Removal of metal ions from essential oils
阅读说明：本技术 从精油中移除金属离子 (Removal of metal ions from essential oils ) 是由 S·强森 于 2018-04-18 设计创作，主要内容包括：本发明涉及从液体中分离金属离子的方法,所述方法包括使包含金属离子的液体与未官能化纤维素接触,将所述金属离子吸附至纤维素中,并将所述液体与纤维素分离,其中所述液体为精油。(The present invention relates to a process for separating metal ions from a liquid, the process comprising contacting a liquid comprising metal ions with non-functionalized cellulose, adsorbing the metal ions into the cellulose, and separating the liquid from the cellulose, wherein the liquid is an essential oil.)
1. A method of separating metal ions from a liquid, the method comprising contacting a liquid comprising metal ions with unfunctionalized cellulose, adsorbing the metal ions to the cellulose, and separating the liquid from the cellulose, wherein the liquid comprises an essential oil.
2. The process according to claim 1, which is a chromatographic process, wherein unfunctionalized cellulose is used as or comprised in a solid phase.
3. The method of claim 1, wherein the unfunctionalized cellulose comprises all or a portion of a filter.
4. A process according to any one of the preceding claims wherein essential oil is selected from citrus oils, such as lemon, orange or grapefruit oil; and essential oils, such as spearmint.
5. The method according to any one of the preceding claims, wherein the essential oil originates from a previous IMAC or silver chromatography step.
6. The method of claim 5, wherein the prior chromatography step utilizes a synthetic polymer carrying metal ions.
7. The method of any one of the preceding claims, wherein the metal ion is Ag+。
8. A system for liquid chromatography comprising means for at least a first and a second chromatography step, wherein for the first step means for IMAC or silver chromatography are provided; and for the second step, providing a column comprising unfunctionalized cellulose.
9. Scavenging chromatography column for removing metal ions such as Ag from essential oils+The use of (a), wherein the column comprises a packing which is or comprises unfunctionalized cellulose.
Technical Field
The present invention relates to the separation of metal ions from liquids, and more particularly to the separation of small amounts of metal ions.
Background
Chromatography is a method commonly used in the field of biology to separate desired or undesired components from liquids, for example for recovering desired pharmaceutically active compounds from liquids during biotechnological preparation of pharmaceuticals, or for removing undesired contaminants.
The principle of chromatography has been well known for decades and involves the utilization of various chemical interactions between the compound to be separated, which is usually present in the liquid phase, and the solid phase, which is often provided in chromatographic columns for continuous chromatographic separations or in vessels for batch chromatographic separations. Such solid phases are known as chromatographic media or resins, or packing materials for continuous liquid column chromatography, which is most commonly used.
For efficient interaction with the compound to be separated (sometimes denoted target), the chromatographic packing may contain certain groups as part of the actual packing material, or may be provided by chemical modification with groups capable of interacting with the target. The latter are commonly referred to as chromatographic ligands, or simply ligands.
The ligands may interact directly with the target, for example, ionic interactions between a charged target and an oppositely charged ligand in ion exchange chromatography. One particular type of interaction is provided in Metal Chelate Affinity Chromatography (MCAC), also known as Immobilized Metal Affinity Chromatography (IMAC), in which groups present on a solid phase form with certain metals metal chelates that are capable of interacting sufficiently with a target to provide an efficient separation suitable for certain situations. A similar principle applies to silver chromatography, which can use silver-coated silica in Thin Layer Chromatography (TLC), and also silver-loaded cation exchangers suitable for column chromatography. An example of such a product that is commercially available is RensaTMResins, which are for example marketed for the separation of pesticides from food products (www.biotage.com).
Silver-loaded cation exchangers are commonly used for the purification and isolation of unsaturated small molecules, such as fatty acids, pheromones and polyaromatic sulfur-containing heterocycles, for analytical and preparative purposes in the food and other fields. A problem that can occur with any metal loaded chromatographic material is that metal ions must leak into the eluent, i.e. into the product stream. Since in the food industry it is often required that food materials, ingredients or products are not contaminated with metals during processing, removal of the leaking metal ions can be introduced as a step following IMAC, MCAC or silver chromatography.
A variety of such metal scavengers have been proposed and there are many products commercially available. Silica provides an example of a metal scavenger for screening purposes.
