OF AMORPHOUS CARBON AND FULLERENES HAVING DIFFERENT MOLECULAR WEIGHTS

The present invention concerns to a process for separating fuUerenes from a solid mixture of fuUerenes with different molecular weight and of amorphous carbon (generally called soot), and also it concerns to apparatuses that are used for performing such a separation of fuUerenes from the above described soot.

As known, the fuUerenes are allotrope substances of the carbon in the form of molecules containing 60, 70, 84 or greater numbers of atoms, which may be used in different industrial application fields of the technique, like the chemical, electronic, mechanic, automotive, biologic, medical, construction industry and in different other industrial application types.

The fuUerenes are obtained in the industrial scale particularly by a solid mixture of fuUerenes with different molecular weight and amorphous carbon present in the soot, which mixture is obtained by means of an industrial manufacturing process wherein two electrodes of graphite are maintained spaced away to each other and subjected to an electric arc at a very high temperature, in the order of 1500°C and greater, in presence of a inert gas atmosphere, with the consequent vaporization of the graphite, and the removal of the evaporated graphite through an inert gas flow and collection of the same one into at least a coupled container, under the form of soot containing such a mixture of fuUerenes and amorphous carbon.

The object of the present invention is developed a process for separating the fuUerenes from the other solid substances contained into the above said mixture obtained with the above specified process, by means of which process it is possible first of all to separate from the considered solid mixture all the types of fuUerenes having different molecular weight, and then to collect selectively the same fuUerenes, finally for being able to use them in the desired applications. The invention refers also to the used apparatuses for performing the various phases of the separating process of different types of fullerenes, in order to obtain and to collect selectively the same fuUerenes.

The invention will be better understood from the following description, by way of not-limiting example only, and referring to the attached drawings, wherein :

- Fig. 1 shows a schematic front view of one used apparatus for separating the fullerenes, in the disassembled condition thereof ;

- Fig. 2 shows, with the same view of Fig. 1, the apparatus of Fig. 1 in the assembled condition thereof ;

- fig. 3 shows the different operative phases executed in the single component parts of the apparatus of Fig. 2, for obtaining the separation of the fullerenes from the solid mixture of fullerenes- amorphous carbon ;

- Fig. 4 shows a schematic front view of a component part of the apparatus for separating the fullerenes of Figs. 1 and 2 ;

- Fig. 5 shows a cutaway front view of another component part of the apparatus for separating the fullerenes of Figs. 1 and 2 ;

- Fig. 6 shows a schematic and cutaway front view of an additional apparatus coupled with the apparatus of Figs. 1 and 2, that is used according to the present process for separating the fullerenes, for extracting the solvents used by the supersaturated solution of fullerenes ;

- Fig. 7 shows a perspective front view of an additional apparatus coupled with the apparatus of Figs. 1 and 2, that is used for washing the fullerenes powders ;

- Fig. 8 shows the various phases used by the apparatus of Fig. 7 during the washing of the fullerenes powders ;

- Fig. 9 shows a schematic front view of an additional apparatus coupled with the apparatus of Figs. 1 and 2, for sonicating and dissolving quickly the powders containing fullerenes ; - Fig. 10 shows a schematic front view of a chromatography column, coupled with the apparatus of fig. 1 and 2, and needed for obtaining the separation of the different types of fuUerenes contained into the powder obtained with the previous operative phases ;

Fig. 11 shows, with a schematic front view, the same chromatography column of fig. 10 together with additional identical columns, in different operative phases of separating the fuUerenes, with the subsequently collection of separated fuUerenes in different lower containers.

The present invention refers to a process for separating fuUerenes from a solid mixture of fuUerenes with different molecular weight and of amorphous carbon (generally called soot), in order to let one or more pure types of fuUerenes available, that may be used in different application fields of the technique, like the chemical, electronic, mechanic, automotive, biologic, medical, construction industry and in different other industrial application types.

Particularly, the separating process of fuUerenes according to the present inventions refers preferably to fuUerenes of which molecules are composed preferably by 60 or 70 atoms of carbon, but the considered process concerns, if it is desired, also the separation of other types of fuUerenes constituted by number of carbon atoms that are different than the above specified ones.

The present invention also refers to apparatuses that are used for performing such a separation of fuUerenes from the above described soot, in order to obtain one or more types of pure fuUerenes, in an industrial and cheap way.

It is noted the fact to obtain in an industrial scale the fuUerenes by means of different processes, particularly in one of these the fuUerenes are obtained by a solid mixture of fuUerenes with different molecular weight and of amorphous carbon, that are present into the soot, which mixture are obtained by means of a manufacturing process wherein two electrodes made of graphite are maintained spaced away to each other into a specific reactor and are subjected to an electric arc at a very high temperature, in the order of 1500°C or greater, in presence of inert gas, with the consequent vaporization of the graphite, and the removing of the evaporated graphite through an inert gas flow and the collecting of the same one into at least a suitable coupled container, in the form of soot containing such solid mixture of fullerenes and amorphous carbon. With this process, so, it is possible to obtain a mixture of soot containing fullerenes and amorphous carbon, which component parts are always combined to each other, under the condition wherein the fullerenes contained into the solid mixture are not in the separated state with respect to the amorphous carbon and therefore they may not be used, when required, for the desired applications, instead as it should be desirable. Indeed, in the above specified industrial process there are not shown how the fullerenes may be separated from the soot mixture, and therefore these latter can't be used for the desired industrial applications.

