Synthesis of neutral titanium dioxide sol with good photocatalytic efficiency
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Date
2019-06
Authors
Lim Sin Jou
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Abstract
The past decade has witnessed impressive growth in the field of nanotechnology and considerable attention has been paid to the development of nanomaterials. Titanium dioxide (TiO2) has attracted more attention due to its superior properties and hence it is usually utilized as coating material. However, various problems arised as the TiO2 sol is commonly synthesized in acidic condition, resulting in limited application. In this project, a neutral (pH 7) transparent TiO2 sol was prepared by precipitate-peptization method using titanium isopropoxide as precursor and lactic acid as peptizing agent. The resulting neutral TiO2 sols were characterized using various analytical tools such as XRD, FTIR, UV-Vis spectroscopy, Zetasizer and TEM. Besides, the sols were also employed for photocatalytic activity study under sunlight and antibacterial efficiency. The neutral TiO2 sol peptized with Ti:H2O ratio = 1:5 and 6g of lactic acid in water bath at 85°C showed the optimal performance, where high photocatalytic activity (93%) and good antibacterial properties were achieved. The TiO2 sol obtained in these conditions possessed high transparency (90%) with small particles size around 19.39 nm, indicates that the aggregation of the sol was suppressed by lactic acid which induced electrosteric stabilization to the solution by bidentate bridging mode. The stability of the sol was found to be -23.5 eV. Moreover, neutral TiO2 sol was activated towards sunlight due to its small bandgap energy which was 2.60 eV and the photocatalytic activity was mostly attributed to the generation of holes and superoxide radicals.