Note: Descriptions are shown in the official language in which they were submitted.
~8g~3
DESCRIPTION
.
PROCESS FOR PREPARING CARBONATED
LIQUIDS WITH ACTIVATED CHARCOAL
. _
Technical Field
. _ _ .
05 This invention relates to carbonated
beverages. More particularly, it relates to consumer
or "at home" prepara-tion of carbonated beverages
having substantially the same palatabili-ty and
effervescence of bottled or canned carbonated beverages.
This invention especially relates -to the preparation
of carbonated beverages from activated charcoal
which contains adsorbed carbon dioxide.
Background of the Invention
Attempts to commercialize point of consump-
tion or at home preparation of carbonated beverages
have not met with any lasting success over the
years. The principal shortcoming of the several
techniques has been that the consumer-prepared
carbonated beverage has been significantly inferior
in one or more aspects to the bottled or canned
carbonated beverages available in s-tores and super-
markets. The most common complaints leveled at the
carbonated beverage prepared by the consumer is that
,
3`
the quality and the guantity o~ the carbonation, the
bubble size and the duration of the effervescence
does not compare favorably with the commercially
available bottled carbonated beverage.
05 On the other hand, there are si~nificant
advantages to consumer preparation of carbonated
beverages vis-a-vis packaged liquid carbonated
beverages. Thus, the use of glass, metal or other
bulky containers is avoided, the necessity of bottling,
shipping and storing carbonated beverages consisting
o~ a ma3or percentage of water is eliminated and the
utility in terms of portability by the user is greatly
enhanced. Thus, campers, packpackers, hun-ters,
fishermen, outdoor spectators, housewives and
travellers can enjoy a carbonated beverage without
having to transport bulky and heavy quantities o~
the canned or bottled variety. Further, disposable
and returnable cans and bottles would no longer be
of major concern to environmentalists who have been
~0 seeking ways to conserve both the country's natuxal
resources and natural beauty.
U.S. Patent No. 2,073,273 to We-ts-tein
discloses a means to prepare a carbonated beverage
wherein water plus sweetener and flavor is placed in
a small pressure vessel and a metal cartridge contain-
ing carbon dioxide is inserted into the sealed
vessel where movement of the cartridge causes a
piercing o~ the cartridge thereby injecting the
carbon dioxide into the water to form the carbonated
beverage. The carbon dioxide also pressurizes the
vapor space above the liquid causing the carbonated
beverage to pass out o~ -the vessel through a serving
nozzle when an external valve is opened. This
de~ice met wi-th some measure o~ success in preparing
un~lavored and unsweetened carbonated water for home
--3--
use, but the carbonation volume was lower than
bottled club soda.
The prior art includes a significant
number of dry compositions for use in preparing
05 carbonated beverages at home. In most of these a
source of carbsnate and acid, kno~n in the art as a
chemical "couple", are combined with sweeteners and
a source of flavor so that upon addition of the
composition to a glass of water, the "couple" reacts
to yield carbon dioxide and at least some measure of
carbonation to the beverage. U.S. Patent No. 2,603,569
to Alther discloses the carbonation of a citric
acid-sucrose complex with a sodium bicarbonate-sucrose
complex. U.S. Patent No. 2,742,363 to Hughes claims
a combination of an alkali metal bicarbonate and a
sulfonic acid ion exchange resin in i-ts hydrogen
form. ~n U.S. Patent Nos. 2,851,359 and 2,953,459
to Diller a highly soluble phosphate and a slowly
soluble phosphate are combinecl with an alkali metal
or ammonium carbonate or bicarbonate to prolong the
ebullition of the beverage. U.S. Patent No. 3,241,977
to Mitchell et al. discloses c:hemical carbonation
with citric, adipic or tartaric acid in finely
divided ~orm and which is saicl to approximate the
carbonation sensation of cola-type beverages sold in
air-tight bottles or cans which are produced by a
satura-ted solution containing several volumes of
carbon dioxide. U.S. Patent No. 3,~11,417 to Feldman
et al. discloses a dry beverage composition adapted
to be reconstituted with water to an effervescent
beverage which includes as an essential carbona-ting
ingredient, an organic compound having a carbonic
acid anhydride group, capable of controlled hydrolysis
in water to releas~ carbon dioxide at a substantially
uniform rate. U.S. Patent No. 3,667,962 to Fritzberg
33
4-
et al. discloses a carbonation composition utilizing
two distinct bodies formed from an a~ueous solution
of a saccharide, one contains an edible food acid
and -the other an edible bicarbonate. Upon addition
05 to water the two t.able-ts dissolve quickly and react
to evolve carbon dioxide.