Other examples of functionalized silica or resin based scavenging materials used as the last step in the field of chromatography are available from Sigma Aldrich
US 6,132,750(Eric per) relates to particles of small size comprising at least on their surface a wall consisting of a mixture of at least one protein and at least one polysaccharide, which mixture has been crosslinked and preferably crosslinked by interfacial crosslinking with a polyfunctional acylating agent forming at least an amide bond and an ester bond with amine, hydroxyl or carboxyl functional groups of the protein and polysaccharide and optionally an anhydride bond, and a hydroxamic group for chelating metal ions on its surface. These particles can be used in cosmetics or pharmaceuticals, in particular for the chelation or release of metal ions.
WO 2007/122720(Niisawa Kazuhiro) describes a method comprising the following steps: (1) treating a metal-containing feedstock with hydrochloric acid to obtain a hydrochloric acid solution of metal ions; (2) treating the hydrochloric acid solution obtained in step (1) with cellulose dispersed in an adsorption aid consisting of at least one organic solvent, so that the cellulose adsorbs the contained metal ions; (3) the metal ions are desorbed and recovered from the cellulose with water or hydrochloric acid.
However, since the metal scavengers proposed and present in the prior art have been suggested for use in treating liquids such as fermentation broths in biotechnological processes and for other purposes where the liquid contaminated with metals is an aqueous liquid, there is a need in the art for new products that can effectively remove even small amounts of metal ions (e.g. silver ions) from non-aqueous liquids (non-aqueous liquids).
WO 2010/002696(Coca cola Co) describes a method for treating an essential oil composition, the method comprising the steps of: contacting the essential oil composition with an adsorbent material and separating the adsorbent material from the treated essential oil. Suggested adsorbent materials include activated carbon, amorphous silica, fuller's earth and diatomaceous earth.
However, there remains a need in the art for improved methods capable of removing even small amounts of metals from non-aqueous liquids.
Disclosure of Invention
The present invention provides a novel method for removing even minute amounts of metal ions from organic liquids. According to the present invention, it has unexpectedly been found that unfunctionalized cellulose is a highly hydrophilic material commonly used in chromatography for the treatment of aqueous liquids, and can be used to effectively separate metal ions from organic liquids such as essential oils.
This may be achieved by a method of separating metal ions from a liquid, the method comprising contacting a liquid comprising metal ions with non-functionalized cellulose, adsorbing the metal ions into the cellulose, and separating the liquid from the cellulose, wherein the liquid comprises an essential oil.
Other embodiments, advantages and other details of the invention will appear from the experimental section below and throughout the application.
Definition of
Herein, the term "scavenger" or "scavenging" is used in the context of detecting and/or removing very small amounts of molecules or compounds.
As used herein, the term "cellulose" is used in the context of the chemical formula (C)6H5O5)nA polysaccharide as defined.
As used herein, the term "heterocellulose" is used for any heteropolymer of cellulose, including those that have not been chemically modified and are represented by the formula (C)6H5O5)nA polysaccharide as defined.
In this context, the term "unfunctionalized cellulose" is used for cellulose which has not been chemically or otherwise modified by derivatization at its OH groups.
In this context, the term "oil" is used for any neutral, non-polar chemical substance that is a viscous liquid at ambient temperature and that is hydrophobic and lipophilic.
In this context, the term "essential oil" is used for a concentrated hydrophobic liquid comprising volatile aromatic compounds from plants.
Detailed Description
In a first aspect, the present invention relates to a process for separating metal ions from a liquid, the process comprising contacting a liquid comprising metal ions with non-functionalized cellulose, adsorbing the metal ions into the cellulose, and separating the liquid from the cellulose, wherein the liquid comprises an essential oil.
The non-functionalized cellulose used in the present invention can be obtained as a slurry from fibrous plant material such as wood or cotton according to known methods. As used herein, non-functionalized cellulose may include microcrystalline cellulose and/or alpha-cellulose, which are cellulose derived from high quality wood pulp, all of which are available from commercial sources such as Sigma Aldrich or food additive manufacturers.
Alternatively, mixtures of cellulose and its other heteropolymers are used in the process of the present invention, provided that the mechanical and other properties of such mixtures are sufficiently similar to those of pure unfunctionalized cellulose to remove metals from the essential oils described herein.
The method of the invention may be chromatography, wherein unfunctionalized cellulose is used as or contained in a solid phase. Thus, if the chromatography is operated as continuous liquid chromatography, the column comprises non-functionalized cellulose as a packed column or a fluidized bed. Alternatively, if the process is a chromatographic process operated in batch mode, the vessel used (vessel, container) contains unfunctionalized cellulose as solid phase.