The object of the present invention is to indicate a separating process of fullerenes from a solid mixture of fullerenes with different molecular weight and of amorphous carbon (soot), obtained with the above specified industrial process, or also with processes of other types known from the state of art, in order to obtain one or more types of pure fullerenes, ready to be used for the desired applications.

An important additional object of the invention is to indicate which apparatuses are used during the performing of the various operative phases of the present separating process in order to obtain the required fullerenes.

Before starting to describe the separating process according to the present invention, it is preferably to specify also that into the solid mixture of fullerenes and amorphous carbon there are present about the 80% in weight of fullerenes of which, the molecules contain 60 atoms of carbon, about 20% in weight of fullerenes of which, the molecules contain 70 atoms of carbon, and about 1% in weight of superior fullerenes, with molecules containing 76, 84, etc... atoms of carbon, and of amorphous carbon.

The percentage in weight of the fullerenes in the soot depends from the synthesis and changes from 5% to 20% in weight. Into the separating process of fullerenes according to the invention, it is indicated as for example the separation of fullerenes with 60 carbon atoms, from the remaining fullerenes with other numbers of atoms, and from the amorphous carbon.

The present separating process of the fullerenes from the soot made available as above specified comprises first of all the use of a first apparatus, numbered with 5 in the figs. 1 and 2m that is substantially constituted by a soxhlet extractor commonly used for separating substances of various kind, different than the fullerenes, that in the Fig. 1 is shown with the various component parts thereof in the disassembled condition and in Fig. 2 is shown with the various component parts thereof in the assembled condition. Such soxhlet extractor is completely realized of transparent material such as glass or plastic material.

Referring to above said Figures 1 and 2, the soxhlet extractor 5 comprises as usual in succession, upward from the lower part thereof the upper part thereof, a distillation flask 6 of spherical shape and with an adequate volume for containing some solvents to be used for the separation, one extraction area or central extractor 7 of vertical cylindrical shape, which comprises the component parts shapes in the way or for the aim that will be described, and an upper condenser 8. The vertical extraction area 7 is shaped with a lengthened chamber 9 with an adequate containment volume, delimited by a lower closing bottom 10, and a porous thimble 11, with an height smaller than the one of the chamber 9, is inserted and extracted with respect to the lower part of the same chamber, which thimble is leant with its porous bottom (not shown) onto the closing bottom 10 and delimits an extraction chamber 12 into which there is introduced in advance from time to time a determined quantity of soot 13, from which the fullerenes are to be separated with the present separating process. Such a lengthened chamber 9 is also shaped with a bent side connector 14, provided for the passage of the solvent in the state of vapour, and joined to the upper end portion of the same chamber, whereas the lower end portion of such a side connector 14 is joined with a lower chamber 15, which is situated under the lengthened chamber 9 and disjointed from the same one through the closing bottom 10. Such a lower chamber 15 is communicating with the upper neck 16 of the distillation flask 6 through a joining part 17, insertable sealingly into the neck 16 of the flask 6. Furthermore, the lengthened chamber 9 is also shaped and communicating in the lower part with a narrow vertical siphon 18, spaced away in the opposed direction from the side connector 14, the lower base 19 of which is joined into the bottom area of the porous thimble 11 in which the soot is contained, a little space above the closing bottom 10 of the central chamber 9, and in the interior of the vertical siphon 18 a vertical small pipe 20 is housed, the upper end portion of which terminates near the head 21 of the siphon 18, by defining with this latter a narrow interval (not shown) for the passage of the solvent coming out, together with the soot, from the extraction chamber 12, and passing at first through the internal chamber of the vertical siphon 18 and then through the vertical small pipe 20, as it will be described, and the lower end portion of such a vertical small pipe 20 is bent and joined with the above said lower chamber 15.

The additional component parts of the soxhlet extractor 5 are moreover constituted, as usual, by an independent and internally hollow connection 22, interposed between the upper part of the lengthened chamber 9 and the lower part of the condenser 8, and adapted to join removably these two component parts, thanks to the fact that such a connection 22 is shaped at its lower part with a flared neck 23 adapted to be hermetically inserted into a correspondent flared neck 24 of the upper part of the lengthened chamber 9, and that such connection 22 is shaped at the upper part with an additional flared neck 25 adapted to be inserted hermetically into a correspondent flared neck 26 of the lower part of the condenser 8. In turn, the condenser 8, in the described example, is shaped with a vertical lengthened shape in which a central and vertical conduit 27 is provided, passing for the entire height of the same condenser and closed at the upper part and hermetically by a closing plug 28, which conduit is communicating at its lower part with all the internal cavities delimited by the above described various component parts and is provided for the circulation of the solvent and the different substances contained into the soot. Such a condenser 8, also, is provided with at least one internal heat exchanger 29, formed by wrapped conduits for the circulation of a cooling means such as for example water, that is supplied by an inlet 30 of such a heat exchanger and is discharged externally by an outlet 31 of the same heat exchanger, and such a cooling means serves for cooling down the solvent vapours and the different soot substances, that penetrate into the internal conduit 27 of the heat exchanger 29, for performing the functions that will be following described.

