Patent Publication Number: US-2022226786-A1

Title: Magnetically Driven Liquid Dispersion Devices

Description:
FIELD OF DISCLOSURE 
     The present disclosure relates to laboratory mixing instruments, and more specifically to improved liquid dispersion devices driven by an external magnetic field that advantageously work with existing magnetic stirring devices. 
     BACKGROUND 
     Dispersion is a widely used laboratory process whereby particles of a first material in a first phase are dispersed in a continuous phase of a second material. The two phases may be in the same or different states of matter. Dispersions may be homogenous or heterogenous mixtures. 
     Dispersion of liquids and other mechanisms of increasing liquid surface area are often used to enhance reaction efficiency and to facilitate various gas-liquid exchange processes. These processes, which include evaporation and gas absorption processes, are often carried out in chemically aggressive media in closed systems. These closed systems often have strict requirements for tightness between equipment components such that a vacuum is maintained and/or to contain the toxic materials that are the subject of the process. Rotary evaporators and chemical scrubbers are examples of such devices. 
     These devices have known drawbacks. For example, gaskets and seals are often required for the operation of these devices. However, these gaskets and seals often also have a detrimental effect on the vacuum or on the level of containment when compared to completely sealed systems, particularly when there are moving parts. Devices and methods that eliminate gaskets containing moving parts are therefore advantageous. For this reason, an external magnetic field such as the one generated by magnetic stirrers is often used as a driving force for various moving objects placed in chemically aggressive media. In addition, bumping, i.e., the rapid boiling that can occur when superheated liquid is nucleated, is known to occur in rotary evaporation systems. Bumping can cause boiling liquid to be expelled from its container, as well as container breakage, both of which are dangerous. Magnetic stirring of superheated liquids with a stir bar can reduce the risk of bumping. 
     In such applications, a magnetic spin bar is placed into a reaction mixture and rotation of the spin bar to achieve mixing is driven by a rotating magnetic field created by an external magnetic stir plate. In this particular magnetically driven application, the primary goal is to achieve stirring of a reaction mixture, but a certain level of dispersing is also achieved by this process. Other known devices employ magnetic fields to drive pumps for the purpose of dispersing liquid. 
     There thus exists a need for a magnetically driven liquid dispersion device able to disperse liquids in open and closed systems where any seals or gaskets are optional and do not involve moving parts. The present disclosure advantageously provides such a system and is able to disperse liquids without a pump, reduces the risk of bumping, and can be used in a variety of conventional distillation processes and chemical reactors. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to magnetically driven liquid dispersion devices configured to be used with existing magnetic stirring devices. In accordance with aspects and embodiments, a magnetically driven liquid dispersion device is provided comprising a rotor, a funnel, and a rotary sprayer. The rotor comprises an Archimedes screw comprising at least one diametric rotor magnet and the rotary sprayer comprises at least one sprayer magnet, and this magnet is preferably a diametric magnet. Diametric magnets are mostly represented by the diametrically magnetized (magnetized across the diameter) cylindrical bodies. Functionally equivalent though not as efficient are diametric composite magnets comprised of radially positioned axial magnets whose magnetization vector is perpendicular to the object&#39;s rotational axis. 
     The funnel comprises a first open end and a second end, and a first compartment at the first open end and a second compartment at the second end, the first compartment having a diameter preferably greater than the second compartment. The rotor has a diameter less than the diameter of the first funnel compartment and at least the first compartment is configured to receive the rotor. In some embodiments, the rotor may include a stem, and the stem may comprise at least one stem magnet, preferably a diametric magnet. The funnel holds the rotor, and thus the at least one diametric screw magnet in a vertical position. 
     In accordance with aspects and embodiments, the funnel defines a cavity above the rotor and the second compartment of the funnel comprises a plurality of openings. The sprayer comprises a bottom compartment and a top compartment, the bottom compartment comprises the at least one diametric sprayer magnet. The at least one diametric sprayer magnet is encapsulated in a solid, inert material. The sprayer comprises a hollow core having a diameter greater than the diameter of the second compartment of the funnel and the hollow core is configured to receive the second compartment of the funnel. 
