Method of extraction of natural wax

Abstract

This invention relates to a method of extraction of wax and more particularly, but not exclusively, the invention relates to extraction of surface wax from date palms. The method for producing wax from raw palm material comprises the steps of: heat treating the separated palm leaflets in a liquid; and drying the leaflets. Leaflets are then beaten, and wax is separated from the remaining residual material. Optionally the residual material is heated in a liquid between 80°C to 100°C and optionally boiled.

Description

[0001] METHOD OF EXTRACTION OF NATURAL WAX

[0002] Field of the Invention

[0003] This invention relates to a method of extraction of fibres and wax and more particularly, but not exclusively, the invention relates to extraction of textile fibres and surface wax from palm leaflets, such as textile fibres and wax from date palms.

[0004] Background

[0005] Date palms are mainly cultivated in the Middle East and North African regions. Typically, global harvests exceed 1 million hectares. The estimated annual byproducts of pruning date palms globally are around 5 million tons (air dry weight), in the form of frond and fruit stalks, leaflets and leaf sheath. These are often treated as agricultural waste.

[0006] Previous attempts to extract fibres from date palm leaflets were limited to milling them into small particles or manually slitting them into long strands with no attempt to remove the non-cellulosic impurities. These tended to be used traditionally in manufacture of fibre fill for cushioning.

[0007] As for the wax extraction, the majority of the palm wax extracted are from the Brazilian carnauba palm and only one published research article investigated the extraction of date palm leaflet wax using a complex supercritical carbon dioxide extraction method.

[0008] Some of these are described in the documents mentioned below.

[0009] Prior Art

[0010] International patent application W02023007223A1 (NAMA WOMEN ADVANCEMENT ESTAB) discloses a method of fibre extraction from palm, using a biological degumming process employed to loosen the date palm leaves structure. The degumming process comprises the steps of retting in warm using a biological enzyme (Laccase). The degumming temperature is from 25°C to 60°C and the degumming treatment time is from 2h to 24h.

[0011] United States patent application US 11370953B2 (SAUDI ARABIAN OIL CO) discloses a method of preparation of date tree waste-based lost circulation material (LCM). The date tree waste LCM may include fibres from the date tree waste produced from processing date trees in the production of date fruits. The date tree waste may include fibres from one or more of the following: date tree trunks, date tree rachis, date tree leaflets, date tree panicles, and date tree roots. The date tree waste LCM may include fibres having lengths in the range of 5 millimeters (5 mm) to 15 mm, diameters in the range of 0.5 mm to 0.8 mm and having an aspect ratio range of 6 to 30.

[0012] Japanese patent application JP2020532607A ( t^^ discloses a method of making of date palm fibre blend lost circulation material (LCM) comprising a ternary blend of fibres made from date palm. Date palm fibre mixed LCM comprises date palm fibre made from date palm trunks, date palm leaves and leaf stem fibres made from date palm leaves and leaf stems, and date palm inflorescence fibres made from date palm inflorescences. The LCM comprises a mixture of 30% by weight date stem fibre, 30% by weight date palm leaf and leaf stem fibre, and 40% by weight date inflorescence fibre.

[0013] International patent application W02012108860A1 (BROWN LAURENCE B) discloses a method of making dental implement made from palm leaflet, the dental implement is usable as dental floss that can be manipulated while held in one hand includes an elongate body cut from dried palm leaflet. A dental implement in accordance with the present invention preferably consists only of dried palm leaflet. A leaflet is dried, and the dried leaflet is cut to the desired length and width to form the dental implement.

[0014] International patent application W02020139088A1 (SULTAN QABOOS UNIV) Preparation of high performance fibre from natural fibre (date palm) a method for preparation of high performance fibre from natural fibre (date palm), the method includes separating raw fibres from the natural fibre source and dewaxing the separated raw fibres with an alcoholic solution of ethanol and water for a predetermined time at a first predetermined temperature. The method further includes sterilizing the dewaxed fibres with an acidified salt solution at a second predetermined temperature and alkalizing the sterilized fibres with an alkali solution at a third predetermined temperature to generate the high- performance fibres.