Naturally, the condenser 8 may be realized with different structural conformations than the one described as example only, as long as it needs to perform always the same function above described, thus without departing from the scope of the present invention.

Before starting to describe the various phases for separating the fullerenes from the soot, which are shown referring to fig. 3, it is noted that Fig. 4 shows in detail an exemplifying embodiment of the condenser 8 and the relative internal heat exchanger 29, whereas Fig. 5 also shows in detail at least an exemplifying embodiment of the internal structure of the porous thimble 11 that is inserted into the chamber 9, and into the extraction chamber 12 there is introduced from time to time the quantity of soot 13 to be separated for obtaining the pure fullerenes, with the operative phases of the process that will described in future. For performing the different separation phases of the soot, together with the present soxhlet extractor 5 there is used a heating apparatus 32 (see Fig. 2) and supplied by the electric supply line 33 by means of an electric cable 34, and the apparatus 32 is equipped with regulating means 35 for controlling its operation and of a thermostatic regulation (not shown) for changing the heating temperature of the heating elements. Such heating apparatus 32 is shaped in a manner to be able to receive and to house on to it a lower spherical portion of the distillation flask 6, in the interior of which there has been introduced in advance a determined quantity of solvent, for the scopes that will be described, and as solvent there is typically used the toluene, which has a relatively low boiling point, of 110,6°C.

It is necessary to note that the soxhlet extractor is used as an alternative to additional types of extractors that may be used for the same scopes, for the fact that it has the advantage to use a smaller quantity of solvent that is allows the recirculation of the solvent, that consequently is recovered during the recirculation and let to circulate again, without adding additional solvent for performing the functions to which it is destined. In this way, thanks to the contact between the lower spherical portion of the distillation flask 6 and the underlying heating apparatus 32, the liquid solvent contained into the distillation flask 6 is progressively heated up to the desired temperature, which corresponds to the evaporation temperature of the same solvent, which temperature is determined by means of the thermostatic regulation of the heating apparatus 32, and the solvent vapours thereby obtained are then let to circulate through different component parts of the soxhlet extractor 5, for separating the fullerenes of the soot as it will be described.

Furthermore, it is necessary also to note that the distillation flask 6 should be filled with a quantity of liquid solvent that doesn't exceed in volume 3-4 times the containing volume of the extraction chamber 12 of the porous thimble 11, for preventing the overflowing of the solvent when it circulates and is introduced into the above said extraction chamber, in the way and for the functions following described.

A magnetic mixer 36 of traditional type is into the lower part of the distillation flask 6, Mixer that is actuated for mixing the solvent contained into the same flask. Fig. 3 shows schematically the different operative separating phases according to the present separating process, and the relative parts of the soxhlet extractor 5wherein such phases are performed, respectively.

In the separating phase 1, it is noted that a determined quantity of soot 13, to be separated for obtaining fullerenes, is inserted in advance into the extraction chamber 12 of the porous thimble 11, while the distillation flask 6 is already filled with a determined quantity of cold solvent 37 at the liquid state, and the underlying heating apparatus 32 is disconnected, therefore under this condition the heat transmitted to the distillation flask 6 starts to heat also the solvent 37 contained into the same one.

In the separating phase 2 it is noted that after a determined connection time of the heating apparatus 32, the solvent 37 heated by this latter starts to evaporate and, raising upward, passes in succession through the upper part of the flask 6, the side connector 14, the upper part of the lengthened chamber 9, the hollowed shaped connection 22 and the vertical conduit 27.

When the cooling water has decreased the temperature of the solvent vapors in a way to get the same solvent return again at the liquid state, such liquid solvent falls down from the vertical conduit 27 and passing through the hollowed shaped connection 22 and the central chamber 9 of the extraction area, as visible in the separating phase 3, it falls down into the extraction chamber 12 of the porous thimble 11, containing the soot, thereby dissolving a certain quantity of soot with a relative part of fullerenes contained therein. Consequently, the solvent with the dissolved particles of soot and of fullerenes passes through minuscule pores or through openings (not shown) provided through the walls of the porous thimble 11, and permeable to the same solvent and to the substances dissolved therein, and then it penetrates through the lower base 19 of the siphon 18, dragging wth it the dissolved particles of soot and of fullerenes.

Under this condition, as visible in the separating phase 4, the considerable volume of solvent, that is into the lower part of the siphon 18, is such to push the same solvent, together with the soot and fullerenes particles, upward the siphon 18, by activating this latter and by allowing the introduction of these substances into the internal vertical small pipe 20, with the consequent passage of these substances along such an internal small pipe, and falling of the same ones down up to penetrate again into the distillation flask 6. This phase ends as long as all the solvent has completely emptied the extraction chamber 12 and is completely discharged into the distillation flask 6, together with the substances dissolved into the same solvent.

