Preparation and antimicrobial properties of chlorinated carbon materials

Article abstract of DOI:10.1023/A:1023339431995

Antimicrobial preparations based on anthracite and carbon fabric and prepared by chlorination were studied as influenced by the moisture content of sorbent, its bulk weight, chlorination temperature, etc.

Full text of DOI:10.1023/A:1023339431995

Russian Journal of Applied Chemistry, Vol. 75, No. 12, 2002, pp. 1960 1964. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 12, 2002,
pp. 1997 2001.
Original Russian Text Copyright
2002 by Stavitskaya, Goba, Kartel’.
SORPTION
AND ION-EXCHANGE PROCESSES
Preparation and Antimicrobial Properties of Chlorinated
Carbon Materials
S. S. Stavitskaya, V. E. Goba, and N. T. Kartel’
Institute of Sorption and Endoecology Problems, Ukrainian National Academy of Sciences, Kiev, Ukraine
Received March 25, 2002
Abstract Antimicrobial preparations based on anthracite and carbon fabric and prepared by chlorination
were studied as influenced by the moisture content of sorbent, its bulk weight, chlorination temperature, etc.
Preparation of efficient antimicrobial materials
based on solid sorbents, polymers, and fibrous ma-
terials is an urgent problem. Such materials can be
obtained as granules, powders, pellets, plates, etc.
They are especially important for local water treat-
ment and can be used in development of new proce-
dures for the water treatment which would be more
progressive than the reagent water treatment, etc.
Materials of this kinds both bactericidal,1 ensuring
death of bacteria upon contact, and bacteriostatic, hin-
dering growth and reproduction of bacteria, antimicro-
bial composites are based on cellulose and some other
fibers, polymers, and activated carbons [1 3]. The an-
timicrobial efficiency is imparted either by impregna-
tion of appropriate materials with active chemical
preparations or by chemical modification of the prep-
aration, introduction of appropriate functional groups,
cations, or anions into the sorbent (fiber) skeleton or
surface. In the latter case, stronger grafting of antimi-
crobial material to the support is achieved.
ical of composites with ionic, labile covalent, or co-
ordination bonding, whereas in the case of strong co-
valent bonding no antibacterial activity is observed.
The aim of this study was to prepare water disin-
fectants based on charcoal and other carbon materials
(activated carbons, carbon fibers) and to evaluate their
antimicrobial effectiveness. It should be noted that
the antibacterial activity has been observed previously
for pure activated carbons [2, 3], which is probably
due to sorption of bacteria onto the developed sorbent
surface. To improve the antibacterial effect, activated
carbon or carbon fiber was impregnated with drugs
(e.g., antibiotics) or some other appropriate com-
pounds [2, 4]. Activated carbon with silver additives
is used in the known domestic Rodnik unit for addi-
tional purification and disinfection of water, in mobile
compact installations, and in special-purpose filters;
activated carbons impregnated with silver and other
antimicrobial additives are widely used for water treat-
ment on airplanes and ships [2]. The possibility of
preparing antimicrobial materials by chlorination of
anthracite and other coals has also been studied. As
known [5], chlorination is the most widely used pro-
cedure for water disinfection. The disinfection effect
of chlorine is based on oxidation and breakdown of
compounds in the photocytoplasm of bacteria, which
causes their death. Water is often treated with gaseous
chlorine or compounds containing active chlorine,
e.g., chloride lime, hypochlorite, chloramine, etc.
Thus, it is believed that the chlorine sorbed or grafted
on the carbon surface, or possibly incorporated in
the surface compounds or skeleton would also exhibit
antimicrobial activity. No published data on biological
(bactericidal, bacteriostatic) activity of chlorinated
carbon materials could be found. At the same time,
Various antimicrobial modifying agents (silver, cop-
per, and mercury salts, antibiotics, heteroorganic com-
pounds, etc.) have been studied [1]. It has been found
that the antimicrobial activity is largely determined by
the type of bonding between the modifying agent and
support, the highest antimicrobial activity being typ-
1
According to Regulations concerning Protection of Surface
Waters from Pollution, water in sources of potable and
public water consumption must contain no pathogenic or-
ganisms, and wastewaters should be disinfected after treat-
ment. The permissible content of Saprophyte and Escherichia
1
coli in potable water must not exceed 100 bacteria ml and
1
3 bacteria l , respectively [GOST (State Standard) 2374 73
Potable Water ].
1070-4272/02/7512-1960 $27.00 2002 MAIK Nauka/Interperiodica