[0015] United States patent application US 2013 / 0149512 A1 (ANANAS ANAM LIMITED) discloses natural non-woven materials.

[0016] A paper by Karima Al Bulushi, Thomas M. Attard, Michael North, Andrew J. Hunt, 2018 is entitled “Optimisation and economic evaluation of the supercritical carbon dioxide extraction of waxes from waste date palm (Phoenix dactylifera) leaves” and published in Journal of Cleaner Production, Volume 186, pages 988-996.

[0017] Chinese patent application CN 204079938U (ZHANG NAIQIONG) discloses a vegetable wax extraction system.

[0018] United States patent application US 2023 / 263182A1 (The State of Israel Ministry of Agriculture & Rural Development Agricultural Res Organization) discloses compositions isolated from date palm trees.

[0019] United States patent application US 2021 / 403828A1 (Jena Trading APS) describes a method for separating wax and fibers from plants.

[0020] International patent application WO 9516013A1 (PVP SA; JACOB MARC THEOPHILE) discloses a process for production of Carnauba wax.

[0021] None of the above techniques were capable of extracting long textile grade fibres from date palm leaflets or were able to extract surface wax.

[0022] An object of the present invention is to valorize large quantities of agricultural residues generated by palm, particularly date palm plantations and to extract long textile fibres from the leaflets and to extract the surface wax.

[0023] Summary of the Invention

[0024] According to a first aspect of the invention there is provided a method for producing wax from raw palm material comprising the steps of: a) heat treating the separated palm leaflets in a liquid; b) drying the leaflets; c) beating the leaflets; d) separating wax from the remaining residual material from c).

[0025] In some embodiments step a) comprises treating in the liquid between 80°C to 90°C.

[0026] Optionally step a) comprises boiling of the liquid. The duration of the heat treatment is typically from 30 minutes to 6 hours, preferably 1 to 5 hours.

[0027] The liquid may be water or a chemical solution.

[0028] Optionally the solution is an alkaline solution and / or includes surfactants, and / or acidic buffers.

[0029] In some embodiments step b) is performed until the moisture level drops below 15%. In some embodiments step b) the leaflets are dried until the moisture level drops below 15%.

[0030] In some embodiments step b) the leaflets are air dried in the shade for 1 -4 days then sun dried for 2 - 4 days.

[0031] In some embodiments step c) comprises passing the dry leaflets against a rotating beating blade.

[0032] In some embodiments following step c), an additional step of chopping pulverizing, or grinding the dried leaves.

[0033] In some embodiments step d) is performed by at least one of: manual screening, centrifugal air or flotation separation.

[0034] In some embodiments step e) is applied after d) and includes purifying the wax from the residual vegetable matter.

[0035] Preferably step e) includes heating the crude wax over its melting point; optionally with stirring.

[0036] In some embodiments, optionally step e) comprises dissolving and heating the wax in a solvent, optionally with stirring. In some embodiments, optionally step e) comprises heating the crude wax powder in a solvent, optionally with stirring.

[0037] Preferably the solvent is from the group comprising: petroleum ether, xylene, toluene, alkanes, alkaline hydrogen peroxide, ethyl acetate, acetone, benzene, naphthas, alcohols or any other nonpolar organic solvent.

[0038] The solvent extraction is performed using, but not limited to, a Soxhlet extractor, distiller, or CO2 extractor. In some embodiments including the step in step e), preferably any one or more of: active carbon, silica gel, activated clay and adsorbents are added to the melted wax or wax solvent mixture.

[0039] Optionally included in step e) is the step of filtration by passing the wax solution through paper, cloth, or membrane or by centrifugation.

[0040] In some embodiments a bleach step may be applied after step d) and / or e).

[0041] In some embodiments, the bleach is hydrogen peroxide, sodium hypochlorite, acids such as but not only hydrochloric acid, chromo-sulphuric acid, phosphoric acid, or ozone bleaching or clays such as fullers earth bleaching.

