U.S. patent application number 08/985082 was filed with the patent office on 2002-05-30 for process and equipment for the reactivation of activated carbon.
Invention is credited to HU, HYOUNG SOO, KIM, HYEON YEOUL, KIM, KWANG NYOUNG, LEE, EUNG TAEK, LEE, JU YOUN, LEE, SANG EUN, LEE, YOUNG HO, OH, HYUN JE, OH, SUNG MIN, SONG, KI SEOP, WANG, CHANG KEUN.
Application Number | 20020065188 08/985082 |
Document ID | / |
Family ID | 19510586 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020065188 |
Kind Code |
A1 |
WANG, CHANG KEUN ; et
al. |
May 30, 2002 |
PROCESS AND EQUIPMENT FOR THE REACTIVATION OF ACTIVATED CARBON
Abstract
A process and a set of equipment for reactivating spent
activated carbon onto which pollutants were adsorbed, are invented.
The present process comprises subjecting the activated carbon to be
reactivated in a mixed solution consisting of ethanol, sodium
hydroxide solution and water to effectuate the desorption of the
pollutants adsorbed on the activated carbon. The present equipment
comprises (A) a mixing tank for mixing given amounts of water,
ethanol and sodium hydroxide solution which are supplied from the
respective receptacles thereof; (B) a reactivation reactor for
receiving the mixed solution from the mixing tank and subjecting
the spent activated carbon filled therein to the mixed solution to
effect the desorption of the pollutants adsorbed on the spent
activated carbon, wherein the reactivation reactor being provided
with a means for regulating temperature of the mixed solution; and
(C) a storage tank for receiving the reactivated carbon.
Inventors: |
WANG, CHANG KEUN;
(DAEJON-SHI, KR) ; LEE, SANG EUN; (SEOUL, KR)
; OH, HYUN JE; (SEOUL, KR) ; LEE, JU YOUN;
(SEOUL, KR) ; KIM, KWANG NYOUNG; (KYOUNGGI-DO,
KR) ; KIM, HYEON YEOUL; (KYOUNGGI-DO, KR) ;
SONG, KI SEOP; (SEOUL, KR) ; LEE, EUNG TAEK;
(SEOUL, KR) ; HU, HYOUNG SOO; (SEOUL, KR) ;
LEE, YOUNG HO; (KYOUNGGI-DO, KR) ; OH, SUNG MIN;
(SEOUL, KR) |
Correspondence
Address: |
STAAS & HALSEY LLP
700 11TH STREET, NW
SUITE 500
WASHINGTON
DC
20001
US
|
Family ID: |
19510586 |
Appl. No.: |
08/985082 |
Filed: |
December 4, 1997 |
Current U.S.
Class: |
502/25 |
Current CPC
Class: |
C01B 32/39 20170801;
Y02P 20/584 20151101; B01J 20/3416 20130101; C01B 32/36 20170801;
H01J 2229/0722 20130101; B01J 21/20 20130101; B01J 20/3475
20130101; B01J 20/20 20130101 |
Class at
Publication: |
502/25 |
International
Class: |
B01J 020/34; B01J
021/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 1997 |
KR |
199726359 |
Claims
What is claimed is:
1. A maethod of reactivating spent activated carbon onto which
pollutants were adsorbed, which comprises a first step of
subjecting the spent activated carbon to a mixed solution of
ethanol, sodium hydroxide solution and water to effectuate the
desorption of the pollutants adsorbed on the activated carbon.
2. A method according to claim 1, which further comprises a second
step rinsing the reactivated carbon.
3. A method according to claim 1, which further comprises a third
step recovering ethanol in waste liquid remaining from the first
step and remaining rinsing water formed from the second step.
4. A method according to claims 2 or 3 wherein the mixed solution
includes 10% to 50% of ethanol and 1% to 4% of sodium hydroxide
solution and water occupying the rest percentage.
5. A method according to claim 4 wherein the temperature of the
mixed solution is ambient to 100.degree. C..
6. A method according to claim 5 wherein the first step is carried
out for 6 to 24 hours.