At this point, into the extraction chamber 12 of the porous thimble 11 it remains the part of soot that has not dissolved yet and removed previously from the liquid solvent and that, being constituted by insoluble powder (that becomes soluble only with the solvent), may not pass through the pores of the porous thimble 11 and thereby is transported with the described modalities into the distillation flask 6, by contaminating the solution contained into the flask 6. At the same time of this, the solvent with the dissolved soot that is fallen into the flask 6 is heated again by the heating apparatus 32, that is still connected, therefore such solvent with dissolved soot is heated again to evaporate and circulate again along the same path of the soxhlet extractor 5, by dragging with it the dissolved particles of soot and fullerenes. In this way, the separating phases previously described are repeated in succession with the same above described sequences, and such phases may be repeated different times, up to the soot and the fullerenes therein contained are completely emptied by the porous thimble 11 and are dissolved into the solvent contained into the distillation flask 6, as visible in the final separating phase of Fig. 5. This dissolving condition of the soot and the fullerenes into the solvent contained into the above said distillation flask 6 is demonstrated as it will be described soon.

Subsequently, the solvent with the soot and the fullerenes therein dissolved are first extracted from the distillation flask 6 and then the fullerenes are completely and selectively extracted from the soot, with the phases that will be follow described, which may require days, and in the practice it has noted that generally there are necessary from 2 to 24 hours for extracting totally the fullerenes from the soot. Meanwhile, when it is required, an additional quantity of soot to be separated is introduced into the porous thimble 11, and additional solvent is introduced into the distillation flask 6, with the same quantity previously used, and in this way additional separating phases identical to the above described ones may be performed, for obtaining additional fullerenes.

In this context, it needed to specify that, as solvent for soot, in the present separating process it has chosen the toluene for its advantages connected to its low cost, to the relative safety of used, to the low boiling temperature that causes low energetic usage for its evaporation, and to the good capacity to bring in solution the fullerenes contained in the soot (solubility at room temperature of 2,8 mg/ml). Naturally, instead of the toluene, also other types of solvent that can perform the above described functions may be used, thus without departing from the scope of the present invention. Since during the different above described separating phases the solvent passes through the soot contained into the porous thimble 11, it turns carbon color contained into the same soot, when the soluble soot is dissolved into the solvent, it doesn't color the same solvent enough, that therefore turns again its starting color, and under this condition into the porous thimble there is no contained soluble soot yet, and the possible insoluble soot that still remains into the porous thimble, containing an insoluble part amorphous carbon, is then removed and discharged, before starting the subsequent separating cycle of additional soot with the same above described operative phases. For extracting the solvent with the solution supersaturated of fullerenes therein dissolved, that are contained into the distillation flaks 6, such a solvent is let to evaporate vacuum-sealed at a determined temperature, in the shown example at 30°C, thereby obtaining a mixture of fullerenes powder, by means of the use of one extracting apparatus constituted by a rotating evaporator 38, commonly known also as rotavapor, see Fig. 6, which is an apparatus commonly used for separating and extracting the solvents from a solution of a relative mixture of interest, through evaporation at low pressure of the same solvent.

Before to describe in detail the conformation and the operation of the extracting apparatus (rotating evaporator 38, in Fig. 4 it is now described as example only a possible embodiment of the condenser 8 and of the relative internal heat exchanger 29, while in Fig. 5 it is described a possible embodiment of the porous thimble 11.

For the scope, as visible in Fig. 4, the condenser 8 is shaped as already above described with a lengthened portion 39 of vertical lengthened shape wherein a central and vertical internal conduit 27 is provided, and in this case with the internal heat exchanger 29 in which at least a conduit 40 for the circulation of the cooling water is housed, which is wound around the central conduit 27 for its entire extension, and is joined at its one end portion to the water inlet 30 and at the other end portion thereof to the water outlet 31. Naturally, the condenser 8 may be shaped with a different manner than the above described one too, as for example the heat exchanger may be formed by an internal hollowed chamber into it (not shown), which includes the entire central conduit 27 and communicates with the relative end portions with the inlet 30 and the outlet 31 of the cooling water, thus without departing from the scope of the present invention.

In turn, in Fig. 5 it is now described a type of porous thimble 11, that is generally realized by a filtering paper permeable towards to the solvent, and in the considered example has a cylindrical shape, and with such a size to be housed removable into the lower part of the internal chamber 9 of the central extraction area 7 of the soxhlet extractor 5, and such a cylindrical porous thimble 11 is shaped (See Figs. 5a and 5b) with a peripheral vertical wall 41 provided with a plurality of pores 42 with reduces dimensions for the passage of the solvent with the soot particles, and delimiting the above-said internal extraction chamber 12, and such a peripheral wall 41 is also opened at its upper part, for the access of the solvent into said internal chamber 12, and is closed at its lower part by the above said porous bottom 43 for the passage of the solvent with the dissolved soot particles.

In fig. 5c it is noted the cylindrical porous thimble 11 containing internally a determined quantity of soot 13 from which the fullerenes are to be separated, and without the solvent has been introduced into the same one.

In Fig. 5d it is noted the cylindrical porous thimble 11 containing both the soot 13 and a determined quantity of liquid solvent 37, in the starting phases for separating the fullerenes from the same soot, whereas in Fig. 5e it is noted the same porous thimble 11 containing the soot 13 and the liquid solvent 37, with a level lower than the previously one that happens during the subsequent separating phases of the fullerenes from the same soot, performed as previously described.

Naturally, the porous thimble 11 may be shaped also with shapes and size different than the described one as example, for performing also the same above described operations, thus without departing from the scope of the present invention.

