An electrophoretic purification system for nanoparticles and its use

Abstract

An electrophoretic system suitable for nanoparticles purification comprising: a vessel (2) with at least two electrodes (3) arranged parallel to each other, wherein the vessel (2) has a drain valve (10) and two connectors, one on the side wall (9) and second at the bottom of the vessel (4), a cover (1) of the vessel with two connectors (8), wherein one of them serves as a socket for an electric wires (7), and a second one is connected to the solvent circulation hose (13), a three-way valve (5) connected to the lower connector (4) on the bottom of the vessel, wherein the three-way valve (5) is connected to the two hoses (13,14), hose (13) connected to the connector (8) throughout the first pump (11), and hose (14) connected to the upper connector on the side wall of the vessel (9) throughout the second pump (12) and reservoir tank (15), the three-way valve (16) is connected to the hose (17) supplying the non-solvent to the system from tank containing the non-solvent (18) using pump (12) and the three-way valve (19) is connected to the hose (20) supplying solvent to the system from tank containing solvent (21) using pump (11). Use of the system.

Description

[0001] An electrophoretic purification system For nanoparticles and its use

[0002] The present invention relates to a system for nanoparticles purification and its use. The invention concerns the field of nanotechnology.

[0003] Electrophoresis is a well-known method for manipulation of nanomaterials, although it is mainly used to deposit nanoparticles in the form of thin layers. The last decade has seen its use in the purification of nanoparticles, including semiconductors in this form.

[0004] The electrophoretic purification process involves exposing a colloidal solution of quantum dots (or other nanoparticles) to an electric field in which the electrophoretic force acts on them. As a result of this force, the quantum dots move towards one of the charged electrodes, where they are deposited in the form of a layer, while the impurities (e.g. excess ligands, unreacted substrates, etc.) present in the solution remain in the liquid phase. For this process to occur, it is necessary to prepare a process mixture containing quantum dots of the appropriate colloidal stability, which can then be characterized by measuring the potential value.

[0005] The main goal of purifying nanomaterials and other substances is to get rid of unnecessary components in the final dispersion, such as excess ligands and unreacted substrates. The purity of quantum dots (and other nanoparticles) is an extremely important parameter in the context of selected industrial applications, e.g. for the production of LED displays. As a result of the purification process, the mass ratio of the inorganic part to the total mass of the dispersed material, i.e. the sum of the organic and inorganic parts, increases. That mass ratio value indicates the degree of nanomaterial purity and it is determined on the basis of thermogravimetric analysis (TGA).

[0006] The described method allows for the purification of nanoparticles in a continuous process, which means that purified nanoparticles are produced non-stop in one system and without interruption. This is possible thanks to the use of at least two reactors in the system at the same time (used alternately for the deposition of nanoparticles on electrodes and redispersion of nanoparticles) and with a constant flow of the reaction mixture containing nanoparticles and impurities.

[0007] CN1 1 3831920A discloses a general method for preparing quantum dots (ZnSe / CdSe) completed with a purification step using electrophoresis. The document presents the use of the method for quite high quantum dots concentration values (up to 1 00 g / l) in a relatively short time (10-60 min) and at low voltage values (up to 20 V). The process for purification is not flow. GB832202A discloses electrophoretic purification of colloidal particles in a continuous process using a semi-permeable membrane and alternately reversing the directions of liquid flows so as to separate two streams with different contents.

[0008] CN106637356A discloses a method of producing metal (silver) nanoparticles completed with an electrophoretic purification step in a mixture of non-polar (e.g. hexane, etc.) and polar solvents (alcohols, e.g. ethanol). Surfactants are used in this process.

[0009] CN21 6738584U discloses a device for depositing layers of quantum dots, which may be several different types of dots. It is equipped with a set of electrodes, a transfer unit and a voltage or current control system. Document does not mention of the possibility of using the device for purifying nanoparticles or using it in a flow process.

[0010] CN1 13809273A discloses the manufacturing of a thin layer of nanoparticles using electrophoresis. Various known semiconductors (e.g. ZnSe, CdSe, etc.) layer can be fabricated in this way. Deposition occurs on two electrodes by applying voltages (one after the other) with opposite signs. In this way, deposition selectivity is achieved. Mixtures of solvents are used, with the second solvent being more polar than the first. Only two electrodes are used, there is no mention of the possibility of conducting a flow process.

[0011] CN1 13089054A discloses method of depositing thin layers of quantum dots using electrophoresis. Two layers of different nanoparticles can be applied or a layer can be removed if it does not meet the required parameters. The nanoparticle solution used in deposition is based on the original solution, i.e. octadecene, hexane or other non-polar substances without the use of a polar additive. The document does not mention a flow process.

[0012] WO201 5066573A2 relates to the composition and method of producing nanoparticles, in particular Si and Ge. The primary solvents used are non-polar alkanes, while polar solvents include alcohols and ketones (including acetone). The document reveals a device with only two electrodes and no mention of a flow process mode.