Many of the dry powder chemical couples
have a common and acknowledged defect, an unpleasant
taste in the beverage directly resulting from the
components of the powder. U.S. Patent No. 2,742,363
to Hughes and U.S. Patent No. 3,476,520 to Hovey
addressed this problem by placing the chemicals in
a container which is pervious to gas and water but
impervious to solid reactants and by-products. U.S.
Patent No. 2,975,603 to Barnes et al. takes another
approach by utilizing carbonated ice containing at
least 25 milliliters of carbon di.oxide per gram of
ice as the source of carbonation.
U.S. Patent No. 2,882,244 to Milton discloses
the preparation and composition of zeolite X.
Milton teaches that zeolite X adsorbs water more
strongly than carbon dioxide and that a more strongly
held adsorbate, such as water, will displace a less
strongly held adsorbate, such as carbon dioxide.
Further, comparison data are presented which show that
at low pressures, ziolite X has a higher adsorptive
capacity for water and carbon dioxide than does
charcoal. However, the data presented for charcoal
are inconclusive on its relative adsorptive capacity
for water and carbon dioxide since they were not
measured at the same pressure. Further, the physical
properties and nature of the charcoal are not presen-ted.
Milton also teaches that common adsorbents such as,
charcoal and silica gel, behave differently from
ziolite X and do not ~xhibit its molecular sieve
--5--
action. Rather than showing preference for polar,
polarizable lmsaturated molecules as does ziolite X,
charcoal and silica gel are said to show a main
preference based on volatility of the adsorbate.
05 U.S. Patent Nos. 3,888,998 to Sampson et
al., 3,992,493 and 4,025,655 to Whyte et al. and
4,007,134, 4,110,255 and 4,147,808 to Liepa et al.
disclose carbonation methods, compositions and
devices whereby carbon dioxide containing molecular
sieves a~e used to carbonate aqueous solutions.
Sampson et al. and Whyte et al. teach the
use of molecular sieves having at least 5 weight
percent adsorbed carbon dioxide for effectin~ the
carbonation of aqueous liquids. Molecular sieves
having larger pore openings (greater than 6 Angstroms)
were found to release carbon dioxide to aqueous
liquids at a high rate but this rate is not sustained
over a long period. Molecula:r sieves having small
pore openings (3-5 Angstroms, particularly 3-4
Angstroms), on the other hand, released carbon
dioxide to aqueous liquids at a slower rate but for
a long period of time. In addition, the large pore
sieves adsorbed suhstan-tially more C02 per unit
weight than the 3-5A sieves. Liepa et al. disclose
carbonation devices composed of molecular sieves
formed into a rigid body having a specific surface
area to mass ratio which may be achieved by providing
vertical channels throu~h the rigid body. These
patentees found that when carbon dioxide is adsorbed
into these discs, it will be released when the disc
is contacted with water. They also teach that
common adsorbents, such as charcoal and silica gel,
do not have the adsorptive capacity necessary to
carbonate a beverage at the point of consumption.
--6--
The use of molecular sieves for carbonating
li~uids may lead to the inefficient use of carbon
dioxide. Rapid release rates of carbon dioxide into
the liquid to be carbonated can result in the loss
05 of a major portion of the carbon dioxide from the
liquid to the surrounding atmosphere. Carbonation
processes which more efficiently utilize carbon
dioxide are therefore highly desirable.
Thus, it is an object of this invention to
provide a simple process for point of consumption
preparation of carbonated beverages which increases
the efficient use of carbon dioxide, i.e., substan-
tially reduces the amount of carbon dioxide escaping
from the beverage during the carbonation process,
while producing a carbonated beverage having substan-
tially the same taste and effervescence of the
commercially available product.
Summary of the Invention
In accordance with the present invention,
it has been found that carbonated water and/or
beverages can be prepared by c:ontacting water with
activated charcoal having carbon dioxide adsorbed
therein. More particularly, this invention is
directed to a method of carbonating an aqueous
liguid which comprises contacting an aqueous liquid
with an effective amount of activated charcoal
having adsorbed -therein at least 2C cm3 of carbon
dioxide per gram of charcoal. In a preferred embodi~
ment, the carbonation is conducted in a closed
vessel under superatmospheric pressure.
Brief Descriptlon of the Drawings
The present invention will be more readily
understood by reference to -the accompanying drawings.
Figure 1 is a graph of the volume of
carbon dioxide adsorbed on two activated coconut
charcoals versus adsorption pressure.
Figure 2 is a graph of the volume of
05 carbon dioxide adsorbed on two activated coconut
charcoals versus the time after pressure on the
charcoals was vented.
Figure 3 and 4 are graphs of the volumes
of carbonation produced in water by various quantities
of coconut charcoal and zeolite 13X versus the time
of carbonation.
