Removal of PCB from oil and other liquids

A technique is disclosed herein for separating out one group of polar particles for example PCB molecules having polar moments of given magnitudes, from a separate group of polar particles, for example oil molecules having polar moments of lesser magnitude, in a mixture of the two. This is accomplished by utilizing a chamber containing a substance which has an affinity for the first particle, preferably neoprene in the case of PCB. The substance is carried by arrangements of electrodes or the like which produce a non-uniform electric field in the chamber which causes the first particle, e.g. the PCB, to be attracted toward the substance carried by the electrodes, e.g., the neoprene, faster than the second particles. In this way, first particles are separated out from the mixture and are absorbed by a particle collecting substance of suitable type.

The present invention relates generally to techniques for separating out 
certain particles from other particles in a mixture of the two and more 
particularly to a system or method of separating out specific molecules 
such as polychlorinated biphenyls (PCB) or other such polar particles 
having given polar moments from other polar particles such as oil 
molecules having polar moments of lesser magnitudes. 
It is presently believed that polychlorinated biphenyls and tri and 
tetrachlorobenzenes (which will be referred to hereinafter as PCB, TCB and 
when blended together as TPCB) may be toxic. Even very small 
concentrations of PCB, e.g., on the order of 100 to 500 ppm, in 
transformer oils and other liquids to which the environment may be 
inadvertently exposed have been required to be removed. However, present 
filtering methods to accomplish this have been found to be difficult, time 
consuming and therefore quite costly. 
Accordingly, it is a primary object of the present invention to provide an 
uncomplicated, reliable and economical system for and method of separating 
PCB molecules which are polar in nature and other polar particles having 
given polar moments from still other polar particles such as oil molecules 
having polar moments of lesser magnitudes. As will be described in more 
detail hereinafter, this is accomplished by utilizing means defining at 
least one chamber section containing therein spaced-apart electrodes which 
carry particle collecting substances displaying an affinity for the 
particles being separated out, for example, the PCB particles, sufficient 
to absorb the particles when they are nearby. Means are also provided for 
applying a non-uniform electric field between the spaced-apart electrodes. 
Thus, a mixture containing the particles to be separated from one another, 
for example, higher polar moment PCB molecules and lower moment oil 
molecules, can be placed in the chamber section and subjected to the 
non-uniform electric field. This, in turn, will cause the polar particles 
having greater polar moments, e.g., the PCB molecules, to be attracted to 
one or the other of the electrodes faster than the polar particles of 
lesser moment, e.g., the oil molecules, thereby separating out the lower 
electric polar moment particles or molecules from those of higher electric 
polar moment. As a result, the particle collecting substance, preferably 
neoprene in the case of PCB molecules, will absorb the intended particles 
or molecules, thereby eliminating them from the mixture. The dipole moment 
is generally of greatest importance, although quadruple and higher order 
multipole moments can also be significant. 
In a preferred embodiment of the present invention and one which is 
especially suitable for use in separating out PCB molecules from a mixture 
including these and oil molecules, a mixture of the two is subjected to 
the non-uniform field in an associated chamber at different temperatures. 
In this way, PCB molecules having polar moments which are greater than the 
polar moments of the oil molecules at one temperature but not necessarily 
the other can be readily removed along with the PCB molecules having 
greater dipole moments at the other or both temperatures. A single chamber 
section may be utilized to accomplish this, in which case the PCB/oil 
mixture would be provided in that chamber section at both temperatures. On 
the other hand, separate chamber sections having their own associated 
non-uniform electric fields and particle collecting substances could and 
preferably would be utilized.

Turning now to the drawings, wherein like components are designated by like 
reference numerals throughout the various figures, attention is first 
directed to FIG. 1. This figure illustrates a system 10 for separating out 
a first group of polar particles having given polar moments from a second 
group having polar moments of lesser magnitudes in a mixture of the two. 