[0013] Kim, D. et al. (Kim, D., Park, H.K., Choi, H., Noh, J., Kim, K., Jeong, S., "Continuous flow purification of nanocrystal quantum dots", (2014) Nanoscale, 6 (23), pp. 14467-14472. DOI: 10.1039 / c4nr04351 k) disclose a method of purifying CdSe quantum dots using electrophoresis in a continuous process, which uses a special microfluidic chip equipped with a syringe pump. The spacing of the electrodes (made of chrome and gold) was less than 1 mm, and the voltage at which the maximum efficiency was achieved was approximately 40-100 V, depending on the composition of the solvent mixture. Ethanol was used as a non-solvent. This method uses a device with two electrodes, and only ethanol is used as a non-solvent (although the authors show that it is used here to increase the value of the dielectric function, so presumably other solvents with such properties can also be used). Due to the use of a micro-set, flows and efficiencies are low.

[0014] Bass, J.D. et al. (Bass, J.D., Ai, X., Bagabas, A., Rice, RM., Topuria, T, Scott, J.C., Alharbi, F.H., Kim, H.-C., Song, Q., Miller, R.D., "An efficient and low-cost method for the purification of colloidal nanoparticles", (201 1) Angewandte Chemie - International Edition, 50 (29), pp. 6538- 6542. DOI: 10.1002 / anie.201 100112) disclose purification of CdSe nanoparticles using electrophoresis in a non-polar solvent with the addition of a polar non-solvent: acetone in a ratio of 1 : 1.5. One of the electrodes is made of aluminum. The voltage used is of the order of 500 V, only two electrodes are used and there is no mention of the possibility of conducting a flow process.

[0015] The aim of this invention is to improve the method of purifying quantum dots (QDs) and other nanoparticles during or after their multi-stage synthesis. Electrophoretic purification is treated as an alternative method to precipitation purification (when centrifugation is used). The products - QDs or other nanoparticles - are efficiently purified from the other components of the post-reaction mixture using a system according to the invention and selected process parameters.

[0016] The invention relates to an electrophoretic system suitable for nanoparticles purification comprising: a vessel with at least two electrodes arranged parallel to each other, wherein the vessel has a drain valve and two connectors, one on the side wall and second at the bottom of the vessel, a cover of the vessel with two connectors, wherein one of them serves as a socket for an electric wires, and a second one is connected to a solvent circulation hose, a three-way valve connected to the lower connector on the bottom of the vessel, wherein the three-way valve is connected to the two hoses, hose connected to the connector throughout a first pump, and hose connected to the upper connector on the side wall of the vessel throughout a second pump and reservoir tank, one three-way valve is connected to the hose supplying the non-solvent to the system from tank containing the non-solvent using pump and the second three-way valve is connected to the hose supplying the solvent to the system from tank containing solvent using pump.

[0017] Preferably at least two vessels connected in series or parallel

[0018] Preferably the connector at the bottom of the vessel is connected with a connector on the side wall of the adjacent vessel by the process mixture circulation hose. Preferably the First and the last vessels are connected by the process mixture circulation hose, which passes through the pump and reservoir tank.

[0019] Preferably electrodes are made from steel or aluminum.

[0020] Preferably electrodes are arranged in perpendicular position with respect to the axis (a) of the vessel.

[0021] Preferably electrodes are arranged in parallel position with respect to the axis (a) of the vessel.

[0022] Preferably vessel is made of glass, polymer materials or ceramics.

[0023] Another aspect of the invention is use of the system.

[0024] Preferably purification of reaction mixture containing nanoparticles comprising: a) introducing a reaction mixture containing nanoparticles into the system through a connector in a mixture of: a solvent selected from the group: n-hexane, toluene, n- octane, cyclohexane, water and a non-solvent selected from the group: ethanol, methanol, 2-propanol, butanol, acetonitrile, ethyl acetate, butyl acetate, acetone and where the ratio of solvent to mixture containing nanoparticles ranges from 0:1 to 1 : 1 by volume and the ratio of non-solvent to mixture containing nanoparticles ranges from 2: 1 to 12:1 by volume, b) depositing nanoparticles on the electrodes, while the current flow is set in the range of 0-6 mA per 100 cm2of surface of the electrodes and the voltage in the range of 15-600 V and while circulating the solution from step a) using pump at a flow rate of at least 10 ml / min, c) removing the reaction mixture without nanoparticles from the system by drain valve, d) washing the entire surface of the electrode system at least once with a non-solvent with a flow rate of at least 10 ml / min, for at least 1 min, e) redispersion of a nanoparticles deposited on electrodes in a step (b) by circulating a solvent with a flow rate of at least 10 ml / min.

[0025] Preferably step (b) lasts 2-20 min.

[0026] Preferably step (e) lasts 2-10 min.

