DE102014225951A1 - Photochemical removal of uranium (VI) compounds from uranium (VI) contaminated liquids - Google Patents

Abstract

The invention relates to a process for the separation of uranium (VI) compounds from uranium (VI) compounds-containing liquids with the process steps of producing a suspension comprising a microstructure comprising at least one flavonoid and at least one amphiphilic substance, adding the uranium (VI ) -Containing liquid to the microstructure to form a suspension containing a flavonoid-uranium (VI) complex, irradiating the flavonoid-uranium (VI) complex to form at least one uranium species having an oxidation state of less than six and remove the uranium species from the suspension.

Description

The present invention relates to a process for removing uranium from contaminated liquids (e.g., waters), in particular a process for the photochemical removal of uranium from contaminated waters / liquids.

The removal of dissolved uranium from water presents a major challenge in water treatment in areas which are e.g. exposed by natural geological conditions, mining or industrial activities of high uranium pollution.

Complexation of uranium with vegetable flavonoids Spectrophotometric determination of uranium (VI) with 5-hydroxy-flavones and 5-hydroxy-7-methoxy-flavones. Brahm Dev, BD Jain, Fresenius 196 (1963) 178-182 ] and the coupling of quercetin to magnetic nanoparticles for the removal of uranium from aqueous solution has been described [ Surface modified magnetic Fe3O4 nanoparticles as a selective sorbent for solid phase extraction of uranium ions from water samples. Susan Sadeghia, Hoda Azhdaria, Hadi Arabib, Ali Zeraatkar Moghaddama, J. Hazardous Materials 215-216 (2012) 208-216 ]. Disadvantageously, this process discloses the production of coated silicon nanoparticles but no chemical change of the bound uranium. The known from the prior art methods are based solely on adsorption, so that sets a balance between dissolved and adsorbed uranium. A disadvantage of this process is that the separation of the uranium is low and less efficient.

The object of the present invention is to provide a process for removing uranium (VI) compounds from uranium (VI) compound-containing liquids, in particular aqueous liquids contaminated with uranium (VI) compounds, such as, for example, waters.

• a) Herstellen einer Suspension, enthaltend eine Mikrostruktur, aufweisend mindestens ein Flavonoid und mindestens eine amphiphile Substanz,
• b) Zugeben der Uran(VI)-Verbindungen-haltigen Flüssigkeit zu der Mikrostruktur, wobei eine einen Flavonoid-Uran(VI)-Komplex enthaltende Suspension entsteht,
• c) Bestrahlen des Flavonoid-Uran(VI)-Komplexes, wobei mindestens eine Uran-Spezies mit einer Oxidationsstufe kleiner sechs gebildet wird und
• d) Entfernen der Uran-Spezies aus der Suspension.

The object is achieved by a process for the separation of uranium (VI) compounds from uranium (VI) compounds-containing liquids with the process steps

• a) preparing a suspension containing a microstructure comprising at least one flavonoid and at least one amphiphilic substance,
• b) adding the uranium (VI) compound-containing liquid to the microstructure to form a suspension containing a flavonoid uranium (VI) complex,
• c) irradiating the flavonoid-uranium (VI) complex, wherein at least one uranium species with an oxidation state smaller than six is formed, and
• d) removing the uranium species from the suspension.

Uranium (VI) compounds according to the invention denotes all substances which have uranium (VI). This is at least one uranium (VI) compound. The fluids may also have multiple different uranium (VI) compounds. Uranium (VI) denotes uranium in its sixfold oxidation state, which in aqueous solution is predominantly present as a divalent uranyl cation (UO ₂ ) ²⁺ due to its high solubility. The lower oxidation states five and four of the uranium are almost insoluble in water. In the method according to the invention, the different solubility of the present in different oxidation states uranium is used. Uranium species with a lower oxidation state are formed as the oxidation state six by photochemical reaction (redox reaction) and these are bound or embedded in one and / or a microstructure, whereby they can be easily removed from the resulting suspension. As a photochemical reaction partner (redox partner) for the uranium (VI) oxidizable, metallophilic, hydrophobic substances are used.