In Fig. 6 it is now schematized the extracting apparatus 38 with its mainly component parts, and the operative phases, that are performed into the same apparatus, are also briefly described. Particularly, Fig. 6 shows an external front view of the extracting apparatus 38, whereas Fig. 6b shows schematically the internal part of the same apparatus. As it is visible from these Figures, the extracting or evaporating apparatus 38 is substantially constituted as usual by a first set of component parts for the introduction and the cooling of the solution of solvent supersaturated of dissolved fuUerenes, and by a second set of component parts for determining the rotation of a first flask containing the solution of solvent supersaturated of dissolved fuUerenes, in order to separate at first the solvent from the fuUerenes and then to collect the separated solvent into a second collecting flask, and finally to collect the fullerene separated into the first flask, such component parts being constituted by transparent material such as glass or plastic material.

Particularly, the first set of component parts is substantially constituted by at least a lengthened cylindrical condenser 44, which is delimiting an internal chamber 45 joined with an inlet valve 46 for the introduction and the circulation into the same chamber of the solvent solution supersaturated of dissolved fuUerenes, that is liquid and is collected and contained into the distillation flask 6 at the end of the above specified phase 5. In the interior of the lengthened condenser 44 there is housed and secured a continuous coil 47 for circulating the cooling water, which is supplied by the water supply line and introduced through one inlet 48 of the coil and discharged through one outlet (not shown) of the same coil, which water serves for cooling down and abating roughly the solvent vapours being developed as it will be described, and that circulate through the internal chamber 45 of the condenser 44, for being then collected as it will be also described. Such an internal chamber 45 is extended beyond the condenser 44, from the opposite part in which the inlet valve 46 is situated, by defining in succession a narrow portion 49, and an enlarged portion 50 with a side protrusion 51, in order to support and to allow a limited rotation around its own longitudinal axis of the assembly of the so shaped parts in the second set of component parts that will be described, and in turn such an enlarged portion 50 ends with a narrow end portion 52, coupled with rotating bearings or similar members 53, adapted to be actuated in rotation in both the rotating directions by an electric motor (not shown) incorporated into the second set of component parts, and into which the neck 54 of the above specified first flask 55 may be inserted removably, and the internal chamber 56 of the first flask 55 is communicating with the internal chamber 45 through and additional internal chamber 57 delimited in the enlarged portion 50. In this way, when the electric motor is actuated in rotation, also the first flask 55 is actuated in rotation through the above said bearings 53 and, thanks to the mutual communication of all the above said internal chambers 45, 56 and 57, and to the inclined arrangement of the first component parts of the so obtained rotating evaporator 38, the liquid solution of the solvent supersaturated of dissolved fullerenes that is introduced through the inlet valve 46 of the same rotating evaporator circulates by gravity through the different internal chambers, finally by collecting itself into the internal chamber 56 of the first flask 55, for performing the subsequent separating phases of the solvent from the fullerenes, that will be described after.

Moreover, the internal chamber 45 of the condenser 44 is shaped, near the above said narrow portion 49, with a short side protrusion 58 defining a hollow conduit, in the end portion of which there is secured a coupling means 59, for example of the type with removable connection, into which there is coupled the neck 60 of the above said second collecting flask 61, delimiting an internal chamber 62 for collecting the solvent, which is communicating through said hollow conduit 58 with the internal chamber 45, as well as with the remaining above described internal chambers 57 and 56, in a manner that the solvent that is separated from the fullerenes may be conveyed, through the different internal chambers 56, 57 and 45, into the internal chamber 62 of the second flask 61, whereas in the internal chamber 56 of the first flask 55 there are collected only the fullerenes separated from the solvent. Finally, all the internal chambers of the rotating evaporator 38 are put in communication with at least an apparatus for producing vacuum, for example with a vacuum pump (not shown), that is let to operate for making a suitable level of vacuum (depression) into the same chambers, in a way that by extracting the air the boiling temperature of the solvent decreases and that also if the boiling temperature of the solvent is higher, the rotating evaporator may so operate at a lower temperature, for example up to 30° C.