[0027] The main advantages (compared to precipitation purification) of the invention are: high process efficiency - possibility of purifying a significant amount of material per unit of time per unit of electrodes surface, possibility to obtain a high degree of nanoparticles purity, easy scale-up and a possible high level of automation, universal method - possibility of purifying a wide range of metallic and semiconductor nanomaterials, controllable and - optional - inert conditions (closed system), possibility to purifying nanoparticles in a continuous process, lower solvent consumption (when purifying the same amounts of nanoparticles) and relatively cheap electrodes and other components of the system.

[0028] Brief description of Drawings:

[0029] Fig. 1 presents scheme of a purification system comprising one glass vessel with the electrodes positioned parallel to the axis "a" of the vessel.

[0030] Fig. 2 presents scheme of a purification system comprising three glass vessels with the electrodes positioned parallel to the axis "a" of the vessel, in which all vessels are connected in series.

[0031] Fig. 3 presents a photo of a purification system comprising one glassvesselwith the electrodes positioned perpendicular to the axis "a" of the vessel.

[0032] Fig. 4 presents a photo of a purification system comprising one glassvesselwith the electrodes positioned parallel to the axis "a" of the vessel.

[0033] 1 -cover of the vessel; 2-process vessel; 3-electrodes module; 4-connector at the bottom of the vessel; 5-three-way valve; 6-power supply; 7-electric wires; 8-connectors in the cover of the vessel; 9-connector on the side wall of the vessel; 10-drain valve; 1 1 -first peristaltic pump for solvent (redispersion); 12-second peristaltic pump for process mixture; 13-solvent circulation hose (redispersion); 14-process mixture circulation hose; 15-reservoir tank; 16-three-way valve; 17-hose supplying the non-solvent to the system; 18-tank with the non-solvent; 19- three-way valve; 20-hose supplying the solvent to the system; 21 -tank with the solvent.

[0034] Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[0035] In one aspect, the present invention is a system suitable for nanoparticles purification. Fig. 1 shows a system comprising a glass vessel 2 with a module of steel electrodes 3 placed inside. The vessel has a drain valve 10 and connectors to which the hoses are connected. One connector is on the side wall 9 and second at the bottom of the vessel 4. A three-way valve 5 is connected to the connector on the bottom of the vessel 4, to which two hoses 13, 14 are connected, one of which is used to circulate the process mixture 14 and is connected to the upper connector of the side wall 9 indirectly through the reservoir tank 15, and the other hose 13 to circulate the solvent. The hose for circulating the process mixture 14 between the three- way valve 5 and the reservoir tank 15 is connected to the second peristaltic pump 12. The three-way valve 5 is connected to the hose 13 connected to the connector 8 throughout the first peristaltic pump 1 1 . The second peristaltic pump 12 ensures circulation of the process mixture in the system at the deposition stage and the hose 14 is led through it to circulate the mixture, while the first pump 1 1 ensures circulation of the solvent for redispersion of the deposited nanoparticles and the hose 13 is connected to it, which ensures solvent circulation during redispersion.

[0036] A cover 1 of the vessel is connected with two connectors 8, wherein one of them serves as a socket for an electric wires 7, and a second is connected to the solvent circulation hose 13.

[0037] The electrical wires 7 are connected at one end to the electrode array inside the vessel and at the other to the DC power supply 6. During the circulation of the process mixture, the peristaltic pump 12 is set so that the liquid flows in the vessel with the electrode system from bottom to top. When circulating the solvent for redispersion, the pump 11 is set to flow in the opposite direction.

[0038] The reservoir tank 15 is an element that performs two functions in the system. Firstly, it is where the post-reaction mixture is located and from which the post-reaction mixture is taken using a hose. Secondly, during the process, the excess of the entire reaction mixture is poured into this tank when its volume exceeds the volume of the reactor (or reactors), but at the same time it is too small to fill the next reactor (which eventually may be run in a process).

[0039] Two additional tanks are connected to the system - one tank 21 contains a solvent and the other tank 18 a non-solvent. Both liquids from the tanks are fed to the system through hoses 20 and 17, respectively. The three-way valve 16 is connected to the hose 17 supplying the nonsolvent to the system from tank containing the non-solvent 18 using pump 12 and the three- way valve 19 is connected to the hose 20 supplying the solvent to the system from tank containing solvent 21 using pump 1 1 . The final dispersion containing purified nanoparticles is poured through a drain valve 10 into a separate, external tank or bottle.

[0040] Inside the glass vessel are placed at least two electrodes arranged parallel to each other. In another embodiment the vessel comprising a pile of electrodes (alternating positive and negative) with the smallest number being 2. It seems to be no upper limit to the number of electrodes, as it depends on the volume of the reactor, and this parameter theoretically has no limit here.

