1. JAMBULINGAM et al.: PROPERTIES OF ACTIVATED CARBONS FROM AGRICULTURAL WASTES 495
Journal of Scientific & Industrial Research
Vol. 66, June 2007, pp.495-500
Characteristic studies of some activated carbons from agricultural wastes
M Jambulingam1,*, S Karthikeyan2, P Sivakumar2, J Kiruthika3 and T Maiyalagan4
1
PG & Research Department of Chemistry, PSG CAS, Coimbatore
2
Department of Chemistry, Erode Sengunthar Engineering College, Thudupathi, Erode 638 057
3
Department of Biotechnology, Government College of Technology, Coimbatore
4
Department of Chemistry, IIT Madras, Chennai
Received 07 September 2005; revised 17 November 2006; accepted 20 February 2007
Agricultural wastes like tobacco stem, bulrush Scirpus acutus stem, Leucaena leucocephala shell, Ceiba pentandra
shell, Pongamia pinnata shell have been explored for the preparation of activated carbon. Characterization studies such as
bulk density, moisture, ash, fixed carbon, matter soluble in water, matter soluble in acid, pH, decolourising power, phenol
number, ion exchange capacity, iron content and surface area have been carried out to assess the suitability of these carbons as
absorbents in water and wastewater. The results obtained show them to be good adsorbents for both organics and inorganics.
Present study reveals the recovery of valuable adsorbents from readily and cheaply available agriculture wastes.
Keywords: Activated carbon, Adsorption, Agricultural wastes, Surface area
IPC Code: C01B31/08
Introduction Materials and Methods
Ancient Hindus in India used charcoal for Agricultural wastes (tobacco stem, bulrush
drinking water filtration and Egyptians used carbonized Scirpus acutus stem, Leucaena leucocephala shell, Ceiba
wood as a medical adsorbent and purifying agent as early pentandra shell and Pongamia pinnata shell), collected
as 1500 BC1. Activated carbon from vegetable material from fallow lands in and around Erode District, Tamil
was introduced industrially in the first part of the 20th Nadu, India, were cut into small pieces (3 cm), dried in
century, and used in sugar refining2. In the US, activated sunlight and used for the preparation of activated
carbon from black ash was found very effective in carbons.
decolorizing liquids3. Agricultural by-products and waste The material to be carbonized was impregnated
materials used for the production of activated carbons with respective salt solutions (ZnCl2, CaCl2, Na2SO4,
include olive stones4, almond shells5, apricot and peach Na2CO3) for varying periods. Accordingly, sufficient
stones6, maize cob7, linseed straw8, saw dust9, rice hulls10, quantities were soaked well with 10% salt solution
cashew nut hull11, cashew nut sheath12, coconut shells (5 l capacity) respectively so that the solution gets well
and jusks13, eucalyptus bark14, linseed cake15 and tea adsorbed for a period of 24 h. At the end of 24 h, excess
waste ash16. Besides these, other sources of activated solution was decanted off and air-dried. Then the
carbon are sulfonated coal17, tyre coal dust, activated materials were placed in muffle furnace carbonized at
bauxite, cement kiln dust18, ground sunflower stalk, shale 400°C for 60 min. The dried materials were powdered
oil ash, rubber seed coat, palm seed coat19, de-oiled and activated in a muffle furnace kept at 800°C for
soya20 , baggase fly ash21, Red mud22 etc. This study 60 min. After activation, the carbons obtained were
explores new activated carbon from biological waste washed sufficiently with 4N HCI. Then the materials
materials through various processes. were washed with plenty of water to remove excess acid,
*Author for correspondence dried and powdered.
Tel: 0422-5397901-902 In Dolomite process, sufficient quantities of
E-mail: jambupsggas@rediffmail.com dried agricultural wastes were taken over a calcium

2. 496 J SCI IND RES VOL 66 JUNE 2007
carbonate bed and the upper layer of waste was also Results and Discussion
covered with a layer of calcium carbonate. The whole Bulk density of carbons obtained from all the
material was carbonized at 400°C for 60 min, powdered materials shows that Bulrush S. acutus carbon has the
well and followed by the thermal activation at 800°C higher bulk density due to its high fibre content and P.
