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Keywords: Natural Sciences
Chemistry & allied sciences
Issue Date: 2017
Abstract: This study was designed to synthesize AgO, SnO2 and TiO2 nanoparticles via both green and chemical methods (precipitation and sol-gel methods). The Daphne alpina leaves extract was used as reducing agent in the green process, while comparatively less toxic reducing agents (C4H11NO for C-AgO, C3H8O for C-SnO2 and ETOH for C-TiO2) were used in the chemical methods. After successful synthesis, the physiochemical properties of the nanoparticles were traced by BET surface area measurement by N2 adsorption-desorption method, X-ray diffraction (XRD), energy dispersive X-rays (EDX) spectroscopy, scanning electron microscopy (SEM), thermogravimetric and differential thermogravimetric (TG/DTG) analysis, diffuse reflectance spectroscopy (DRS) and fourier transform infrared (FTIR) spectroscopy. These analytical techniques further confirmed the successful synthesis of all the desired nanoparticles. XRD confirmed the mixed geometrical phase (cubic and hexagonal) of silver oxides nanoparticles. Both the tin dioxide (G-SnO2 and C-SnO2 NPs) nanoparticles have cassiterite mineral phase with tetragonal geometry while the titanium dioxide nanoparticles (G-TiO2 and C-TiO2 NPs) have anatase mineral phase with tetragonal geometry. The nanoparticles synthesized by green method have high surface area as compared to their analog prepared by chemical methods. The SnO2 and TiO2 nanoparticles synthesized by green (G-SnO2 and G-TiO2 NPs) and chemical (C-SnO2 and C-TiO2 NPs) methods were used as adsorbent for the adsorption of cadmium ions (Cd2+). The Batch method was applied for the Cd2+ ions adsorption process at pH 4 and 6, while temperature was ranging from 293 to 323 K. The NaNO3 was used as xx background electrolyte while the Cd2+ ions concentrations were ranging between 10-100 ppm. The equilibrium concentration of Cd2+ ions was measured by atomic absorption spectrometer (AAS). The Langmuir model was applied to determine the maximum sorption capacity (Xm) and binding energy constant (Kb). A set of equations were used to determine Cd2+ sorption mechanism and also calculated the changes in enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG). The effect of temperature was more pronounced on Kb values as compared to Xm values, the increase in Kb values with temperature suggest that the adsorption process was thermodynamically favored. The decrease in the ΔG with increase in pH and temperature proposed that the adsorption process was more spontaneous at high pH and temperature. All the synthesized metal oxides (MO NPs) nanoparticles by green (G-AgO, G-SnO2 and G-TiO2 NPs) and chemical method (C-AgO, C-SnO2 and C-TiO2 NPs) were used a photocatalysts for the degradation of rhodamine 6G. The degradation rate constant was calculated by applying pseudo first order reaction. Both titanium dioxide (G-TiO2 and C- TiO2 NPs) have high photocatalytic activity compared to tin dioxide (G-SnO2 and C- SnO2 NPs) and silver oxide (G-AgO and C-AgO NPs). The AgO and SnO2 NPs fabricated by using both the green and chemical methods were functionalized with moxifloxacin using sonochemical method. Both the pure and moxifloxacin functionalized nanoparticles were screened against the selected microbial strains. The Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger are the selected microorganisms used during xxi antimicrobial study. The both silver oxide synthesized by green and chemical methods and its moxifloxacin functionalized analog have high antimicrobial activity as compared to tin dioxide (G-SnO2 and C-SnO2 NPs) and its functionalized analog (MG-SnO2 and MC-SnO2 NPs). The moxifloxacin functionalized have positive effect on the antimicrobial activity of both silver oxides (G-AgO and C-AgO NPs) and in dioxide nanoparticles (G-SnO2 and C-SnO2 NPs).
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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