Description of the Preferred Embodiments
Beverage carbonation with activated charcoal
having carbon dioxide adsorbed thereon provides a
system which makes more efficient use of the carbon
dioxld~ than is obtained with a process which utilizes
zeolites containing adsorbed carbon dioxide. Although
zeolites adsorb more carbon dioxide per uni-t weight,
under ambient conditions, than does activated charcoal,
when the sieves are i.mmersed in water, the initial
rate of CO2 releases from the! sieves is much higher
than ~rom the activated charcoal. Conse~uently, the
activated charcoal provides a higher Co2 retention
efficiency in the beverage compared to molecular
sieves. The fact that the charcoal surfaces are
mostly hydrophobic in nature may explain why the
activated charcoal exhibits a more controlled initial
rate of CO2 release on immersion ln water, compared
with the highly hydrophilic ~ionic) molecular sieves.
Activated charcoals are prepared by the
destructiv~ pyrolysis of natural and syn-thetic
organic materials. Among the widely used natural
produc-ts are coal, petroleum, polysaccharides, such
as sugars and starches and cellulosics. such as woody
~ 3
--8--
by-products, coconut shells, hard and soft woods,
fruit pits and corncobs. Synthetic polymeric
materials such as saran, polyfurfuryl alcohol and
polystyrene-divinyl benzene copolymers, can be used
05 to prepare activated charcoals with very uniform
mocroporous structures. These starting materials
are converted to activated charcoals by first carbon-
izing at 400-500C to eliminate the bulk of the
volatile matter and then oxidizing (activating) with
gas at ~00-1000C to develop the porosity and surface
area. Not all activated charcoals may be employed
in the sùbject invention. The activated charcoal
must have an adsorptive capacity for carbon dioxide
at ambient conditions and the adsorbed carbon dioxide
must be released when the charcoal is contacted with
wa-ter. Only activated charcoals having pores in -the
r~nge of about 4 to about 20 Angstroms can adsorb
C2 at ambient temperature and pressure. However,
charcoals having pores as wide as about 50 Agstroms
can be filled with adsorbed carbon dioxide at sub-
ambient temperatures and/or pressures about 1 atmos-
phere. Thus, activated charcoal having pore sizes
of about 4 to about 50 Angstroms and having the
ability to adsorb C02 and desorb it when contacted
with water may usefully be employed in the subject
invention, with activated charcoal prepared from
natural products being preferred and activated
charcoal prepared from coconut shells being parti-
cularly preferred.
Carbon dioxide is adsorbed onto the activated
charcoal by contacting the charcoal with gaseous or
liquid carbon dioxide. Since water displaces the
C2 from the charcoal, the adsorption ~or loading)
should be conducted under anhydrous conditions. The
- 9 -
charcoal should be dehydrated before being loaded
with CO2 by such means as subjecting it to dry heat
to reduce its adsorbed moisture conten-t. One conven-
ient method of preparing the co2 loaded charcoal is
05 in a column packed with the activated charcoal. A
stream of heated dry gas, such as carbon dioxide,
air or nitrogen, is passed through the column -to
reduce the moisture content of the charcoal and then
gaseous or liquid carbon dioxide is passed through
the column to load the activated charcoal. The
adsorption can be conducted at ambient or slightly
above ambient temperature and substantially atmospheric
pressure, i.e., just enough positive pressure to
ensure a flow of carbon dioxide through the column.
Where hiyher loading of the activated charcoal is
desired or where the subsequent carbonation is to be
conducted in a closed vessel at superatmospheric
pressure, -the CO2 adsorption onto the charcoal is
conducted at sub-ambient tempexature or super-
atmospheric pressure or, for maxirnum loading, acombination of both. Any sub-ambient temperature is
useful with a practical limit being the sublimation
temperature of dry ice at 1 atmosphere, minus 78.5C.
Elevated pressures of up to several hundred pounds,
usually about 80 psig, preferclbly up to about 50
psig, can be usefully employed. To summariæe, -the
C2 loading conditions include a temperature of
about 35 to minus 78C and a pressure of 0 to about
80 psig.
To be usefully employed in the subject
carbonation process, the activated charcoal should
contain at least 20 cm3 to CO2 per gram of charcoal,
preferably 40 cm3/gram. As used herein the volume
of adsorbed CO2 is measured at standard conditions
of temperature and pressure, OC and 1 atmosphere.
--10--
This minimum level is readily obtained at ambient
conditions. Where lower temperatures and/or higher
pressures are employed the adsorptive capacity of
the useful activated charcoals is 400 cm3 of CO2/gram
05 or higher.