for 60 min. In Acid process, dried material was treated pinnata carbon has the lower bulk density, which can
with excess of H2SO4. Charring of the material occurred be attributed to the material hardness (Tables 1-5). Ash
immediately accompanied by evolution of heat in fumes. content for all the varieties of carbons is very low
When the reaction subsided, mixture was left in an air thereby increasing the fixed carbon content except for
oven maintained at 140-160°C for 24 h. In chemical the carbon obtained from P. pinnata and Bulrush S.
activation process, 1 part of the material and 1.5 parts acutus carbon by H2SO4+NH4S 2O8. Except carbons
of H2SO4 were mixed with 0.4 parts of NH4S2O8 and prepared by Acid process, carbon obtained from all other
kept in muffle furnace at 120°C for 14 h. At the end of processes exhibit small amount of leaching property.
this period, the product was washed with large volume
Characterization studies on porosity, surface
of water to remove free acid, dried at 110°C and finally
area. Iodine number, CCl4 activity and phenol adsorption
activated at 800°C for 60 min.
capacity clearly indicate that the carbons obtained by
pH and conductivity were analyzed using Elico
various processes will depend only on the composition
pH meter (model L1-120) and conductivity meter (model
of raw agricultural waste surface area properties of
M-180), respectively. Moisture content (%) by mass, ash
Na2SO4 process for Bulrush Scirpus acutus carbon, HCl
(on dry basis) % by mass, bulk density, specific gravity,
process for Leucaena and C. pentandra shell waste
porosity, matter soluble in water, matter soluble in acid,
carbon, chloride process for tobacco waste and
phenol adsorption capacity, carbon tetrachloride activity,
Dolomite process for Pongamia carbon.
iron content were analyzed as per standard procedures.
Estimation of Na and K was done using Elico Model Iron content is almost uniform for all the five
Flame Photometer. BET surface area was measured at carbons. This level of iron content will not affect the
liquid N2 temperature using Quantachrome Analyzer. effluent water without the problem of iron leaching into
Table 1 — Activated carbon from Tobacco stem
Sl. No Properties HCl H2SO4 ZnCl2 Na2SO4 Na2CO3 CaCO3 CaCl2 H2SO4 + H2SO4 +
NH4S2O8 H2 O2
1 pH 6.71 5.50 6.20 8.63 8.15 9.03 7.19 7.80 6.98
2 Moisture content, % 9.2 10.2 26.8 11.8 11.8 4.4 19.2 10.8 8.8
3 Ash content, % 10.69 14.46 10.16 13.89 10.68 8.78 14.20 8.36 8.86
4 Volatile matter, % 12.20 9.30 9.81 14.40 11.40 16.80 14.90 11.20 10.50
5 Fixed carbon 74.6 73.5 59.8 73.1 68.8 75.2 68.8 81.0 83.1
6 Conductivity, ms/cm 0.23 0.20 0.41 0.19 0.42 0.31 0.26 0.59 0.92
7 Specific gravity, S 1.10 1.33 1.49 0.89 1.25 1.48 1.32 1.88 1.37
8 Bulk density, D 0.63 0.69 0.51 0.44 0.56 0.42 0.36 0.66 0.49
9 Porosity 24.55 33.08 72.48 50.56 39.20 64.86 65.15 54.26 42.34
10 Matter soluble in water, % 0.60 0.58 0.78 1.03 2.42 1.88 2.66 1.81 1.84
