Abstract:
This research was designed to ascertain the removal efficiency of Cd2+ and
Pb2+ ion from aqueous solution using capped chromic oxide nanoparticle
(CCONP) synthesized by method of co-precipitation and thermal
degradation of chromic hydroxide (Cr(OH)3), stabilized and capped using
polyvinyl alcohol (PVA). The physicochemical characterization of the
synthesized CCONP was evaluated using x-ray diffractograms (XRD),
scanning electron microscope (SEM) and Fourier Transform infrared
spectrophotometer (FTIR). The CCONP obtained was more of crystalline
than amorphous with very small particles inapparently soft agglomerates
with a size of 7.7 nm. The amount of Cd2+ and Pb2+ ions before and after
treatment of the aqueous solution was evaluated using atomic absorption
spectrometer (AAS). Adsorption experiments were conducted in batches and
the adsorption property of CCONP was studied using adsorption isotherm
models and optimized using response surface methodology (RSM) Analysis.
The adsorption isotherm models revealed that the adsorption process of Cd2+
and Pb2+ ions onto CCONP was a physical process, favorable and
exothermic. The energy of affinity for Pb2+ ions on CCONP was higher. The
adsorption process for Cd2+ ions on CCONP was spontaneous and the
adsorption capacity of CCONP for Pb2+ ions was higher. However,
optimisation analysis revealed that the cadmium ions were slightly more
adsorbed on CCONP and removed from the aqueous solution compared to
lead ions. This observation was in agreement with the Kf values obtained
from Freundlich isotherm in which the Kf value for cadmium ions (59.52)
was higher than that of lead (51.99).