Now it is described the second set of component parts of the rotating evaporator 28, which are constituted by a receptacle with vertical extension 63, with a shape of a cylindrical basin supported onto the floor by a lower base 64, and delimiting a collecting chamber 65 opened on its upper part and closed on its lower part, into which chamber there is introduced in advance a water bath with an adequate volume, which is heated by means of electrical heating elements (not shown) incorporated into the receptacle 63 and supplied by the electric supply line through an AC power socket 66 and an electric cable 67 equipped with a plug 68, and that are switched on and off through a lower control panel 69, with the possibility of thermostatic regulation of the heating temperature of the water at different levels. The rotating evaporator 38 is supported onto its shaped upper part by a vertical column 70, that is interposed between the rotating evaporator and the vertical receptacle 63, and it is supported onto the floor by a lower enlarged platform 71. Such a vertical support column 70 has a height slightly greater than the height of the vertical receptacle 63 in a way to support the rotating evaporator 38 at a height higher than the one of the same receptacle, and with an inclination that may be regulated and such as to allow to submerge at least partially the first rotating flask 55 in to the thermostatically regulated water bath contained into the collecting chamber 65 of the same receptacle. In particular, the rotating evaporator 38 is supported by a rounded protruding flange 72 that is strictly enclosed around the enlarged portion 50 of the same rotating evaporator, and that is fixed to a rotating disc with horizontal axis 73, supported in rotation by a control panel 74 applied onto the upper part of the vertical column 70. A regulating lever (75) is applied onto the side protrusion 51 of the rotating evaporator 38, which lever 75 is handled by the user for moving such a rotating evaporator into different inclined positions, thanks to the rotation of the rotating disc 73 in the control panel 74 and therefore to the correspondent rotation of the rounded protruding flange 72. When the regulating lever 75 has been moved into a determined regulating position of the inclination of the rotating evaporator 38, such a regulation position be maintained by a stopping mechanism (not shown) incorporated into the control panel 74, so that the rotating evaporator may operate without being able to be moved from this position. Furthermore, an additional regulating lever 76 is also assembled on to the lower part of the vertical column 70, which can be handled by the user for lifting the rotating evaporator 38 along the vertical column 70 to different heights with respect to the height of the receptacle 63, in each one of them such a rotating evaporator is maintained by means of the stopping mechanism of the control panel 74, without being able to be moved from this position during the working phase of the same rotating evaporator. By acting on to either one or both the levers 75 and 76, be possible to regulate the inclination and/or the height of the rotating evaporator 38 with respect to the receptacle 63 to different and variable positions within determined limits, for being able to maintain always submerged the first flask 55 at least partially into the water bath of the receptacle 63, depending on to the dimensions and the volume of containment of the same flask, thereby for performing correctly the separation phases of the fullerenes from the solvent, and finally wherein, in the control panel 74 of the vertical column 70 there is installed an electric motor (not shown), supplied by the electric sully line and controlled by such a panel, for actuating in rotation the first rotating flask 55 through suitable transmission members (not shown) co-operating with the rotating bearings 53.

Referring always to fig. 6, it is now described how the separation of the solvent containing the fullerenes from the same fullerenes happens.

For this scope, the liquid solution supersaturated of dissolved fullerenes, contained into the distillation flask 6, is at first completely introduced into the rotating evaporator 38 through the inlet valve 46 of the same one, and, by passing through the different internal chambers 45 and 57, is collected into the internal chamber 56 of the first flask 55, that is partially submersed into the water bath contained into the collecting chamber 65 of the cylindrical receptacle 63. Such a water bath is heated at a determined temperature, that in the example is about 30°C, and is maintained constantly for the entire duration of the separating phase of the solvent from the fuUerenes, while all the internal chambers of the rotating evaporator 38 are maintained at a determined level of vacuum, thereby reducing the boiling temperature of the solvent, that in this case is about at 30°C, by heating also the external wall of the first flask 55 at this temperature, that is not dangerous for the contact by the user.

At the same time of which, the flask 55 is slowly actuated in a determined rotating direction with the above described mechanism, and under this condition it is progressively determined the evaporation of the solvent, that lifts upward along this flask, and, thanks to the continuous rotation of this latter, allows a distribution of the solvent vapours along the internal surfaces of the external wall of the same flask, that speeds up and facilitates the evaporation of such solvent vapours. The solvent vapours that lift upward reach the internal chamber 45 of the rotating evaporator 38, wherein they cool down by contacting the lower temperature of the condenser 44, thereby condensing in the liquid state and, passing through the hollowed conduit 58, they collect themselves into the second collecting flask 61. When all the solvent is evaporated and is collected into the second flask 61, the rotation of the first flask 55 is stopped, wherein only all the fuUerenes separated from the solvent remain, which have a powder shape 77. At this point, the first flask 55 containing the fuUerenes powder 77 is detached from the soxhlet evaporator 38 and the washing of the same fuUerenes powder is performed, by using a funnel with a porous septum 78 (See Fig. 7), a washing solvent, preferably diethyl ether having an evaporation temperature of 34°C, and a collecting receptacle 79 shown in Fig. 8, and by performing the operation shown in fig. 8.

Such a funnel 78 in the example is realized with an upper chamber 80 of circular shape, shaped with a bottom 81 provided with a set of through holes 82 and joined with a lower conduit 83 adapted to be introduced into the neck 84 of the underlying collecting receptacle 79, and a porous septum (not shown) is housed into the space comprised between the bottom 81 and the lower conduit 83, which allows the passage of the ether solvent only but not of the powder of fuUerenes 77. As it is visible in Fig. 8a, first of all the lower conduit 83 of the funnel 78 is inserted into the neck 84 of the collecting receptacle 79 up to penetrate for a segment into the internal chamber 85 of the same receptacle, so the flask 55 containing all the powdered fullerene 77 is kept in correspondence of the funnel 78 and the powder of fuUerenes 77 is gradually poured into the upper chamber 80 of the funnel, together with the ether solvent (not shown) adapted to wash such a powder of fuUerenes, contained into a separated receptacle (not shown), thereby removing the grease remainders and the hydrocarbon remainders (which are ether- soluble) that are produced during the previous preparation phases of the fuUerenes. In this way, while the powder of fuUerenes 77 is progressively washed from the ether solvent, by remaining collected into the upper chamber 80 of the funnel 78, the ether solvent 86 passes through the porous septum, by falling again into the internal chamber 85 of the receptacle 79, from which it is recovered by passing through a side outlet opening 87 and collected in the above said separated receptacle. After various washings performed in the same described way, and when all the powder of fuUerenes 77 has been washed, by remaining always collected into the upper chamber 80 of the funnel, all the solvent is collected into the internal chamber 85 of the receptacle 79, by acquiring a pale yellow colour, indicating that the complete washing of the powder of fuUerenes 77 has been effected (See fig. 8b).