     In accordance with aspects and embodiments, the sprayer is positioned on the funnel to align with the plurality of openings, and the top compartment of the sprayer comprises sprayer holes. In some embodiments, the sprayer rests on the top of the first compartment of the funnel. In other embodiments, the sprayer is positioned above the first compartment of the funnel. The rotor is configured to rotate within the funnel when exposed to an external rotating magnetic field. In accordance with aspects and embodiments, rotation of the rotor causes rotation of the sprayer about the second compartment of the funnel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a rotor of a magnetically driven liquid dispersion device with one encapsulated magnet in accordance with aspects and embodiments; 
         FIG. 1B  shows an overhead view of rotor of a magnetically driven liquid dispersion device with one encapsulated magnet in accordance with aspects and embodiments; 
         FIG. 1C  shows a rotor of a magnetically driven liquid dispersion device with two encapsulated magnets in accordance with aspects and embodiments; 
         FIG. 1D  shows a rotor of a magnetically driven liquid dispersion device with a stem and three encapsulated magnets in accordance with aspects and embodiments; 
         FIG. 2A  shows a funnel of a magnetically driven liquid dispersion device with a closed second compartment in accordance with aspects and embodiments; 
         FIG. 2B  shows a funnel of a magnetically driven liquid dispersion device with an open second compartment in accordance with aspects and embodiments; 
         FIG. 2C  shows a funnel of a magnetically driven liquid dispersion device with a closed second compartment and an additional joint in accordance with aspects and embodiments; 
         FIG. 3A  shows a rotor and funnel assembly of a magnetically driven liquid dispersion device in accordance with aspects and embodiments; 
         FIG. 3B  shows a rotor and funnel assembly of a magnetically driven liquid dispersion device in accordance with aspects and embodiments; 
         FIG. 4  shows a rotary sprayer of a magnetically driven liquid dispersion device in accordance with aspects and embodiments; 
         FIG. 5A  shows a magnetically driven liquid dispersion device in accordance with aspects and embodiments; 
         FIG. 5B  shows a magnetically driven liquid dispersion device in accordance with aspects and embodiments; 
         FIG. 6  shows a magnetically driven liquid dispersion device in a thin film evaporation system in accordance with aspects and embodiments; 
         FIG. 7  shows a magnetically driven liquid dispersion device in a modified thin film evaporation system in accordance with aspects and embodiments; 
         FIG. 8  shows a magnetically driven liquid dispersion device in a chemical scrubber system in accordance with aspects and embodiments; and 
         FIG. 9  shows a magnetically driven liquid dispersion device in a photochemical reactor system accordance with aspects and embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides an improved device for the dispersion of liquids, and more specifically provides a magnetically driven liquid dispersion device. The disclosed magnetically driven liquid dispersion devices are constructed of simple, known, components and are configured to be used with existing magnetic stirrer devices to achieve enhanced liquid dispersion. The enhanced dispersion achieved by the disclosed devices, specifically the thin film created by the devices, facilitates improved gas-liquid exchange and other chemical processes involving phase transfer. 
     The disclosed magnetically driven liquid dispersion devices include a rotor that comprises an Archimedes screw. An Archimedes screw, also known as a water screw or screw pump, is a screw that has helical surface surrounding a central cylindrical shaft, and in operation is fit inside a hollow pipe. As used herein, “Archimedes screw” refers to the screw itself, independent of any pipe surrounding it. When the bottom of the screw is inserted into a liquid and rotated axially, the bottom end of the screw scoops up a volume of liquid. As the shaft turns, liquid is pushed vertically up the pipe/tube surround the screw by the rotating helicoid until it pours out from the top of the pipe/tube surrounding the screw. As used herein, the rotor may also be called a “spin bar” by those of skill in the art, and the terms may be used interchangeably. 
