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2016 - 201922020 - 20221
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Subject: Chemistry × Author: Manpreet Kaur × Start date: 2010 × Type: Thesis ×
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    Synthesis of boron and phosphorous doped graphene fabricated with magnesium ferrite – bentonite nanocomposite for the remediation of pollutants
    (Punjab Agricultural University, 2022) Manpreet Kaur; Manpreet Kaur
    Graphene oxide (GO) doped with heteroatoms are gaining interest in depollution of water because of their large surface area. The boron-doped GO (B-GO), phosphorous-doped GO (P-GO) and boron and phosphorous co-doped GO (BPGO) in different w:w ratios were synthesized and fully characterized using analytical techniques viz. FT-IR, XRD, SEM-EDS, TEM, BET, Mössbauer and XPS. In order to impart magnetic features to doped GO materials, magnesium ferrite-bentonite (MGF-B) was used to fabricate nanocomposite of MGF-B and BPGO having hierarchical nanoflowers like morphology (HNFs). TEM of co-doped GO showed more wrinkled surface than doped GO, whereas in case of HNFs, chiffon-like BPGO nanosheets were wrapped on the MGF-B surface, resulting in a porous flower-like morphology. The synthesized materials were explored as adsorbents for the removal of Pb(II) and As(III) ions and as photocatalysts for the degradation of martius yellow, p-nitrophenol and malathion from synthetic waste water. The trend for the percentage removal of heavy metals by adsorption and degradation of organic pollutants by photocatalysis in the descending order was found to be: HNFs > BPGO-1:1 > BPGO-1:5 > BPGO-1:0.2 > MGF-B > P-GO > B-GO > GO. The adsorptive and photocatalytic potential of HNFs was greater as compared to pristine, doped and codoped GO due to high surface area, remarkable charge transfer ability and layered structure of codoped GO sheets. The HNFs possessed appreciable saturation magnetization than doped and co-doped GO layers, which led to its easy separation and reusability. Box-Behnken design was utilized for exploring the simultaneous effects of the independent variables on removal of metal ions and degradation of organic pollutants (as dependent variable) using HNFs. The adsorption and photocatalytic mechanism was proposed on the basis of adsorption isotherm, thermodynamic, kinetic and quenching studies. Enhanced activity of HNFs with adsorption of heavy metal could be defined by the electronic structural properties of elements. The best adsorbent and photocatalyst were also tested for spiked solution containing different metal ions and real life industrial water matrices.
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    ThesisItemOpen Access
    Synthesis and antifungal activity of Mannich bases and their transition metal complexes
    (Punjab Agricultural University, Ludhiana, 2016) Manpreet Kaur; Manpreet Kaur
    In the present work Mannich base ligands and their transition metal complexes with Cr(III), Fe(III), Zn(II), Cu(II), Co(II) and Ni(II) salts were synthesized by ultrasonicator and conventional technique respectively. The crude products were purified by successive washings with ethanol and characterized on the basis of physical measurements and spectral studies. The antifungal activity of the synthesized compounds was screened in vitro against Bipolaris oryzae and Fusarium verticilloides using spore germination inhibition method in comparison with Propiconazole 25 EC taken as a standard to reveal the potency of the synthesized compounds. All the synthesized compounds possessed moderate antifungal potential. Most of the compounds have ED50 values significantly higher as compared to Propiconazole 25 EC. The observed trend for antifungal activity was: Mannich base ligands< Transition metal complexes< Propiconazole 25 EC. The increased activity of metal complexes can be attributed to enhanced lipophilicity on chelation.
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    Nickel adsorption studies on synthesized graphene oxide and magnetic graphene oxide
    (Punjab Agricultural University Ludhiana, 2016) Manpreet Kaur; Manpreet Kaur
    Adsorptive properties of magnetic graphene oxide (MGO) nanocomposite are investigated for facile removal of Ni (II) ions from water. Graphene oxide (GO), magnetic oxide nanoparticles (MO NPs) and magnetic graphene oxide (MGO) were characterized by X-ray diffractiion pattern (XRD), 57Fe Mössbauer spectroscopy, Vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and FT-IR spectroscopy as analytical tools. TEM images of MGO reveal uniform spherical homogenous distribution of MO NPs with agglomeration over the graphene nanosheet. Mössbauer analysis shows significant ferric oxide phase along with super paramagnetic maghemite and goethite phase. A comparative analysis of the GO, MO NPs and MGO for the removal of Ni (II) ions from synthetic waste water was carried out by batch method and Ni (II) content was estimated spectrophotometrically. The effect of operating parameters including adsorbent dose, temperature, contact time, pH, initial metal ion concentration of Ni (II) were studied. Optimum pH for adsorption was 10. Values of ∆Go, ∆H˚ and ∆S˚ were found to be negative for all adsorbents, indicating spontaneous and exothermic nature of adsorption process. NPs showed small variation in the percentage removal. The trend for the percentage removal of Ni (II) in the descending order was MGO > MO NPs > GO. Langmuir and Freundlich isotherms fit the data better than D-R isotherms. The advantage of MGO is enhancement of adsorption potential due to presence of MO NPs along with GO, their magnetic separation after adsorption and solubility problem of GO is overcome.