Evaluation of Adsorption Potential of Novel Perovskite Lanthanum Ferrite/Graphene Oxide (LaFeO3-GO) Hybrids for Phosphate Removal from Water

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

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had excellent sorption capability, high selectivity, and stability towards PO4 -3 ions, thus

presenting sustainable solution in improving water quality.