[0041] The optimal and maximum number of electrodes depend on the size of the reactor in which the electrodes are placed. Optimally, the entire volume of the reactor through which the process mixture flows should be filled with the electrode system. Optimally, these electrodes are placed at a distance of 4-5 mm from each other. The maximum number of electrodes is determined by the minimum distance between them, which in practice is 1 mm due to allowing liquid to flow between them and the technical difficulties associated with making the system. Another factor that determines the number of electrodes in the reactor is the sum of the surfaces of the electrodes per 1 g of quantum dots. Assuming that the surfaces of positive and negative electrodes are comparable, the minimum area of the electrodes is approximately 100 cm2 / 1 g QDs, and the optimal area is approximately 200 cm2 / 1 g QDs.

[0042] Generally, it is possible to use electrodes at any angle relative to the vessel axis. Vessel axis is understood as a direction indicated between connectors 4 and 9. The system for electrophoretic purification of nanoparticles will function properly both when the electrodes are placed perpendicular (Fig. 3), parallel (Fig. 4) or at an angle of 45 degrees to the axis "a". It seems that the most optimal positioning of the electrodes is perpendicular and parallel in relation to the vessel axis. Then the liquid flows continuously along the electrodes, washing them more thoroughly than in other positions, and the risk of potential contaminants falling by gravity onto the surface of the electrodes is limited.

[0043] Generally, it is possible to use many different types of pumps in the system, i.e. peristaltic pumps, centrifugal pumps, piston pumps, etc. In a preferred embodiment the peristaltic pump is used.

[0044] Material from which electrodes can be made:

[0045] - steel;

[0046] - aluminum.

[0047] Generally, the electrodes can be made of any electrically conductive material. In a preferred embodiment electrodes are made of steel.

[0048] Material from which a process vessels can be made:

[0049] - g^ass;

[0050] - polymer materials, e.g. polycarbonate,

[0051] - ceramics.

[0052] Generally, the process vessel can be made of any material that does not conduct electricity and which is chemically resistant. In a preferred embodiment the vessel is made of glass.

[0053] Generally, a wide range of nanomaterials can be purified by the method described. Metallic nanoparticles such as silver nanoparticles, gold nanoparticles, copper nanoparticles, iron oxide nanoparticles, etc. Semiconductor nanoparticles such as quantum dots (i.e. based on CdSe, CdS, ZnS, ZnSe, InP, CulnS, PbSe, PbS, perovskites), ZnO nanoparticles, etc. Non-metal nanoparticles such as graphene, etc. Generally, nanomaterials with different shapes, sizes and structures (such as core-shell) can be purified by the method described. In another embodiment the purification system for nanoparticles comprising two or more vessels. In Fig. 2 is shown a system comprising three glass vessels connected in series. The vessels are connected to each other by connector 4 at the bottom of the vessel with a connector 9 on the side wall of the adjacent vessel by the process mixture circulation hose 1 . The first and the last glass vessels are connected by the process mixture circulation hose 14, which passes through the second peristaltic pump 12. In another embodiments glass vessels are connected parallel to each other or both in series and in parallel. Generally, the use of a single or combined reactors affect the total mass of the purified product per unit of time (more reactors, and therefore more electrodes mean more purified nanomaterial in the same unit of process time). For large amounts of nanoparticles to be purified, it is therefore better to use connected reactors. System comprising at least two process vessels can also operate in a continuous process. In conclusion, the reactors can be connected in series, in parallel, or both in series and in parallel (in the case of a larger number of reactors).

[0054] In another aspect, the present invention relates to the use of the system for purification of nanomaterials.

[0055] Materials and methods for

[0056] Blue-emitting ZnSe(Te) / ZnSe / ZnS quantum dots were synthesized according to the following procedure. and tellurium of the

[0057] The system for the flow synthesis consists of a furnace (tubular reactor) and a steel tube 160 cm long and 0.3175 cm (1 / 8 inch) in diameter, through which a flow of reaction solution is conducted, a flow meter with apparatus, a peristaltic pump, an argon source, and also flexible tubes with high chemical and thermal resistance surrounded by heating bands connected to temperature controllers.

[0058] 1.1 g (0.006 moles) of anhydrous zinc acetate (Zn(Ac)z), 5.37 g (0.019 moles) of oleic acid (OA) and 35.51 g (0.14 moles) of 1 -octadecene (ODE) were weighed and all the ingredients were placed in a glass flask.

[0059] Under the fume cupboard, the system was connected to a Schlenk line and the flask with the reagents was placed in a heating basket and connected to a temperature controller set on a magnetic stirrer (500 rpm). The solution was pre-gassed at room temperature for 5 minutes and with the pressure in the flask gradually reduced until it reached 1 mbar. Later, the solution was heated to 120°C in about 12 minutes. At this temperature, the solution was degassed again for a further hour. Argon was then connected to the system and a 1.5 M solution of selenium precursor (0.237 g selenium) in diphenylphosphine (1.56 g diphenylphosphine) (Se- DPP) was rapidly injected and the solution incubated at 120°C for 30 min.

