TITLE:
Adsorption of Natural Aluminium Dye Complex from Silk-Dyeing Effluent Using Eucalyptus Wood Activated Carbon
AUTHORS:
Saowanee Chuyingsakuntip, Chaiyot Tangsathitkulchai
KEYWORDS:
Adsorption; Activated Carbon; Dyeing Effluent; Eucalyptus Wood
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.4 No.8,
August
2,
2013
ABSTRACT: Two activated carbons with
controlled pore size were prepared from Eucalyptus wood by physical activation
with carbon dioxide, giving the BET surface area and pore volume of738 m2/g and0.39 cm3/g, and921 m2/g and0.53 cm3/g for the carbon sample
AC1 and AC2, respectively. These activated carbons were then used to remove the
residual dye left after the silk-dyeing process. The dye solution used for
adsorption study was a cationic aluminium dye complex of [Al(brazilein)2]+ derived from a
mixture of alum and extract of the heartwood of Ceasalpinia sappan Linn.,
with initial dye concentration of 220 mg/l. Effects of adsorbent dosage,
adsorption time and temperature in the range of 25℃40℃ on dye
adsorption were investigated. It was found that the adsorption kinetics of this
dye complex was best described by the pseudo-second order model.
Adsorption isotherms of this dye complex were well fitted by Langmuir isotherm
equation. The adsorption capacities for the uptake of this dye complex
at 25℃, 30℃ and 40℃ were 718.7, 1240.4 and 1139.5 mg/g and 1010.5, 1586.1
and 1659.0 mg/g for carbon sample AC1 and AC2, respectively. From these
results, it can be concluded that activated carbon containing a higher
proportion of mesopores gave better dye removal efficiency,
emphasizing the fact that a proper pore size distribution of carbon adsorbent
is crucial for the effecttive removal of relatively large size of the
dye molecules. Thermodynamic parameters, including free energy, enthalpy and
entropy of adsorption, were also determined. The adsorption enthalpies for
the removal of this dye complex of AC1 and AC2 were 105.3 and 55.6 kJ/mol,
respectively, indicating that the adsorption is an endothermic process. It was
found that the adsorption of this dye complex is spontaneous at the
temperatures under investigation.