Preferably, the metallophilic hydrophobic substance is a secondary plant metabolite from the class of flavonoids.

Flavonoids are phytochemicals known to those skilled in the art, which can be divided into different groups. The flavonoids according to the invention also include the glycosylated representatives. For the purposes of the invention, glycosylated flavonoid refers to all flavonoids to which at least one saccharide is bound to proteins, lipids or aglycones via a glycosidic bond.

Preferably, the flavonoid is at least one flavonoid selected from flavonols and flavones, more preferably from morin, kaempferol, myricetin, hesperidin, rutin, fisetin, isoquercitrin, spiraeoside, luteolin, apigenin, most preferably quercetin and chrysin.

Preferably, the amphiphilic substance is a phospholipid. According to the invention, phospholipids are phosphodiesters which have a hydrophilic (hydrophilic) head group and a hydrophobic (water-repellent) side group. The person skilled in the art is aware of the various types such as phosphoglycerides and sphingomyelins (non-glyceride-based lipids), phospholipids.

Preferably, the phospholipid is selected from natural plant lecithin, natural animal lecithin, 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) and mixtures of this. The skilled person is aware of natural lecithins such as vegetable soy lecithin and egg yolk animal lecithin.

The person skilled in the art is aware of further amphiphilic substances which form microstructures in aqueous solution, for example amphiphilic polymers or surfactants.

Phospholipids form microstructures in aqueous solutions because of their amphiphilic properties.

Preferably, the microstructure of at least one flavonoid and at least one amphiphilic substance, a mono- or multilamellar microstructure selected from vesicle, micelle and bilayer, more preferably liposome. Microstructure according to the invention denotes a structure with a size of 25 nm to 100 microns. The person skilled in the art knows the various microstructures. He is also known under what conditions and with what phospholipid he can produce what kind of microstructure.

The person skilled in the art is also familiar with liposomes under the name lipid vesicles. He can classify these, depending on their size, in "multilamellar vesicle" (MLV), "small unilamellar liposome vesicle" (SUV) and "large unilamellar vesicle" (LUV). LUVs have a mean size of 120 to 140 nm.

For example, such a system consists of animal phospholipids, e.g. Lecithin and plant flavonoids, e.g. Quercetin as a reducing agent for the photochemical reaction of the uranium (VI) -containing compound to at least one uranium species with a lower oxidation state.

According to the invention, a microstructure consisting of at least one flavonoid and at least one amphiphilic substance is produced. For this, a solution comprising the flavonoid and the amphiphilic substance is first prepared.

Preferably, the amphiphilic substance is a phospholipid, so that a solution containing at least one flavonoid and at least one phospholipid is prepared.

For this purpose, a phospholipid solution is preferably prepared with a concentration of 10 to 50 mg / ml, more preferably from 15 to 35 mg / ml, most preferably from 20 to 30 mg / ml.

The solvent used is a solvent or solvent mixture which can dissolve the respective phospholipid.

The solvents are preferably polar solvents selected from chloroform, methanol, water and ethanol.

Particularly preferred is a solvent mixture of chloroform, methanol and water, with chloroform having a volume fraction of 55% to 75%, more preferably of 65%, methanol with a volume fraction of 25% to 45%, particularly preferably 35% and water with a Volume fraction of 1% to 15%, particularly preferably 8%, based on the volume of solvent, can be used. The skilled worker is familiar with the common solvents (mixtures) for dissolving the various lipid classes.

In a preferred embodiment of the invention, first a film is produced from the phospholipid solution and then a suspension containing a phospholipid microstructure is produced. The expert is known from the literature, such as Bangham, Hill and Miller, Meth. Memb. Biol., 1, 1 (1974) He knows how to make a film from phospholipids.

By way of example, the preparation of a phospholipid film and a suspension containing a phospholipid microstructure will be described below with reference to a preferred embodiment of the invention, without restricting the process according to the invention to these. The exemplary preparation should only clarify in what proportions the individual components are used according to the invention. The person skilled in the art is aware that for the removal of uranium (VI) compounds from relatively large volumes of uranium (VI) contaminated liquids, it correspondingly increases the total volume of, for example, the phospholipid solution to be withdrawn and adjusts the other components according to the exemplary preparation.