[0060] After this time, a peristaltic pump set to a speed of 1.3 ml / min was started and the reaction solution was passed through a tubular reactor, heated to 250°C, which is part of the flow synthesis system. For the first 10 minutes, the reaction solution was collected in a separate beaker. Subsequently, the reaction solution containing the resulting ZnSe seeds (cores) was collected into a flask for about 42 minutes, until a volume of 54 ml was collected. The collected solution was degassed again for 10 minutes at 100°C. The Ar supply was turned off, the solution was heated to 210°C and then 0.056 M tellurium solution (0.016 g tellurium) in trioctylphosphine (1.86 g trioctylphosphine) (Te-TOP) was injected into the reaction mixture. The solution was then heated to 300°C and incubated for 60 minutes at 300°C. The resulting ZnSe(Te) cores were used further in the synthesis, i.e. during the growth of the ZnSe shell.

[0061] Synthesis of ZnSe shell

[0062] In an anaerobic atmosphere, 60 ml of a 0.75 M solution of zinc precursor (8.25 g zinc) in oleic acid (26.73 g OA), 12.46 g TOP and 12.13 g trioctylamine (TOA) were melted on a hotplate at 180°C and then transferred to a glass bottle. 15.12 ml of a 1.2 M solution of selenium (1 .48 g Se) in trioctylphosphine (12.47 g TOP) (Se-TOP) was drawn into a syringe.

[0063] Under the fume hood, a tube and needle were connected to the syringe with Se-TOP. The syringe was placed in a syringe pump set to a flow rate of 126 pl / min.

[0064] The zinc precursor bottle was placed on a heating plate set at 180°C and with 200 rpm stirring. The bottle was capped with a ferrule cap, and a hose fitted to the peristaltic pump was drawn through one of the ferrules (feed rate 501 pl / min), an argon feed hose was connected to the other and the argon was unscrewed.

[0065] To the solution of the ZnSe(Te) cores obtained in the earlier step, after their incubation at 300°C, precursor solutions were supplied by connecting hoses with needles and septum to the flask, and the injection of Se-TOP (126 pl / min) and Zn(OA)2 (501 pl / min) was started. Both injections should last 120 min. After the injections were completed, the heating basket was turned off and the flask was left in the heating basket to cool the reaction solution.

[0066] The reaction solution was poured into a vessel and weighed. A mass of ethanol corresponding to the mass of the reaction solution and a mass of 2-propanol corresponding to twice the mass of the reaction solution were added to the vessel. The solution was centrifuged for 10 min at 4500 rpm. After completion, the precipitate was dried and dispersed in 17.5 g (0.2 moles) of hexane. The resulting ZnSeTe / ZnSe product was used in the further part of the synthesis, namely during the growth of the ZnS shell. Synthesis oFZnS shell

[0067] 8.69 g (0.036 moles) of hexadecylamine (HDA), 16.1 1 g (0.057 moles) of oleic acid (OA), 145.65 g (0.412 moles) of trioctylamine (TOA) and 3.3 g (0.018 moles) of anhydrous zinc acetate were weighed and all ingredients were placed together in a glass flask. In an anaerobic atmosphere, 54 ml of a 0.75 M solution of the zinc precursor (7.43 g Zn) in oleic acid (24.06 g OA) was melted on a hotplate at 180°C and was transferred to a glass bottle. A 13.5 ml 1 .2 M solution of the sulphur precursor (0.53 g sulphur) in trioctylphosphine (11 .22 g TOP) was drawn into a syringe.

[0068] Under the fume hood, a tube and needle were connected to the syringe containing the sulphur precursor. The syringe was placed in a syringe pump set to a flow rate of 225 pl / min. The bottle containing the zinc precursor was placed on a heating plate set at 180°C and with stirring at 200 rpm. The bottle was capped with a ferrule cap, and a hose fitted to the peristaltic pump (feed rate 900 pl / min) was threaded through one ferrule, an argon feed hose was connected to the other and the argon was unscrewed. The sulphur precursor and zinc precursor are ready to be added at a further stage of the synthesis.

[0069] A system was connected to the Schlenk line under the fume cupboard and the flask with the reagents weighed in the first step (HDA, OA, TOA and anhydrous zinc acetate) was placed in a heating basket and connected to a temperature controller set on a magnetic stirrer (500 rpm). Initially, the solution was degassed at room temperature for 5 minutes and with the pressure in the flask gradually reduced until a range of 1 -10 mbar was reached. Later, the solution was heated to 120°C in about 12 minutes. At this temperature, the solution was degassed again for 10 minutes. Argon was then connected to the system and the solution was heated to 180°C. The ZnSeTe / ZnSe product obtained at the earlier stage (dissolved in hexane) was then taken into syringes and injected vigorously into the solution over about 1 minute. The solution was heated to 185°C and simultaneous administration of the prepared zinc and sulphur precursors was initiated over approximately 60 min. Simultaneously, the solution was heated to 330°C during the administration of the precursors. Once 330°C was reached and the feed of both precursors was completed, the heating basket was turned off and the flask was left to cool in the heating basket.

