Predicting optical and photocatalytic properties of metal coupled TiO2 particles using response surface methodology (rsm)
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Date
2019-07
Authors
Tan Zhi Hui
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Abstract
Titanium dioxide (TiO2) particles are commonly used as photocatalyst and also as filler in polymer encapsulation of light emitting diodes (LEDs). For both applications, the photocatalytic performance of photocatalyst and the photostability of filler could be enhanced by coupling TiO2 particles with different metals such as argentum (Ag), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn) and nickel (Ni) through impregnation method assisted by ultraviolet (UV) light. In this research, Ag-TiO2 particles showed the best photocatalytic performance in Rhodamine B (RhB) dye removal with rate constant (2nd order kinetic photodegradation) of 0.1011 ppm-1min-1 and the highest photodegradation efficiency at 60 mins (98.4 %) amongst the other metal coupled TiO2 particles which only exhibited 1st order kinetic reaction. This is because coupling TiO2 with Ag reduced the recombination rate of photoinduced electron-hole pairs and thus make Ag-TiO2 particles to be a potential photocatalyst. Meanwhile, Mn-TiO2 particles were the most photostable with the lowest photodegradation 1st kinetic order rate constant (0.0051 min-1) and photodegradation efficiency at 60 mins (26.30 %) while showed the highest reflectivity (~ 65 %) amongst the other metal coupled TiO2 particles. This is because coupling TiO2 with Mn increased the free radical scavenging ability and make Mn-TiO2 particles to be potential filler in LEDs’ encapsulation. Next, the photocatalytic performance of Ag-TiO2 particles were optimised using Design of Experiment (DOE) and Response Surface Methodology (RSM). The optimum synthesis parameters for Ag-TiO2 particles were 52 ppm of Ag(I) ion solution, 40 mins of UV irradiation and 511 ºC of annealing temperature which the highest rate constant and photodegradation efficiency at 60 mins could be achieved.