[0042] Some embodiments include an initial step of separating palm leaflets from palm fronds.

[0043] Preferred embodiments of the invention will now be described, by way of example only, and with refence to the Figures in which:

[0044] Brief Description of the Drawings

[0045] Figure 1 is a process flow diagram illustrating steps of extraction of textile fibres and surface wax from palm leaflets;

[0046] Figure 2 is a photograph of leaflet fibres morphology before degumming (left) and after degumming (right);

[0047] Figure 3 shows an image of palm leaflet fibres after scraping;

[0048] Figure 4 shows an image of palm leaflet fibres after degumming;

[0049] Figure 5 shows an image following wax extraction from a date palm leaflet and;

[0050] Figure 6 is an FTIR spectra of the resulting wax after the extraction method which indicates the quality of the extracted wax. Referring to Figure 6, the FTIR provides information about functional groups present in a sample based on the absorption of infrared light at different wavelengths. The leaflet wax, a natural wax, is composed mainly of fatty acids, and esters. The peaks around 2912 cm-1, 2848 cm-1, 1730 cm-1, and 1 169 cm-1are particularly indicative of the long-chain hydrocarbon structure of the wax and ester linkages. Some of the peaks at 2219 cm-1and 2132 cm-1may be due to impurities.

[0051] Methodology for Fibre Extraction

[0052] The method is shown diagrammatically as a series of steps in Figure 1 . Referring to Figure 1 , there is shown a process flow diagram for extraction of textile fibres and surface wax from palm leaflets.

[0053] Initial Preparation

[0054] The leaflets are separated from the date palm fronds either manually by hand, knife, or by using a mechanized system with blades to peel off the leaflets, which are then collected for further processing.

[0055] Pre-Soaking

[0056] Fresh green leaflets may be used directly for fibre extraction; however, pre-soaking may enhance the quality of the extracted fibres. Whereas, for dry leaflets they must be presoaked in water for 1 -5 days at room temperature or they might be boiled between 80°C to 100 °C to shorten the pre-soaking time and also enable the extraction of the surface wax.

[0057] Scraping

[0058] Palm leaflets are then scraped to remove the non-fibrous surface layer and facilitate the fibre extraction. The scraping action can be performed using a reciprocating blunt scraper along the length of the leaflets. It can also be performed using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary beater. In this case the leaflets are fed into the clearance 0.1 to 0.4 mm between the rotating scraping blades and the stationary beater, in one or multiple strokes from one or both ends. It is important that the scraping is performed while the leaflets are still moist.

[0059] In other embodiments, the scraping method includes feeding the leaflets between two feed rollers into a rotating cylinder with a saw tooth wire, that has a tooth pitch between 6 - 16 teeth per inch, a tooth angle between 40° - 60°, a tooth height 1.5 - 5 mm, and a wire thickness 0.4 - 1 mm.

[0060] Brushing

[0061] After scraping, the extracted fibres can be then brushed for further refinement and remove residual surface impurities. Brushing is performed by a rotating drum with multiple blunt blades or short metal combs, in which the fibres are held from one end and fed into the clearance between the rotating drum and a flat metal surface, in one or multiple strokes from one or both ends.

[0062] Degumming

[0063] The degumming is an optional step used to further remove intra and inter fibre bundles gum and fibrillate the bundles into smaller bundles and / or individual fibrils with less than 25pm diameter. This can be achieved by using an enzyme degumming process or chemical degumming process or a combination of both.

[0064] During the degumming process, an acidic pretreatment of the fibres is required. In embodiments, the fibres are heated in diluted sulfuric acid, or 0.2% phosphoric acid solution, or 0.1 M sodium phosphate buffer with pH ranging between 2 - 3 and the temperature ranging between 50 - 100°C and duration 0.5 - 3 hours.

