An Analysis Of TGA Analysis: Thermal Gravimetric Analysis

Good Essays
3.1.3. TGA analysis
Thermal gravimetric analyses (TGA) were recorded under N2 atmosphere over the temperature range of 25- 800 oC at a heating rate of 15 oC/min, to evaluate both the composition and the thermal stability of f-silica and AgNPs/f-silica. As shown in Fig. 1D the mass loss noticed between 25 oC and 180 oC represents the physically adsorbed water. Adsorbed water accounted 7.4%, 6.43% and 2.2% for f-silica, AgNPs/f-silica sample using [Ag+] = 0.005 M, and AgNPs/f-silica sample using [Ag+] = 0.05 M, respectively. The decrease in the amount of physically adsorbed water can be attributed to the increasing amount of AgNPs anchoring on the functionalized silica surface, which due to the increase of the precursor [Ag+]. The second weight
…show more content…
The effects of contact time, IC concentration, and temperature on adsorption were investigated. The adsorption kinetic was determined by analyzing adsorption capacity of the aqueous solution at different time intervals.

4. 1. Variation of AgNPs/functionalized silica composition
The proficiency of AgNPs/ f-silica samples for the adsorptive elimination of IC from aqueous solutions has been assessed with respect to several synthesis factors. These factors are [Ag], [Nigella seed], and the reflux time. The synthesis conditions, the abbreviation symbol and the IC removal efficiency of each sample are listed in Table 1.

4. 1. 1. Effect of [Ag]
The effect of AgNPs/f-silica samples prepared at various AgNO3 concentrations on the adsorption rate of the IC was examined (Fig. 4A and Table 1). The adsorption efficiency reached a maximum at ca 0.03 M (sample S3) and after that, it decreases. This was probably as a result of the increase in the formation of larger particles of AgNPs as the [Ag] increased (Sinha et al., 2015; Venkatesham et al., 2014). Our findings appear to be well supported by the increase in the [Ag], results in an increase in the density of nuclei that leads to high collision possibility between nuclei. Hence, the growth rate of AgNPs is enhanced and therefore an increase of particle size is obtained. It is reasonable to state that the binding of the dye molecules to the AgNPs/f-silica depends on the surface area available for interaction. Smaller particles having the larger surface area accessible for interaction will give more adsorption productivity than the larger particles and

Related Documents

  • Decent Essays

    The coagulant addition significantly affect the settling time. At the initial stage, a fast and steady reduction in height of the flocs-supernatant interface with time was seen for both FC and alum coagulants; this phenomena is called the regime of zone settling. Thereafter, the height of the flocs-supernatant interface reduce slowly with time approaching steady state (transition settling), finally a position called compression settling of slurry is achieved. The increase in flocs size prefers the flocs settling speed and hence diminishes the settling time of the flocs generated. The flocs formed by alum settle faster than the flocs formed by…

    • 805 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    Al, Alloy 1 And Elece

    • 1504 Words
    • 7 Pages

    Fig. 2 and Table 1 present the open circuit potential versus time curves and self-corrosion rate of Al, Alloy 1 and Alloy 2 electrodes in 2 M NaCl electrolyte, respectively. Corrosion rates were obtained by weight loss measurements in 2 M NaCl solution after 60 min. As seen in Table 1, the corrosion rate increases in the following order: Al <Alloy 1 < Alloy 2. Fig.…

    • 1504 Words
    • 7 Pages
    Decent Essays
  • Decent Essays

    Methyl Red Lab Report

    • 1181 Words
    • 5 Pages

    Fig. 4.3 shows the obtained results. The figure indicates that, for MR, the adsorption is strong in acidic medium. As the pH increase, the adsorption capacity for nZVI decreases. For MR, the adsorption is high in acidic medium and increases with the increase in solution pH.…