     The Archimedes screws of the present disclosure include one or more diametrically magnetized inserts encapsulated in the screw shaft. Diametrically magnetized magnets are magnetized across their diameter, rather than axially, i.e., along the axis of the magnet. The north and south poles in cylindrically shaped diametric magnet are, for example, located on the curved surfaces of the magnetic at opposite sides. Notably, the magnets in traditional spin bars used with magnetic mixing devices are axially magnetized. 
     The Archimedes screws having diametric magnets are housed in an inverted funnel having dispersion openings in the void in the funnel above the screw. These openings fluidly connect the rotor compartment of the funnel to a rotary sprayer. The rotary sprayer comprises an additional diametric magnet, which magnetically couples the rotor to the rotary sprayer. The rotor couples to an external magnetic field, i.e., the magnetic field generated by a magnetic stirrer. The rotating external magnetic field causes rotation of the rotor, and thus Archimedes screw, within the funnel. Liquid accumulates above the screw and is dispersed through the openings in the funnel. The sprayer in turn spins in the rotating magnetic field generated by the one or more magnets in the screw. As liquid is pushed up the funnel by the screw into the cavity above the screw, liquid is pushed out of the funnel openings, enters the rotary sprayer, and is dispersed by pressure buildup and centrifugal force. As can be understood, the present disclosure is most effective for use with liquids, dispersion, and mixtures, and may experience decreased and limited effectiveness for compositions having a significant amount of solids and/or relatively large solids elements. In most embodiments, the sprayer disclosed herein is used in conjunction with the Archimedes screw rotor. However, it should be understood that in other embodiments, the sprayer may also be used in conjunction with a traditional magnetic spin bar. 
     In accordance with aspects and embodiments, rotors for the disclosed liquid dispersion device are shown in  FIGS. 1A-1D . Referring to  FIGS. 1A-1B , rotor  10  has Archimedes screw  1  and diametric magnet  2 . Diametric magnet  2  has poles  2 A and  2 B and is positioned vertically and within screw  1 . Archimedes screw  1  may have one or more start threads, and may, for example, have one start, thread, two start threads, or three start threads. An exemplary two-start thread screw  1  is shown  FIG. 1B . The threads may further be right or left-handed screw threads depending on the type of magnetic stirrer being used. For example, right-handed stirrers such as those manufactured by Corning and ChemGlass require a right-handed screw thread whereas left-handed stirrers, such as those manufactured by Heidolph, require a left-handed screw thread. Archimedes screw  1  is constructed from an inert material and is most preferably constructed of polytetrafluoroethylene (PTFE). Diametric magnets  2  may be neodymium magnets. Other suitable materials for Archimedes screw  1  and diametric magnet  2  will be readily selected by those of skill in the art. Materials for the Archimedes screw may include various fluorinated polymers, while magnets may also include high temperature neodymium magnets and cobalt-samarium magnets. 
     As shown in  FIG. 1C , rotor  10  may have a plurality of diametric magnets  2 . Rotors  10  are suitable for use in single flask processes. Rotors for use in stacked flasks may have additional components. For example, and referring to  FIG. 1D , rotor  15  for use with stacked flasks has Archimedes screw  1  and stem  3 . Screw  1  of rotor  15  includes one or more encapsulated diametric magnets and is shown on  FIG. 1D  with two diametric magnets  2 . Stem  3  of rotor  15  also has one or more diametric magnets encapsulated therein and is shown with a single diametric magnet  2  in stem  3 . The number of diametric magnets  2  in a given rotor and their positions within the rotor will be readily selected by those of skill in the art. 