[0065] In the enzyme degumming process, in preferred embodiments, the fibres are soaked for 6 hours in an acid pectinase enzyme solution, 4 g pectinase powder / 100 g dry fibres, in a treatment solution ratio of 1 :20, with enzyme activity 30,000 U / g at pH 4 and 50 °C while maintaining continuous agitation, for removing the pectin. In other embodiments, the fibres are boiled at 80 °C in 0.1 M sodium phosphate buffer pH 2:3 for at least one hour. After boiling, the fibres may be soaked for 24 hours in the sodium phosphate buffer at room temperature. The fibres are thoroughly rinsed with tap water after removing the fibres from the phosphate buffer. Afterwards, the fibres are soaked for 6 hours in an acid pectinase enzyme solution, 4 g pectinase powder / 100 g dry fibres, in a treatment solution ratio of 1 :20, with enzyme activity 30,000 U / g at pH 4 and 50 °C while maintaining continuous agitation, for removing the pectin.

[0066] Then the fibres are soaked in an enzyme solution of laccase and acid xylanase using 4 g enzyme powder / 100 g dry fibres, in a treatment solution ratio of 1 :20, with laccase activity 2,000 U / g and xylanase activity 100,000 U / g, at pH 4.8 for 10 hours with continuous agitation at 50 °C for first 2 hours, then raised to 60 °C for the remaining 8 hours, for removing the lignin and hemicellulose. The enzyme treatment can also be conducted in an enzyme mix containing all 3 enzymes; pectinase, laccase, and xylanase. After completing the enzyme treatment, the fibres are scoured in an alkaline solution of 2% including soda ash, sodium hydroxide, potassium hydroxide, or lye concentrate at temperature 80 °C for 2 hours.

[0067] In any of the previous steps the treatment may include surfactant such as Triton X-100 and / or chelating agent such as Ethylenediaminetetraacetic acid (EDTA). After the scouring process, the fibres are beaten using rotary serrated rollers, steel or wooden mallet or any combination thereof. Finally, the fibres are neutralized in a solution of 5% acetic acid for 30 mins at room temperature, then rinsed with tap water.

[0068] In the chemical degumming process, in preferred embodiments, the fibres are initially treated in a rich mix of alkaline pectinases enzyme solution, that may include but not limited to, polygalacturonases, pectin esterases, pectin lyases, pectate lyases, and rhamnogalacturonan lyases, at pH 8 - 9 and temperature 45°C - 80°C, for a duration of 2 - 48 hours depending on the treatment temperature.

[0069] Afterwards, the fibres are boiled at 90 - 100 °C for 2 to 3 hours in a solution containing 0.5 - 1 % Sodium hydroxide, 0.1 - 0.5% hydrogen peroxide, 0.3% Ethylenediaminetetraacetic acid, in addition to, 0.3% sodium silicate or 1% sodium sulfite, while maintaining continuous agitation. After completing the chemical treatment, the fibres are neutralized in a 5% acetic acid solution and then rinsed in water.

[0070] The fibres morphology before and after degumming is illustrated in Figure 2.

[0071] Drying

[0072] After washing, the fibres are dried to a moisture content of less than 20%, preferably less than 15%. The first step in the drying is either roll squeezing to remove as much water as possible or centrifugal dewatering using a mechanized drying system.

[0073] The second drying step involves air drying the fibres in open air for several days depending on the ambient conditions or oven drying at temperature 80°C until the moisture content drops below 15%. The resulting fibres at the end of the scraping method is shown in Figure 3, while the resulting fibres after the degumming method are shown in Figure 4.

[0074] Below is a Table which shows properties of the materials obtained using the abovementioned method steps.

[0075] Technical Data

[0076] Table 1 shows average properties of long textile fibres extracted from date palm leaflets after scraping and after degumming using the above methods.

[0077] It will be appreciated that variation may be made to the aforementioned embodiments, without departing from the scope of protection as defined by the claims.

[0078] For example, the method can also be used to extract long textile fibres from the leaflets of other palm species, including but not limited to washingtonia palm, oil palm, coconut palm, and sugar palm.

