature of 50°C under air-blowing. At the end of the irradiation the air-water mixture was separated while still hot (40-45 °C) and allowed to cool to room temperature in a beaker. The water (lower phase) was removed by simple discharging (lanolin remains adherent to the beaker). The recovered lanolin (45 g) was dried in an oven at 50 °C for 16 hours.

Experiment L4: 20 g lanolin (charged with plant treatment chemicals at a concentration of 5 ppm) in 150 ml milli-Q water were heated for 3 hours in the above-described reactor at a temperature of 60°C under air-blowing. In this experiment there was no irradiation step. At the end of the heating the air-water mixture was separated while still hot and allowed to cool slowly in a beaker. The water (lower phase) was removed by simple discharging (lanolin remains adherent to the beaker). The recovered lanolin (23,76 g) was dried in an oven at 50 °C for 16 hours.

Table 3 summarizes the results obtained for Experiments L0 to L4. Table 3

nf = not found

ppm = mg/Kg

(D%) = percentage variation relative to sample LI

* the presence of this pesticide, banned in European countries, exemplifies the degree of pollution present in commercial lanolin, although for non-pharmaceutical use.

The experiments performed and the analysis of the results obtained show that it is possible to effectively remove the residues of undesired chemicals, in particular deriving from the use of plant treatment chemicals and pesticides in agriculture, by using the method according to the invention. The removal of said residues has proved effective in the case of direct degradation of the biphasic or multi-phase mixture containing polluted animal waxes, but it can be made faster by generating hydroxyl radicals by adding a catalyst.

The plant and the method according to the invention as described and illustrated are capable of numerous variants and modifications falling within the same inventive principle.

Claims

1. Method of purifying wax of animal origin from undesired chemicals, comprising the steps of:

providing a certain amount of wax of animal origin to be purified;

mixing the wax of animal origin with water or another suitable fluid and optionally air or gas or a mixture of gases, thus obtaining a multi-phase mixture of water, wax of animal origin and optionally air or gas(es);

heating said multi-phase mixture and maintaining said mixture under continuous stirring conditions;

causing degradation of the undesired chemical contained in the wax;

removing the degraded undesired chemical from the multi-phase mixture by applying a compressed air or gas flow, or by phase separation of the multi-phase mixture; separating the purified wax of animal origin from the multi-phase mixture.

2. Method according to claim 1, wherein said wax of animal origin is beeswax or lanolin.

3. Method according to claim 1 or 2, wherein said multi-phase mixture comprises wax of animal origin in a ratio from 10 to 40% w/w of wax.

4. Method according to any of the preceding claims, wherein heating of the multi-phase mixture is carried out until a temperature between about 80°C and l00°C is reached.

5. Method according to any of the claims 1 to 4, wherein the step of maintaining the multi phase mixture under continuous stirring conditions comprises the step of insufflating compressed air or gas into the mixture (bubbling) or subjecting the mixture to a treatment with ultrasounds, or a combination of both (bubbling and ultrasounds), in order to maintain the multi-phase mixture under continuous stirring conditions.

6. Method according to any of the preceding claims, wherein the step of causing degradation of the undesired chemical comprises the step of irradiating said multi-phase mixture with ultraviolet (UV) radiation in order to cause photodegradation of said undesired chemical.

7. Method according to claim 6, wherein the irradiating step has a duration of at least one hour.

8. Method according to claim 7, wherein the irradiating step has a duration comprised between one and sixteen hours.

9. Method according to any of the preceding claims, wherein the step of causing degradation comprises the step of adding to the multi-phase mixture a reagent selected from H2O2 and O3, or a catalyst selected from T1O2 and ZnO and irradiating the mixture thus obtained with UV radiation, thus generating hydroxyl radicals (ΌH).

10. Method according to any of the preceding claims, wherein the step of separating the purified wax of animal origin from the multi-phase mixture comprises the step of interrupting the step of maintaining the multi-phase mixture under continuous stirring conditions in order to allow natural separation of the phases due to the wax/water immiscibility.

11. Method according to any of the preceding claims, wherein the step of causing degradation of the undesired chemical contained in the wax can determine discoloration and/or deodorization of the wax of animal origin.

12. Plant for purifying wax of animal origin, comprising a reactor (13), in which a reaction chamber (27) is defined receiving a multi-phase mixture of wax of animal origin, containing a certain amount of an undesired chemical, and water, and means (31) for causing degradation of the undesired chemicals present in a certain amount of wax of animal origin contained in the reaction chamber (27).

13. Plant according to claim 12, wherein the means (31) for causing degradation of the undesired chemicals comprise at least an UV lamp received within the reaction chamber (27).

14. Plant according to claim 12 or 13, wherein the reactor (13) further comprises a lateral surface (19) in which there is defined a first, lower end (21) closed by an air-permeable and/or gas-permeable porous base (15), functionally connected to a compressed air or gas line (l7a), and a second, upper end (23) that can be closed by means of a closure element (25); the porous base (15), the lateral surface (19) and the closure element (25) defining among them said reaction chamber (27); at least one UV lamp (31) integrally attached to the closure element (25) and housed within the reaction chamber (27) when said closure element (25) closes said upper end (23).

15. Plant according to any of the claims 12 to 14, wherein the reactor (13) further comprises a thermostatic jacket (29) externally surrounding the lateral surface (19), and wherein the thermostatic j acket (29) allows to maintain the reaction chamber (27) and therefore the multi phase mixture contained therein at a temperature from about 80°C to l00°C.