Synthesis and characterization of undoped and Ag doped TiO2, ZnO and ZnS nanoparticles for the photocatalytic degradation of 2-chlorophenol under UV irradiation.

Show simple item record Onkani, Shirley Priscilla 2022-04-22T04:02:35Z 2022-04-22T04:02:35Z 2019-07-08
dc.description M.Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. en_US
dc.description.abstract Phenol, 2-chlorophenol (2-CP) is used in the manufacture of several chemical compounds including other chlorophenols, dyes, dentifrice and pesticides. The usage of these chemicals results in the discharge of 2-CP that is harmful to most biota in the environment. Therefore there is need to remove or degrade 2-CP from the environment, especially in water. This research focused on the synthesis, characterization and application of Ag doped semiconductor (TiO2, ZnO, and ZnS) nanoparticles for the removal of 2-CP from water. Sol-gel and co-precipitation methods were used to synthesize the nanoparticles with different Ag contents (1%, 3% and 5%). Silver metal was used as a doping agent due to its antibacterial activity and ability to improve the photocatalytic activity of the semiconductors for 2-CPdegradation under UV irradiation. Characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), Ultra-violet visible spectroscopy (UV-Vis) and photoluminescence spectra (PL) were used to characterize the structural, optical and physical properties of the nanoparticles, while Transmission electron microscopy (TEM) was used to characterize the surface of the nanoparticles. The XRD results confirmed the formation of anatase, wurtzite and blend phases of TiO2, ZnO and ZnS nanoparticles, respectively. The band gaps of the synthesized nanoparticles were 3.42 eV, 3.23 eV and 3.12 eV for TiO2, ZnO and ZnS nanoparticles respectively. The TEM images showed that all synthesized nanoparticles were uniform in shape. Photocatalytic degradation of 2-CP under UV irradiation confirmed that the semiconductor’s photocatalytic activities improved with the addition of Ag ions. The best removal percentage was obtained at doped Ag percentages of 5, 1 and 5 % using TiO2, ZnO and ZnS, respectively. In addition, the effects of various parameters affecting the photocatalytic degradation such as pH, initial concentrations of 2-CP and amount of catalyst (Ag doped TiO2, ZnO and ZnS, respectively) loading were examined and optimized. At the different initial concentrations of 2-CP, namely, 8, 20 and 50 ppm, the highest degradation efficiency was obtained at pH of 10.5 and 5 mg of catalyst dosage. However a decrease in initial concentration of 2-CP showed an increase in the photocatalytic efficiency. The degradation percentage of 2-CP obtained with Ag doped TiO2; ZnO and ZnS nanoparticles were 74.74, 57.8 and 45.49 %, respectively. Doping of these materials with Ag enhanced their photocatalytic activity; thus, they have the potential of degrading phenolic compounds, especially 2-chlorophenol, in water. en_US
dc.language.iso en en_US
dc.publisher Vaal University of Technology en_US
dc.subject Chemical compounds en_US
dc.subject Photocatalytic degradation en_US
dc.subject Ag doped semiconductor en_US
dc.subject TiO2 en_US
dc.subject ZnO en_US
dc.subject ZnS en_US
dc.subject Synthesized nanoparticles en_US
dc.subject Undoped en_US
dc.subject Silver doped en_US
dc.subject.lcsh Dissertations, Academic -- South Africa en_US
dc.subject.lcsh Nanostructured materials en_US
dc.subject.lcsh Chemical kinetics en_US
dc.subject.lcsh Nanoparticles en_US
dc.subject.lcsh Photodegradation en_US
dc.subject.lcsh Photocatalysis en_US
dc.title Synthesis and characterization of undoped and Ag doped TiO2, ZnO and ZnS nanoparticles for the photocatalytic degradation of 2-chlorophenol under UV irradiation. en_US
dc.type Thesis en_US
dc.contributor.supervisor Mtunzi, Fanyana M., Prof. Diagboya, N. Paul, Dr. Klink, Michael, Dr.

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