[0079] According to another aspect of the invention, there is provided a fibrous product derived using the aforementioned method.

[0080] Fibrous products produced according to the method may be used to make or incorporated in, a myriad different items or products, including: an item of clothing or footwear: a sheet of flexible material; items for use in automotive or construction, (such as boards or insulation panels) or rope or twine.

[0081] Methodology for Wax Extraction

[0082] The method is shown diagrammatically as a series of steps in Figure 1 .

[0083] Initial Preparation

[0084] The leaflets are separated from the date palm fronds either manually by hand, knife, or by using a mechanized system with blades to peel off the leaflets, which are then bundled for further processing.

[0085] Treatment

[0086] Fresh or dry leaflets may be boiled between 80°C to 100°C, preferably 80°C to 90°C, from 1 hour to 5 hours, either in water only or in a chemical solution which may include but is not limited to alkaline solutions, surfactants, or acidic buffers.

[0087] Drying

[0088] In embodiments, the leaflets are then air dried in the sun for 1 -4 days or inside an oven at 80 °C until the moisture level drops below 15%, other drying techniques can be applied such as using microwave. In a preferred embodiment, the leaflets are then air dried in the shade for 1 -4 days then sun dried for 2 - 4 days, until the moisture level drops below 15%.

[0089] Beating

[0090] After the leaflets become fully dry, they are then beaten to release the crude wax. Beating may be done manually by hand or mechanically by passing the dry leaflets against a rotating wooden or metal beating blade.

[0091] Leaflets chopping (optional)

[0092] Leaflets may be chopped to loosen more wax. The chopping may be performed using a rotary cutter, pulverizer, or grinder. Separation

[0093] A separation method is then applied to separate wax from any other residual vegetable matter or impurities. The separation method may include but is not limited to manual screening, centrifugal air flotation separations, or both.

[0094] Crude wax refinement

[0095] Refinement of the crude wax is done to purify the wax from the residual vegetable matter. This process may include but is not limited to 1 ) simply heating the crude wax over the melting point with continuous stirring to melt the wax 2) heating the crude wax powder in a solvent such as but is not limited to petroleum ether, xylene, toluene, alkanes, alkaline hydrogen peroxide, ethyl acetate, acetone, benzene, naphthas, alcohols or any other non-polar organic solvent. The solvent extraction is performed using, but not limited to, a Soxhlet extractor, distiller, or CO2 extractor.

[0096] In other embodiments, refinement of the crude wax is done to purify the wax from the residual vegetable matter. This process may include but is not limited to 1 ) simply heating the crude wax over the melting point with continuous stirring to melt the wax 2) dissolving and heating the wax with continuous stirring in a solvent such as, but is not limited to xylene, toluene, alkanes, alkaline hydrogen peroxide, ethyl acetate, acetone, benzene, naphthas, alcohols or any other non-polar organic solvent.

[0097] Bleaching (optional)

[0098] Bleaching may be done if needed to give a better appearance to the extracted wax. Chemical or other bleaching methods can be used such as hydrogen peroxide, sodium hypochlorite, acids such as but not only hydrochloric acid, chromo-sulphuric acid, phosphoric acid, Ozon bleaching or clays such as fullers earth bleaching.

[0099] Purification

[0100] After wax melting the melt or wax solvent mixture is purified by any purifying technique such as but not limited to 1 ) addition of adsorbents like active carbon, silica gel, activated clay, or any other adsorbent. 2) filtration by passing the wax solution through paper, cloth, or membrane. 3) centrifugation. Any of those techniques may be used separately or combined.

[0101] Mixing (optional)

[0102] Palm leaflets wax can be mixed with other additives or waxes to improve its properties like color, hardness, gloss, melting point, or any other needed properties to serve the final application. This process can be done after or before the cooling of the purified wax.

[0103] Cooling

[0104] Cooling of the wax may be done by any of the following methods but not limited to 1 ) air cooling by letting the wax air dry at room temperature or lower temperature, 2) cooling in a mold to produce well-shaped products, and 3) water cooling by exposing the wax melt to cold water.

