Effect of the TiO2 Colloidal Size Distribution on the Degradation of Methylene Blue

Abstract

TiO2 is the most commonly used photocatalyst in water treatment. The particle size of TiO2 is an important factor that significantly influences its activity during photocatalytic degradation. In the presence of liquid, the properties of nanopowders composed of exactly the same product clearly differ according to their aggregation size. In this study, TiO2 nanoparticles with a controlled size were fabricated by focused ultrasound dispersion. The high energy generated by this system was used to control the size of TiO2 particles in the suspension. The constant high energy released by cavitation enabled the dispersion of the particles without a surfactant. The activities of the prepared TiO2 photocatalysts for methylene blue (MB) degradation were then compared. The dye degradation effect of the photocatalyst was as high as 61.7% after 10 min when the size of the powder was controlled in the solution, but it was only as high as 41.0% when the aggregation size was not controlled. Furthermore, when the TiO2 concentration exceeded a certain level, the photocatalytic activity of TiO2 decreased. Controlling the size of the aggregated photocatalyst particles is, therefore, essential in water-treatment technologies utilizing TiO2 photocatalytic properties, and adjusting the TiO2 concentration is an important economic factor in this photocatalytic technology. This study contributes to the development of processes for degrading dyes, such as MB, released from wastewater into aquatic environments.

Novel ultrasonic technology for advanced oxidation processes of water treatment

“…Consequently, strong and uniform energy is transmitted inside, and the generation and collapse of cavitation bubbles are repeated. 49,50 When a cavitation bubble collapses, the intense energy latent in the bubble is released outward, and the energy physically and chemically affects the methylene blue molecule. In the experiment, methylene blue samples were circulated through the equipment at a rate of 5.0 mL min −1 using a pump (LongerPump, WT600-1F) to irradiate ultrasonic waves, and cooling water was also circulated at a rate of 10.0 mL min −1 using the same pump to control heat generation and transfer ultrasonic energy to the sample.…”

“…During the measurement, samples were collected and measured at approximately 2 mL, and in the case of a sample using TiO 2 , the measurement was carried out after the TiO 2 was removed using a cylinder filter. Degradation (%) was calculated using the following equation, according to the concept that the absorbance of the Beer–Lambert law is proportional to the concentration: 49,51 where A 0 is the absorbance of undegraded methylene blue, and A is the absorbance of degraded methylene blue. Degradation (%) was calculated through the corresponding calculation formula here.…”

“…This focused approach was employed to predict the degradation effect of organic dyes. 49,50 This study aimed to demonstrate that water treatment technology using a focused ultrasonic system is more effective than other methods. Simultaneously, we aimed to determine the optimal conditions of focused ultrasonic equipment for water treatment technology.…”

Recent Advances in Black TiO2 Nanomaterials for Solar Energy Conversion

“…TiO 2 nanosheets were proved to exhibit superior photocatalytic activity for CO 2 reduction than the nanoparticle, thanks to its much higher surface area and surface activity [ 17 ]. In addition, the effects of the particle size of TiO 2 on photocatalytic pollutant removal were thoroughly investigated by Kim et al [ 18 ]. The photocatalytic degradation efficiency for methylene blue can be effectively improved by controlling the particle size and TiO 2 concentration in the reaction mixture [ 18 ].…”

“…In addition, the effects of the particle size of TiO 2 on photocatalytic pollutant removal were thoroughly investigated by Kim et al [ 18 ]. The photocatalytic degradation efficiency for methylene blue can be effectively improved by controlling the particle size and TiO 2 concentration in the reaction mixture [ 18 ].…”