Preferably, 500 to 1000 .mu.l, more preferably 600 to 800 .mu.L Phospholipidlösung be placed in a suitable vessel and the solvent or the solvent mixture is evaporated. Preferably, the volume of the phospholipid solution is taken up with a suitable volumetric instrument such as a pipette and dropped into the appropriate vessel. The person skilled in the art is familiar with suitable vessels such as, for example, pistons, vials or cuvettes. The solvent or solvent mixture can be removed by methods known to the person skilled in the art, for example by means of a vacuum and / or an air stream (also argon, or nitrogen stream), so that a phospholipid film is formed.

Preferably, the phospholipid film is hydrated with a suitable amount of water to form a suspension. Preferably, the suspension is incubated in a water bath for several hours. Preference is given to incubating for 1 to 24 hours, more preferably from 3 to 15 hours, most preferably from 5 to 9 hours. The water bath preferably has a temperature of from 40 to 80.degree. C., more preferably from 50 to 60.degree. During the incubation, the vessel is permanently or at fixed intervals, for example, every 10 min. shaken vigorously.

Preferably, the suspension is repeatedly snap-frozen and thawed again and filtered through a suitable filter. The skilled worker is also known to suitable methods. Preferably, the suspension is flash frozen 2 to 15 times, more preferably 3 to 10 times, most preferably 4 to 6 times, and then thawed. Preferably, the suspension is snap-frozen in liquid nitrogen and thawed at room temperature. Shock-frozen means according to the invention the rapid, within less than 5 min., Freezing of the suspension. Preferably, a hydrophobic filter such as a polycarbonate filter having a pore size of 100 nm is used. Advantageously, all larger structures are removed from the suspension.

Preferably, we treated the filtered phospholipid suspension in an ultrasonic bath, so that form the at least one microstructure.

To produce the microstructure, from at least one flavonoid and at least one phospholipid, the flavonoid is added to the phospholipid suspension, so that a flavonoid-phospholipid solution is formed. Preferably, the flavonoid is added undissolved as a solid, so that the following phospholipid and flavonoid concentrations are obtained.

Preferably, the flavonoid is used as a powder in a molar ratio of flavonoid to phospholipid of 1:50, more preferably 1:35, most preferably 1:20.

The phospholipid is preferably used as the phospholipid suspension at a concentration of 1 to 10 mg / ml, more preferably from 3 to 7 mg / ml, most preferably from 4 to 5 mg / ml phospholipid per ml.

After the addition of the flavonoid to the phospholipid suspension is incubated again, for example in a water bath. The incubation is preferably carried out for 1 to 5 h, more preferably for 2 to 3 h, most preferably for 2 h. The water bath preferably has a temperature of from 40 to 80.degree. C., more preferably from 50 to 60.degree.

In a particular embodiment of the invention, the flavonoid is added as a solid to the dry phospholipid film and then the phospholipid film is hydrated with the flavonoid according to the described method, so that a suspension containing a microstructure consisting of at least one flavonoid and at least one amphiphilic substance, arises.

Advantageously, the flavonoid is mainly incorporated from the aqueous phase into the hydrophobic region of the microstructure and stabilized there.

Advantageously, the microstructure has a large surface area, whereby a correspondingly larger amount of flavonoid can be absorbed.

According to a further embodiment, the photochemical conversion of uranyl (VI) ions is characterized in that the amphiphilic substances form mono- or multilamellar structures (vesicles) on the surface of which the photoreduction of the uranium by an organic ligand takes place.

According to a further embodiment, the photochemical conversion of uranyl (VI) ions is characterized in that the amphiphilic substances form micelles, ie molecular assemblies having a hydrophobic interior, on the surface of which the binding and photoreduction of the uranium by an organic ligand takes place.

According to yet another embodiment, the photochemical conversion of uranyl (VI) ions is characterized in that the amphiphilic or substances are present as a coating of particulate support materials, on the surface of which the binding and photoreduction of the uranium by an organic ligand takes place.