The loaded charcoal is a stable product
and can be stored until it is desired to prepare
carbonated beverages. However, since water will
displace the adsorbed carbon dioxide from the
activated charcoal, it is important that appropria-te
storage conditions be used. Efficient storage may
be provided by storing the charcoal under substan-
tially anhydrous conditions. Where elevated pressures
were used for the CO2 adsorption, the adsorption
level may he maintained by storing the charcoal at
substantially the same pressure employed for the
adsorptio~ or at a storage pressure slightly above--
the adsorption pressure. Similarly, where lower
temperatures are employed to increase the CO2 adsorp-
tion over that obtained at ambient or slightly aboveambient temperatures, the storage temperature should
be no more than the adsorp-tion temperature to maintain
the CO2 loading. The ac-tivated charcoal can be
packaged under anhydrous conditions in sealed packages
which can then be stored at a required temperature,
for example, in a refrigerator or a freezer. Where
elevated storage pressures are required, the storage
vessel obviously must be capable of maintaining that
pressure during the storage period. Since s-torage
pressures of 80 psig are contemplated by this inven-
tion, a soft drink can or similar metal container
can safely serve as a storage vessel. By providing
the proper storage containers or packages and the
necessary storage temperature and/or pressure,
activated charcoal containing adsorbed carbon dioxide
can be stored essentially indefinitely. A shelf
life of several months and usually substantially
longer, can be readily achieved.
The water employed to prepare carbonated
05 beverages according to this invention may be any
type of drinking water available to the user.
Household tap water, bottled water, fresh drinking
water from a campsite stream, etc., are examples of
water available at point of consumption preparation
of these carbonated beverages.
In accordance with the practice of this
invention water and activated charcoal containing at
least 20 cm3 of adsorbed carbon dioxide per gram of
charcoal are contacted in a vessel, Vi2 . drinking
glass, pitcher, pressure vessel, etc. The water
- displaces the carbon dioxide releasing it to the
body of water where it is dissolved to produce
carbonated water. In a preferred embodiment, color-
ing, flavorin~ and sweetener are added to or dissolved
in the water so as to produce a carbonated beverage.
The coloring, flavoring and swee-tener can conveniently
be provided in a syrup form~ available commercially,
or in a dry mix, also available commercially. In
this Eashion, such familiar beverayes as carbonated
cola, carbonated root beer, carbonated lemon-lime
soda, carbonated cream soda, etc., can be prepared
at home. Only the ingenuity of the user, the availa-
bility of flavored syrup or dry mix and the individual
tastes of the consumers limit the variety of carbonated
beverages which may be prepared by the process of
this invention.
The carbonation achieved by the prac-tice
of this inven-tion under normal conditions of temper-
ature and pressure generally exceeds 1 volume and
generally is in the range of 1.3 - 1.5. C'arbonation
-12-
in the soft drink beverage industry is expressed as
"volumes of carbonation" or "volumes of C02" and is
defined as -the volume of C02 (measured at standard
conditions of 0C and 1 atmosphere) dissolved per
05 volume of carbonated liquid.
Where higher volumes of carbonation are
desired, i.e., from 1.5 to about 4.0, the carbonation
must be conducted, in accordance with the present
invention, in a closed vessel at superatmospheric
pressure of up to about 80 psig. In achieving these
higher carbonation levels, it is preferred to use
activated charcoal having higher loadings of C02,
e.g., above about 80 cc/g, preferably about 100
cc/g. These levels may be achieved at loading
conditions of reduced temperature and/or elevated
- pressure. Since the upper limit of loading pressure
is about 80 psig there is an inherent safety aspect
in this superatmospheric carbonation, the maximum
pressure that is developed in the closed vessel is
that which was employed in preparing the loaded
charcoal. Although it is preferred that a head space
be provided above the li~uid in the closed carbonation
vessel, this is not cri-tical when activa-ted charcoal
is the source of the carbonation since this material
releases the carbon dioxide at such a slow rate that
it is rapidly taken up by the liquid being carbonated.
Thereore closed vessel carbonation with activated
charcoal can be conducted without an appreciable
head space. This is not the situation where molecular
sieves are the carbonation medium. The rapid release
of the carbon dioxide from molecular sieves requires
that an appreciable head space (vapor space) be
provided above the liquid where the carbonation is
conducted in a closed vessel. Even where a head
space is provided, the carbon dioxide released from
-13-
molecular sieves may develop an undesirable high
pressure.
