Abstract
The photocatalytic activity of eco-friendly zinc oxide doped silica nanocomposites, synthesized via a co-precipitation method followed by heat-treatment at 300, 600, and 900 °C is investigated. The samples have been characterized by employing X-ray diffraction method, and further analyzed using the Rietveld Refinement method. The samples show a space group P63mc with hexagonal structure. The prepared composites are tested for their photocatalytic activities for the degradation of methyl orange-based water pollutants under ultra-violet (UV) irradiation using a 125 W mercury lamp. A systematic analysis of parameters such as the irradiation time, pH value, annealing temperatures, and the concentration of sodium hydroxide impacting the degradation of the methyl orange (MO) is carried out using UV-visible spectroscopy. The ZnO.SiO2 nanocomposite annealed at 300 °C at a pH value of seven shows a maximum photo-degradation ability (~98.1%) towards methyl orange, while the photo-degradation ability of ZnO.SiO2 nanocomposites decreases with annealing temperature (i.e., for 600 and 900 °C) due to the aspect ratio. Moreover, it is seen that with increment in the concentration of the NaOH (i.e., from 1 to 3 g), the photo-degradation of the dye component is enhanced from 20.9 to 53.8%, whereas a reverse trend of degradation ability is observed for higher concentrations.
Highlights
To meet the demand and supply of developing countries, numerous small and largescale industries are flourishing
A terns, a broad hump is present at ◦2θ~21.98°, which reveals the presence of amorphous broad hump is present at 2θ~21.98, which reveals the presence of amorphous silica
The specific surface area decreases from 16.8 m2 /g and 0.001 m2 /g on increasing the annealing temperature from 300 to 900 ◦ C due to blocking of SiO2 pores via the penetration of ZnO into these pores
Summary
To meet the demand and supply of developing countries, numerous small and largescale industries are flourishing. Numerous water treatment techniques, such as chemical oxidation, adsorption, precipitation, coagulation, electrolysis, photo-degradation, and many more, are employed for the filtration and purification at the industry level before releasing it into the environment [8,9,10]. The core of the silicon dioxide will act as an electron-trapping centre These trapping centres deal with the electron generated from ZnO due to the process of photon irradiation and excitation, which reduces the recombination rate of EHPs, and in turn, contributes to an enhanced photocatalytic performance [26]. In light of the above, the present work reports on the synthesis of ZnO.SiO2 nanocomposites, the examination of their structure, and photo-degradation of methyl orange pollutant of the nanocomposite. This report explains the correlation between the structure and the parameters such as temperature, pH, irradiation time, and NaOH concentration affecting the photo-degradation performance of nanocomposites
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