According to a further embodiment, the photochemical conversion of uranyl (VI) ions is characterized in that the microstructure formed from amphiphilic substances at the phase boundary to water-insoluble liquid phases, such as. Oils are present, at the surface of the binding and photoreduction of the uranium is carried out by an organic ligand.

Preference is given to the microstructure of at least one flavonoid and at least one amphiphilic substance, the uranium (VI) compounds-containing liquid.

The microstructure, consisting of at least one flavonoid and at least one amphiphilic substance, is advantageous when adding the uranium (VI). Compound-containing liquid as an aqueous suspension.

Preferably, only so much uranium (VI) compound-containing liquid is added to the suspension that the flavonoid is in molar excess.

Preferably, the flavonoid is in a 2-fold to 10-fold, particularly preferably in a 2-fold to 5-fold molar excess.

Uranium (VI) refers to all uranium (VI) species that can occur in the uranium (VI) compound-containing liquid.

Preferably, the suspension containing the microstructure, comprising at least one flavonoid and at least one amphiphilic substance, and the uranium (VI) compounds-containing liquid is mixed intensively, so that from the flavonoid and the at least one uranium (VI) compound, a flavonoid Forms uranium (VI) complex. Advantageously, this complex is predominantly in the hydrophobic region of the microstructure in the suspension, whereby the complex is additionally stabilized. The flavonoid acts as an organic ligand and complexes the U (VI) compounds in variable stoichiometry and / or with phospholipids of the microstructure. Advantageously, a correspondingly large amount of the complex can be absorbed by the large surface of the microstructure.

The amphiphilic or hydrophobic substances are lipids or lipid mixtures which, due to their chemical headgroup structure, e.g. have by their content of phosphate or hydroxyl groups, affinity for uranyl (VI) ions and the added organic ligands coordination sites for uranyl (VI) ions have such. Hydroxyl, carbonyl or carboxyl groups.

Preferably, the suspension containing the microstructure with the flavonoid-uranium (VI) complex is irradiated with light in the UV / VIS range.

The flavonoid absorbs the light and the photochemical reaction (redox reaction) occurs whereby the flavonoid oxidizes and the uranium (VI) to at least one uranium species with an oxidation level less than six, such as the water-insoluble uranium (V) and / or the water-insoluble Uranium (IV) is reduced. The photochemical reaction preferably produces uranium (V), which is preferably located in the hydrophobic region of the microstructure and is stabilized by it.

According to the invention UV means ultraviolet and denotes ultraviolet radiation, also ultraviolet light having a wavelength in the range from 100 nm to 380 nm. VIS denotes light in the visible range at a wavelength in the range from 380 to 750 nm. According to the invention, absorbing means the property of a substance or material (UV / VIS absorber) to absorb radiation in the UV / VIS range, ie to absorb it.

Preferably, the suspension containing the flavonoid-uranium (VI) complex is irradiated with light having a wavelength of 150 to 750 nm, more preferably 200 to 700 nm, most preferably 300 to 600 nm.

The suspension containing the flavonoid-uranium (VI) complex is preferably irradiated with the light from a mercury-vapor lamp for 5 to 130 s, particularly preferably for 25 to 100 s, very particularly preferably for 30 to 70 s.

In a particular embodiment of the invention is irradiated with natural light. Advantageously, therefore, no additional artificial light source is needed, which consumes additional energy. Preferably, the irradiation with natural light is longer than with an artificial light source, such as a lamp, preferably from minutes to several hours, more preferably 30 min. Irradiation with natural light depends on the weather conditions; for example, clouds would be irradiated longer than in a cloudless sky.

Advantageously, the at least one uranium species having at least one oxidation state less than six, such as uranium (V) and uranium (IV), is not soluble in water. Predominantly, the uranium species with oxidation states smaller than six remain in the hydrophobic region of the microstructure and are stabilized by them.

Advantageously, stabilization of the uranium species with an oxidation level less than six prevents reoxidation back to oxidation level six. In a particular embodiment of the invention, the uranium species having an oxidation state of less than six are present in the aqueous phase, for example when the hydrophobic region of the microstructure is supersaturated with the uranium species. The uranium species is then present in the aqueous phase as a precipitate.