[0070] The reaction solution was poured into a vessel and weighed. A mass of ethanol corresponding to the mass of the reaction solution and a mass of 2-propanol corresponding to twice the mass of the reaction solution were added to the vessel. The solution was centrifuged for 10 minutes at 4500 rpm. After completion, the precipitate was dried and dispersed in toluene so that the final concentration of the blue-emitting ZnSe(Te) / ZnSe / ZnS quantum dots was about 100 mg / ml. The synthesis of red-emitting CdSe quantum dots was performed according to the procedure described in X. Peng, DOI 10.1007 / s12274-013-0341 -7. The CdSe cores were coated with an inorganic CdS shell by a reaction carried out according to a modified procedure originally proposed by Bawendi [Bawendi, Nature, DOI: 10.1038 / NMAT3539],

[0071] The synthesis of green-emitting CdSe@ZnS quantum dots was performed according to the modified (without additional ZnS shell) procedure described in Y. Fu DOI: 10.1039 / C7RA06957J.

[0072] The synthesis of silver nanoparticles was performed according to the procedure described in A. J. Frank, DO1 10.1021 / ed100166g.

[0073] The synthesis of perovskite quantum dots was performed according to the procedure described in L. Protesescu, DO1 10.1021 / nl5048779.

[0074] Solvents: n-hexane, toluene, n-octane, cyclohexane, water. The preferred solvent is hexane.

[0075] Non-solvents:

[0076] Ethanol, methanol, 2-propanol, butanol, acetonitrile, ethyl acetate, butyl acetate, acetone. The preferred non-solvent is ethyl acetate.

[0077] Proportions (all ratios given are by volume):

[0078] The ratio of solvent to nanoparticles dispersion ranges from 0: 1 to 1 :1;

[0079] The ratio of non-solvent to nanoparticles dispersion ranges from 2:1 to 12: 1 ;

[0080] The preferred solventmanoparticles dispersion ratio is 0.25:1 and the preferred nonsolventmanoparticles dispersion ratio is 3.75: 1.

[0081] Generally, we use solvent and non-solvent in the volume ratios described above to prepare the process mixture. In addition, we then use a non-solvent (e.g. ethyl acetate) to wash the nanoparticles deposited on electrodes from any remaining contamination and finally use a solvent (e.g. toluene) to redisperse the nanoparticles from the electrodes.

[0082] Flow reaction:

[0083] Flow is used, among others, in order to introduce mixing into the process vessel, which allows maintaining the uniformity of the deposition of nanoparticles on the electrodes and avoiding their remaining in dead volumes (parts of the vessel not filled with electrodes). Additionally, it prevents local overheating of the reaction mixture and allows the process to be carried out continuously when connected to a technological installation, which helps maintain controlled process conditions.

[0084] In the case of deposition of nanoparticles on electrodes, the liquid flows from bottom to top of the process vessel (preferred), but flow from top to bottom of the process vessel is also possible. In turn, in the case of redispersion, flow from top to bottom of the process vessel is preferred, but liquid flow in the other direction is also possible.

[0085] Redispersion of nanomaterials in a flow system:

[0086] Redispersion is a step necessary to transfer the nanoparticles deposited on the surface of the electrodes into a stable dispersion in the selected solvent. Redispersion in the flow is used to avoid the need to disassemble the system and conduct the redispersion process in a separate vessel, which is associated with mass losses of purified material and longer process time. Additionally, redispersion in the flow system allows the entire process to be carried out in a completely closed system, which provides protection against contamination from the outside (e.g. dust) and allows the process to be carried out in a protective atmosphere (e.g. oxygen free, moisture free, etc.).

[0087] Key parameter ranges for the electrophoretic purification process:

[0088] - voltage: 15-700 V;

[0089] - flow rate: 10-600 ml / min;

[0090] - deposition time: up to 20 minutes;

[0091] - process temperature: 15-30 °C;

[0092] - distance between electrodes: 1 - 40 mm.

[0093] Preferred ranges for the electrophoretic purification process:

[0094] - voltage: 150-600 V;

[0095] - flow rate: 150-300 ml / min;

[0096] - process temperature: 21 -23 °C.

[0097] Photoluminescence (PL) spectra were measured to determine the position and broadening (FWHM - Full Width at Half Maximum) of PL peak. Maximum photoluminescence emission peak (PL Amax), FWHM and Photoluminescence Quantum Yield (QY) were measured on spectrometer Hamamatsu Quantaurus-QY Absolute PL quantum yield, C1 1347-1 1. The average particle size was measured by Dynamic Light Scattering (DLS) in an Anton-Paar Litesize r 500. TGA was measured on Netzsch STA 409 Luxx thermal analyzer.

[0098] Samples containing ink compositions were stored at room temperature. In addition, the samples were stored away from light sources and sealed. :-reaction mixture of blue¬ mixture:

[0099] To 120 ml of the post-reaction mixture from the synthesis of blue-emitting quantum dots, 60 ml of n-hexane (solvent) and 540 ml of ethyl acetate (non-solvent) were added.

