Abstract:
In the present study, iron-nickel-silicon mixed oxide nano surface was
synthesized by sol-gel method. The nanoparticles thus obtained were
characterized by means of EDX, XRD and SEM techniques. Elemental analysis
exhibited the presence of iron, nickel, silicon and oxygen elements in the mixed
oxide with a composition of Fe0.78Ni0.76Si0.46O3. The results showed that the ironnickel-
silicon mixed oxide nanoparticles were successfully synthesized. The
average crystallite size was calculated from the XRD data to be approximately
18 nm. The specific surface area of this multi-component nano oxide was found
to be 78.30 m2g-1. The point zero charge of this surface was observed to be at
pH 9.80. The adsorption property of mixed oxide for removal of organic cationic
(Methylene Blue abbreviated as MB) and anionic (Orange Green abbreviated as
OG) dyes were assessed with various parameters including effect of pH, contact
time, initial dye concentration, temperature and dose of mixed oxide. The
adsorbent was tested for removal of dyes from synthetic solution. The maximum
adsorption capacity of nano mixed (Fe-Ni-Si) oxide for both MB and OG dyes at
pH 7. Kinetic study showed that both MB and OG followed pseudo-second-order
kinetics equation with the constant 30.09×10-2 gmol-1min-1 for MB and 8.0 ×10-2
gmol-1min-1 for OG at room temperature. The free energy, ΔG°, was negative
which proves that the adsorption was spontaneous. The enthalpy change, ΔH°
was positive for MB and negative for OG which indicates that adsorption
processes were endothermic and exothermic in nature, respectively. Adsorption
isotherm was interpreted by Langmuir equation from the obtained data and
maximum adsorption capacity of oxide monolayer for MB dye was 30.09×10-4
molg-1. With the increase of adsorbent dose the percentage of dye removal was
increased but amount adsorbed of dyes per gram adsorbent was decreased.
The catalytic property was examined by photodegradation of MB and OG.
