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Many of the dyes are carcinogenic in
nature and their existence in the aquatic system prevents normal
biochemical reactions occurring in living systems creating a major
problem for the environment. Dyes impart color, which is
esthetically unacceptable, and reduces sunlight penetration into
natural water. Among the techniques for the removal of dyes from
water, adsorption on a suitable adsorbent is a low cost and
environment friendly process. In the present study, water spiked
with the common dye, methylene blue, has been interacted with Saraca
asoca leaf powder (SALP), a low cost, locally available biomaterial
as an adsorbent. The batch adsorption process was carried out with
pH, initial concentration of dye, adsorbent loading, and temperature
as the variables. The adsorbent material was characterized with
scanning electron microscopy, energy dispersive X-ray,
Fouriertransform infrared, CHNS, zeta potential, thermogravimetric
analyzer, atomic absorption spectrophotometer measurements and a
number of physical parameters such as bulk density, and moisture
content were also determined. Adsorption kinetics was tested with
Lagergren pseudo-first order, Ho’s pseudo-second order, and
intra-particle diffusion models. Validity of Langmuir, Freundlich,
and Temkin isotherm models were tested with the adsorption
equilibrium data to work out the adsorption capacities. The batch
adsorption under appropriate conditions can remove the dye from
water from 82 to 96%. Langmuir adsorption capacity had the values of
30–125 mg g−1. These results along with the thermodynamic
measurements indicated SALP to be a promising adsorption for removal
of the dye, methylene blue from water. |