7. An equipment for the reactivation of spent activated carbon onto
which pollutants were adsorbed which, comprises (A) a mixing tank
for mixing given amounts of water, ethanol and sodium hydroxide
solution which are supplied from the respective receptacles; (B) a
reactivation reactor for receiving the mixed solution from the
mixing tank and subjecting the spent activated carbon filled
therein to the mixed solution to effectuate the desorption of the
pollutants adsorbed on the spent activated carbon, wherein the
reactivation reactor being provided with a means for regulating
temperature of the mixed solution; and (C) a storage tank for
receiving the reactivated carbon.
8. An equipment according to claim 7, which further comprises a
means for recovering ethanol for receiving the waste liquid from
the reactivation reactor and recovering ethanol in the waste
liquid.
9. An equipment according to claim 8, in which the means for
recovering ethanol comprises: (A) an evaporator for receiving the
waste liquid from the reactivation reactor to evaporate ethanol in
the extraction liquid; (B) a condensor for collecting the ethanol
evaporated; and (C) a receptacle for receiving the liquid ethanol
from the condenser and supplying it to the mixing tank for
re-use.
10. An equipment according to claim 9, in which the distiller is
heated by the means for regulating temperature.
Description
BACKGROUND OF THE INVENTION
[0001] 1. FIELD OF THE INVENTION
[0002] The present invention relates to a process and an equipment
for the reactivation of spent activated carbon onto which polluants
were adsorbed.
[0003] 2. DESCRIPTION OF THE PRIOR ART
[0004] Activated carbon is widely used in the purification of
contaminated water and air because of its excellent capabilities of
adsorbing various inorganic or organic substances.
[0005] After being used, the activated carbon is generally
reactivated. Reactivation process allow the activated carbon to
recover its adsorption capacities and thereby, the reactivated
carbon is re-used in the adsorption process. However, the courrent
reactivation methos generally demand very high costs and thus,
limit adopting the activated coabon-utilizing purification
process.
[0006] There are various conventional methods for the reactivation
of the used carbon, for example, thermal reactivation, solvent
extraction or wet oxidation, etc., depending on the nature of the
pollutants adsorbed on the activated carbon.
[0007] As being the most available reactivation method, the thermal
reactivation requires the reactivation furnace to be processed at
high temperatures of 900.degree. C. to 1000.degree. C. similar to
that used in the production of the activated carbon. Therefore, the
construction and maintenance of the thermal reactor demands high
costs.
[0008] The existing solvent extraction method is inadvantageous
because the adsorption recovery efficiency of the reactivated
carbon is low and there is possibility that a portion of the
harmful solvent used remains in the reactivated carbon.
[0009] The wet oxidation is deficient in the degradation or
desorption of the pollutants irreversibly adsorbed on the activated
carbon.
[0010] Therefore, there has been a need for new methods and/or
equipments permitting the reactivation of the spent activated
carbon, which can highly recover the adsorption capacities of the
activated carbon and is also less costly to use and operate.
SUMMARY OF THE INVENTION
[0011] The present invention provides a method of the reactivation
of spent activated carbon onto which pollutants were adsorbed,which
comprises a first step of subjecting the used activated carbon to a
mixed solution including ethanol, sodium hydroxide solution and
water to effectuate the desorption of the pollutants adsorbed on
the activated carbon.
[0012] In addition, the present invention provides an equipment for
reactivating the spent activated carbon onto which the pollutants
were adsorbed, which comprises (A) a mixing tank for mixing given
amounts of water, ethanol and sodium hydroxide solution which are
supplied from the respective receptacles thereof, (B) a
reactivating reactor for receiving the mixed solution from the
mixing tank and subjecting the spent activated carbon filled
therein to the mixed solution to effectuate the desorption of the
pollutants adsorbed on the spent activated carbon, wherein the
reactivation reactor being provided with a means for regulating
temperature of the mixed solution; and (C) a storage tank for
receiving the reactivated carbon.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 is a flow sheet illustrating the process for the
reactivation of activated carbon according to the present
invention.
[0014] FIG. 2 shows the equipment for the reactivation of activated
carbon according to the present invention.
[0015] FIG. 3 shows bar graphs of phenol adsorption recovery of
reactivated carbons 1 to 4 according to the present invention.
[0016] FIG. 4 shows bar graphs of humic substances adsorption
recovery of reactivated carbons 1 to 4 according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] According to the present invention, ethanol is preferably
used in the amount of 10% to 50% based on the mixed solution of
ethanol, sodium hydroxide solution, and water, and sodium hydroxide
solution is used in the amount of 1% to 4% based on the mixed
solution.