Preferably, the at least one uranium species with an oxidation level less than six is separated by centrifugation and / or filtration from the suspension.

Thus, all uranium species with an oxidation number less than six, which are located in the microstructure, as well as those uranium species, are advantageous. Species present as a precipitate in the aqueous phase, separated. Preferably, the microstructure and separated from the liquid with. Advantageously, unreacted, but in the hydrophobic region of the microstructure located on at least one flavonoid complexed uranium (VI) is separated with. Those skilled in the art are familiar with other methods of separating solids from liquids.

The at least one uranium species having an oxidation state of less than six is preferably more preferably 80 to 100% by weight, more preferably 90 to 100% by weight, very preferably 95 to 100% by weight, even more preferably quantitatively, based on the total amount of uranium species with an oxidation state less than six, separated.

Compared to the prior art adsorption-based process, in which a balance is established between dissolved and adsorbed uranium, the process according to the invention has the advantage that the solubility of the uranium itself is reduced photochemically and the corresponding product, ie uranium Species having at least one oxidation state less than six, is stabilized by a suitable hydrophobic microenvironment. This can be a higher or more effective separation of the uranium species with an oxidation state less than six from the aqueous solution. The prerequisite for this process is the enrichment of the at least one uranium (VI) -containing compound with a suitable reducing agent at the interface between an aqueous and a hydrophobic phase at which the photoreduction takes place and the product (uranium species having an oxidation state of less than six). can reach the hydrophobic phase by diffusion over the shortest possible distance.

In the photochemical conversion of uranium (VI) species in the aqueous phase (liquid), amphiphilic or hydrophobic substances are added to the aqueous phase (liquid), the suspended structures such as e.g. Microdrops, vesicles or liposomes form on the surface of uranium (VI) species (compounds containing) alone or in complex with other added organic ligands, such as flavonoids, physically or chemically bind. By binding of the uranium (VI) species or their complexes with one or more organic ligands to the suspended microstructures, the uranium (VI) species are present at the phase boundary between the aqueous outer phase and a hydrophobic phase within the microstructures. Exposure of the suspension by natural sunlight or artificial sources in the visible and near UV spectral region results in photoreduction of the uranium (VI) species by the amphiphilic or hydrophobic substances themselves or by the one or more organic ligands acting as reducing agents in this photochemical reaction , Due to the lower water solubility of the uranium species with an oxidation level less than six, such as uranium (V) - and uranium (IV) -Photoprodukte, these accumulate preferentially in the interior of the microstructures. By established separation methods such as e.g. Centrifugation or filtration, the water-insoluble microstructures including the uranium (IV) species and uranium (V) species contained therein can be separated from the aqueous phase and thus reduce the dissolved amount of uranium (VI) compounds in the aqueous phase.

The present invention provides a cost effective process that allows the light-driven transfer of dissolved oxidation stage six uranium into sparingly soluble uranium of lower oxidation state than six and the subsequent separation with the aid of easy-to-obtain and process biomolecules. In addition to the use of synthetic materials for this process, a process is described that can be performed with readily available biological materials such as fats and plant metabolites.

According to a further embodiment, the photochemical conversion of uranyl (VI) compounds is characterized in that the amphiphilic or hydrophobic substances are present alone or with at least one organic ligand as a densely packed suspension in a column, and the uranium (VI) compounds containing aqueous solution (liquid) is brought in flow under exposure to the material in contact.

embodiments

Based on the listed representations and embodiments, the invention will be explained in more detail without limiting it to these. Show

1 : UV-VIS Absorption Spectra and Photoreactivity of the Uranium (VI) Quercetin Complex in LUVs. B) the absorption spectrum of LUVs from DMPE comprising Quercentin with a DPME concentration of 4 mg / ml, c) the absorption spectrum of LUVs from DMPE comprising a uranium (VI) -quercetin complex after addition of uranyl nitrate with a final concentration of 0.4 mM to the LUVs from DMPE and d) the absorption spectrum of the sample from c) after 60 s exposure.