The relative quantities of activated
charcoal and water to be employed in practicing this
05 invention so as to prepare carbonated liquids depend,
obviously, on a number of factors, such as, the
volume of carbonation desired in the beverage, the
quantity of carbonated beverage being prepared, the
amount of carbon dioxide which escapes from the
surface of the liquid and the quantity of carbon
dioxide adsorbed on the charcoal. Generally, about
0.2 to about 12 grams of activated charcoal loaded
with carbon dioxide will be reguixed to prepare one
fluid ounce of carbonated beverage. This range
provides for a carbonation volume of from 1.3 to
- about 4~0, a C02 loading of 20 to 400 cm3/gram and a --
C2 utilization of about 50%. Those skille~ in the
art can appreciate that the necessary amoun~ is
readily calculable or can be determined by a few
sample preparations.
Carbonaton is usually achieved in accor-
dance with the present invention by placing the C02
loaded activated charcoal in a vessel and adding
the liquid to be carbonated so that it covers the
charcoal, Since the charcoal remains in the vessel
following carbonation, the carbonated liquid and the
charcoal must be separa~ed by, for example, decanting,
filtration or straining of the carbonated liquid.
Alternatively, the charcoal can be confined in a
chamber in the vessel having a surface which is
pervious to gas and liquid but impervious to solids.
In a similar fashion the loaded activated charcoal
can be contained in an envelope or bag having a
surface which permits the passage of CO2 and water
but retains the solid charcoal within its interior.
-14-
When carbonation is conducted at super-
atmospheric pressure, a closed vessel or assembly,
capable of withstanding pressure of up to abou-t 80
psig can be employed. In one embodiment, a rigid
05 receptacle in the shape of a wide-mouth bottle
serves as -the container for the liquid to be
carbonated. A domed cover adap-ted to be affixed to
the container serves as the receptacle for the
charcoal. This domed cover is provided with a
hinged screen which extends across the open end of
the cover. When the cover is affixed to the container,
the screen partitions off the inside of the cover
from the lower containPr. The openings in the
screen are sized to permit free passage of gas and
liquid while preventing the passage of the activated
charcoal in the form it is being employed. In use,-
the domed cover is removed from the lower container,
and tap water is placed in -the lower container.
Optionally, a flavored syrup or dry mix containing
coloring, flavoring, and sweetener is admixed with
the water in the lower container. The screened
portion of the cover is swung back, the necessary
quantity of CO2 loaded activated charcoal is placed
inside the domed cover, the sc:reen is placed back
into position and retained the:re by fastening means
provided for -that purpose. The cover is then affixed
to the lower container and the entire assembly is
placed in an inverted position so as to bring the
water and activated charcoal into contact. Following
a sufficient period of time for the water to displace
the carbon dioxide and effect carbonation of the
liguid, the apparatus is returned to its upright
position. A spring loaded, manually operated
valve, provided in the domed cover for the purpose,
is depressed -to relieve the pressure within the
-15-
closed vessel. The cover is then removed to dispense
the carbonated beverage into serving glasses.
In another embodiment, the charcoal and water
are both placed in the same portion of the apparatus
05 and the cover is affixed. Following sufficient time
for the carbonation, the cover is removed and the
beverage is poured through a screen to separate the
charcoal from the beverage.
The activated charcoal may usefully be employed
in a variety of shapes and forms. Granules, powder
or pellets are readily available forms of activated
charcoal which may be employed. By combining these
forms of charcoal with appropriate, inert binders,
such as clay, etc. discs o activated charcoal may
be prepared which can be employed in practicing this
inventio~.
In a preferred embodiment, activated charcoal
in the form of discs, is loaded with C02 at an
elevatecl pressure of up to about 50 psig or up to
about 80 psig and, optionally, a low temperature,
for example 0 to -78C, to maximize the C02 adsorption.
The discs can then be packagecl under the same elevated
pressure in containers similar to beverage cans
provided with removable or pierceable covers. Where
~5 the CO2 adsorption was conducted under low temperature,
the packaged discs can be stored in a household
refrigerator freezer until needed. Preferably the
container should be provided with a resealable cover
to permit a number of discs to be packaged therein
and removed as needed over a period of time. Upon
resealing the remaining discs will provide pressure
in the container.
When a carbonated beverage is to be prepared,
the container is removed rom storage, the necessary
number of charcoal discs are removed and the container
-16-
is resealed and returned to storage. Although the
discs should be used fairly promptly after removal
from the pressuri~ed container, the release of the
C2 from activated charcoal is sufficiently slow so
05 that the bulk of the CO2 is retained despite exposure
to atmospheric pressure. For example, an activated
charcoal held at about 100-110 psig and than vented
to one atmosphere will, at two minutes after venting,
retain cibout 50% more than its 1 atmosphere capaci-ty.
As discussed above, carbonation with a chemical
"couple~' usually produces a salty taste which is
unpleasant to a large percentage of the public.