     The rotors of the disclosed liquid dispersion device are positioned within inverted funnels. Funnels  20  and  25  of the disclosed liquid dispersion devices are shown in  FIGS. 2A and 2B , respectively. Inverted funnel  20  has bottom  20 A and top  20 B. Bottom  20 A is open and top  20 B is closed. Funnel  20  has first compartment  21  having open end  20 A and second compartment  22  having closed end  20 B. Compartment  21  is preferably wider than compartment  22  and narrows at shoulder  23 . Second compartment  22  has openings  24 . Similarly, inverted funnel  25  has first compartment  21  and a second compartment  26 . Inverted funnel  25  has bottom  25 A and top  25 B. Both  25 A and top  25 B are open. Compartment  21  is preferably wider than compartment  26  and narrows at shoulder  23 . Second compartment  26  has openings  24 . As shown on compartment  26 , openings  24  may be grouped together and a plurality of groupings may be positioned on compartment  26 , vertically spaced from one another. The size and shape of inverted funnels  20  and  25  are determined by the opening/joint sizes used in the chemistry apparatus. Closed funnels  20  are more universal and must be used under vacuum. Open funnels  25  can be used under normal pressure. The disclosed inverted funnels secure the rotor, and thus the encapsulated diametric magnets therein, in an upright position. As used herein, “upright position” includes substantially vertical positions, including rotors held at angles up to +/−15° from perpendicular to horizontal. Funnels of appropriate size and shape will be readily selected by those of skill in the art. In some embodiments, and referring to  FIG. 2C , an additional joint  40  may be sealed to the funnel to eliminate any gaskets used to seal the connection between the device and the rest of the chemical apparatus. Sprayer  30  must be placed in advance onto compartment  22  prior to attaching joint  40  unless compartment  22  is equal or larger in diameter than compartment  21 . In this case sprayer  30  may need to be supported by sleeve  50  as in  FIG. 5B . 
     In accordance with aspects and embodiments and as shown in  FIG. 3A , rotor  10  fits within compartment  21  of inverted funnel  20 . As shown in  FIG. 3B , rotor  15  fits within compartments  21  and  26  of inverted funnel  25 . The diameter of compartment  21  of funnels  20  and  25  is slightly greater than the diameter of Archimedes screw  1  of rotors  10  and  15 . The diameter of compartment  26  of funnel  25  is similarly slightly greater than the diameter of stem  3 . The difference in diameter between rotors  10  and  15  and compartment  21  of funnels  20  and  25  respectively may be about 1-2 mm. These differences in diameters allow rotors  10  and  15  rotate freely within funnels  20  and  25  and allow the liquid to reach opening  24  bypassing stem  3 . 
     A magnetic rotary sprayer is fit onto the narrow compartment of the funnel and positioned to surround openings in the narrow compartment of the funnel. In accordance with aspects and embodiments and referring to  FIG. 4 , rotary sprayer  30  has bottom compartment  31  and top compartment  33 . Sprayer  30  is configured to receive the narrow compartment of an inverted funnel. Bottom compartment  31  contains diametric magnet  32 . Bottom compartment  31  is constructed of a solid, inert material, such as PTFE and has hollow core  31 A. Diametric magnet  32  has hollow core  32 A, which aligns with hollow core  31 A to allow passage of the narrow compartment of an inverted funnel through both solid compartment  31  and magnet  32  encased therein. Upper compartment  33  defines an empty space having top opening  33 A. Opening  33 A aligns with hollow core  31 A. Upper compartment  33  has sprayer holes  34 . Although sprayer  30  is shown with a single diametric magnet, in some embodiments, sprayer  30  more comprise a plurality of diametric magnets. In other embodiments, sprayer  30  may instead include a plurality of axial magnets position radially. 
     Complete assemblies of magnetically driven liquid dispersing devices are shown in  FIGS. 5A and 5B . In accordance with aspects and embodiments and referring to  FIG. 5A , rotary sprayer  30  is fit onto narrow compartment  22  of inverted funnel  20 . Top compartment  33  of rotary sprayer  30  aligns with openings  24  in compartment  22  of funnel  20 . Rotary sprayer  30  rests on shoulder  23  of funnel  20  and surrounds openings  24 . Similarly, and referring to  FIG. 5B , rotary sprayer  30  is fit onto narrow compartment  26  of inverted funnel  25 . Rotary sprayer  30  may be adjusted to align with a grouping of openings  24 . As shown in  FIG. 5B , a sleeve  50  may be fit onto narrow compartment  26  of funnel  25  and may provide additional support for the rotary sprayer  30  such that rotary sprayer  30  is positioned on compartment  26  at height above shoulder  23 . Sleeve  50  may also cover one or more groupings of openings  24  and may be airtight. 
