ELECTROSTATIC PRECIPITATOR

Abstract

An electrostatic precipitator for introducing sub-millimeter sized particles into a carrier material. The carrier material has a melting point which lies above 0° C., preferably above room temperature. The electrostatic precipitator comprises a casing having an inlet for inserting a gas flow into the casing and having an outlet for guiding a gas flow out of the casing. A channel for passing the gas flow from the inlet to the outlet is provided. A discharge electrode is provided on a first side of the channel. A collecting electrode is provided at a second side of at least a part of the channel. The electrostatic precipitator applies an electric field between the discharge electrode and the collecting electrode. A receiving volume is provided with a molten material as carrier material.

Claims

1. Electrostatic precipitator for introducing sub-millimeter sized particles into a carrier material, wherein the carrier material has a melting point which lies above 0° C., preferably above room temperature, wherein the electrostatic precipitator comprises a casing having an inlet for inserting a gas flow into the casing and having an outlet for guiding a gas flow out of the casing, wherein a channel for passing the gas flow from the inlet to the outlet is provided between the inlet and the outlet, wherein a discharge electrode is provided on a first side of the channel and wherein a collecting electrode is provided at a second side of at least a part of the channel, the second side being located opposite to the first side such that the electrostatic precipitator is adapted for applying an electric field between the discharge electrode and the collecting electrode, wherein adjacent to the collecting electrode and between the collecting electrode and at least a part of the channel, a receiving volume is provided, wherein located in the receiving volume is a molten material as carrier material, wherein the carrier material has a melting point which lies above 0° C., preferably above room temperature.

2. Electrostatic precipitator according to claim 1, wherein a heater is provided for heating the carrier material positioned in the receiving volume.

3. Electrostatic precipitator according to claim 1, wherein the electrostatic precipitator is a one-stage precipitator, wherein the one-stage precipitator comprises a first stage having a first chamber which is adapted for applying an electric field acting on the sub-millimeter sized particles being present in the gas stream and wherein the first chamber is further adapted for collecting the sub-millimeter sized particles at the receiving volume, and wherein the first chamber is further in fluid communication with the channel.

4. Electrostatic precipitator according to claim 1, wherein the electrostatic precipitator is a two-stage precipitator, wherein the two-stage precipitator comprises a first stage which is adapted for applying an electric field acting on the sub-millimeter sized particles for electrically charging the sub-millimeter sized particles being present in the gas stream and wherein the two-stage precipitator comprises a second stage with a second chamber, wherein the second chamber is adapted for collecting the electrically charged sub-millimeter sized particles at the receiving volume, and wherein a first chamber of the first stage and the second chamber are in fluid communication with the channel.

5. Electrostatic precipitator according to claim 4, wherein the first stage comprises at least one of a ion blower and the first chamber having an arrangement of electrodes for forming an electric field.

6. Electrostatic precipitator according to claim 1, wherein the electrostatic precipitator comprises a loading inlet for loading the receiving volume with carrier material and that the electrostatic precipitator comprises an unloading outlet for unloading carrier material from the receiving volume.

7. Electrostatic precipitator according to claim 1, wherein the casing is formed at least in part from an electrically insulating material.

8. Electrostatic precipitator according to claim 1, wherein the casing is formed at least in part from an electrically conductive material, wherein the collecting electrode is formed by the electrically conductive material of the casing.

9. Arrangement of an electrostatic precipitator and a system for forming sub-millimeter sized particles from a particle compound, wherein the electrostatic precipitator and the system for forming sub-millimeter sized particles are arranged for guiding sub-millimeter sized particles from the system for forming sub-millimeter sized particles into the electrostatic precipitator, wherein the electrostatic precipitator is arranged according to claim 1, and wherein the system for forming sub-millimeter sized particles comprises an aerosol generator, the aerosol generator comprising a nebulizing chamber with a first inlet, a second inlet and an outlet, wherein a tank for receiving particle compound solution is connected to the first inlet for introducing a solution of particle compound into the nebulizing chamber and wherein a tank for receiving carrier gas is connected to the second inlet for introducing a carrier gas stream into the nebulizing chamber, wherein a nebulizer is provided in the nebulizing chamber to form an aerosol out of the particle compound solution such that the carrier gas stream guides the aerosol out of the nebulizing chamber through the outlet, wherein the outlet is connected to the electrostatic precipitator through a dryer for forming dry sub-millimeter sized particles by evaporating the solvent of the aerosol.