This is one of the serious drawbacks of this type of
point of consumption carbonation. However, the salt
produced by the "couple" must reach a threshold
concentration before the consumer becomes aware of
the salty taste. Often 0.5 to 1.0 volumes of
carbonation can be produced from a chemical couple
before the consumer can perceive a salty off-flavor.
Therefore since there are economic advantage for
using the "couple", carbonation can be achieved by
combining a low level of chemical "couple" carbonation
with -the carbonation from CO2 loaded charcoal to
produce a high level of carbonation in soft drink
~5 beverages without a noticeable salty off-taste.
The following examples will serve to illustrate
the subject inven-tion.
-17-
EXAMPLE 1
. . . _
Several adsorbents of varying types were examined
for their adsorptive properties. These included
activated carbons, natural polymeric materials and
05 various inorganic adsorbents. For use in carbonation,
there are two important re~uiremen-ts for an adsorbent:
~irst, it must adsorb enough carbon dioxîde at
ambient temperature so that an inordinate quantity
will not be required for carbonation and secondly,
the carbon dioxide adsorbed mus-t be released when
the adsorbent is in contact with water for a short
period of time.
The CO2 adsorption capacity of various adsorbents
was measured on an all glass volumetric BET (Brunauer,
Emmett, and Teller~ gas adsorption apparatus. Small
amounts of weighed adsorbent were outgassed (<10 5
mm Hg) on the BET at ambien-t or elevated temperatures
depending on the properties of -the sample. A measured
aliquot of CO2 gas was then entered into the system
and -the CO2 uptake by the adsorbent measured as a
function of temperature and pressure. The CO2
adsorption capacities of the various adsorbents
investigated were reported in cubic centimeters of
C2 at STP (0C, 760 mm Hg~ per gram of adsorbent.
For screening purposes the volume of CO2 adsorbed
per gram at 34C and one atmosphere of CO2 was taken
as an indicator of the efficiency of an adsorbent in
retaining CO2; the higher the volume of CO2 adsorbed,
the more efficient is the adsorbent (i.e., less
soiid is needed for delivering a certain volume of
CO2). The temperature of 34C (93F) was chosen to
represent approxima-tely the stora~e temperature
duriny the summer mon-ths.
18-
The results for those commercial charcoals
~hich showed superior adsorptive properties are
presented in Table I below. Data for zeolite 13X,
which has a larger adsorptive capacity than zeolite
05 lOX or the type A zeolites, is also listed for
comparison purposes. The result for other commercial
and experimental charcoals as well as for charcoals
- prepared in the laboratory are presented in Table II
below. The adsorption data presented in both tables
was obtained at 1 atmosphere pressure and, in most
cases, at three temperatures, 34, minus 18 and minus
7~C.
~ 3g3
--19--
TABLE I
Pore Diameter (A) Volume of C0
Manufacturer's Adsorbed (cc(STP~/gm)
Data Manufacturer 34C -18C -78C
05 Zeolite 13X 10 Union Carbide 82 111 ~153
Soconut Charcoal (PCB) 15-20 Calgon 52 121 ~ 250
Coconut Charcoal (208C) 7~ 8 Sutcliffe 44 100 ~ 204
Speakman
Coconut Charcoal (AC~ 15-17 Barneby Cheney 48 108 7 304
10 Coconut Charcoal (BD~ 11 Barneby Cheney 50 -~
Saran*Charcoal 4-6 Dow Chemical 75 158 ---
Carbosphere * 13 Alltec~ 72
-
* Trade Mark
,~
93
-2~-
TABLE II
Com~ercial and Experimental Charcoals
Volume of C0
Pore Adsorbed tcc/2)
05 Charcoal Diameter (~) Manufacturer 34C-18C -78C
AB, Coconut charcoal 20-25 Barnebey Cheney43 85 ?244
SG~, Coal charcoal18 Calgon 37 g2 423
CAL, Coal 20 Calgon 36 99 402
BPL, Coco~ut 8-10 Calgon 38 --- ---
10 PXC, Coconut ~10 Calgon 26
AFC, Coal N.A. Calgon
Low activated coconut N.A. Walker, P.J.