11 Matter soluble in acid, % 0.81 0.13 1.14 1.59 1.24 1.50 1.03 0.61 1.44
2
12 Surface area, m /g 385 351 1250 342 760 271 1204 858 723
13 Sodium, w/w % 1.1 5.1 8.0 5.0 6.1 8.0 12.0 1.5 6.0
14 Potassium, w/w % 4.1 5.1 8.6 6.7 3.6 4.1 3.0 4.0 1.0
15 Yield, % 40 50 46 32 31 60 47 50 65

3. JAMBULINGAM et al.: PROPERTIES OF ACTIVATED CARBONS FROM AGRICULTURAL WASTES 497
Table 2 — Activated carbon from Pongamia pinnata shell
Sl. No Properties HCl H2SO4 ZnCl2 Na2SO4 Na2 CO3 CaCO3 CaCl2 H2SO4 + H2SO4 +
H4 S2O8 H2O2
1 pH 6.42 5.02 6.54 9.60 8.22 9.11 8.25 7.18 6.05
2 Moisture content, % 5.2 7.4 10.8 5.6 9.6 9.0 7.2 6.4 5.6
3 Ash content, % 15.75 9.74 10.06 7.70 10.04 16.81 19.00 27.00 9.02
4 Volatile matter, % 8.8 10.2 15.8 13.6 11.5 17.6 8.0 9.1 6.8
5 Fixed carbon 87.5 82.1 73.4 76.6 85.2 70.4 81.6 81.0 84.6
6 Conductivity, ms/cm 0.35 0.66 0.13 0.61 0.49 0.14 0.66 0.10 0.81
7 Specific gravity, S 0.45 0.63 0.93 0.92 0.83 0.93 0.50 0.83 1.25
8 Bulk density, D 0.33 0.40 0.32 0.37 0.39 0.39 0.34 0.38 0.43
9 Porosity 40.00 51.81 49.21 59.78 53.01 58.06 32.00 54.22 65.60
10 Matter soluble in water, % 1.51 1.35 1.44 0.89 1.05 1.04 1.86 2.35 2.20
11 Matter soluble in acid, % 0.55 0.89 1.25 1.47 1.03 0.78 1.64 1.31 1.64
2
12 Surface area, m /g 289 514 219 722 602 746 228 322 455
13 Sodium, w/w % 8.2 1.3 6.0 13.0 18.0 1.0 1.2 3.0 8.5
14 Potassium, w/w % 1.2 1.4 1.9 3.7 1.3 1.3 9.0 1.8 6.0
15 Yield, % 49 65 51 39 41 50 42 56 55
Table 3 — Activated carbon from Ceiba pentandra shell
Sl. No Properties HCl H2SO4 ZnCl2 Na2SO4 Na2 CO3 CaCO3 CaCl2 H2SO4 + H2SO4 +
H4 S2O8 H2O2
1 pH 5.55 6.41 5.35 8.57 9.60 8.30 8.13 8.09 6.71
2 Moisture content, % 12.0 6.6 8.5 6.6 4.0 9.0 6.5 4.9 6.2
3 Ash content, % 10.04 11.64 10.96 15.09 7.42 7.02 17.12 14.67 12.83
4 Volatile matter, % 14.5 20.2 25.0 20.8 17.3 25.2 22.2 10.5 17.4
5 Fixed carbon 69.3 69.5 62.9 68.7 74.0 63.7 73.8 76.5 72.6
6 Conductivity, ms/cm 0.13 0.29 0.19 0.17 0.05 0.24 0.14 0.16 0.08
7 Specific gravity, S 1.17 0.97 0.98 0.96 1.20 1.19 1.07 0.92 1.02
8 Bulk density, D 0.43 0.37 0.30 0.34 0.53 0.30 0.43 0.38 0.41
9 Porosity 63.25 61.86 69.39 64.58 55.83 74.79 59.81 58.70 59.80
10 Matter soluble in water, % 0.85 0.51 0.87 0.43 1.00 1.68 0.55 0.25 0.85
11 Matter soluble in acid, % 0.63 0.48 0.43 0.45 0.62 1.80 0.68 0.45 0.85
12 Surface area, m2/g 1143 424 321 430 429 750 261 309 403
13 Sodium, w/w % 4.0 1.1 7.0 1.2 6.0 4.0 3.0 5.6 1.3
14 Potassium, w/w % 2.0 4.0 7.0 5.0 3.0 9.0 1.3 5.0 4.0
15 Yield, % 60 40 32 36 36 41 32 35 44

4. 498 J SCI IND RES VOL 66 JUNE 2007
Table 4 — Activated carbon from Scirpus acutus stem
Sl. No Properties HCl H2SO4 ZnCl2 Na2SO4 Na2CO3 CaCO3 CaCl2 H2SO4 + H2SO4 +
H4 S2O8 H2O2
1 pH 6.13 5.22 6.42 9.04 9.51 8.02 8.64 7.54 6.04
2 Moisture content, % 8.9 8.6 4.2 6.6 16.0 1.1 15.6 12.0 12.1
3 Ash content, % 4.15 12.87 19.38 17.28 13.89 10.89 10.79 26.70 12.11
4 Volatile matter, % 12.8 12.9 10.0 15.8 12.5 10.2 11.0 11.6 9.1
5 Fixed carbon 82.2 79.8 81.0 82.2 82.0 79.1 83.0 81.1 80.1