10. Arrangement according to claim 9, wherein the nebulizer comprises a piezo element for emitting ultrasound waves, wherein the piezo element is designed for working in a frequency of more than 2 MHz.

11. Method for placing sub-millimeter sized particles in a carrier material, wherein the carrier material has a melting point which lies above 0° C., preferably above room temperature, wherein the method comprises the following steps: a) Providing an electrostatic precipitator according to claim 1; b) Providing a carrier material in the receiving volume, wherein the carrier material is in the form of a molten material; c) Guiding the sub-millimeter sized particles in a gas stream into the inlet and into the channel; d) Applying an electrostatic field between the discharge electrode and the collecting electrode such that the sub-millimeter sized particles are guided into the molten carrier material; and e) Removing the carrier material with embedded sub-millimeter sized particles from the receiving volume.

12. Method according to claim 11, wherein the carrier material has a melting point which is lower compared to a melting point of the sub-millimeter sized particles and which is lower compared to a degradation temperature of the sub-millimeter sized particles.

13. Method according to claim 11, wherein the sub-millimeter sized particles have a size in the range of ≥1 nm to ≤10 μm.

14. Method according to claim 11, wherein the temperature of the molten material in the receiving volume is controlled by a control loop.

15. Use of an electrostatic precipitator for forming at least one of a pharmaceutically active composition, a crop protection item and a food item, wherein the electrostatic precipitator is configured according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0096] These and other aspects of the invention will be apparent from and elucidated with reference to the figures and examples described hereinafter, wherein even individual features disclosed in the figures and the examples and in the disclosure as a whole can constitute an aspect of the present invention alone or in combination, wherein additionally, features of different embodiments can be carried over from one embodiment to another embodiment without leaving the scope of the present invention.

[0097] In the drawings:

[0098] FIG. 1 shows an exemplary view of an electrostatic precipitator according to an embodiment of the disclosure;

[0099] FIG. 2 shows an exemplary view of an electrostatic precipitator according to a further embodiment of the disclosure;

[0100] FIG. 3 shows an exemplary view of an electrostatic precipitator according to a further embodiment of the disclosure;

[0101] FIG. 4 shows an arrangement of an electrostatic precipitator according to an embodiment of the disclosure and a spray drying device;

[0102] FIG. 5 shows an arrangement of an electrostatic precipitator and a system for forming sub-millimeter sized particles from a particle compound; and

[0103] FIG. 6 shows the improved water-solubility of particles treated with an electrostatic precipitator according to an embodiment of the disclosure.

DETAILED DESCRIPTION

[0104] FIG. 1 shows an electrostatic precipitator 10, which is designed as a melt electrostatic precipitator like described in detail below. Such an electrostatic precipitator 10 may be used to convert sub-millimeter sized particles 40 e.g. of pharmaceutically active compounds into a solid dispersion in order to increase the bioavailability of active pharmaceutical ingredients, for example. Further examples comprise food items or crop items which comprise a carrier with sub-millimeter sized particles 40.

[0105] In order to achieve this, the electrostatic precipitator 10 is arranged as follows.

[0106] The electrostatic precipitator 10 comprises a casing 12 having an inlet 14 for inserting a gas flow into the casing 12, which is visualized by the arrow 16. Further, the electrostatic precipitator 10 comprises an outlet 18 for guiding a gas flow out of the casing 12, which is visualized by the arrow 20. Further, a channel 22 is provided for passing the gas flow from the inlet 14 to the outlet 18.

[0107] FIG. 1 further shows that the electrostatic precipitator 10 is a two-stage precipitator, wherein the two-stage precipitator comprises a first stage with a first chamber 24 which is adapted for electrically charging particles 40 being present in the gas stream and wherein the two-stage precipitator further comprises a second chamber 26 which is adapted for collecting the electrically charged particles 40. Both of the first chamber 24 and the second chamber 26 are in fluid communication with the channel 22. In other words, the channel 22 passes through the first chamber 24 as well as through the second chamber 26, wherein the second chamber 26 is located downstream to the first chamber 24 with regard to the flow direction of the gas stream.

