Ultrasonic-assisted pH Swing Method for the Synthesis of Highly Efficient TiO2 Nano-size Photocatalysts

Abstract

A new route for the preparation of nanocrystalline TiO 2 particles based on the pH swing method assisted by ultrasonic irradiation in the presence of a surfactant (Pluronic P-123) has been successfully achieved. The prepared TiO 2 catalysts were calcined from 400 to 800°C and characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infra-red spectroscopy (FTIR), gas adsorption measurements (BET) and thermogravimetirc measurements (TAG/DTA) analyses. Characterization results revealed that the enhancement in the particle size of TiO 2 by the pH swing method could be controlled by combining the pH swing with ultrasonic irradiation. Increasing the calcination temperatures led to an increase in both the particle and pore size, whereas the surface area and pore volume gradually decreased. A synergistic effect was observed in the combined process of pH swing with ultrasonication, yielding small TiO 2 particles as well as high surface area, pore volume, pore diameter, and crystalline anatase phase. The activity of the catalysts was investigated for the oxidation of 4-chlorophenol (4-CP). TiO 2 prepared with 15 times pH swing and calcined at 700°C was found to show the highest rate for the oxidative degradation of 4-CP when compared to the TiO 2 sample prepared with just 1 time pH swing and to the commercial P-25 TiO 2 Degussa photocatalyst. Thus, a novel approach in controlling the various physico-chemical parameters of TiO 2 nanoparticles was developed.

Preparation and Characterization of Mesoporous MoO3/TiO2 Composite with High Surface Area by Self-Supporting and Ammonia Method

“…Strong peaks of MoO 3 (I)/TiO 2 (Fig. 3a) orrespond to the diffraction patterns of (101), (112), and (200) planes of anatase [32]. Exactly, characteristic peaks of mesoporous MoO 3 /TiO 2 composite (Fig.…”

Solvent-free chemoselective oxidation of alcohols by hydrogen peroxide using a new synthesized copper complex as reusable heterogeneous nanocatalyst

“…One of the popular techniques for nanocatalysts fabrication is ultrasonic irradiation method. [13]. By using nanocatalyst, some improvement in reaction conditions are happened such as good yields, short reaction times and mild reaction conditions.…”

Preparation and properties of visible light responsive ZrTiO4/Bi2O3 photocatalysts for 4-chlorophenol decomposition

“…The particle size is especially well-controlled by ZrO 2 in binary oxide catalysts [18]. Some studies have also explored the application of ultrasound for the preparation of nano-particles, especially TiO 2 [19][20][21][22][23][24][25][26][27][28]. During ultrasonic irradiation, ultrasonic waves consisting of compression and rarefraction cycles produce cavitation bubbles in a liquid.…”

“…During ultrasonic irradiation, ultrasonic waves consisting of compression and rarefraction cycles produce cavitation bubbles in a liquid. After several compression/rarefaction cycles, the cavitation bubbles collapse violently and adiabatically at extremely high temperatures of up to 5000 • C and pressures of about 500 atm [19,20]. Such extreme temperatures and pressures within a small reactor can induce many changes in the morphology of the TiO 2 nano-particles during the preparation process.…”

“…Ultrasonic irradiation is usually favorable for mass transfer during the preparation of metal oxide particles. This would alter the kinetics of the reactions during nano-material preparation [19,20].…”