(Univ. of Penn.) 54
Beechwood N.A.Yale University 52
PX-21* Petroleum <20Amoco 37
JXAC, Coal Union Carbide 28
Ambersorb*XE-347 Rohm & Haas 38
Laboratory~ E~ed Charcoals
ActivationVolume of C0 A~sorbed
Temp. (C)(cc/g) at 34C
Prepared From
Cellulose (ashless800 43
filter paper)
Cellulose 1000 48
Sugar (sucrose) 800 43
charcoal
Birchwood 950 34
Polyfurfuryl Alcohol 700 27
(PFA)
* Trade Mark
l~'' '`i
The data in Table I show that the commercial charcoals
tested had somewhat lower capacities than æeolite
13X under essentially ambient conditions but that
the charcoals exhibited superior adsorptive capacities
05 at low temperature (-78C is the approximate
sublimation point of dry ice at one atmosphere). In
addition, the COCOllUt charcoals adsorbed more than
twice as much-C02 at minus 18C than at 34C while
zeolite 13X shows an increase o~ only about 35%.
Althouyh the polymer based charcoals, saran and
carbosphere, showed exceptional adsorptive capacities,
they did not always release C02 upon contact with
water. The coconut charcoals showed significant C02
adsorption and released it into water in a reasonably
short time.
-22-
EXAMPLE 2
The effPct of pressure on the adsorptive capacity of
two coconut charcoals of Example I, identified as
PCB and 208C, was evaluated. The CO2 adsorption of
05 each was measured at pressures ranging from 0 to in
excess of 100 psig. Following the Co2 adsorption
measurements at the high pressure, the vessel was
vented and the CO2 retained in each charcoal was
measured. The results from the measurements made
with increasing pressure are presented in Figure 1
where the CO2 adsorption on each charcoal is plotted
against pressure. The CO~ retained on each charcoal
during the venting of the closed vessel is presented
in Figure 2 where the CO2 retained is plotted against
time after venting. Figure 1 shows that a pressure ~
of 50 psig approximately doubles the CO~ adsorptive
capacity of either coconut charcoal tested. Figure
2 shows that two minutes after the pressure vessel
was opened and vented to one atmosphere the charcoals
retained about 50% more C02 than their capacities at
one atmosphere.
-23-
EXAMPLE 3
The CO~ adsorption of some of the adsorbents of
Example 1 was loaded at 30C and approximately 80
psig and was measured at several different combinations
05 of temperature and pressure. The results are presented
in Table III, together with the data from Example 1
which was obtained at 1 atmosphere and 34C.
-24-
TABLE III
Press. C0 A~sorbed
Adsorbent ~ psig 2cm /g_
Coconut Charcoal 30 81 128
05 (208C3
0 25 136
-17.5 6 138
34 0 4~
_
Coconut Charcoal 30 78 130
(PCB)
0 20 137
-17.~ ~2 ~139
34 0 52
-- ~-
Coconut Charcoal 30 79 97
~ (SGL)
0 25.5 103
-17.5 6.5 105
34 37
Petroleum Charcoal 30 80 215
(PX-21)
34 0 37
Zeolite 13X 30 80 95
0 16 99
-17 ~ 0 101
34 0 82
-25-
These data show that within the range of temperatures
and pressures evaluated, the C02 adsorbed i6 dependent
upon temperature and pressure employed. Charcoal is
a superior carbon dioxide adsorbent at low temperatures
05 and/or high pressures.
~26-
EXAMPLE 4
. .
Carbonation of wat~r under ambient conditions
of temperature and pressure was evaluated for the
activated coconut charcoal and zeolite 13X of Example
05 1. The adsorption capacity of each was:
Volume adsorbed,
cc.g
Adsorbent 34C', l atm
Coconut charcoal (PCB 4X10 mesh) 52
Zeolite 13X (1/16" pellets)82
Each test run was conducted as follows:
Eight ounces of distilled water in a drinking
glass were cooled to 5C. Without stirring, two ice
cubes were added, ~ollowed by either ten or fifteen
grams of the CO2 loaded adsorbent. The carbonation
in solution was measured as a function of time using
an Orion specific ion CO2 electrode and was reported
in volumes o carbonation (cubic centimeters, CO2
(STP) per milliliter of beverage).
The data for the ten gram tests are presented
in Figure III and that for the fifteen gram tests in
Figure IV. In each instance the volumes of carbonation
are plotted against the time after in~roduction of
the adsorbent into the water. These data show that
the coconut charcoal carbonated the water -to a
higher volume of carbonation than zeolite 13Xr even
though the zeolite cntained significantly more CO2.
These data were evaluated by the performance
factors used by Sampson and Whyte (U.S Patent Nos.
31888~998~ 3/~92~493 and 4,025, 655) to evaluate
carbonation systems. This performance factor combines
the fraction of saturation obtained (effectiveness)
g3
-27-
with the efficiency of carbonation for a given time
period (4 minutes in this instance~. These results
are summarized in Table IV below:
-28-
TABLE IV
E'our-minute
Weiqht of adsorbent Performance Factor ~
Coconut zeolite- zeolite
05gm/8 oz. water Charcoal 13X _ 13X(l)
6 ~ -- 0.32
0.44 ~.~6 --
12 ~ - 0.31
0.38 0.19 ---
24 ~ - 0.21
(1)Example IV, Table 5 of the Sampson and Whyte patents.