At his point, the powder of fuUerenes so washed in a complete manner is picked up from the funnel 78 and dissolved in toluene into the flask 88 that is submitted to a sonication treatment, for the scope that will be described, by using the sonication apparatus 89 for generating ultrasounds shown in Fig. 8. As it is visible in fig. 9a, such a sonication apparatus 89 is preferably shaped like a lengthened basin 90 of parallelepiped shape, that delimits an internal chamber 91 opened on its upper part and adapted to contain a determined volume of water and a flask 88 containing the washed powder of fuUerenes 77, and is closed on its lower part by a closed bottom 92, as well as it is provided with lower feet 93 for being laid onto the floor. The lengthened basin 90 is closed on its upper part by a cover 94, after that the toluene and the flask 88 with the washed powder of fullerenes 77 have been introduced into the above said internal chamber 91, for performing the sonication of the powder of fullerenes.

A generator of ultrasounds (not shown) is incorporated into the lengthened basin 90 and supplied through an electric cable 95 by an external power supply 96 for determining the propagation of ultrasound waves (marked with 97) generated into the water 98 into which the flask 88 containing the washed powder of fullerenes 77 is submerged.

The scope of the sonication of the powder of fullerenes 77 is to speed up the dissolving of the solutes in determines solvents, in the present case in toluene, and such a sonication produces a sonic cavitation that is the energetic result that is exploited for allowing a better and faster dissolving of the fullerenes into the solvent.

At the end of this operative phase, the fullerenes dissolved into the solvent (in this case, into toluene) are contained into the flask 88. At this point, it is necessary to separate to each other the different types of fullerenes dissolved into the solvent, in the present example the fullerene C60 from the fullerene C70 and from the other fullerenes contained with a greater atom number of carbon, as for example 76, 84, etc... carbon atoms. For performing these separating phases, according to the invention it is used at least a flash chromatography column 99 (See Fig. 10), together with additional types of apparatuses that will be following described, and by performing the operative phases that will be described too.

As usual, the flash chromatography column comprises a vertical column 100 of cylindrical shape, preferably made of borosilicate glass, delimiting an internal chamber 101 with a free upper opening 102 for introducing the materials used for the separation of the fullerenes, and that is extended downward with one narrow part 103, in which a traditional cock 104 is applied, which is actuated manually from a closed position to an opened one of the passage port of such a narrow part 103, respectively for preventing or for allowing the passage through it of the material that is introduced from time to time into the internal chamber 101, which cock may be actuated also in the opposed direction. A suitable mixture of powders of absorbent material, called stationary phase, marked with 105, is initially introduced into the internal chamber 101 through the upper opening 102, and this mixture deposits it onto the bottom 106 of the column 100, into which there has been arranged in advance a cotton flock 107, for preventing the outgoing of the stationary phase 105 from the column. Alternatively, to the cotton, it is possible to use also a filter, but the experience shows that the cotton flack prevents in a better way the exit of the stationary phase 105 from the column, and so it is preferably used.

For obtaining the stationary phase 105, that already described it is introduced into the internal chamber 101 of the column 100, there are mixed into a separate receptacle (Becker), not shown, some active carbon, preferably NORIT A, 100 mesh, Aldrich, and granular silica gel (preferably of the Firm Carlo Erba), together with a determined quantity of solvent, in the present case toluene, wherein the quantity of used active carbon is of the extent of twenty times by weight with respect to the quantity of fullerenes previously dissolved into the toluene and the ratio of weight between the active carbon and the silica gel is 1:2, while in turn the used quantity of toluene is of the extent equal in weight to the half of the toluene previously used as solvent for the powdered fullerenes. Referring now to Fig. 11, that show the different operative phases for separating the fullerenes to each other, by using the column 100 wherein the above described mixture has been already introduced, it is noted that in the phase a) a solution called eluent solution 108, and constituted by the compounds to be separated, is gradually introduced above the stationary phase 105, which solution is contained into a receptacle 109 and in the considered case is formed by the solution of toluene and the powder of fullerenes 77 to be separated.

The separation of the fullerenes is made by exploiting the different absorption of the different fullerenes to be separated during the contact with the stationary phase 105 ; in fact, when such fullerenes are in contact with the surface of the stationary phase 105, without penetrating into the same, there are created some weak interactions between these substances, which slow down in a different way the elution of the different components to be separated, in this case of the fullerene C 60 and of the fullerene C 70, depending on the different force with which such substances interact to each other. In particular, the fullerene C 60 will interact less easily with the molecules of the stationary phase 105, by creating some weak interactions with such molecules and it will slow down less during its descent along the column 100, therefore it will come out from the lower outlet of the column before the remaining fullerenes with a greater number of carbon atoms, in the present example the fullerene C 70, which fullerenes will have on the contrary some greater interactions with the molecules of the solid stationary phase 105 and therefore they will come out from the column 100 in longer times than the ones of coming out of the fullerene C 60.

