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Among many environmental pollutants, dyes releasing from industries play a
m ajor role in contaminating the aquatic environment. Most of the dyes are non
biodegradable, stable and carcinogenic due to their synthetic nature and
aromatic structure. Therefore it is necessary to reduce the pollution load
including decolourization of industrial effluents before disposal. Though the
adsorption on to commercial activated carbon is a promising method, it is
expensive. The present study was carried out to investigate the possibility of
using a low cost adsorbent for the removal of carcinogenic dye, Rhodamine B in
a more effective manner.
Three different forms of sawdust, formaldehyde treated sawdust (SD), base
treated sawdust (BTSD) and acid activated charred sawdust (AASD) were
prepared and used for the removal of Rhodamine B from an aqueous solution.
Batch experiments were carried out to investigate the potential efficiency of the
three forms of sawdust to remove Rhodamine B from the aqueous solution as a
function of the initial Rhodamine B concentration, Contact time and
tem perature. Equilibrium was found to be attained at about 30 min, 50 min and
60 min respectively for SD, BTSD and AASD. Based on Langmuir isotherms, the
maximum adsorption capacity was found to be 319.5 mgg-1 at 6 0 °C for AASD
among three different forms of sawdust.
Various isotherms and kinetic models were fitted to describe the adsorption
process and the activation parameters were evaluated in all three types of
sawdust. Kinetic data of all three types of sawdust were well fitted for the
second order rate model. Based on Langmuir, Frendlich and D-R isotherms, a
better adsorption capacity was obtained for the AASD adsorbent compared to
SD and BTSD. Thermodynamic parameters suggest that the adsorption of
Rhodamine B onto all three type of adsorbent is spontaneous and the process
is physisorption. SEM images revealed that AASD has more porous and
irregularities in the surface which makes it a better adsorbent. IR spectral data
reveal the disappearance of many functional groups in AASD adsorbent
compared to SD and BTSD.