[0108] For producing an electrostatic field in order to electrically charge the particles 40, a discharge electrode 28 and a counter electrode 30 are provided at the first chamber 24. The counter electrode 30 is part of the casing 12 and also acts as collecting electrode 32 at the second chamber 26 and also at the first chamber 24 like described below. The counter electrode 30 and the collecting electrode 32, respectively, may be on ground potential and may be formed by the stainless steel metal block which forms the casing 12. Thus a corona discharge may be realized between the discharge electrode 28 and the counter electrode 30 in the first chamber 24 by applying voltage to the discharge electrode 28.

[0109] Particles 40 located between the discharge electrode 28 and the counter electrode 30 and thus in the channel 22 in the first chamber 24, or first stage, respectively, are charged and move along the electric field to the collecting electrode 32 in the second chamber 26 or second stage, respectively. No further charging is required in the second stage. Instead, the particles 40 move in an electric field generated by two electrodes of different potential. However a field electrode 34 may be provided opposite to the collecting electrode 32 with regard to the channel in the second chamber in order to create an electric field also no corona discharge is required in the second chamber 26.

[0110] It is further provided that adjacent to the collecting electrode 32 and between the collecting electrode 32 and at least a part of the channel 22, a receiving volume 36 is provided for receiving a molten material 38, i.e. a carrier material. This allows thus that by influence of the electric field, the sub-millimeter sized particles 40 are guided into the molten material 38 and thus provide a finely dispersed solid dispersion with the carrier material. The collecting electrode 32 may be formed by the base 15 of the casing 12, which might be formed from a metal, for example.

[0111] The hood 13 of the casing 12 may be made of hard tissue which has electrical insulating properties. The hard tissue hood 13 is equipped with a hole where the loaded gas can flow. Furthermore, there are two holes for the wire of the discharge electrode 28 for the first stage and for the field electrode 29 in the second stage. Both the discharge electrode 28 and the field electrode 29 are connected to a high voltage source (HPS 350 W, iseg Spezialelektronik GmbH, Radeberg, Germany).

[0112] In order to keep the molten material 38 in a molten state, a heater 42 is provided for heating the molten material 38 positioned in the receiving volume 36. With this regard, FIG. 1 shows that the heater 42 is positioned at a side of the collecting electrode 32 being opposite to the channel 22. This allows that the collecting electrode 32 is heated to keep the melt in a liquid state. Otherwise the sub-millimeter sized particles 40 would only collect on the surface of a solidified melt, which would not show the positive effects. In addition, the temperature is preferably adequately controlled to prevent destruction of the carrier material as molten material 38 and further to prevent melting of the sub-millimeter sized particles 40 in the melt. Sub-millimeter sized particle production can only start once the carrier matrix has liquefied and is present as molten material 38, or of the molten material 38 is provided in the receiving volume 36 in a molten state.

[0113] In a non-limiting detail, the electrostatic precipitator 10 contains a cartridge heater (160 W, Otom GmbH, Braunlingen, Germany) as heater 42 and a temperature sensor (EF7, Otom GmbH, Braunlingen, Germany). A controller (ETC 7420, ENDA, Istanbul, Turkey) ensures that the temperature of the melt can be kept constant. Generally, a temperature sensor 19 may be provided in order to realize a temperature control loop.

[0114] Not shown is a power supply which might be an AC power supply or a DC power supply for enabling the electrodes to provide an electric field.

[0115] A two-stage electrostatic precipitator like shown in FIG. 1 improves the dry separation of sub-millimeter sized particles 40 because of the absence of turbulence due to corona discharge. The separation and redispersion of already deposited particles 40 on a wet surface is more efficient than in a dry electrostatic precipitator. For this reason, the electrostatic precipitator 10 formed as melt electrostatic precipitator can also be designed as a single-stage system.

[0116] This is shown in FIG. 2. According to FIG. 2, a further embodiment of an electrostatic precipitator 10 is shown. With this regard, the electrostatic precipitator 10 according to FIG. 2 works with a comparable effect as described before with regard to FIG. 1. Therefore, mainly the differences between FIG. 1 and FIG. 2 are referred to, wherein the same reference numbers refer to the same or comparable elements. Further, all features as described with regard to FIG. 1 may be transferred to FIG. 2 unless not clearly excluded.