According to that just specified, so, in the phase b) of the Fig. 11 it is noted that the eluent solution 108 is in the upper part of the column 100 and starts to separate in its fullerenes C 60, marked with 108", and C 70, marked with 108', while above such fullerenes the toluene solvent 110 is poured, this toluene is contained into a separated receptacle 109', with the scope to facilitate the elution process. In this way, along the column 100 both the stationary phase 105 and the fullerenes in the separating phase and the toluene 110 descend in succession, and this descent is facilitated and speed up by a pressure of inert gas applied in the opened upper part of the column 100 and, in the example, constituted by nitrogen, wherein such pressure is preferably comprised from 1,2 to 1,5 atm., and is marked with 111 in the Fig. 10. Thanks to the pressure of the inert gas and the presence of the stationary phase 105 into the column 110, the descent of the stationary phase 105 and both fullerenes C 60 and C 70 thereby continues along the column 100, which fullerenes continue to spate to each other thanks also to the toluene solvent 110, and under this condition when the stationary phase 105 is completely descended with the entire volume thereof, it stops in the lower part against the cotton flack 107 (not shown in Fig. 11), that prevent a further descent along the column 100, in order to allow always the contact of such a stationary phase 105 with the fullerenes which descend along the same column, for prosecuting always the reciprocal separation of the same fullerenes.

This position of end of descent of the stationary phase 105, is marked with a delimiting sign 112 (See Fig. 10), that is marked on to the glass of the column 100 and signals he top of the same stationary phase. In the phase c) of Fig. 11 it is noted that the fullerene C60 108", that descends faster, has descended up to near the bottom 106 of the column 100, while the fullerene C 70 108', that descends slower, has descended up to near middle height of the same column, and the toluene 110 is continuously poured onto the upper part of such a column. So, in the subsequent phase d) of Fig. 11 it is noted that the fullerene C 60 108" has descended up to the bottom 106 of the column 100 and, when it starts to elute, that is to separate from the remaining soaring fullerene 108', tends to acquire a violet colour, that is the colour that is formed by the assembly of the fullerene 108" and the toluene 110. At this point, the cock 104 is manually actuated in the opened position thereof, therefore all the fullerene C 60 108" is completely discharged into the underlying collecting receptacle 113, wherein the narrow outlet part 103 of the column 100 has been temporally introduced into, and this phase ends when all the fullerene C 60 with the acquired violet colour has been introduced into the above said collecting receptacle 113. Subsequently, the cock 104 is closed again, and the receptacle 113 containing the fullerene C 60 is removed from the position under the cock 104 and let available for using this fullerene for the required application.

Finally, in the phase e) of Fig. 11 it is noted that the fullerene C 70 108' still contained into the column 100 is descended up the bottom 106 of the same column and, since it is already separated from the fullerene C 60, tends to clarify progressively and its arrival onto the cotton flack 107 (not shown in this phase) is signalled by a halo of orange colour onto the same cotton. Subsequently, such a colour changes and becomes orange-brown, also in this case, so, the cock 104 is manually actuated in the opening position thereof, therefore all the fullerene C 70 108' is completely discharged into the underlying collecting receptacle 114, wherein the narrow outlet part 103 of the column 100 has temporally inserted into, and this phase ends when the fullerene C 70 with the orange-brown colouring that has acquired has been introduced into the above said collecting receptacle 114. Subsequent, the cock 104 is closed again, and the receptacle 114 containing the fullerene C 70 is removed from the position under the cock 104 and let available for using this fullerene for the desired application. Under this condition, so, the column is again arranged for performing the separation of additional powders of fullerene with the same operative phases just described.

During the different above described operative phases a)-e), it is necessary to prevent carefully that the level of the solution contained into the column 100 descends under the top 112 of the stationary phase 105, thereby causing the emersion of the used solvent, in this case toluene, fact that would determine the "breaking" of the stationary phase by making it then not abler to perform the mutual separation of the fullerenes. Finally, it is necessary to verify carefully that the quantities of the activated carbon NORIT A of the stationary phase 105 be maintained into the established described limits, that is with a ratio in weight of 1:2 between the activated carbon and the silica gel, by minimizing the loss of the fullerene C 60 adsorbed irreversibly by the stationary phase.

If it should use a greater quantity of the above said activated carbon, for gram of fullerenes not separated yet, a part of desired C 60 should adsorb irreversible by the stationary phase, and therefore lost, thereby decreasing the quantity of fullerene obtained at the end of the above described operative phases.

When all the separated fullerenes have been introduced into the relative collecting receptacles 113 and 114, it is possible to select the receptacles containing the fullerenes C 60 only, in case it is desired only this type of fullerenes for the desired applications, and this is performed by using at least a traditional apparatus for liquid chromatography of the type HPLC (high- pressure/performance liquid chromatography) and its detector instruments, which is able to recognize such a fullerene C 60 with the traditional technique. In such a case, all the receptacles containing C 70 and possible fullerenes with greater numbers of atoms that are recognized as such, are separated and possibly rejected, if it is not required their usage.

At this point, the fuUerene C 60 is extracted into a rotating evaporator 38 identical and operative in the same manner of the one described in the Fig. 6, with the water bath preferably at 30° C.

Subsequently, the powder of fuUerene C 60 is washed with the ether solvent or acetone with high purity level, for removing any possible impurity of toluene. A typical final return of the fuUerene C 60 thereby obtained is equal or greater to the 55% in weight with respect to the starting mixture of fullerenes.