The system is especially suitable for separating out PCB molecules from a 
mixture including these and oil molecules. Therefore, for purposes of 
clarity, system 10 will be specifically described with regard to the way 
in which it acts on this particular PCB/oil mixture. At the same time, it 
will be apparent that the system may be utilized with other types of 
mixtures containing polar particles of lesser and greater dipole moments. 
Before turning to the specific components making up system 10 and in order 
to fully understand how this system functions, it is important to 
understand how the PCB and oil molecules are affected in an electric field 
and the reasons why. To this end, reference is made to FIG. 2 which 
illustrates a first group of interconnected electrodes 12 which are 
energized by a potential +V.sub.1 and a second group of interconnected 
electrodes 14 which are maintained at a lesser potential -V.sub.2 which 
may or may not be ground potential. In any case, the two sets of 
electrodes are positioned in spaced relationship with one another so as to 
produce a non-uniform electric field E therebetween, as partially 
indicated by dotted lines. Two PCB molecules generally indicated at 16 and 
two oil molecules 18 are shown between electrodes 12 and 14 in non-uniform 
electric field E. 
It is important to note that both types of molecules 16 and 18 in field E 
possess their own permanent and/or induced polar moments which are free to 
change orientation in an applied non-uniform electric field. Thus, as 
illustrated in FIG. 2, the PCB and oil molecules closer to electrodes 12 
are disposed in the manner shown, that is, with their negative sides 
oriented towards the more positive electrodes. At the same time, the PCB 
and oil molecules closer to electrodes 14 are similarly disposed such that 
their positive sides are oriented towards the more negative or ground 
electrodes. The electric field functions to orient the molecules, and by 
its non-uniformity, to attract the molecules to the regions of increasing 
field and hence increasing force upon them. The non-uniform field is 
stronger as positions are approached toward the electrodes from 
intermediate points therebetween. In theory, a polar molecule such as 
those shown could find itself in a position exactly between the two groups 
of electrodes such that the net force acting on it by the field is zero. 
However, this is an unstable state of equilibrium and is in practice a 
highly remote possibility, since the molecules being separated and, in 
fact, the entire mixture is in a dynamic state, e.g., a flowing stream. 
Still referring to FIG. 2, it should be further noted that different polar 
particles have permanent and/or induced electric dipole moments which 
differ in magnitude from one another as evidenced by their respective 
dielectric constants. For example, transformer oil molecules of either 
parafinic or napthalic base are characterized by relatively low dielectric 
constants, e.g., on the order of 2.2 to 2.3 at room temperature 
(25.degree. C.). On the other hand, many but not all PCB molecules are 
characterized by relatively high dielectric constants at room temperature, 
e.g. as high as 5.8. Therefore, a molecule characterized by a larger 
dielectric constant and therefore a greater dipole moments, for example, a 
PCB molecule 16, will be subjected to a greater force by field E than the 
molecules characterized by smaller dielectric constants and therefore 
dipole moments of lesser magnitude, for example, the oil molecules 18. As 
a result, the molecules 16 will be drawn to their respective electrodes 
with greater force and therefore faster than the otherwise adjacent 
molecules 18, thereby causing the higher moment PCB molecules to separate 
out from the lower moment oil molecules. 
It should be noted from the foregoing, that the field E must be non-uniform 
as in accordance with the present invention. Otherwise (if the field were 
uniform), polar particles would not be attracted to one electrode over the 
other since the net force on these particles would be zero. On the other 
hand, the non-uniform field can be a DC field or an AC field since the 
particles are free to change orientation. Thus, in an AC field, when for 
example the electrodes 12 change polarity, the adjacent molecules 16 and 
18 will change orientation that is, rotate 180.degree. relative to 
electrodes 12, simply change polarity by induction. 