[0105] Formation

[0106] Solidified wax can be formed into any required shape such as but not limited to powder, pellets, flakes, and blocks. The resulting wax at the end of the extraction method is shown in Figure 5. The FTIR spectra of the resulting wax after the extraction method is shown in Figure 6.

[0107] Technical Data

[0108] Table 2 Properties of surface wax extracted from date palm leaflets using the above method.

[0109] Above is a Table which shows properties of a material obtained using the abovementioned method steps.

[0110] It will be appreciated that variation may be made to the aforementioned embodiments, without departing from the scope of protection as defined by the claims.

[0111] For example, the method can also be used to extract surface wax from the leaflets of other palm species, including but not limited to washingtonia palm, oil palm, coconut palm, and sugar palm.

[0112] Wax products produced according to the method may be used to make or incorporated in a myriad different items or products, including use in food, cosmetics, automobiles and furniture wax and as a coating for dental floss.

Claims

Claims1 . A method for producing wax from raw palm material comprising the steps of: a) heat treating the separated palm leaflets in a liquid; b) drying the leaflets; c) beating the leaflets; d) separating wax from the remaining residual material from c).

2. A method as claimed in claim 1 wherein step a) comprises treating in the liquid between 80°C to 90°C.

3. A method as claimed in claim 2 step a) comprises boiling in the liquid.

4. A method as claimed in claim 1 to 3 wherein the duration of the heat treatment is from 30 minutes to 6 hours, preferably 1 to 5 hours.

5. A method as claimed in claim 2 to 4 wherein the liquid is water or a chemical solution.

6. A method as claimed in claim 5 wherein the solution is an alkaline solution and / or includes surfactants, and / or acidic buffers.

7. A method as claimed in claims 1 to 6 wherein step b) comprises drying the leaflets until the moisture level drops below 15%.

8. A method as claimed in claim 1 to 7 wherein step b) comprises the leaflets are air dried in the shade for 1 - 4 days then sun dried for 2 - 4 days.

9. A method as claimed in claims 1 to 8 wherein step c) comprises passing the dry leaflets against a rotating beating blade.

10. A method as claimed in claim 1 to 9 including after step c) the step of chopping pulverizing or grinding the dried leaves.1 1. A method as claimed in claim 1 to 10 wherein step d) is performed by at least one of: manualscreening, centrifugal air or flotation separation.

12. A method as claimed in claim 1 including further step e) after d) of purifying the wax from the residual vegetable matter.

13. A method as claimed in claim 12 where step e) includes heating the crude wax over its melting point; optionally with stirring.

14. A method as claimed in claim 12 or 13 where step e) comprises heating the crude wax powder in a solvent, optionally with stirring.

15. A method as claimed in claim 14 where the solvent is one of: petroleum ether, xylene, toluene, alkanes, alkaline hydrogen peroxide, ethyl acetate, acetone, benzene, naphthas, alcohols or any other non-polar organic solvent.

16. A method as claimed in claim 12 to 15 in which the solvent extraction is performed using, but not limited to, a Soxhlet extractor, distiller, or CO2 extractor.

17. A method as claimed in claim 12 to 16 including the step in step e) adding to the melted wax or wax solvent mixture adsorbents; preferably any one or more of: active carbon, silica gel, activated clay,18. A method as claimed in claim 12 to 17 including the step in step e) of filtration by passing the wax solution through paper, cloth, or membrane or by centrifugation.

19. A method as claimed in claim 1 to 18 including a bleach step after step d) and / or e).

20. A method as claimed in claim 19 wherein the bleach is hydrogen peroxide, sodium hypochlorite, acids such as but not only hydrochloric acid, chromo-sulphuric acid, phosphoric acid, or ozone bleaching or clays such as fullers earth bleaching.21 . A method as claimed in claims 1 to 20 including an initial step of separating palm leaflets from palm fronds.

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