[0018] In a further preferred embodiment of the present invention,
the mixed solution of ethanol, sodium hydroxide solution, and water
is heated ambient to 100.degree. C.. In direct connection, since
the desorption of the pollutants adsorbed on the activated carbon
proceeds at lower temperature, the present process and equipment
advantageously require lower expenditure of energy and more
convenient operation and maintenance.
[0019] In a still further preferred embodiment, the desorption of
the pollutants adsorbed on the activated carbon in the mixed
solution of ethanol, sodium hydroxide solution and water proceeds
for a period of 6 to 24 hours.
[0020] The reactivation process and the equipment of the present
invention can be applied to drinking water and wastewater treatment
plants, air pollution-preventing equipments etc. It is especially
useful in the purification of drinking water, since solvents used
by the present invention, i.e., ethanol and sodium hydroxide are
food grade and not harmful.
[0021] The reactivation process according to the present invention
will be described in detail in reference to the accompanying
drawings.
[0022] FIG. 1 is a flow sheet illustrating the physico-chemical
process according to the present invention for the reactivation of
spent activated carbon onto which pollutants were adsorbed. As
shown, 1% to 4% of NaOH, 10% to 50% of ethanol and water are mixed
in a mixing tank, and the mixed solution in the mixing tank is
circulated into a reactivation reactor filled with the spent
activated carbon to be reactivated. The reactivation tank is
tightly closed and heated to normal temperature and 100.degree. C.
for 6 to 24 hours. As a result, the pollutants are desorbed from
the activated carbon. The waste liquid formed by such desorption
reaction in the reactivation reactor is transported via a
receptacle into a distiller. Ethanol is recovered from the waste
liquid in the distiller by evaporation, followed by condensation.
The recovered ethanol is circulated into the mixing tank and
recycled for the next reactivation process. Meanwhile, after the
waste liquid formed by the desorption reaction in the reactivation
reactor exits to the receptacle, the activated carbon in the
reactivation reactor is in situ washed with tap water in order to
remove the residual ethanol and NaOH from the activated carbon.
Additionally, ethanol in the washing water is also recovered for
re-use. As a final procedure, the reactivated carbon is transported
to a storage tank or an adsorber.
[0023] FIG. 2 shows an equipment for the reactivation of the
activated carbon according to the present invention. This figure
illustrates three receptacles 1, 2 and 3 for containing water,
ethanol and NaOH solution, respectively. The respective solvents
are circulated by pumps P1, P2 and P3 into a mixing tank 4. After
the solvents are mixed in the mixing tank 4, the mixed solution are
circulated by a pump P4 into a reactivation reactor 5 filled with
the spent activated carbon onto which pollutants were adsorbed. The
temperature in the reactivation reactor 5 is increased by the heat
supplied from a boiler 6 and/or a heater 12, the heater being
equipped within the reactivation reactor 5. After the completion of
the desorption, the resulting waste liquid in the reactivation
reactor 5 is circulated by a pump P6 into a receptacle 8 and then,
the activated carbon in the reactivation reactor 5 is washed with
tap water while the washing water flows via valves to a distiller
9. The washed activated carbon in the reactivation reactor 5 is
carried to a storage tank 7. The waste liquid in the distiller 9 is
heated by the boiler 6 to evaporate the ethanol. The evaporated
ethanol is condensed and collected. The ethanol in the storage tank
11 is circulated by a pump P7 into the mixing tank 4 for
re-use.
[0024] The following examples are given merely as illustrations of
the present invention and demonstration of the preferred
embodiments of the present invention, and are not to be considered
as limiting.
EXAMPLES
[0025] The activated carbon used for water treatment for 1 year and
4 months was subjected to the reactivation process of the present
invention. 108 cases in the desorption process were established by
varying the amount of ethanol between 10% and 50%, the amount of
NaOH between 1% and 4% and the condition of temperature ambient to
100.degree. C., and UV254 absorbance was measured on the waste
liquid formed through the desorption process. The results are
summarized as follows.
