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Author: Grewal, Jaspreet Kaur × End date: 2022 × Start date: 2020 × Type: Thesis ×
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    Evaluation of doped strontium ferrite nanoparticles functionalized with silica, carbon quantum dots and Cl-doped graphene for the removal of contaminants
    (Punjab Agricultural University, 2022) Grewal, Jaspreet Kaur; Manpreet Kaur
    Doped spinel ferrites and their functionalized nanocomposites with silica (SiO2), carbon quantum dots (CQDs) and chlorine doped graphene oxide (Cl-GO) have attracted immense interest as adsorbents and photocatalysts for water remediation. This work reports the facile strategy for the synthesis and evaluation of Sr1-xTixFe2O4+δ, SiO2, CQDs, Cl-GO and their functionalized nanocomposites for the removal of Cd(II), As(III), p-nitrophenol, pendimethalin and martius yellow from contaminated water. The structural, magnetic, adsorptive and photocatalytic properties were comprehensively studied using different analytical techniques viz. XRD, XPS, FTIR, BET, VSM, TEM, SEM-EDS and 57Mӧssbauer spectroscopy. TEM micrographs revealed the decreased extent of agglomeration in Sr0.4Ti0.6Fe2O4.6 and Sr0.7Ti0.3Fe2O4.3 due to the introduction of non-magnetic Ti4+ ions. TEM image of Sr0.4Ti0.6Fe2O4.6-Cl-GO NC displayed wrinkled nanosheets of Cl-GO containing ferrite NPs with particle size of 25-30 nm distributed over their surface. The fabrication of core-shell nanostructures with SiO2 was clearly visible from their TEM micrographs. The trend for the percentage removal of heavy metals by adsorption and degradation of organic contaminants by photocatalysis in the descending order was found to be: Sr0.4Ti0.6Fe2O4.6-Cl-GO > Sr0.4Ti0.6Fe2O4.6-CQDs > Sr0.4Ti0.6Fe2O4.6@SiO2 > SiO2@Sr0.4Ti0.6Fe2O4.6 > Sr0.4Ti0.6Fe2O4.6. The increased adsorption potential of functionalized nanocomposites as compared to pristine NPs was attributed to the increased surface area, functional moieties, and decreased particle size. The higher photocatalytic efficiency of Sr0.4Ti0.6Fe2O4.6-Cl-GO nanocomposite could be ascribed to the fast charge transfer, stabilization and hindered recombination of electron-hole pairs at the interface of Cl-GO and Sr0.4Ti0.6Fe2O4.6 NPs. Box-Behnken Design (BBD) of response surface methodology was utilized for exploring the simultaneous effects of independent variables on the removal of heavy metal ions and organic pollutants using Sr0.4Ti0.6Fe2O4.6-Cl-GO nanocomposite. The best adsorbent and photocatalyst were also tested for spiked solution containing different metal ions and real life water matrices.