Returning to FIG. 1, attention is now directed to the various components 
making up system 10. These components include a supply 20 of transformer 
oil including mainly oil molecules of either the parafinic or napthalic 
base recited above and small concentrations of PCB molecules, e.g., 100 to 
500 ppm. For purposes of the present discussion, it will be assumed that 
all of the PCB molecules are characterized by relatively high dielectric 
constants, that is, as high as 5.8 and, in any event, higher than the 
dielectric constants of the oil molecules, without taking into account the 
particular temperature of the mixture or the frequency of field E 
(assuming an AC field). System 10 also includes an assembly generally 
indicated at 22 which is designed in accordance with the present invention 
for reliably and economically separating out the higher polar order PCB 
molecules from the oil mixture 20 in an uncomplicated way. To this end, 
assembly 22 includes a housing 24 defining an inner chamber 26, an inlet 
28 into the chamber at one end thereof and an outlet 30 at the opposite 
end of the chamber. 
Chamber 26 is separated into a number of chamber sections by a plurality of 
electrode arrangements 32. In the specific assembly illustrated, three 
such arrangements are provided, a portion of one of which is specifically 
illustrated in FIG. 3. Each arrangement includes an electrically 
conductive grid 34 comprised of an outer frame 36 and cross wires 38 
extending in a grid-like fashion across the frame. As best illustrated in 
FIG. 3, elongated needle-like electrodes 40 are electrically connected to 
and supported at the various junctures of wires 38 so as to project out 
from opposite sides of the grid in directions normal thereto. The three 
electrodes arrangements are disposed within and extend entirely across 
chamber 26 in longitudinally spaced, parallel planes normal to the 
longitudinal axis of housing 24. In this way, the center arrangement and 
one end arrangement together define a chamber section 26a while the center 
arrangement and the other end arrangement together define a second chamber 
section 26b. 
Each of these chamber sections 26a,26b serves to contain a non-uniform 
electric field E of the type described with regard to FIG. 2. In order to 
accomplish this, the three electrode arrangements 32 are respectively 
maintained at different potentials +V.sub.1, -V.sub.2 and +V.sub.3, as 
illustrated schematically in FIG. 1. These three potentials can be either 
AC or DC and the potentials +V.sub.1 and +V.sub.3 can be identical, for 
example from the same positive source and the potential -V.sub.2 can be 
either a positive or a negative potential less than that of the potential 
+V.sub.1 and +V.sub.3 or it can be maintained at ground potential. On the 
other hand, the center electrode arrangement can be maintained at a higher 
potential than the end arrangements. Thus, a single power supply could be 
utilized. In any event, the resultant fields between the three electrode 
arrangements are to be non-uniform fields corresponding to the field E, 
described previously. 
For reasons to be discussed in detail hereinafter, the end sections of each 
of the electrodes 40 disposed within either one of the electric field 
containing chamber sections 26a,26b is coated or otherwise provided with a 
substance generally indicated at 42 in FIG. 3. This substance is selected 
to have an affinity for the PCB molecules sufficient to absorb the 
molecules when the two come in contact with one another or are in close 
proximity to one another. In other words, substance 42 serves as a means 
of absorbing out of the oil mixture any higher order PCB molecules which 
are attracted to or otherwise come in contact with the substance. The wire 
grid work may also be coated with the substance 42 (as shown in FIG. 3) as 
the electric field is also non-uniform near the grid wires. In a preferred 
embodiment, this substance 42 is neoprene which has been shown to have the 
appropriate affinity for PCB molecules, although it is not entirely clear 
exactly how its affinity mechanism functions. It is believed that an 
absorption process takes place between the PCB molecules and like 
molecules such as TCB (the blend of which are referred to herein as TPCB) 
and the neoprene which is a polychloroprene, i.e., 
poly(2-chloro-1,3-butadine). It is believed that this process is carried 
out by the formation of chemical bonds. The chlorine atoms which are part 
of the PCB molecules are believed to become bonded (chemically) to the 
neoprene. Similarly, the chlorine atoms in the neoprene become bonded 
(chemically) to the TPCB. The result is a "least energy" state where the 
chlorine atoms are shared between the molecules. Thus, the TPCB molecules 
form cross-links between the neoprene molecules. This process produces a 
macromolecule which is a hybrid of the TPCB and neoprene. The overall 
process is indirectly evidenced by the softening and swelling of the 
neoprene as it absorbs the PCB molecules and can be directly shown by 
actually measuring a decrease in TPCB in a given oil sample subjected to 
this absorption process. 