6 Conductivity, ms/cm 1.98 4.10 0.90 1.13 1.69 0.45 0.67 0.77 0.20
7 Specific gravity, S 1.31 1.05 0.66 0.83 0.63 0.43 0.62 1.05 0.91
8 Bulk density, D 0.46 0.75 0.36 0.35 0.42 0.28 0.32 0.70 0.48
9 Porosity 55.34 40.00 58.14 44.44 49.40 55.56 60.98 44.00 40.74
10 Matter soluble in water, % 0.89 0.41 0.69 1.15 1.34 0.96 0.52 1.06 0.62
11 Matter soluble in acid, % 0.80 0.40 0.65 1.55 1.57 1.43 0.65 1.32 1.77
2
12 Surface area, m /g 901 554 612 429 480 263 762 501 559
13 Sodium, w/w % 6.6 1.4 1.6 3.1 4.2 8.8 2.1 5.2 6.1
14 Potassium, w/w % 63 1.9 5.0 4.5 1.6 4.11 10.9 50 67
15 Yield, % 42 39 43 39 30 51 49 54 37
Table 5 — Activated carbon from Leucaena leucocephala seed shell
Sl. No Properties HCl H2SO4 ZnCl2 Na2SO4 Na2CO3 CaCO3 CaCl2 H2SO4 + H2SO4 +
H4 S2O8 H2O2
1 pH 6.74 6.67 6.96 8.10 9.05 9.50 7.86 6.95 7.25
2 Moisture content, % 10.9 12.0 15.0 10.9 15.0 10.4 18.2 10.6 10.9
3 Ash content, % 14.50 10.94 15.57 17.07 7.12 1.57 16.07 5.67 16.85
4 Volatile matter, % 20.00 26.70 27.50 31.20 30.00 24.20 27.80 31.30 34.20
5 Fixed carbon 73.80 73.50 59.80 73.10 69.00 72.10 69.70 81.00 84.30
6 Conductivity, ms/cm 0.13 0.20 0.69 0.33 0.22 0.17 0.14 0.29 0.49
7 Specific gravity, S 1.00 1.31 1.09 0.81 1.05 1.08 1.35 1.98 1.07
8 Bulk density, D 0.83 0.89 0.41 0.44 0.76 0.52 0.46 0.86 0.79
9 Porosity 24.55 33.08 72.48 50.56 39.20 64.86 65.15 54.26 42.34
10 Matter soluble in water, % 0.90 0.48 1.78 2.03 1.42 2.88 2.06 0.81 0.84
11 Matter soluble in acid, % 0.91 0.23 1.12 1.50 1.44 1.70 1.43 0.81 0.44
2
12 Surface area, m /g 278 341 1320 342 798 229 1204 888 713
13 Sodium, w/w % 2.2 5.8 8.4 7.4 6.4 4.0 5.0 15.5 10.0
14 Potassium, w/w % 13.1 7.9 7.6 10.7 7.0 6.6 2.9 9.0 8.0
15 Yield, % 45 51 40 31 42 52 39 50 65

5. JAMBULINGAM et al.: PROPERTIES OF ACTIVATED CARBONS FROM AGRICULTURAL WASTES 499
120 the high concentrations (40 mg /l & 60 mg/l), adsorbent
20 mg/L was able to remove 83.5 % of the dye molecules present
100 40 mg/L in the solution.
Dye removal, removal
60 mg/L
80
Percentage of dye %
Conclusions
60
Based on surface area, the following activated
40
carbons/processes are comparable with the commercially
available activated carbons: I) Tobacco stem / ZnCl2
20 process; ii) P. pinnata shell / Dolomite process; iii) C.
pentandra shell / HCl process; iv) Bulrush S. acutus stem
0
0 50 100 150 200 250
/ HCl process; and v) L. leucocephala shell / ZnCl2
Timemin
Time,
min
process. These carbons can be conveniently used for
textile effluents removal. In general, all these carbons
Fig. 1 — Influence of time on percentage of dye removal-
will be efficient for the adsorption of organics as seen
concentration variation
from adsorption of Rhodamine-B from its solution with
treated water. The level of Na and K content is high L. leucocephala shell.
only in the case of tobacco waste carbon. In general, Na
and K content are high in sulphate and chloride process References
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