    • 1181 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    From fig. 1 and 4, it is clear that the resistivity decreases with increasing temperature ensuring the semiconducting nature of the prepared spinel ferrites [20]. This could be ascribed to the increase in the drift mobility of electric charge carriers that are thermally activated on increasing the temperature. Fig.1. Variation of Electrical Resistivity (ρ) of CoCrxFe2-xO4 (x=0.0 to 1.0) with temperature…

    • 1962 Words
    • 8 Pages
    Decent Essays
  • Decent Essays

    This can be due to energy released after the adsorption process being higher than that need to the solvent molecules. The negative value of enthalpy indicates that the process is exothermic and the physisorption behavior may be physical in nature and it can be easily reversed by supplying the heat equal to the adsorption system. The positive value of entropy significantly suggests that the random orientation in solute-solvent complex or interface between solid/solution during the adsorption. When ΔS is positive, increased spontaneity is favoured in the molecular movement. The negative value of enthalpy and positive value of entropy signifies that molecular dipoles are spontaneously and allinged oriented at all…

    • 793 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    The instability starts near the interface and causes a sinuous movement to the interface. At higher temperature gradients, the instabilities increase and the movement becomes continuous. When temperature gradients are a sinuous wave was observed [26]. Also, when the concentration at the interface is less than the concentration at the slot the surface tension at the free surface accordingly reduces. This implies that the surface tension is inversely proportional…

    • 899 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    Cumnox Reaction Lab Report

    • 1018 Words
    • 5 Pages

    4. The optimization in calcination temperature of CuMnOx (CuMn8) precursor The optimum calcination temperature of the CuMnOx catalyst was 300oC and further increasing the calcination temperature the activity of the catalyst was decreases. There was a correlation between the surface area and the calcination temperature of the catalyst. When the calcination temperature of the CuMnOx catalyst was increased above 300oC, the surface area was decreases and its analysis by BET measurement. The crystallinity was also increased as the increasing of the calcination temperature of the precursor, therefore the diffraction peaks at the XRD analysis was more crystalline phases produced by calcination at (200 - 400oC) temperature.…

    • 1018 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    Table 3 shows the BET surface area of both the fresh and hydrothermally aged SCR catalysts. For fresh BEA zeolite and SCR catalysts, as the doping amount of catalytic additive increases, the BET surface area decreases, probably because the additive Cu, Ce, and Nb species blocked some of the zeolite channel, hindering the entry of N2 into the pores (Bin et al. 2014). After aging at 600 °C, all the samples showed 3-20 m2/g increased BET surface area. Aging condition of 600 °C is a relatively mild aging temperature, which can enhance the catalytic activity compared to that of the fresh one (Briot et al.…

    • 1164 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    3 (a) and (b), HAc recovery mostly depends on EA or MA flow rate in the solvent stream. In addition, high PX flow rate also enhances EA or MA performance to have a high HAc flow rate in the extract stream. It was consistency with the LLE result from the previous work, the separation efficiency will be higher with the high amount of PX as the solvent. By comparing Figs. 3 (a) and (b), MA showed slightly better performance than EA on the extractor, MA produced high HAc flow rate in the extract stream with the same amount of MA and EA input on solvent stream.…

    • 1263 Words
    • 6 Pages
    Decent Essays
  • Decent Essays

    According to the experimental results obtained, a mechanism which can be proposed for the adsorption of Pb2+ ions on the Fe3O4@GMA-AAm surface was shown in scheme 3. The equilibrium adsorption capacity (qe) (mg g−1) for Pb2+ ions was calculated according to the following equation: ( Eq.1) where C0 and Ce (mg L−1) are respectively the initial and equilibrium Pb2+ ions aqueous concentrations. V is the volume (mL) of Pb2+ ions aqueous solution; m is the mass (mg) of adsorbents used in the experiment. The removal percentage of metal ions was calculated using the following equation: ( Eq.2) (Scheme 3) 3.3. Adsorption study of the Fe3O4@GMA-AAm…

    • 1394 Words
    • 6 Pages
    Decent Essays