[0100] Process

[0101] The previously prepared process mixture was transferred into a 300 ml process vessel from a reservoir tank (1000 ml bottle) with a steel electrode module placed inside, and then the liquid was circulated in the system using a peristaltic pump. The flow rate was set at 200 ml / min. The electrodes were connected to the power supply and a 100 mA current at 130 V was started. When the current began to flow through the system, the quantum dots began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 20 minutes, the current flow through the system was stopped by turning off the power supply, the liquid circulation was stopped and the process vessel was emptied by draining the liquid using the drain valve. The surface of the electrodes with the quantum dot layer deposited was washed with approximately 30 ml of ethyl acetate and left to dry for 3 minutes. After this time, the deposited layer was redispersed by circulating toluene (about 40 ml) in the system until the layer of quantum dots was completely rinsed from the electrodes. The dispersion of quantum dots in toluene was poured through a drain valve to a sealed bottle. of post-reaction mixture of blue¬ mixture:

[0102] To 200 ml of the post-reaction mixture from the synthesis of blue-emitting quantum dots, 50 ml of n-hexane (solvent) and 750 ml of ethyl acetate (non-solvent) were added.

[0103] Process

[0104] The prepared process mixture was transferred into a system of three process vessels (each with a capacity of 300 ml) from a reservoir tank (1000 ml bottle) with steel electrode modules placed inside, and then the liquid was circulated in the system using a peristaltic pump. The flow rate was set to 200 ml / min. The electrodes were connected to the power supply and a 150 mA current at 100 V was started. When the current began to flow through the system, the quantum dots began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 5 minutes, the current flow through the system was stopped by turning off the power supply, the liquid circulation was stopped and the process vessels were emptied by draining the liquid using drain valves. The surface of the electrodes with the embedded layer of quantum dots was washed with approximately 50 ml of ethyl acetate and left to dry for 3 minutes. After this time, the deposited layer was redispersed by circulating toluene in the system (3 portions of 20 ml each) until the layer of quantum dots was completely rinsed from the electrodes. The dispersion of quantum dots in toluene was poured through a drain valve to a sealed bottle.

[0105] :-reaction mixture of silver of the process mixture:

[0106] To 5 ml of the post-reaction mixture from the synthesis of silver nanoparticles, 20 ml of acetone (non-solvent) was added.

[0107] Process

[0108] The prepared process mixture was transferred into a 50 ml process vessel with a steel electrode module placed inside. The electrodes were connected to the power supply and a 15 mA current at 50 V was started. When the current began to flow through the system, the silver nanoparticles began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 10 minutes, the current flow through the system was stopped by turning off the power supply and the process vessel was emptied. The layer was left to dry for 1 minute and then the material was redispersed using about 2 ml of demineralized water. The dispersion of silver nanoparticles in water was poured to a sealed vial. reactor mixture:

[0109] To 2 ml of the post-reaction mixture from the synthesis of perovskite quantum dots, 4 ml of n-hexane (solvent) and 4 ml of acetone (non-solvent) were added.

[0110] Process

[0111] The prepared process mixture was transferred into a 50 ml process vessel with a steel electrode module placed inside. The electrodes were connected to the power supply and a 20 mA current at 500 V was started. When the current began to flow through the system, the perovskite quantum dots began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 15 minutes, the current flow through the system was stopped by turning off the power supply and the process vessel was emptied. The layer was left to dry for 1 minute and then the material was redispersed using about 1 ml of toluene. The dispersion of perovskite quantum dots in toluene was poured to a sealed vial. 5 The oF post-reaction mixture oF reactor of the process mixture:

[0112] To 30 ml of the post-reaction mixture from the synthesis of green-emitting quantum dots, 15 ml of n-hexane (solvent) and 270 ml of ethyl acetate (non-solvent) were added.

[0113] Process

[0114] The previously prepared process mixture was transferred into a 300 ml process vessel from a reservoir tank (500 ml bottle) with a steel electrode module placed inside, and then the liquid was circulated in the system using a peristaltic pump. The flow rate was set at 300 ml / min. The electrodes were connected to the power supply and a 50 mA current at 33 V was started. When the current began to flow through the system, the quantum dots began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 60 minutes, the current flow through the system was stopped by turning off the power supply, the liquid circulation was stopped and the reaction process vessel was emptied by draining the liquid using the drain valve. The surface of the electrodes with the quantum dot layer deposited was washed with approximately 30 ml of ethanol and left to dry for 3 minutes. After this time, the deposited layer was redispersed by circulating toluene (about 20 ml) in the system until the layer of quantum dots was completely rinsed from the electrodes. The dispersion of quantum dots in toluene was poured through a drain valve to a sealed bottle. oF post-reaction mixture oF red- dots using single reactor of the process mixture:

[0115] To 50 ml of the post-reaction mixture from the synthesis of red-emitting quantum dots, 50 ml of n-hexane (solvent) and 200 ml of ethyl acetate (non-solvent) were added.

