Magnetic Al2O3/ZrO2/Fe3O4 nanocomposite: Synthesis, characterization, and application for the adsorptive removal of nitrate from aqueous solution

Abstract

Excess amount of nitrate in water systems has a tremendous health effect on human beings and demands the proper mitigation approach. In response to this, in this report, a novel Al2O3–Fe3O4–ZrO2 (AlMZr) ternary nanocomposite was synthesized at metals mole percent ratio Al:Fe:Zr (25:70:05) by co-precipitation method under a nitrogen atmosphere. It was dried at 60°C and characterized using state-of-the-art instruments like XRD, FTIR, BET, and SEM-EDX. Elemental composition was determined by FAAS. The average crystallite size was obtained as 2.5 nm with the corresponding surface area 296.5 m2/g. Nitrate adsorption isotherms and D-R studies revealed that the adsorbent undergoes both physi- and chemisorption. From the kinetics study, the pseudo-second order model well fitted with the experimental data. The thermodynamic study revealed the favorability of nitrate adsorption at low temperatures. From desorption and regeneration studies it was also observed that desorption has been more favored by sonication than a shaker and the adsorbent showed fairly good regeneration. The order for the influence of co-existing ions on the tendency of nitrate removal was ClO4− > SO42− ≈ HCO3− > Cl− > F−. The present study suggests the ternary magnetic nanocomposite, Al2O3/Fe3O4/ZrO2, for the uptake of excess NO3− from aqueous systems with better recyclability.