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2016 - 201912020 - 20211
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Subject: Chemistry × Author: Manmeet Kaur × End date: 2022 × Type: Thesis ×
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    ThesisItemOpen Access
    Evaluation of synthesized ferrite nanocomposites with N-doped graphene and carbon microspheres for the removal of heavy metals and organic pollutants
    (Punjab Agricultural University, Ludhiana, 2021) Manmeet Kaur; Manpreet Kaur
    Magnetic ferrites and their nanocomposites with nitrogen doped graphene oxide (N-GO) and hollow mesoporous silica have received immense interest as adsorbents and photocatalysts for water decontamination. This work reports facile strategy for the synthesis and evaluation of N-GO, MFe2O4 NPs (M= Mg, Ca), MFe2O4-NGO (M= Mg, Ca) and hollow mesoporousnanocomposites for the removal of Pb(II), Ni(II), As(III), CR dye and PNP from contaminated water.NCs of NGO with MFe2O4 NPs were prepared using ultra sonication method. For dual core shell nanocomposite, hollow mesoporous SiO2 core was synthesized using polyethylene glycol (PEG) and cetyltrimethyl ammonium bromide (CTAB) as cotemplates. Synthesized SiO2 was used as template over which MgFe2O4 NPs were loaded using sodium dodecyl sulphate (SDS) as a surfactant to synthesize MgFe2O4@SiO2 core-shell nanocomposite. This nanocomposite was further loaded with N-GO in order to design NGO@MgFe2O4@SiO2 dual core nanocomposite by ultra sonication method. Structural, magnetic and surface properties of the nanocomposites were analyzed using various physicochemical techniques. The effectiveness of NPs and nanocomposites for the removal of Pb(II), Ni(II) and As(III) and photodegradation of CR and PNP was studied.MgFe2O4@SiO2 displayed maximum heavy metal removal whereas, NGO@MgFe2O4@SiO2 dual corenanocomposite exhibited maximum photocatalytic degradation for organic pollutants. The mechanism of adsorption and photocatalysis from spiked water was investigated by batch experiment studies.The adsorption data was best fitted into Langmuir adsorption isotherm and followed pseudo-second-order kinetic model.The degradation mechanism for CR and PNP was proposed on the basis of mass spectrometric analysis of products formed during photodegradation. Also, the comparative photocatalytic activity of spiked distilled water and contaminated water revealed reduction in photocatalysis of 17% and 22% in the contaminated water. The synthesis of NCs of MgFe2O4 NPs with doped carbon material and core-shell synthesis using SiO2 core provide new synthetic strategy for further modification of pristine ferrite NPs for future applications.
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    ThesisItemOpen Access
    Chemistry and biological activity of flavonoids from zest and pith of kinnow peel
    (Punjab Agricultural University Ludhiana, 2016) Manmeet Kaur; Uppal, S.K.
    Different extracts from zest (flavedo, orange part) and pith (albedo, white part) of kinnow peel were prepared by three extraction procedures i.e. conventional, ultrasonic assisted extraction and soxhlet extraction methods using different solvents (hexane, benzene, isopropylalcohol, ethylacetate and acetone). Soxhlet extraction method was found to be the best method giving maximum total phenolic and flavonoid content for kinnow zest extracts in isopropylalcohol solvent with values 40.41 mg gallic acid equivalent (GAE) g-1 dry weight (DW) and 6.07 mg quercetin equivalent (QE) g-1 DW, respectively whereas the values were found to be 37.34 mg GAE g-1 DW and 5.08 mg QE g-1 DW, respectively in kinnow pith extracts. The yields of hesperidin isolated from zest and pith of kinnow peel were found to be 0.6 and 1.4%, respectively. Whereas, yields of naringin were found to be 0.032 and 0.05% from zest and pith of kinnow peel, respectively. Aglycone forms, methylated and acetylated derivatives of isolated compounds were prepared which were identified by melting point, TLC, FT-IR and 1HNMR data. All zest and pith extracts, isolated compounds, their aglycone forms and derivatives were investigated for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity using 3,5-di-tert-butyl-4-hydroxytoluene (BHT) as a standard and antibacterial activity by disc plate method against Bacillus aryabhattai, Acinetobacter sp. and Klebsiella sp. using tetracycline as standard. Among all the extracts, isopropylalcohol extract showed highest antioxidant and antibacterial activities, whereas among different isolated and synthesized compounds, aglycone forms were found to be more effective than isolated compounds.