Adsorption Properties Of Natural Coal Adsorbents
Adsorption properties of natural coal adsorbents
V.V. Brutko
Institute of Colloid Chemistry and Chemistry of Water, Ukrainian National Academy of Sciences, Vernadsky avenue 42, 03680 Kyiv, Ukraine
The preparation and study of efficient and cheap adsorbents which can be applied for the cleaning of natural and waste waters from various contaminants are currently the important problem related to environmental protection. In this context, natural coal adsorbents (natural porous coal, natural graphite and the thermoexfoliated (bloated) graphite, TEG), being quite cheap, are promising for the application in the water cleaning processes.
The low-temperature adsorption of nitrogen, water and hexane at 20ºC at these adsorbents was studied. From the obtained data the structural-sorption characteristics of the sorbents were estimated (Table).
Table.Specific area (S), arbitrary monolayer capacity (am) with respect to hexane, nitrogen and water, effective pore radius (ref) of carbon adsorbents
Sorbent
am, mmol/g
S, m2/g
ref, nm
n‑C6H14
H2O
n‑C6H14
N2
H2O
Natural Porous Coal
0.10
1.960
3.0
5.0
127.5
1.8−3.0
r(N2)=2.7
Natural Graphite (Zavalie)
0.01
0.084
3.0
2.0
4.0
−
r(N2)=8.0
Thermoexfoliated Graphite
0.05
0.096
15.0
24.1
5.2
1.7−2.3
r(N2)=6.2
From the structural-sorption analysis it can be concluded that the sorbents possess mesoporous structure with gap-like pores.
To estimate the applicability of the studied adsorbents for the cleaning of water, the adsorption of anionic surfactant (Na-dodecyl benzene sulphonate − sulphonol), anionic dye (vermilion direct) and cationic dye (crystal violet) from water solutions at the chosen adsorbents were studied.
It was shown that the amount of the sulphonol, kationic and anionic dye adsorbed at TEG is a¥=31.0; 22.0; 10.0mg/g, respectively. This is by one decimal order of magnitude higher than the adsorption capacity of natural porous coal and natural graphite with respect to the same substances. It can be therefore concluded that TEG is the most promising of the materials with respect to its application in water cleaning.
Related articles::