[0116] Process

[0117] The previously prepared process mixture was transferred into a 300 ml process vessel from a reservoir tank (500 ml bottle) with a steel electrode module placed inside, and then the liquid was circulated in the system using a peristaltic pump. The flow rate was set at 150 ml / min. The electrodes were connected to the power supply and a 13 mA current at 300 V was started. When the current began to flow through the system, the quantum dots began to move towards the positive electrodes, gradually settling on their surface and forming a layer. After 15 minutes, the current flow through the system was stopped by turning off the power supply, the liquid circulation was stopped and the reaction process vessel was emptied by draining the liquid using the drain valve. The surface of the electrodes with the quantum dot layer deposited was washed with approximately 30 ml of ethanol and left to dry for 3 minutes. After this time, the deposited layer was redispersed by circulating toluene (about 40 ml) in the system until the layer of quantum dots was completely rinsed from the electrodes. The dispersion of quantum dots in toluene was poured through a drain valve to a sealed bottle.

[0118] Purity degree:

[0119] Table 1 Properties of the blue-emitting QDs dispersion purified by using electrophoretic and precipitation purification Table 2. Optical parameters of quantum dots after electrophoretic purification

[0120] Table 3 The average particle size measured using DLS for different nanomaterials after electrophoretic purification

Claims

AMENDED CLAIMS received by the International Bureau on 16 June 2025 (16.06.2025) Claims1 . An electrophoretic system suitable for nanoparticles purification comprising: at least two vessels (2) connected in series or parallel, wherein the vessels are connected to each other by connector (4) at the bottom of the vessel with a connector (9) on the side wall of the adjacent vessel by the process mixture circulation hose (1 ) and the first and the last glass vessels are connected by the process mixture circulation hose 14, which passes through the second pump(12), each vessel (2) with at least two electrodes (3) arranged parallel to each other, wherein the vessel (2) has a drain valve (10) and two connectors, one on the side wall (9) and second at the bottom of the vessel (4), a cover (1) of the vessel with two connectors (8), wherein one of them serves as a socket for electric wires (7), and a second one is connected to a solvent circulation hose (13), a three-way valve (5) connected to the lower connector (4) on the bottom of the vessel, wherein the three-way valve (5) is connected to the two hoses (13,14), hose(13) connected to the connector (8) throughout a first pump (1 1), and hose (14) connected to the upper connector on the side wall of the vessel (9) throughout a second pump (12) and reservoir tank (15), the three-way valve (16) is connected to the hose (17) supplying the non-solvent to the system from tank containing the non-solvent (18) using pump (12) and the three-way valve (19) is connected to the hose (20) supplying the solvent to the system from tank containing solvent (21) using pump (11), wherein the electrodes (3) are placed at a distance of 4 to 5 mm from each other.

2. The system according to claim 2, wherein the connector (4) at the bottom of the vessel is connected with a connector (9) on the side wall of the adjacent vessel by the process mixture circulation hose (14).

3. The system according to claim 2 or 3, wherein the first and the last vessels are connected by the process mixture circulation hose (14), which passes through the pump (12) and reservoir tank (15).

4. The system according to claim 1 , wherein electrodes (3) are made from steel or aluminum.

5. The system according to claim 1 , wherein electrodes (3) are arranged in perpendicular position with respect to the axis (a) of the vessel.

6. The system according to claim 1 , wherein electrodes (3) are arranged in parallel position with respect to the axis (a) of the vessel.

7. The system according to claim 1 , wherein vessel (2) is made of glass, polymer materials or ceramics.

8. Use of the system according to claims 1 -8.

9. The use according to claim 9, wherein purification of reaction mixture containing nanoparticles comprising: a) introducing a reaction mixture containing nanoparticles into the system through the connector (4) in a mixture of: a solvent selected from the group: n-hexane, toluene, n-octane, cyclohexane, and a non-solvent selected from the group: ethanol, methanol, 2-propanol, butanol, acetonitrile, ethyl acetate, butyl acetate, acetone and where the ratio of solvent to mixture containing nanoparticles ranges from 0:1 to 1 :1 by volume and the ratio of non-solvent to mixture containing nanoparticles ranges from 2: 1 to 12:1 by volume, b) depositing nanoparticles on electrodes (3), while the current flow in the range of 0-6 mA per 100 cm2of surface of the electrodes and the voltage in the range of 15- 600 V and while circulating the solution from step a) using pump at a flow rate of at least 10 ml / min, c) removing the reaction mixture without nanoparticles from the system by drain valve (5), d) washing the entire surface of the electrode system at least once with a non-solvent with a flow rate of at least 10 ml / min, for at least 1 min, e) redispersion of a nanoparticles deposited on electrodes in a step (b) by circulating a solvent with a flow rate of at least 10 ml / min.

10. The use according to claim 9 or 10, wherein step (b) lasts 2-20 min.1 1 . The use according to any claim 9-1 1 , wherein step (e) lasts 2-10 min

Images