PREPARATION AND ANTIMICROBIAL PROPERTIES OF CHLORINATED CARBON MATERIALS 1961
Table 1. Preparation conditions of chlorinated carbon materials
1
Sample no.
Carbon sorbent
Weight gain, g g
1
2
Air-dry anthracite chlorinated at room temperature
0.40
0.44
Anthracite preliminarily dried at 200 C for 1.5 h and chlorinated at room
temperature
3
4
5
6
7
Sample no. 2 treated without air at 900 C for 20 min
Weight loss
0.37
Wet anthracite chlorinated at room temperature
Initial anthracite without chlorination
Air-dry BAU chlorinated at room temperature
0.27
0.37
BAU preliminarily dried at 200 C for 1 h and chlorinated at room
temperature
8
Initial chlorinated anthracite (similar to sample no. 2) for dilution
0.38
Mixture of sample no. 8 + initial anthracite in indicated ratios:
9
10
11
3 : 1
2 : 1
1 : 1
Air-dry DOU chlorinated at indicated temperature, C:
12
13
14
15
16
room
0.26
0.08
Weight loss
200
450
650
Initial chlorinated activated anthracite for dilution
Mixture of sample no. 16 + sample no. 5 in indicated ratios:
17
18
19
20
1 : 2
1 : 3
Chlorinated sample no. 16 triple treated with distilled water (3 200 ml)
Carbon fabric chlorinated at room temperature
the high sorption capacity of activated carbons for
chlorine is well known, and even during World War I
these materials were used in respirators [2]. Moreover,
it has been found [5] that the sorption capacity of car-
bon materials increases after their chlorination.
NaOH. The amount of chlorine sorbed by the carbon
material was evaluated from the difference of the con-
centrations of chlorine in the blank test (without
carbon material) and after reaction with a weighed
amount of a support. The initial concentration of
chlorine was 0.62 mol l ; both weight and volume
concentration of chlorine in the carbon material were
estimated.
1
In our study, we analyzed for the first time ac-
tivated anthracite; in our previous experiments we
used charcoals commercial with varied surface nature,
activated (BAU) and oxidized charcoal (DOU) [4],
and AUT carbon fabric.
The time of chlorination varied because of the dif-
ferent reaction rates in each particular case; it was
determined by the fact that equal amounts of chlorine
were used in each experiment.
The chlorination was performed with gaseous chlo-
rine obtained from a reaction of concentrated hydro-
chloric acid with crystalline potassium permanganate;
in all the tests, 100 ml of HCl was added dropwise to
100 g of KMnO4. The chlorine formed was passed
through a carbon material (anthracite, charcoal, or
fabric) placed in a standard vessel (column), when
the experiment was performed at room temperature, or
in a tubular reactor, when the experiments were per-
formed on heating to 200 950 C with a furnace.
The amount of carbon material was different for each
treatment; it was determined by the reactor capacity
and bulk weight of the material.
Along with chemical analysis, the increase in the
coal weight after chlorination was also determined.
These data were used only for tentative comparison of
the results, because the increase in the material weight
may be due to both sorbed chlorine and water vapor,
especially when a preliminarily dried carbon material
is used.
We prepared more than 20 samples of chlorinated
carbons, with the type of carbon, sorbent moisture
content (wet, air-dry, and dried at high temperature),
and chlorination temperature (room, 200, 450, 650,
and 950 C) varied. The preparation conditions of
the samples are listed in Table 1.
After being passed through a reactor, unchanged
chlorine was fed into a vessel with ice-cooled 1 M
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 12 2002

1962
STAVITSKAYA et al.
Table 2. Sorption of chlorine, A, by activated anthracite and carbon fabric as influenced by experimental conditions
1
(initial concentration of chlorine c0 = 0.62 mol g )
A
A
Sample Sample
ceq,*
Sample Sample
ceq,*
no.
weight, g
M
no.
weight, g
M
1
1
1
1
mmol g
mg g
mmol g
mg g
1
2
4
8
62.8
60
60
0.08
0.1
0.14
0.08
8.6
10.1
9.93
9.03
305.3
358.6
352.5
320.6
13
14
15
20
40.9
41.4
40.5
45
0.02
14.7
14.8
15.2
2.88
521.8
525.4
539.9
102.2
0.006
0.004
0.49
64.2
*
(c ) Equilibrium concentration of chlorine.
eq
Table 3. Antimicrobial properties of chlorinated carbons
Disinfecting effect at indicated
carbon : water ratio
Concentration of sorbed chlorine
Sample no.*
Chlorine
smell
1
1
1
1
mmol g
mg g
mmol ml
mg ml
50 mg : 100 ml
100 mg : 100 ml
5
2
3
5
100
100
7
100
100
10.1
358.6
5.77
204.8
+
+
4
100
100
13
14
15
10
11
18
12
7
14.7
14.8
15.2
521.8
525.8
539.9
36
100
100
25
100
100
100
30
Inactive
Inactive
4.29
4.79
152.3
170.0
100
100
35
100
100
35
+
+
20
102.3
*
Conditions of sample preparation are listed in Table 1.
The data on the sorption capacity for chlorine, re-
proceed simultaneously; the composition of the car-
bon material and chemical nature of the surface can
also affect the process.
calculated to the weight and volume of the carbon
material, are listed in Tables 2 and 3. As seen, sorp-
tion of chlorine is rather high, but depends strongly
on the experimental conditions. The smallest sorption
Taking into account the possible use of chlorinated
carbons as antimicrobial materials, we evaluated (even
if approximately) the strength of chlorine binding in
the samples of carbon materials prepared. For this pur-
pose, we determined the amount of active chlorine
easily removed from the surface with water (Table 4);
1-g sample was shaken with distilled water (100 ml)
for 1.5 h , then the solid phase was filtered off, and
the concentration of chlorine in the filtrate was de-
termined [8]. In some cases, we used 0.1-g samples
and 50-ml water portions (conditions similar to those
when the antimicrobial activity was determined). It
should be noted that the amount of chlorine desorbed
1
(102 mg g ) is observed for carbon fabric; anthracite
samples exhibited high sorption capacity (A = 300
1
550 mg g ), similar results were recorded for com-
mercial charcoals.
As seen from Table 2, the amount of sorbed chlo-
1
rine increases, (from about 300 to 350 mg g ) with
increasing treatment temperature, which indicates
chemical interaction of chlorine with carbons, and the
mechanism of such an interaction may be rather com-
plex [6, 7]. Various processes (e.g., chemical sorption,
substitution reactions, addition reactions, etc.) may
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 12 2002

