Synthesis and characterization of zinc oxide nanoparticles and its application in water purification

Abstract

The synthesis of Zinc Oxide (ZnO) nanoparticles is designed by sol-gel method in the thesis. The reaction temperature is maintained at room temperature and the reaction time is constant for the preparation of ZnO nanoparticles. The precursor salt concentration is also kept fixed for the synthesis procedure. The calcination temperature is maintained at 450°C. The different types of characterization techniques such as XRD, FTIR, FESEM and EDX for ZnO nanoparticles have been completed. Water pollution is one of the global issues and there is increase in heavy metals, bacteria and other contaminants in water bodies with time. Cadmium is one of the heavy metals which lead to toxic effects in humans even present in small concentration. In the thesis work, removal of cadmium ions, Cd (II) is done with the help of synthesised ZnO nanoparticles by adsorption process. The antibacterial property of ZnO nanoparticles is also evaluated by varying three different concentrations of ZnO nanoparticles. The efficiency of ZnO nanoparticles as an adsorbent is investigated for removal of Cd (II) ions from synthetic water. Batch mode experiment is performed to evaluate the effect of various parameters of the adsorption process. The parameters such as pH of the solution and amount of adsorbent dose are studied and removal efficiency of Cd (II) ions and adsorption capacity of Cd (II) ions by ZnO nanoparticle is calculated from the measurement data. The isotherm, kinetics and thermodynamics parameters of adsorption process for Cd (II) ions are also determined in the study. The adsorption isotherm data is found to be agreed with Langmuir isotherm model. Pseudo second order model is best described the adsorption kinetics value with high regression coefficients. Thermodynamic study results reveal that the adsorption process is endothermic and spontaneous. This suggests the positive outcome for the removal of cadmium ions from aqueous solution by zinc oxide nanoparticles. The efficiency of ZnO nanoparticles is also tested for removal of Cd (II) ions in real water sample analysis such as tap water and pond water collected for the adsorption experiment. The nanoparticle is found to be effective in removing Cd (II) ions from the two samples. It is found from the analysis that the prepared ZnO nanoparticles can be utilized for the removal of heavy metal ions such as Cd (II) ions from aqueous solution and collected any type of real water. Therefore, it can replace the conventional adsorbent for the removal of heavy metal ions.