Having decreased assembly 22, attention is now directed to the way it 
functions in overall system 10. To this end, suitable means such as pump 
44 is provided for directing a continuous stream of oil from supply 20 
into chamber 26 through entry 28, as indicated by arrows 45. This stream 
of oil passes through the chamber and specifically into and through 
sections 26a and 26b across electrode arrangements 32 and thereafter out 
of the chamber through exit 30. Flow path 45 can be a closed path as 
illustrated in FIG. 1 or it can be opened, that is, calling for a single 
pass through assembly 22. In either case, as the oil passes through either 
chamber section 26a or 26b its TPCB molecules and its oil molecules are 
affected by the non-uniform electric fields in these chamber sections in 
the manner described with regard to FIG. 2. In other words, all of the 
polar molecules in either one of the chamber sections 26a,26b are 
attracted to one or the other of the electrode arrangements in that 
chamber section. Those molecules characterized by higher dielectric 
constants, e.g., the higher moment TPCB molecules, are drawn to the 
associated grids 34 with greater force than those molecules characterized 
by lower dielectric constants, e.g., the lower electric moment oil 
molecules, as indicated previously. In this way, the non-uniform electric 
fields serve to separate out the TPCB molecules from the oil molecules and 
also serve to draw them into contact with the neoprene for permanently 
separating them from the mixture. The flow rate of the oil through chamber 
26 is adjusted to maximize the TPCB removal rate. More specifically, the 
intensity in each of the non-uniform electric fields and the flow rate 
should be selected so as to allow the TPCB molecules to be not only 
separated from the oil molecules in the mixture but also to be attracted 
sufficiently close to the electrodes to be absorbed by the neoprene while 
the oil molecules are carried away by the flow of the mixture through the 
chamber. The particular magnitude of each field E and of the specific flow 
rate for best results can be readily determined by one with ordinary skill 
in the art, depending on the particular mixture and particles being 
separated. Obviously, even in the absence of fields E, some of the TPCB 
molecules will come in contact with the neoprene. However, the presence of 
these fields assures that a substantially greater number will do so, 
thereby increasing efficiency of the overall process. 
Having described system 10 both structurally and functionally, it is to be 
understand that the present invention is not limited to the specific 
embodiment described. For example, as stated previously, the principles 
which underlie this system are valid for systems which are intended to 
separate most other polar particles having given electric moments from 
polar particles having moments of lesser magnitudes. Thus, the particular 
type of particle collecting substance 42 utilized will depend upon the 
specific polar particles being separated out of a given mixture. Moreover, 
this substance can be merely coated onto the various electrodes 40 and 
grid wires 38 as illustrated in FIG. 3 or it can be provided in other 
ways. For example, each entire electrode arrangement 32 including its grid 
34 could be coated or, for purposes of convenience, a separate mesh-like 
(open-porosity) layer of substance 42 could be disposed across and 
directly against each electrode arrangement. In this latter case, when a 
given separate layer of substance 42 becomes saturated with the particles 
being absorbed (or otherwise retained by suitable mechanisms, such as 
physical adherence), the separate layer can be readily removed and 
replaced with a new layer. 
In addition to the various modifications just recited which could be made 
to system 10, it should be noted that the electrode arrangements 32 do not 
have to extend transverse to the flow path of mixture 20 through chamber 
26. As illustrated in FIG. 4, these arrangements could be disposed in a 
direction parallel to the flow of oil so as to define parallel chamber 
sections 26a' and 26b'. In this case, the non-uniform electric field in 
each chamber section extends transverse to the flow path, as indicated by 
dotted lines in FIG. 4. Thus, as the oil mixture flows through these 
chamber sections, the higher moment polar molecules are attracted to one 
side or the other faster than the lower moment molecules. In this regard, 
the flow rate should be selected to allow the higher moment molecules to 
reach the electrode arrangements while carrying away the lower moment 
molecules. Otherwise, the system functions in the same way as previously 
described system 10. Moreover, it is within the contemplation of the 
present invention to provide more than two chamber sections 26 whether 
they are transverse to or parallel with the flow of oil and it is equally 
possible to provide a single chamber section. 
