Abstract:
The release of excessive phosphate (PO4
-3
) into freshwater reservoirs may cause serious
environmental concerns including eutrophication and water quality deterioration. In lieu,
novel perovskite lanthanum ferrite/graphene oxide (LaFeO3-GO) hybrids were synthesized
to evaluate its PO4
-3
sorption performance from water. Current study also compares
viability of bimetallic LaFeO3-GO hybrids with lanthanum/graphene oxide (La-GO) and
iron/graphene oxide (Fe-GO) composites under a series of systematically designed sorption
experiments. The superior sorption capacity of (103.11 mg/g) LaFeO3-GO for PO4
-3 was
observed as compared to (83.67 mg/g) La-GO and (84.22 mg/g) Fe-GO, which was
attributed to its highly amorphous characteristics, stable structure, and larger specific
surface area. Moreover, the PO4
-3
sorption data of GO composites were well fitted with
Pseudo second order and Freundlich model. Thermodynamic studies indicated that PO4
-3
uptake using GO composites is spontaneous (-ΔG) and endothermic (+ΔH) in nature. The
interfering ions investigations revealed the selective PO4
-3
uptake by GO composites from
water. Moreover, the reusability potential of LaFeO3-GO hybrids up to fifth cycle for PO4
-
3
uptake was observed to be 48.50 %. In accordance, the dominant role of charge
neutralization, multilayered physio-chemisorption, and complexation reactions between
bimetallic LaFeO3-GO and PO4
-3
ions were evidenced, as revealed by X-ray diffraction
(XRD) and Fourier transform infrared spectroscopy (FT-IR). In comparison, La-GO and
Fe-GO also indicated involvement of ligand exchange and reduction pathways during PO4
-
3 sorption process. Overall, these findings suggested that perovskite LaFeO3-GO hybrids
xvi
had excellent sorption capability, high selectivity, and stability towards PO4
-3
ions, thus
presenting sustainable solution in improving water quality.