[0117] With regard to FIG. 2, the electrostatic precipitator 10 is a one-stage precipitator, wherein the one stage precipitator comprises a first chamber 24 which is adapted for applying an electrical field which acts on the sub-millimeter sized particles 40 being present in the gas stream and wherein the first chamber 24 is further adapted for collecting the sub-millimeter sized particles 40 at the collecting electrode 32, and wherein the first chamber 24 is further in fluid communication with the channel 22.

[0118] It is thus shown that the same electrical field is used for charging the particles 40 as well as for collecting the particles 40. The electrical field is built up, again, by the discharge electrode 28, and the collecting electrode 32, wherein the discharge electrode 28 is connected to a power supply 17 being designed as a DC power source or an AC power source and the collecting electrode 32 is connected to ground. Further, the discharge electrode 28 and the field electrode 34 as shown in FIG. 1 are combined to the discharge electrode 28 in FIG. 2. Correspondingly, the counter electrode 30 and the collecting electrode 32 as shown in FIG. 1 are combined to the collecting electrode 32 in FIG. 2.

[0119] According to this embodiment, an especially simple arrangement may be realized, as only two electrodes, i.e. the discharge electrode 28 and the collecting electrode 32, are required. Further, such an electrostatic precipitator 10 may be especially small so that an application even in limited building space is possible.

[0120] FIG. 3 shows a further embodiment of an electrostatic precipitator 10 according to the disclosure. Again, the same reference numbers refer to the same or comparable elements compared to FIGS. 1 and 2. Further, all features as described with regard to FIGS. 1 and 2 may be transferred to FIG. 2 unless not clearly excluded.

[0121] The embodiment of the electrostatic precipitator 10 according to FIG. 3 is arranged in a concentric arrangement, in which the discharge electrode 28 forms, together with an inner field electrode 29, the axis of the channel 22.

[0122] The outer pipe 31 is grounded and acts as a receiving electrode in the charging stage for ions and as a collecting 32 electrode for charged sub-millimeter sized particles 40 in the collection stage. The inner pipe 33 forms the field electrode, or discharge electrode 28, respectively, required to build up the electric potential like described above. A tungsten wire may be mounted to a hemisphere on the inner pipe 33 and may form the discharge electrode 28. That part forms a first stage 35, or charging state respectively, of the electrostatic precipitator 10. Downstream of the first stage 35, a second stage 39, or collecting stage, respectively, is provided at which the sub-millimeter sized particles 40 are collected in the molten material 38 as carrier material.

[0123] Both the inner pipe 33 and the outer pipe 31 may be made of stainless steel and may be electropolished to facilitate particle harvesting and cleaning. A sealing cap 37 at the outlet 18 may be made of polyvinyl chloride and acts as a seal that isolates the discharge from the outer collection electrode. The gas enters the precipitator 10 through inlet 14 and proceeds through the first stage 35 and the second stage 39 so that the gas stream is depleted with regard to the sub-millimeter sized particles 40 and the latter are collected in the molten material 38.

[0124] It has to be noted that a one-stage arrangement may be formed correspondingly as described above.

[0125] Further, it has to be noted that the receiving volume 36 is provided at the inner wall of the outer pipe 31, or collecting electrode 32, respectively. The molten material 38 may thus flow down at this inner wall and may be inserted into the channel 22 at the top and may leave the channel at the bottom of the channel 22 in case the precipitator 10 is arranged in a vertical arrangement like shown in FIG. 3. It may further be provided, that the precipitator 10 may work in a rotating manner, which gives more possible arrangements and a longer collection time of the molten material 38.

[0126] FIG. 4 shows an electrostatic precipitator 10, wherein the electrostatic precipitator 10 is coupled to a device for producing sub-millimeter sized particles 40. In the non-limiting example of FIG. 2, the device is formed as a spray drying device 44.