From the foregoing, it should be apparent that only those polar molecules 
or other such particles having greater electric polar moments relative to 
other such molecules or particles can be separated out of a mixture of the 
two in an efficient manner. Thus, in the case of PCB molecules, those 
having greater dipole moments as evidenced by their dielectric constants 
can be efficiently separated out of an oil mixture containing oil 
molecules characterized by dielectric constants of lesser magnitudes. 
However, at a given temperature, for example room temperature (25.degree. 
C.), not all of the PCB molecules in a typical supply of transformer oil 
have the same dielectric constants and therefore they do not all have the 
same dipole moments. Some of these PCB molecules are characterized by 
dielectric constants as low as or approximately as low as the oil 
molecules. On the other hand, applicants have found that the dielectric 
constants of PCB molecules vary with temperature in an electric field at a 
given frequency, for example, a frequency of 1 kHz. More important, it has 
been found that those PCB molecules having relative low dielectric 
constants at one temperature can be made to display substantially greater 
dielectric constants at another temperature. This is best illustrated in 
Table I below, and the graphs of FIGS. 6-8 to be discussed hereafter. 
Table I sets forth the dielectric constants for a number of different 
types of PCB molecules at 25.degree. C. and also at 100.degree. C. within 
an AC electric field having a frequency of 1 kHz. The description of each 
type of PCB molecule shown in Table I is unimportant for purposes of the 
present invention and, hence will not be described here. It suffices to 
say that one can readily determine how the dielectric constants of 
different PCB molecules will change with temperature (and also with 
frequency, as will be discussed) in a given mixture. 
TABLE I 
______________________________________ 
(Dielectric Constants of PCB at 1000 Hz) 
25.degree. C. 
100.degree. C. 
______________________________________ 
5.7 4.6 
5.8 4.9 
5.6 4.6 
5.0 4.3 
4.3 3.7 
3.0 4.9 
2.7 4.2 
2.5 3.7 
2.7 3.3 
______________________________________ 
Assuming for the moment that oil mixture 20 described above contains the 
PCB molecules shown in Table I, it should be apparent that if this mixture 
is maintained at room temperature, those PCB molecules having dielectric 
constants which are below 3.0 will be attracted to electrode arrangements 
26a,26b only slightly faster than the oil molecules which have nearly the 
same dielectric constant. However, applicants have not only found that 
changing the temperature of the oil mixture, for example increasing it 
from 25.degree. C. to 100.degree. C., increases the dielectric constants 
of the lower moment PCB molecules (as indicated in Table I) but that this 
change in temperature has no appreciable effect on the oil molecules. Thus 
the dielectric constants of these latter molecules remain unchanged. As a 
result, system 10 as described previously can be modified such that oil 
mixture 20 passes through either or both of the chamber sections 26a,26b 
at varying temperatures, for example at 25.degree. C. and 100.degree. C. 
In this way, the higher order PCB molecules (at 25.degree. C.) can be 
removed and, at a different time, for example during a second pass through 
assembly 22 or in a second or third chamber section thereof, the oil can 
be provided at the higher temperature for removing the previously lower 
moment PCB molecules. 
Referring to FIG. 5, an assembly 22' which is provided specifically for 
maintaining the oil mixture 20 at different temperatures is shown. This 
assembly, like assembly 22 includes an overall housing 24' and three 
longitudinally spaced sets of electrode arrangements 32. While these sets 
of electrodes are shown parallel to the flow path 45', they could be 
transverse thereto as shown in FIG. 1. In the particular assembly 
illustrated in FIG. 5, each set of electrode arrangements defines two 
chamber sections 26a" and 26b". Moreover, the various electrode 
arrangements are appropriately energized to produce associated non-uniform 
electric fields. Moreover, in the case of assembly 22', the first pair of 
chamber sections 26a",26b" which may be referred to as station 1 receives 
the flow of oil at room temperature and thereby separates out those higher 
moment PCB molecules at that temperature. Thereafter, the oil passes 
through a section of chamber 26' which serves as heating station H.sub.1. 