The data of the Sampson and Whyte patents are based
on results obtained at 0C whereas the remaining
results were obtained at 5~C.
-29-
Charcoal is less hydrophilic than zeolite and
therefore releases its C02 more slowly allowing more
to be dissolved into the water and less lost to the
air. This difference in the release of C02 can be
05 seen not only in the levels of carbona-tion attained,
but in the time taken to achieve these levels.
Zeolite has maximum carbonation at about one minute
whereas charcoal has a maximum around 5 minutes.
This sustained release of the charcoal also means
that CO~ was still being desorbed after ten minutes
while zeolite 13X had been effectively desorbed by
this time. The continued release of C02 bubbles
from the charcoal simulated the look of a highly
carbonated beverage.
~epetition of carbonation with 15g of coconut
charcoal showed values ranging from 1.3-1.5 volumes.
Carbonation values of 1.3-1.5 volumes were also
obtained when 20g charcoal were used.
-30-
Example 5
The ability of -the activated coconut charcoal
and zeolite 13X of Example 4 to carbonate water was
evaluated in the following manner. The adsorbed
05 carbon dioxide content of the charcoal and the
zeolite was 52 and 82 cc/g, respectively.
A weighed amount of loaded adsorbent was placed
in a porous bag and suspended in the headspace of a
180 ml container containing 126 ml water. The
container was closed and inverted to wet the charcoal.
The system was either shaken or allowed to sit as
specified and equilibrated in a cold water bath.
The equilibrium pressure and temperature were recorded.
Any pressure buildup generated during the carbonation
was also noted. The results are presented in Table V.
-31-
TABIE V
Adsorbent Water Max. Press Volume of
wt. (&) T~e: Handling (Rsi ~ Carbonation
(F) (from equil-
05 ibrium head-
space pressure)
Coconut Charcoal (PCB)
8.4 80 Shaken while 18 1.55
Carbonating
Shaken 32 2.18
39 Shaken 34 3.15
Charcoal submerged 37 3.7
while carbonating
Charcoal wet once 48 3.35
quickly, not in
contact with water
while carbonating
Zeolite 13X
7.5 44 Zeolite submerged 50 2.55
47 Zeolite submerged ~80, ---
vented
quickly~L-
80 psig
-32-
Beverages having carbonation volumes greater
than three volumes were obtained when 15g of coconut
charcoal (PCB) were used to carbonate 126 ml water
~120g adsorbent/qt~ at 40F (4.5C). The C02 release
05 ~rom zeolite 13X, however, was so fast that -the
initial pressure buildup was much greater than 80
psig and had to be vented which limited the carbonation
volume to about 2.5. A typical beverage container
can withstand only 80-100 psig. The coconut charcoal
showed a more sus-tained release generating pressure
of less than 50 psig even when the charcoal was wet
once and the C02 was allowed to release into the
vapor space rather than the beverage. A conventional
glass or metal beverage container can sustain such a
pressure and can be used to prepare carbonated
- beverages from C02 loaded activated charcoal.
-33-
EXAMPLE 6
One of the coconut charcoals of Example 1 and a
chemical "couple" were utilized together in a closed
system to prcduce a carbonated beverage. The chemical
05 "couple" employed was sodium bicarbonate and citric
acid.
Orange flavored carbonated beverages were
prepared in the fashion of Example 5 by placing the
necessary ~uantities of water, and orange flavored
dry mix, the chemical "couple" and the CO2 loaded
coconut charcoal ~208C) in the container. Various
amounts of chemical "couple" and charcoal ~ere employed.
The ~olumes of carbonation obtained were measured
with a CO2 electrode. The results are presented in
15 Table VI below.
TABLE VI
ORANGE BEVERAGE AT 6C
.
Vol. o~
Carbonation
~0 Coconut Charcoal Contributed by Total
(208C~ grams~_. Chem ''Couple" Vol. Carbonation
1.2 2.3
3~ 2.0 3.0
1~0 0 3-5
The use of a ch~mical "couple" can significantly
reduce the amount of charcoal required to carbonate
a beverage in a closed container. The combination
-34
of chemical "couple" and charcoal can produce carbonation
levels similar to that of commercial bottled or
canned soft drinks.
In the foregoing examples, the volume of carbon
05 dioxide adsorbed by the activated charcoal or other
adsorbent under test is reported in terms of standard
temperature and pressure t0C. and 760mm) regardless
of the conditions used for -the adsorption.