Alternatively, the process of the invention may be a filtration process, wherein the unfunctionalized cellulose comprises all or a portion of the filter. It is well known that the efficiency of scavenger filters is directly related to the density and average particle size of the cellulose fibers. The use of coarser grades, i.e. longer fibres, lower density powder in the filtration will result in lower adsorption efficiency. The use of finer grades, shorter fibers, denser powders will result in faster adsorption and capture of more ions from the eluent at higher column flow rates.
As understood by those skilled in the art, the unfunctionalized cellulose of the present invention may be provided in any form suitable for a particular application, provided that suitable conditions are capable of adsorbing the amount of metal ions described herein. Illustrative conditions are exemplified in the experimental section below.
The essential oil from which the metal ions are separated may be any essential oil, such as citrus oil (citrus oil) or sesame oil (cultured oil), or more specifically eucalyptus oil, lavender oil, peppermint oil, spearmint oil, cedar wood oil, rose oil, clove oil, and the like. It is well known that essential oils are volatile, usually concentrated plant essences, and can be present in various plant parts, including but not limited to roots (as in vetiver), leaves (as in spearmint leaves), flowers (as in roses), citrus fruits (as in bergamot), and seeds (as in fennel). Examples of essential oils are citrus oils, including oils from citrus, sweet orange, lemon, bergamot, mandarin, lime, tangerine, and grapefruit, or any combination thereof.
As understood by those skilled in the art, small amounts of diluents may be included in such essential oils. Diluents which can be used according to the invention can be selected from the following classes: hydrocarbons, ketones, ethers, esters, more suitably the hydrocarbon cyclohexane, heptane limonene (heptanes).
The invention comprises the separation of metal ions from essential oils that may be intended for use in the food or pharmaceutical industry. Thus, the essential oil to be purified according to the invention may have been contaminated with metal ions resulting from earlier steps in the process, such as previous steps of chromatography; or the metal ion is derived from one of the components of the oil, such as a pesticide in contact with the fruit used to produce the citrus oil.
As mentioned above, metal-loaded cation exchangers are widely used in the food industry, but also in other fields, such as the pharmaceutical industry. In most of these applications, there is a risk of metal ions leaking from the solid phase, and it is even more important to remove the final product if it is intended for human application.
Thus, the process of the invention mayTo include essential oils originating from previous chromatographic steps using different chromatographic principles, such as metal loaded cation exchangers or silver chromatography. Thus, the process of the present invention can use unfunctionalized cellulose as a scavenger to separate the target from the essential oil in one of the later steps of the multi-step process. The column packing used in the previous step of the method of the invention may comprise a synthetic polymer carrying metal ions. An example of the preparation of such a column packing is presented in example 1 below. Alternatively, the column packing used in the previous step of the method of the invention may be a commercially available product, for example
In the process of the present invention, the metal ions separated from the liquid may be positively charged monovalent or polyvalent metal ions, such as transition metal ions. Thus, the metal ions may be selected from Au+Or Au2+；Ag+、Cu+、Pt2+、Pd2+、Ni+And Co+. In an advantageous embodiment, the metal ion is silver, i.e. Ag+。
As will be understood by those skilled in the art from this specification, the essential oil should be maintained under conditions in which all or substantially all of the metal to be removed is present in ionic form. Thus, for example, reducing conditions should be avoided.
Without wishing to be bound by any theory, the surface of the unfunctionalized cellulose may allow penetration of metal ions, since it has a porous structure. The positive technical effect of the present invention may be due to the formation of salts between the cellulose and the metal ions, but it may also include metal clusters and/or colloidal metals.
To illustrate the effect of the present invention, example 2 shows a typical eluent concentration profile (profile) of silver ion migration into orange oil. The composition of the different volumes of eluate has been measured and found to range from 0.6 to 2 ppm. If the oil composition is complex, the removal performance of the unfunctionalized cellulose may be affected. In one embodiment of the invention, the undesirable effects of the oil are minimized by diluting the oil base with an organic solvent or limonene. For example, citrus oil/lemon oil diluted with cyclohexane and/or limonene improves the efficiency of unfunctionalized cellulose as a silver ion scavenger compared to undiluted citrus oil/lemon oil. This enables improved separation of silver ions by the unfunctionalized cellulose used in the present invention.