2 : Absorption spectrum of the uranium (VI) quercetin complex in LUVs from DMPE Irradiation times of 0, 10, 25, 40, 60, 90, and 130 s (a to g, where a is 0 s and g is 130 s) with a UV mercury vapor lamp.

example 1

materials

Quercetin (3, 3 ', 4', 5, 7-pentahydroxyflavone) was purchased with the highest purity available (98%) from Sigma Aldrich Co. Dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidylglycerol (DMPG) were obtained from Avanti Polar Lipids, INC., Deuterated acetone and deuterated acetonitrile from Deutero GmbH. The reagents used had analytical grade and were used without further purification.

Preparation of a uranium (VI) -containing liquid

Samples of a uranium stock solution of UO ₂ (NO ₃ ) ₂ .6H ₂ O were prepared by adding an appropriate amount of distilled water. Aliquots of the uranium stock solution were diluted as desired. The pH of the sample solutions was adjusted by adding 1 and 0.1 M NaOH and HClO ₄ .

Production of a crosscenta strain solution

A concentrated quincentine stock solution was prepared by dissolving 1 mg of quinoline in 10 ml of acetone (spectroscopic purity). The concentration of the quinoline stock solution was determined from a 1000-fold dilution of the stock solution. The absorption spectrum of the obtained solution was measured. The transverse centine concentration of the diluted solution was estimated from the molar extinction coefficient of the transverse centin at the 370 nm band (2.0 × 10 ⁴ M ^-1 cm ^-1 ) ( Kudrinskaya et al., 2010 ). Subsequent dilutions of the stock were made as needed. The concentration of the stock solution was then recalculated from the concentration of the diluted solutions of Quercin. The buffer solutions were prepared in high purity water from a Millipore Milli-Q system (resistance greater than or equal to 18 MΩ cm). The Uranly (VI) -quercentin complexes were obtained by mixing freshly prepared solutions of U (VI) nitrate (uranium (VI) compound) and Quercentin at different molar ratios.

a) Preparation of Quercentin Liposome Samples

The method of lipid thin film formation and extrusion ( Bangham et al., 1974 The desired amount of DMPE or DMPG was taken from a solution of chloroform: methanol: water (65: 35: 8) (V: V: V) at a concentration of 25 mg / ml. The solvent was removed with a stream of nitrogen to deposit a lipid film on the walls of the vessel. Last residues of organic solvent were removed by vacuum drying in one hour. The Quercentinpulver was added to the dry lipid film with a molar ratio of 1:20 Quercentin: lipid and the film was hydrated with the required amount of water, followed by incubation in a water bath at 60 ° C (for DMPE) and 50 ° C ( for DMPG) for 2 h with repeated vigorous shaking with a vortex mixer every 10 min. After five freeze drying cycles, the material is extruded through a 100 nm pore size polycarbonate filter. The large unilamellar vesicles (LUVs) were treated by sonicating the lipid dispersion with an Elma transsonic cleaning bath, analogous unit model (from Elma GmbH & Co.LG) for 1 min prior to extrusion to allow good extrusion.

b) Quercetin uranium (VI) complex formation

For the preparation of quercetin uranium (VI) complexes, 6.5 μL uranium stock solution (10 mM uranyl nitrate) was added to the unilamellar vesicles (150 μL of a suspension containing 4 mg / mL lipid and 1 mg / mL quercetin).

1 shows the absorption spectrum of free quercetin in water ( 1a ) and in association with so-called Large Unilameller Vesicles (LUVs) produced from DMPE ( 1b ). The maximum at 369 nm is clearly visible on the scattering background of the LUVs. The addition of uranyl led to the instantaneous formation of a double-band absorption with maxima at 391 and ~ 431 nm ( 1c ), which proves the accessibility of quercetin in LUVs for the formation of a complex with uranyl. Although measured in aqueous solution, the positions of the maxima are more similar to those of the complex in acetone than in water, which is consistent with the hydrophobic microenvironment of the LUVs.