In this station, means are provided for heating the oil to a second 
elevated temperature, for example, a temperature between 25.degree. C. 
and 100.degree. C. The oil then passes into a second pair of chamber 
sections 26a", 26b" (station 2) for separating out some of the previously 
lower order PCB molecules (at room temperature) but are now elevated polar 
moment molecules (as a result of heat). After passing through station 2 
the oil mixture passes into still another heating station H.sub.2 which 
includes means for heating the oil to an even higher temperature, for 
example 100.degree. C. Thereafter, the oil passes through another 
separating station, e.g. Station 3, and finally out of the housing. 
It should be obvious from the foregoing that assembly 22' could include 
more than three separating stations so as to more gradually heat up oil 
mixture 20. On the other hand, as discussed briefly above, a single 
station could be utilized and the oil could be continuously heated up or 
otherwise changed in temperature (depending on the types of PCB particles 
present) and caused to make several passes through the same or different 
stations. 
In addition, applicants have found that they can vary the dielectric 
constants (and hence the dipole moments) of the PCB molecules by varying 
the frequency of the non-uniform electric fields (see FIG. 8). In this 
way, it is possible to "fine tune" assembly 22'. More specifically, by 
maintaining the field E in station 1 at a frequency f1 and by maintaining 
the fields in stations 2 and 3 at, for example, different frequencies f2 
and f3, it is possible to maximize the efficiency of assembly 22'. The 
particular values for temperatures T1, T2, T3, and so on, and the values 
for frequencies f1, f2, f3, and so on, could be readily provided by means 
of routine experimentation (in view of the present disclosure) in order to 
optimize the particle separating capabilities of assembly 22'. Moreover, 
it is to be understood that the utilization of these temperature and 
frequency variations are not limited to separating out PCB molecules, but 
rather any other polar particles having dipole moments which are sensitive 
to these parameters in the same way as the PCB molecules. 
Referring to FIGS. 6-8, the graphs shown there illustrate how the 
dielectric constants of some PCB type molecules vary with temperature and 
frequency. It is to be understood that the particular molecules 
represented in these graphs do not necessarily include those shown in 
Table I above. Moreover, it is to be understood that the graphs (and also 
Table I) are provided for exemplary purposes only. 
FIG. 6 illustrates the effect of chlorination on the dielectric constant of 
the hydrocarbon diphenyl. It will be observed that a dielectric constant 
about 6 at 20.degree. C. occurs with certain degrees of chlorination. 
The dielectric constant of the chlorinated diphenyl, however, increases 
rapidly as the solidification point is approached. The effect of 
temperature change on the dielectric constant of typical chlorinated 
diphenyls of commercial use is illustrated in FIG. 7. At temperatures 
below 20.degree. C., values of between 4 and 6 are readily obtained as the 
graph shows. For trichlor diphenyl a value in excess of 6 and increasing 
occurs as the temperature is decreased below 10.degree. C. 
The graph of FIG. 8 illustrates the effects that temperature and frequency 
have on chlorinated aromatic PCB (Askarel Liquids). These liquids have 
been primarily used for fire-resistant transformers and capacitors. They 
are biphenyl with 2 to 6 chlorine atoms attached to the rings. They are 
used alone or mixed with tri- or tetrachlorobenzene (PCB and TPCB). The 
liquids used have viscosities similar to transformer oil. 