[0026] When the desorption was carried out at the ambient
temperature, the UV absorbance of the extracted solution by the
present invention is 8,000 to 30,000 times as high as that from tap
water. For the desorption temperature of 60.degree. C., the
extracted solution by the present invention increases the UV254
absorbance by 16,000 to 80,000 times of the tap water treated. For
the desorption temperature of 100.degree. C., the extracted
solution by the present invention increased the UV254 absorbance by
16,000 to 80,000 times of the tap water treated.
[0027] Particularly, when the desorption was performed for 12 to 24
hours at 80.degree. C. to 100.degree. C., the mixed solution
consisting of 20-40% of ethanol, 24% of NaOH and water increased
the UV254 absorbance by 50,000 times or more as compared to tap
water.
[0028] It is expected that such unexpected results are derived from
the synergistic effects occurred by the combination of the
selective solvents and temperature for the desorption according to
the present invention.
[0029] FIGS. 3 and 4 are bar graphs of the recovery of adsorption
capacities of the activated carbon which was reactivated by the
reactivation process of the present invention. The adsorption
capacity recovery was evaluated by adsorbing phenol (FIG. 3) or
humic substance (FIG. 4) on the reactivated carbon for 48
hours.
[0030] As shown in FIG. 3, typically, the recovery of phenol
adsorption by the reactivated carbon according to the present
invention ranges from 80% to 120%. Especially, when 20% of ethanol,
0.4% of NaOH and temperature of 100.degree. C. are utilized for the
desorption, the adsorption recovery amounts to approximately 120%
as presented in bars 1 and 2. Bars 1 and 2 indicate the results
obtained by using the reactivated carbon in the amounts of 0.5 g
and 1.5 g, respectively. Bars 3 and 4 indicate the results obtained
by utilizing 20% of ethanol, 0.4% of NaOH and temperature of
200.degree. C. as the desorption conditions while using 0.3 g and
1.Og of the reactivated carbon, respectively. As shown in FIG. 4,
the humic substance adsorption recovery of the reactivated carbon
according to the present invention is from 80% to 100%. Generally,
the humic substance adsorption recovery is comparatively lower than
the phenol adsorption recovery but it is still acceptable
considering the lower cost. Bars 1 and 2 indicate the results
obtained by utilizing 20% of ethanol, 0.4% of NaOH and temperature
of 100.degree. C. as the desorption conditions while using 0.5 g
and 1.5 g of the reactivated carbon, respectively. Bars 3 and 4
indicate the results obtained by utilizing 20% of ethanol, 0.4% of
NaOH and temperature of 200.degree. C. as the desorption conditions
while using 0.3g and 1.Og of the reactivated carbon,
respectively.
[0031] The removal of the humic substance by the reactivated carbon
was determined by a column test. The reactivated carbon was formed
by subjecting the activated carbon used in a water treatment plants
for 16 months in the equipment depicted in FIG. 2 for 12 hours
while using the mixed solution of 20% of ethanol, 4% of NaOH and
water and the temperature of 100.degree. C. as the desorption
conditions. The column test revealed that the humic substance
removal efficiency of the reactivated carbon of the present
invention corresponds to about 90% compared to that obtained by
fresh activated carbon. This result indicates that the reactivation
process of the present invention is comparable to the prior thermal
reactivation in terms of its humic substance removal.
[0032] The iodide adsorption was tested for the reactivated carbon
of the present invention. This activated carbon has been used in a
water treatment plant for 16 months in the equipment of the present
invention for 24 hours while using the mixed solution of 20% of
ethanol, 2% of NaOH and water and the temperature of 100.degree. C.
as the desorption conditions. This test revealed that the iodine
number of the reactivated carbon ranges to 80%-90% of the fresh
activated carbon. Table I below shows the iodine number of the
reactivated and fresh carbon. The iodine number was evaluated by
the Korean Granular Activated Carbon Test Method KSM 1802 which is
same as AWWA procedure.
1 TABLE I Active Carbon Types Iodide Adsorption (mg/g) Regenerated
by the present process 1023 Fresh 1212 Korean Standard Rating 1
1,100 or more Korean Standard Rating 2 1,000 to 1,100 Korean
Standard Rating 3 900 to 1,000
[0033] As can be shown in Table I, the reactivated carbon of the
present invention recovered the iodine number significantly, and
therefore, it is concluded that the process for the reactivation of
the spent activated carbon according to the present invention can
be successfully applied to water and air purification
industries.
* * * * *