c) Irradiation of the Quercetin-Uranium (VI) Complex

To form uranium species with an oxidation state of less than six, the quercetin uranium (VI) complexes were irradiated. Upon exposure of the LUV-bound quercetin-uranyl complex, bleaching of the UV-Vis absorption was observed ( 1d ). To further elucidate the role of the lipidic microenvironment, the same experiment with LUVs from DMPG was repeated ( 1 Detail). Here, the addition of uranyl caused a further red-shifted absorption of the complex. The band at 445 nm is closer to the absorption of the complex in water, whereas that at 431 nm in DMPE is closer to that in acetone. The spectral shifts correlate with the degree of hydrophobicity of the phospholipid head groups in the two Types of vesicles. The data suggest a topology of the uranyl-quercetin complex close to the head groups in a position that is sensitive to the more hydrophilic glycerol and the more hydrophobic ethanolamine segment in DMPG and DMPE, respectively.

Further, an experiment was conducted to observe the photoreaction caused by different successively accumulated exposure times in the time range of 5-130 seconds. 2 shows the incremental photoreaction of the uranyl (VI) quercetin complex in DMPE-LUVs. A clear photodegradation after 130 seconds was observed along with the formation of a new maximum at longer wavelengths, especially at 960 nm after the UV exposure time. This maximum is indicative of the formation of U (V) before insoluble U (IV) occurs, which precipitates in aqueous solution.

Uranyl precipitation and the disappearance of U (VI) IR absorption bands upon exposure further show that uranyl serves as a redox partner and not as a catalyst for the photoreaction of quercetin.

The uranium species with an oxidation level less than six were separated by centrifugation.

The data show that quercetin is a suitable and cost-effective natural product involved in the photoreaction with U (VI) in the hydrophobic microphase of lipid vesicles. This property opens a new path to the light-driven bioremediation of uranyl-contaminated waters. Insoluble uranyl species of a redox state smaller than VI can thus be shielded in the hydrophobic core of a bilayer, where they are stabilized. Associated with such vesicles, they can be removed from water by simple centrifugation.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Spectrophotometric determination of uranium (VI) with 5-hydroxy-flavones and 5-hydroxy-7-methoxy-flavones. Brahm Dev, BD Jain, Fresenius 196 (1963) 178-182 [0003]
• Surface modified magnetic Fe3O4 nanoparticles as a selective sorbent for solid phase extraction of uranium ions from water samples. Susan Sadeghia, Hoda Azhdaria, Hadi Arabib, Ali Zeraatkar Moghaddama, J. Hazardous Materials 215-216 (2012) 208-216 [0003]
• Bangham, Hill and Miller, Meth. Memb. Biol., 1, 1 (1974) [0023]
• Kudrinskaya et al., 2010 [0067]
• Bangham et al., 1974 [0068]

Claims (8)

Process for the separation of uranium (VI) compounds from uranium (VI) compound-containing liquids with the process steps a) preparing a suspension containing a microstructure comprising at least one flavonoid and at least one amphiphilic substance, b) adding the uranium (VI) compound-containing liquid to the microstructure to form a suspension containing a flavonoid uranium (VI) complex, c) irradiating the flavonoid-uranium (VI) complex, wherein at least one uranium species with an oxidation state smaller than six is formed, and d) removing the uranium species from the suspension. A method according to claim 1, characterized in that the flavonoid at least one flavonoid is selected from flavonols and flavones. Method according to one of claims 1 or 2, characterized in that the amphiphilic substance is a phospholipid. Method according to one of claims 1 to 3, characterized in that the microstructure of at least one flavonoid and at least one amphiphilic substance, a mono- or multilamellar microstructure. Method according to one of claims 1 to 4, characterized in that the flavonoid is used as a powder in a molar ratio of flavonoid to phospholipid of 1:50. Method according to one of claims 1 to 5, characterized in that only so much uranium (VI) compounds-containing liquid is added to the suspension, that the flavonoid is in molar excess. Method according to one of claims 1 to 6, characterized in that the suspension containing the flavonoid-uranium (VI) complex is irradiated with light having a wavelength of 150 to 750 nm. Method according to one of claims 1 to 7, characterized in that the at least one uranium species with an oxidation level less than six are separated by centrifugation and / or filtration from the suspension.

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