[0127] The spray drying device 44 is designed, per an embodiment, for the production of active ingredient particles 40 in the sub-millimeter sized range, for example. For the production of sub-millimeter sized particles 40, solvent containing pharmaceutically active compound, for example, is sprayed into a cyclone as droplet separator 46 with a known cut off particle diameter like indicated by arrow 48 via a nozzle 50. Further, atomizing gas is guided into said nozzle 50 like indicated by the arrow 52 and is also inserted into the droplet separator 46. The aerosol conditioning is then separated in the cyclone, or the droplet separator 46, respectively and the smallest droplets enter a drying chamber 54. Further, a drying gas is added to the drying chamber 54, wherein the drying gas, such as drying air, is indicated by arrow 56.

[0128] With the help of spray drying, particles 40 in the sub-millimeter sized range are generated. These enter the electrostatic precipitator 10, are charged and move in an electric field towards the melt, after which the melt encloses the particles 40. The advantage of this process, per an embodiment, is the isolated presence of sub-millimeter sized particles 40 in a carrier matrix. Agglomerate formation can be avoided and the distribution of the active ingredient during administration shall be improved.

[0129] FIG. 5 shows an arrangement 58 of an electrostatic precipitator 10 and a system 60 for forming sub-millimeter sized particles from a particle compound. The electrostatic precipitator 10 and the system 60 for forming nanoparticles are arranged for guiding sub-millimeter sized particles from the system 60 for forming nanoparticles into the electrostatic precipitator 10 like described below.

[0130] The electrostatic precipitator 10 is arranged like described above and is not shown in detail.

[0131] The system 60 for forming sub-millimeter sized particles comprises an aerosol generator 62, the aerosol generator 62 comprising a nebulizing chamber 64 with a first inlet 66, a second inlet 68 and an outlet 70, which is formed as a tube 73. A tank 72 for receiving particle compound solution is connected to the first inlet 66 for introducing a solution of particle compound into the nebulizing chamber 64 by means of a pump 71, such as a gear pump, and wherein tank 74 for receiving carrier gas is connected to the second inlet 68 for introducing a carrier gas stream into the nebulizing chamber 64 such as by using a flow regulator 75. Both of the first inlet 66 and the second inlet 68 may be positioned in a tangential manner.

[0132] It is further shown that between flow regulator 75 and nebulizing chamber 64, a conditioning device 65 is provided. Such a conditioning device 65 may introduce a solvent into the carrier gas stream. By enriching, such as by saturating, the carrier gas with a solvent before the carrier gas enters the nebulizing chamber 64, it can be prevented that a precipitation of dry particles occurs in the nebulizing chamber 64, which may be attributed to a rapid droplet drying. In more detail, carbon dioxide as carrier gas may be taken from a pressurized cylinder as tank 74 was guided through a wash bottle filled with acetone to enrich the carbon dioxide with acetone before entering the nebulizing chamber 64.

[0133] Providing sub-millimeter sized particles to be present in the matrix in an isolated and thus non-agglomerated form.

[0134] Further provided in the nebulizing chamber 64 is a nebulizer 76 which is provided to form an aerosol out of the particle compound solution. The nebulizer 76 may comprise a piezo element which may emit ultrasonic waves in a frequency of e.g. 3 MHz, for example. The formed aerosol may be guided by the carrier gas stream out of the nebulizing chamber 64 through the outlet 70 and may further be guided to a dryer 78. By means of the dryer 78, such as comprising a heater 79, the solvent of the aerosol may be evaporated and preferably condensed in a condenser 80 of the dryer 78.

[0135] Downstream of the condenser 80, the dry particles may be guided by the solvent free carrier gas stream, which may be formed from carbon dioxide, into the inlet 14 of the electrostatic precipitator 10. Downstream of the electrostatic precipitator 10, a filter may be provided for collecting sub-millimeter sized particles 40 which are not guided into the carrier material.

