Synthesis and characterization of multi - component (Fe-Ni- Si) oxide surface and its application in removing organic dyes from water

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.