PREPARATION AND ANTIMICROBIAL PROPERTIES OF CHLORINATED CARBON MATERIALS 1963
Table 4. Desorption of chlorine from chlorinated carbons (carbon sample m = 1 g, water portion V = 100 ml, contact
time
= 1.5 h)
Equilibrium concentration of chlorine
Equilibrium concentration of chlorine
after desorption ceq
after desorption ceq
Sample no.
Sample no.
1
1
1
1
mmol l
mg ml
mmol l
mg ml
4
5
4
4
6
4
4
6
6
2
3
4
1.52 10
4.0 10
1.42 10
0.0
1.28 10
1.00 10
8.00 10
1.52 10
5.39
1.70
5.04
0.0
4.54
3.55
0.28
5.39
14
15
1.04 10
4.0 10
0.9 10
1.16 10
8.00 10
2.00 10
0.0
3.69
0.14
3.20
4.12
0.28
0.07
0.0
16
7
16a*
17
4
4
6
4
10
11
12
13
18
20
*
Carbon sample m = 0.1 g, V = 150 ml.
from samples of chlorinated charcoals (BAU, DOU)
and carbon fabric is 10 20 times smaller compared
to that in the case of chlorinated anthracite (Table 4).
Data on the antimicrobial properties of the sam-
ples studied are listed in Table 3. As seen, unmodified
activated anthracite exhibits zero antimicrobial ac-
tivity; a similar behavior is observed for carbon fabric.
At the same time, almost all samples of chlorinated
anthracite and charcoals possess strong disinfection
activity. Dilution of chlorinated samples with straight
anthracite decreases the recovery of available chlorine
into water (Table 4) and completely eliminates anti-
microbial activity (Table 3).
Moreover, we determined in some cases the rate
of chlorine desorption from the carbons (see figure);
the desorption was effected by triple treatment of
a sample with distilled water (3 200 ml).
Our results showed that, under such conditions,
only insignificant amount of chlorine is desorbed;
however, the resulting concentration of chlorine in
the solution is comparable with that used in at com-
mon water treatment. Actually, the initial concentra-
tion of chlorine for efficient water disinfection is
Correlation of the disinfection effect with the
amount of the sorbed and desorbed weakly bound
chlorine (Table 4) shows no direct dependence be-
tween these parameters. In our opinion, sample nos. 2,
4, 7, 12 cannot be used in practice because of the
strong smell of chlorine.
1
1 10 mg l [8], and after the reaction with bacteria
and impurities, the residual concentration decreases
1
to 0.3 0.5 mg l .
Some samples, including those chlorinated at high
temperatures (e.g., sample nos. 3, 15 and charcoals
BAU and DOU), possess the strongest disinfection
activity and liberate insignificant amount of chlorine
into solution.
As seen from the figure, most of weakly bound
chlorine is removed after first treatment with water,
and then its amount decreases fast.
We also studied mixed samples of carbon materials,
in which a chlorinated sample was diluted with pure
anthracite in various ratios to decrease their activity
and amount of desorbed chlorine (sample nos. 10, 11,
etc; Table 1), and a sample three times washed with
distilled water (sample no. 19).
The antimicrobial activity was evaluated with re-
spect to E.coli K12, because the coli-index (content
of bacteria per liter of water) is a standard character-
istic of the water quality [2, 8].2
Chlorine desorption after triple treatment with water
(3 200 ml) of anthracite sample no. 16; m = 15 g and
2
These tests were performed at the Kiev Research Institute of
General and Public Hygiene, Kiev, Ukraine.
= 15 min. (c ) Equilibrium chlorine concentration and
eq
(V) distilled water volume.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 12 2002

1964
STAVITSKAYA et al.
CONCLUSIONS
REFERENCES
1. Novye voloknistye sorbenty meditsinskogo naznache-
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(1) Chlorinated carbon materials are promising an-
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bound chlorine were prepared, which possess high
antimicrobial activity with respect to E.coli K12
(bacteria commonly used in evaluation of hygienic
requirements); the amount of chlorine desorbed from
these materials into water is close to that satisfy-
ing sanitary requirements to potable water (GOST
2874 54).
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