EXAMPLES

[0136] When using the arrangement 58 according to FIG. 5, Particle shape and size of the particles, obtained with the aerosol generator 62, were investigated with a scanning electron microscope (SEM) (Hitachi H-S4500 FEG, Krefeld, Germany) at 1 kV with a magnification of up to 25,000. The load of phenytoin as particulate compound in xylitol as carrier material was determined via UV-Vis spectroscopy after dissolving in a mixture of isopropyl alcohol (Carl Roth GmbH & Co. KG, Karlsruhe, Germany) and demineralized water at a wavelength of 212 nm. An SEM picture shows small particles at the outlet of the aerosol generator in a size range 50-200 nm. The particles are shaped rectangular, which is a common observation in phenytoin crystals. The drug load of the melt increases with increasing time of precipitation until it reaches a limit of 1.76 wt. % after 15 minutes of loading, e.g. by an application of voltage of 7 kV a corona discharge at the discharge electrode.

[0137] The following example is further presented to provide those of ordinary skill in the art with a full and illustrative disclosure and description of how to make biologically active compositions by using an electrostatic precipitator 10 according to the disclosure as an exemplary embodiment.

[0138] In the context of this disclosure, an electrostatic precipitator 10 was used which was designed as a melt electrostatic precipitator (MESP). For this purpose, a pharmaceutically acceptable carrier is used as carrier substance which has a lower melting temperature than the deposited pharmaceutically active compound, but at the same time forms a solid at room temperature. The pharmaceutically acceptable carrier as carrier material is molten in the electrostatic precipitator 10 and subsequently loaded with sub-millimeter sized particles 40 of the pharmaceutically active compound by electrostatic precipitation. During powder recovery there is no redispersion in the air and inhalation during product handling is minimized.

[0139] Spray drying experiments were conducted with the drug naproxen (Tokyo Chemical Industry CO., LTD., Tokyo, Japan) dissolved in acetone (Merck KGaA, Darmstadt, Germany). According to BCS classification, naproxen is classified as a Class II active substance and is thus solubility limited in terms of its bioavailability. Naproxen was chosen mainly for its physical properties. The melting temperature is 152-158° C. and the solubility of naproxen in acetone is high, so that a concentration in the spray liquid up to 20 wt-% does not cause any difficulties. Xylitol (Xylisorb 300, Roquette Pharma, Lestrem, France) was selected as pharmaceutically acceptable carrier to match the deposited sub-millimeter sized particles 40. Xylitol has a melting temperature of 92-96° C., allowing it to be molten without dissolving the separated naproxen particles 40. Furthermore, xylitol has a high water solubility, which should facilitate the dissolution of the solid dispersion.

[0140] In order to prepare a solid dispersion of sub-millimeter sized particles 40 of naproxen in xylitol by usage of an electrostatic precipitator 10 according to an embodiment of the disclosure, the following procedure was used.

[0141] The active pharmaceutical naproxen was dissolved in acetone (5 wt-%) and then sprayed at 50° C. in a spray drying device. 44 To avoid explosive air mixtures, carbon dioxide is used for both spraying and drying. The prepared solution is sprayed with the help of a two-substance nozzle 50, which is operated with a HPLC pump (BlueShadow Pump 80P, KNAUER, Berlin, Germany) and a volume flow of 100 ml/min. Carbon dioxide is used as atomizing inert gas at a pressure of 3.5 bar and a mass flow of 3.7 kg/h. The aerosol was forced into a cyclone as droplet separator 46, where large droplets (larger than the cut off size diameter) are separated, small droplets (<3 μm) generate the conditioned aerosol and enter the drying section through the dip pipe.

[0142] Carbon dioxide is also supplied as drying gas via a drying gas distributor at an overpressure of 0.3 bar and a mass flow of 7.5 kg/h. Afterwards, the dried particles 40 are first charged in a two-stage electrostatic precipitator 10 and then separated into the molten xylitol in an electric field. The melting tank, or the receiving volume 36, respectively, of the electrostatic precipitator 10 is equipped with a pan such as made from aluminum to facilitate the removal of the product, which may be provided independent from the specific embodiment for performing batch processes. After the melt has cooled down, the solid dispersion can be further processed.

[0143] When using the electrostatic precipitator 10, a voltage of 4 kV may be applied by using a current of 5 mA, wherein generally, the voltage used should lie above the corona onset voltage. The electrodes used were formed from tungsten (discharge electrode 28) and V2A steel (collecting electrode 32 and base 15). The flow rate of the gas stream was set to be 5.5 m3/h. However, the before named parameters should be understood as being exemplary values only and can be varied in dependence of the specific application and the specific embodiment of the electrostatic precipitator 10.

