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Adsorption of arsenic(V) from aqueous solutions by goethite/silica nanocomposite
Attinti, R.; Sarkar, D.; Barrett, K. R. & Datta, R.
Abstract
Silica nanoparticles were synthesized and
coated with goethite, creating a nanocomposite. The
nanocomposite was tested for removal of arsenic, As(V),
from aqueous solutions. We used scanning electron
microscopy (SEM), Fourier transform infrared spectrometry,
and a Zetasizer to characterize particle size, surface
morphology, functional groups, and surface charge of the
nanocomposite. SEM results showed that the size of the
synthesized silica nanoparticles ranged from 150 to
250 nm. Batch sorption studies were carried out on the
adsorption of As(V) as a function of pH, contact time,
initial concentration, and ionic strength. Maximum
adsorption occurred at pH 3.0. The adsorption capacity did
not change significantly with increasing ionic strength. A
kinetics study revealed that adsorption of As(V) by the
goethite/silica nanocomposite was rapid: Equilibrium was
reached within 120 min. Adsorption kinetics followed a
pseudo-second-order kinetic model. The adsorption data
were analyzed by both the Langmuir and Freundlich isotherm
models. The maximum adsorption capacity of goethite/
silica nanocomposite for As(V) from the Langmuir
isotherm was 17.64 mg g-1, which is larger than that of
several other adsorbents. The nanocomposite adsorbent
showed high efficiency in removing arsenic from aqueous
solutions, even at low initial concentrations.
Keywords
Isotherms; Kinetics; Nanomaterials; Water treatment
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