The chemical composition differs between different oils. For example, the main chemical components of spearmint oil are α -pinene, β -pinene, carvone, 1, 8-cineole, linalool (linalool), limonene, myrcene, caryophyllene, and menthol. In orange oil: alpha-pinene, sabinene (sabinene), myrcene, limonene, linalool, citronellal, neral (neral), and geranial. In lemon oil: alpha-pinene, camphene, beta-pinene, sabinene, myrcene, alpha-terpinene, linalool, beta-bisabolene, limonene, trans-alpha-bergamotene, nerol (nerol), and neral. Rose oil is one of the most complex compounds, the main chemical components of which are citronellol, phenethyl alcohol, geraniol, nerol, farnesol (farnesol) and rose wax (stearpoten).
As mentioned above, even if only very small amounts of metal ions are present in the essential oil, its removal can be very important. Thus, the process allows the metal content of the purified essential oil to be less than 0.05ppm, for example silver in orange oil.
In contrast, the EPA has established National Secondary Drinking Water Regulations (National Secondary Drinking Water Regulations) as a guideline to help public Water systems manage their Drinking Water for aesthetic considerations (e.g., taste, color, and odor). Silver is included in this list as a contaminant. According to this list, Ag is not considered to be present in less than 0.10mg/L (0.10ppm) of drinking water+There are risks to human health.
In example 3, the ratio between the amount of resin and the amount of scavenger is evaluated. The level of silver migration and cellulose clearance were measured. The results show that the unfunctionalized cellulose of the present invention has a scavenger capacity to scavenge about 0.5-0.7mg of silver per gram of unfunctionalized cellulose to remove silver ions to < 0.05ppm in the combined collected oil (orange oil).
In comparative example 4, a commercially available resin for silver removal was compared with the method of the present invention under the same removal conditions. 125mg of resin was used, and the recorded capacity was 3-3.5mmole/g (thiourea functionality). 630 grams of orange oil were treated. Analysis of the oil showed a silver concentration of 1.13ppm before the scavenger, a silver concentration of 0.315ppm in the final eluate after the scavenger, and 0.248ppm in the combined eluate. The results show that despite the high capacity of the resin, the resin is less efficient at scavenging silver to a lower concentration range in oil.
The function of the metal-loaded resin is to interact with and fix impurities in the oil, such as certain classes of pesticides. In example 5, the oil had been blended with 40ppm malathion, an organic thiophosphate pesticide. The results show that the silver migrates to different extents, from 0.3ppm to 0.7ppm, depending on the oil. The cellulosic material removes silver to a silver content of less than 0.1ppm silver.
The corresponding experiment with orange oil was performed in batch mode. Orange oil was incorporated into malathion and chlorpyrifos pesticides. Purification (removal of pesticides) was performed by suspending silver resin beads in oil. It has been found that encapsulating the resin in a "tea bag" of high quality paper or cotton significantly reduces the migrating silver while maintaining performance.
In a second aspect, the present invention relates to a system for liquid chromatography comprising at least one chromatography column and at least one second chromatography column, wherein a first column packing comprises a synthetic polymer loaded with metal ions and a second column packing comprises non-functionalized cellulose. As mentioned above, the second post may be as discussed above in the context of the first aspect of the invention.
System parameters such as the distance between the column of unfunctionalized cellulose and its previous steps, the available surface area of the unfunctionalized cellulose, flow rates, etc., should be adjusted to ensure that in such systems the metal ions present in the purified essential oil remain in ionic form.
The invention also relates to a system for liquid chromatography comprising means for at least a first and a second chromatography step, wherein for the first step means for IMAC or silver chromatography are provided; for the second step, a column comprising unfunctionalized cellulose is provided. An example may be a chromatography column for silver chromatography, downstream of which a scavenger column comprising non-functionalized cellulose is attached. The scavenger column may be arranged as a post-column (post-column); or as the lower portion of a silver chromatographic column. Alternatively, the chromatographic column for silver loaded cation exchange or IMAC is connected to a scavenger column comprising non-functionalized cellulose, which removes at least a part of the content of metals, preferably leached silver ions (Ag), leached from the previous step according to the invention+)。
Furthermore, the present invention relates to the use of non-functionalized cellulose for the preparation of a chromatography packing for scavenging metal ions.
Finally, the invention relates to a scavenger chromatography column comprising a packing which is or comprises non-functionalized cellulose. As can be seen from the above, such scavenger columns are advantageously used for removing metal ions from essential oils. Accordingly, all of the details provided above with respect to the method of separating metal ions from essential oils will also apply to this and other aspects of the present invention.
Experiment of
The examples of the present invention are provided for illustrative purposes only and should not be construed as limiting the invention as defined by the appended claims. All references provided below or elsewhere in this application are incorporated herein by reference.
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