Referring now to FIGS. 9 and 10, attention is directed to modified systems 
10' and 10" for separating out a first group of polar particles having 
given polar moments from a second group having polar moments of lesser 
magnitudes in a mixture of the two, for example, mixture 20. Like system 
10, systems 10' and 10" are especially suitable for separating out PCB 
molecules from a mixture including these and oil molecules. Therefore, for 
purposes of clarity, these two latter systems will be specifically 
described with regard to the way in which they act on this particular 
PCB/oil mixture. At the same time, it will be apparent that the system may 
be utilized with other types of mixtures containing polar particles of 
lesser and greater polar moments in the same manner described with respect 
to system 10. 
With specific reference to FIG. 9, system 10' is shown including a housing 
50 through which mixture 20 is caused to flow by means of a suitable pump 
or the like, as indicated by the arrows 51. At the same time, a chamber 52 
defined within housing 50 contains a continuous supply of charged neoprene 
particles 53 which are placed therein by suitable means generally 
indicated by arrow 55. These particles are suitably charged by any 
suitable means, e.g., by means of an ionizer. Therefore, these particles 
not only serve to collect PCB molecules as described above, but also 
because of the net charges on them, they serve to produce inter-particle 
non-uniform electric fields within chamber 52. Thus, the PCB molecules 
respond to the charged neoprene particles 53 in the same way as the PCB 
molecules in system 10 respond to the neoprene coated ends of electrodes 
40 (see FIG. 3). Obviously, as the charged particles saturate after 
absorbing PCB molecules they must be replaced. This can be accomplished 
intermittently by shutting down the system or by providing a continuous 
"fresh" supply of charged particles. 
Referring to FIG. 10, modified system 10" is shown. This system also 
includes a housing which is generally indicated at 54 defining an internal 
chamber 56. The previously recited mixture 20 is directed into this 
chamber through an inlet 57, as indicated by the arrow 58. However, 
external pumping means or the like are not provided. Rather, a network of 
electrically conductive grids in combination with charged neoprene 
particles are utilized to carry the mixture through the chamber. More 
specifically, as seen in FIG. 10, system 10" includes an arrangement of 
spaced-apart electrically conductive grids 60 which extend across the 
chamber between inlet 57 and an outlet 61 and which are connected to a 
suitable AC power supply 62 for providing a series of AC fields within 
chamber 56. At the same time, charged neoprene particles 64 of like charge 
(which may be identical to those previously described particles 53) are 
directed into chamber 55 near one end thereof through an appropriate inlet 
65, as indicated by arrow 66. The overall (and constantly changing) but 
preferably uniform AC field within chamber 56 is specifically selected to 
cause charged particles 64 to move through the chamber towards the outlet 
end thereof (the right side of the chamber as viewed in FIG. 10). At the 
same time, mixture 20 is caused to enter chamber 56 through inlet 57, for 
example by means of gravity. The moving particles 64 in part transfer 
their momentum to this mixture causing both to move through the chamber 
towards outlet 61. 
Because the particles 64 are charged, the PCB molecules in the mixture 
respond to them in the manner described with regard to system 10'. In 
other words, the charged particles serve not only as a means of collecting 
the PCB molecules but also as a means of producing the necessary 
non-uniform electric field. This latter field must be contrasted with the 
changing field or fields produced by grids 60 which, as stated, is 
preferably a uniform field merely serving as an "electrical pump" or 
"electrical wind pump" for pumping the mixture 20 and charge particles 
through chamber 55 by means of an electric body force on the particles. In 
this regard, the very last grid indicated at 68 is preferably disposed at 
the angle shown so as to direct the charged particles towards a particle 
trap 68 below and in front of outlet 61 while the mixture 20 (less the 
absorbed PCB molecules) passes through the outlet. 
The system 10" and system 10' can be either an open looped or a closed 
looped system in the same manner as previously described system 10. It is 
also to be understood that system 10' and system 10" are equally 
applicable for use in separating out other types of polar particles in the 
same manner as system 10. Finally, with regard to the system 10", while 
the network of grids has been shown for producing an AC field within 
chamber 56, a single pair of grids could be utilized to provide a single 
DC field such that the charged particles are caused to be attracted to one 
of the grids, specifically one disposed near the exit side of the chamber, 
for example, the inclined grid 60a.