     In operation, the disclosed magnetically driven liquid dispersing devices are positioned in an external rotating magnetic field, i.e., on top of a magnetic stirrer. Referring to  FIG. 5A  as an example, bottom  20 A of funnel  20  is positioned in a flask containing liquid reaction mixture. The diametric magnet  2  in rotor  10  magnetically couples to the external rotating magnetic field and the external field causes rotor  10  to rotate within compartment  21  of funnel  20 . Liquid is scooped up by screw  1  at open end  20 A and is directed upward along the screw threads towards end  20 B of funnel  20 . When liquid reaches the top of screw  1  at shoulder  23  of funnel  20 , it is further directed into empty compartment  22 . Fluid directed into compartment  22  exits funnel  20  via openings  24  and enters compartment  33  of rotary sprayer  30 . Diametric magnet  32  in sprayer  30  magnetically couples to diametric magnet  2  in rotor  10 , which causes sprayer  30 , having a hollow core, to rotate about compartment  21  of funnel  20 . As fluid enters compartment  33 , centrifugal force causes the liquid to exit compartment  33  through sprayer holes  34 . The liquid sprayed out of sprayer holes  34  is dispersed onto the interior walls of the flask. The dispersion of liquid onto the interior walls of the flask accelerates liquid evaporation. The setup may also be used to wash down solid crust formed on the flask walls above the reaction mixture. 
     The disclosed magnetically driven liquid dispersion device may be used to accelerate liquid evaporation by dispersing liquid into the walls of a flask. In accordance with aspects and embodiments, and referring to  FIGS. 5A and 6 , thin film vacuum evaporator system  1000  is shown. Magnetically driven dispersion device  100  is placed in evaporating flask  200  containing liquid reaction mixture  210  via the distillation head  500  and stationary gasket seal  230 . Joint  60  on flask  200  facilitates a sealed connection of the evaporating flask  200  to distillation head  500  having a condenser and vacuum port (not shown). Flask  200  containing liquid reaction mixture  210  sits on/in heat source  400 , as in traditional rotary evaporation, however flask  200  advantageously does not rotate. Thus, a gasket able to maintain vacuum while holding a rotating flask in the rotary evaporator is advantageously omitted from system  1000  and replaced by the stationary gasket seal  230 . Heating element  400  may be an oil bath, water bath, heating mantle, or any other suitable heat source. Magnetic stirrer  300  has one or more horizontally positioned axial magnets that generate an external rotating magnetic field. The external rotating magnetic field generated by magnetic stirrer  300  causes rotor  10  having diametric magnets  2  to rotate within flask  200 . Diametric magnets  2  further couple to diametric magnet  32  in sprayer  30 . Archimedes screw  1  of rotor  10  causes liquid  210  to travel upwards in inverted funnel  20  from compartment  21  to compartment  22 , out of openings  24 , and into sprayer  30 . Sprayer  30  in turn disperses liquid  210  onto the interior walls of flask  200 . Constant stirring of liquid  210  is achieved by rotor  10 , which advantageously eliminates bumping commonly observed in rotary evaporators under vacuum. Moreover, system  1000  has a smaller footprint than traditional rotary evaporators, which advantageously allows for easy assembly in a fume hood. The stationary nature of system  1000  also allows for additional attachments to a multi-neck flask (which will be used in place of single neck flask  200 ). These attachments include, but are not limited to, an addition funnel, various sensors, and gas inlet tubes. 