[0144] The formed solid dispersion was characterized as follows. The solid dispersion produced was investigated to prove the functionality of the electrostatic precipitator 10. The particle size was measured with the Laser Diffraction Particle Sizer (Mastersizer 3000, Malvern Panalytical, Kassel, Germany) for wet dispersions. The solid dispersion was released using the USP Dissolution Apparatus 2 (DT 6, Erweka, Heusenstamm, Germany). The UV/Vis spectrometer (Lambda 25, PerkinElmer, Waltham, USA) was used to quantify the active substance content in the solution. Calibration and measurements with naproxen were performed at a wavelength of 230 nm.

[0145] The following could be observed.

[0146] The experiments were carried out by means of a spray drying test for a period of 2 hours. The aluminium pan containing the solidified melt was examined in a scanning electron microscope. A particle size of 100-300 nm was expected. Single particles with a diameter of approximately 200 nm were identified. No agglomerates could be found.

[0147] An improvement in water solubility can potentially lead to an increase in bioavailability. For this purpose, 1 g of the particle-loaden xylitol is weighed and dissolved in a release apparatus under the conditions of the United States Pharmacopeial Convention. USP <1092> The Dissolution Procedure. 2012.c. As a reference, the same amount of the commercially available active ingredient naproxen is dissolved under identical measuring conditions in order to investigate the effect on the dissolution.

[0148] FIG. 6 shows the dissolution kinetics of the active pharmaceutical naproxen embedded in xylitol compared to unprocessed naproxen. In detail FIG. 6 shows a dissolution test in a UV/Vis spectrometer with sub-millimeter sized naproxen particles 40 in xylitol compared to unprocessed naproxen, wherein line A shows the sub-millimeter sized naproxen particles 40 in xylitol and line B shows unprocessed naproxen.

[0149] At first sight, the improvement in the dissolution rate can be recognized by the slope of the dissolution graph. After approximately 100 s, in the case of processed naproxen the entire dose is released. In comparison, the release of the unprocessed naproxen takes 300 s in this test. Thus, when using an electrostatic precipitator 10 according to an embodiment of the disclosure, a significant improvement in water solubility and thus in bioavailability could be observed.

[0150] Drug loads of the precipitated API in the xylitol melt were determined at different applied voltages. Voltages between the corona inception and the corona breakdown were chosen and experiments at a constant loading time were performed. With increasing applied voltage an increase of precipitated API was observed. At a loading time of 5 min drug loads of up to 0.25 wt. % could be obtained.

[0151] All the features and advantages, including structural details, spatial arrangements and method steps, which follow from the claims, the description and the drawing can be fundamental to the invention both on their own and in different combinations. It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0152] As used in this specification and claims, the terms “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

LIST OF REFERENCE SIGNS

[0153] 10 electrostatic precipitator [0154] 12 casing [0155] 13 hood [0156] 14 inlet [0157] 15 base [0158] 16 arrow [0159] 17 power supply [0160] 18 outlet [0161] 19 temperature sensor [0162] 20 arrow [0163] 22 channel [0164] 24 first chamber [0165] 26 second chamber [0166] 28 discharge electrode [0167] 29 field electrode [0168] 30 counter electrode [0169] 31 outer pipe [0170] 32 collecting electrode [0171] 33 inner pipe [0172] 34 field electrode [0173] 35 first stage [0174] 36 receiving volume [0175] 37 sealing cap [0176] 38 molten material [0177] 39 second stage [0178] 40 sub-millimeter sized particles [0179] 42 heater [0180] 44 spray drying device [0181] 46 droplet separator [0182] 48 arrow [0183] 50 nozzle [0184] 52 arrow [0185] 54 drying chamber [0186] 56 arrow [0187] 58 arrangement [0188] 60 system [0189] 62 aerosol generator [0190] 64 nebulizing chamber [0191] 65 conditioning device [0192] 66 first inlet [0193] 68 second inlet [0194] 70 outlet [0195] 71 pump [0196] 72 tank [0197] 73 tube [0198] 74 tank [0199] 75 flow regulator [0200] 76 nebulizer [0201] 78 dryer [0202] 79 heater [0203] 80 condenser [0204] 82 filter