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Theses

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2018 - 201912020 - 20221
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Subject: Chemistry × Author: Joshi, Pragati × Type: Thesis ×
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    ThesisItemOpen Access
    Characterization of nanoferrogels for electroanalysis of control release Simazine
    (G. B. Pant University of Agriculture and Technology, Pantnagar, 2022-05) Joshi, Pragati; Zaidi, M.G.H.
    Present thesis demonstrates supercritical synthesis of nanoferrogels (NFGs) derived control release formulations (CRFs) of simazine (SZ). CRFs were synthesizedthrough free radical polymerization of selected acrylamide derivatives in presence of bisacrylamide in supercritical carbon dioxide (SCC). Ferrite nanoparticles with crystallite size (10.5 nm) were synthesized through chemical methods and employed for synthesis of NFGs. Thesis further demonstrates the development of working electrodes (WEs) from supercritically synthesized polypyrolle/ graphene oxide (PPY/GO) nanocomposites for detection and quantification of SZ released from CRFs. All polymerization reactions leading to synthesis of CRFs were conducted at common temperature, pressure and time. Square wave voltammetry (SWV) has been employed as a novel and viable alternative to spectral and chromatographic methods for monitoring of SZ release from CRFs. Formation of all synthesized products were ascertained through diverse analytical methods. SWV was conducted over triple electrode assembly constituting Ag/AgCl as reference, platinum foil of 1cm2 area as counter electrode coupled with WEs in KCl (0.1M, pH3.5). WEs has rendered limits of detection (Molar): 2.92 × 10-10 and quantification: 9.03 × 10-10 of SZ in KCl (0.1 M, pH 3.5). Cyclic voltammetry reveals enhanced electrochemical response of WEs towards release of SZ from NFGs over HGLs based CRFs. Potential of NFGs towards SZ release was compared with analogous HGLs derived CRFs under identical electrochemical conditions over 6h. SWV reveals 60-80% release of SZ from HGLs derived CRFs. Whereas, NFGs derived CRFs has rendered remarkable slow release of SZ by 45-55%. Developed CRFs may find their future applications in conditioning of drought affected agricultural fields along with simultaneous control release of herbicides through supercritically produced CRFs for future sustainable agriculture. Moreover, high thermal stability of synthesized materials may improve their shelf life in thermally activated soil media.
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    ThesisItemOpen Access
    Development of electrochemical sensors for chlorpyrifos detection
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-06) Joshi, Pragati; Mehtab, Sameena
    CHL is an OP insecticide and known to generate toxic effects by inhibiting the AChE activity. The overuse or misuse of CHL is contributing adversely to the health of living organisms and also disturb ecosystem, hence it is very important issue to detect low level amount of CHL. In the present investigations, we developed simple, selective and sensitive technique for a CHL monitoring. PIN/WC/SSPE EC sensor was designed by different proportions of PIN/WC on SSPE and characterized using SEM, CV, SWV and EIS. A well defined peak was obtained for the oxidation and reduction of CHL in CV. The LOD obtained by SWV for bare, 5% PIN/WC/SSPE and 30% PIN/WC/SSPE were 4.8 × 10-8 M, 5.94 × 10-8 M and 4.49 × 10-8 M respectively. LOQ for bare, 5% PIN/WC/SSPE and 30% PIN/WC/SSPE were 14.5×10-8 M, 18 × 10-8 M and 13.6 × 10-8 M respectively. EC investigation shows peak current was linearly related to the concentration of CHL, thus increasing detection sensitivity of proposed sensor. This could be achieved due to the synergistic blend of WC in PIN matrix having high electrical conductivity, fast electron transfer, large surface area and good absorption of NC on to the SSPE. The future prospects of developed EC sensor involves trace level CHL detection in biological and environmental samples.