     The disclosed magnetically driven liquid dispersion devices may be used in other distillation processes, including in dual flask thin film evaporator systems employed for less thermally stable liquids. In accordance with aspects and embodiments and referring to  FIG. 7  and  FIGS. 5A  and B, system  1100  has flasks  200  and  220  in fluid communication with one another and distillation head  500 . The flasks sit over magnetic stirrer  300 . The bulk of liquid  210  is stored in flask  200  at or below room temperature. A magnetically driven liquid dispersion device  100  having rotor  15  with a stem  3  in funnel  20  is seated in flask  200  and extends through flask  220  and distillation head  500  to stationary gasket seal  230 . Sprayer  30  on inverted funnel  20  is positioned within flask  220 . The external rotating magnetic field generated by magnetic stirrer  300  causes rotor  15  having diametric magnets  2  to rotate within funnel  20 . Diametric magnets  2  further couple to diametric magnet  32  in sprayer  30 , causing it to rotate about compartment  22  of funnel  20 . Archimedes screw  1  of rotor  15  causes liquid  210  to travel upwards in inverted funnel  20  from compartment  21  to compartment  22 , out of openings  24  and into sprayer  30 . Sprayer  30  in turn disperses liquid  210  onto the interior walls of flask  220 . Flask  220  is heated with a heating mantle  410 . Liquid dispersed onto the interior walls of flask  220  is partially distilled preferably under vacuum and partially returned to the bottom flask  200 . System  1100  having magnetically driven liquid dispersion device  110  reduces overall residence time of liquid  210  at elevated temperatures. 
     The disclosed magnetically driven liquid dispersion devices may further be used in chemical scrubber systems. In accordance with aspects and embodiments and referring to  FIGS. 5B and 8 , system  1200  has flask  200  containing liquid absorbent  210 . Chemical scrubber  1200  has column  610  packed with media  620 , and gas inlet  630  and gas outlet  640 . A magnetically driven liquid dispersion device  110  having rotor  15  with stem  3  in funnel  25  is arranged in flasks  200  and column  610 . Sprayer  30  is positioned within column  610  above media  620 . The external rotating magnetic field generated by magnetic stirrer  300  causes rotor  15  which has diametric magnets  2  to rotate within funnel  20 . Diametric magnets  2  further couple to diametric magnet  32  in sprayer  30 . Archimedes screw  1  of rotor  15  causes liquid  210  to travel upwards in inverted funnel  25  out of openings  24 , and into sprayer  30 . Sprayer  30  in turn disperses liquid  210  at the top of column  610 . Open end  25 B can be used to sample liquid  210  to monitor consumption of the chemicals. 
     The disclosed magnetically driven liquid dispersion devices may also be used in reactors, including photochemical reactors. For example, and referring to  FIGS. 5B and 9 , magnetically driven liquid dispersion device  110  is used in photochemical reactor system  1300 . System  1300  has flask  200  containing reaction liquid  210  over magnetic stirrer  300 . Photochemical reactor  700  has quartz tube  710  connected to flask  200  and UV source  720 . Magnetically driven liquid dispersion device  110  is positioned in flask  200  and extends through quartz tube  710  to stationary gasket seal  230 . Sprayer  30  is positioned at the top of tube  710 . The external rotating magnetic field generated by magnetic stirrer  300  causes rotor  15  having diametric magnets  2  to rotate within funnel  25 . Diametric magnets  2  further couple to diametric magnet  32  in sprayer  30 , causing it to rotate about compartment  26  of funnel  25 . Archimedes screw  1  of rotor  15  causes liquid  210  to travel upwards in inverted funnel  25  from compartment  21  to compartment  26 , out of openings  24  and into sprayer  30 . Sprayer  30  in turn disperses liquid  210  onto the interior walls of tube  710 , creating a thin film. The thin film of liquid  210  on interior walls of tube  710  absorbs UV irradiation. The thin film created by magnetically driven liquid dispersion device  110  facilitates photochemical reactions. Other suitable systems and configurations for the disclosed magnetically driven liquid dispersion devices will be readily selected by those of skill in the art. 
     Although certain representative embodiments and advantages have been described in detail, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the systems, processes, and methods disclosed herein. It is intended that the specification and examples be considered as exemplary only.