Efficient wastewater treatment with nanobubble-integrated TiO2 photocatalytic reactor


May 16, 2023

(Nanowerk News) Urbanization and industrialization have led to increasing environmental problems, with dye wastewater, due to its high toxicity, posing a significant challenge. Traditional treatment methods, including physical, biological and chemical approaches, are inadequate due to inefficiencies, high energy consumption and incomplete remediation. Therefore, there is an urgent need for alternative waste treatment techniques.

In 1972, Fujishima pioneered the use of titanium dioxide (TiO2).2) in the photocatalytic decomposition of water for hydrogen production. Since then, photocatalytic technology has evolved for wastewater treatment applications, taking advantage of its effective mineralization capabilities, fast reaction rates and lack of secondary pollution.

TiO2, because it is non-toxic, chemically stable, and low cost, is a widely used photocatalyst. To transition this technology from experimental research to practical application, a simple, efficient, and easy-to-assemble photocatalyst reactor design is essential.

Recent advances have seen the integration of photocatalytic technology with various advanced oxidation (AOP) processes to improve performance. TiO coupling2Photocatalysts based with AOP such as Fenton oxidation, plasma oxidation, and ozone oxidation have shown improved handling of organic pollutants.

Nanobubbles (NBs), due to their unique physical properties, have also proved useful in wastewater treatment, enhancing the photocatalytic performance of TiO22 by 11.6% compared to the non-bubble method.

However, the main challenge is the need for TiO2 re-separation and recovery2 post-degradation, complicating reactor design. To avoid this problem, a photocatalyst is still required for the reactor assembly.

In this study (Advanced Sensors and Energy Materials, Degradation of Rhodamine B in a photocatalytic reactor containing TiO2 nanotube array combined with nanobubbles”), to TiO2 Nanotube arrays coated with titanium mesh are used to assemble photocatalytic reactors integrated with nanobubbles technology. Schematic diagram of photocatalytic reactor coupling with nanobubbles for organic pollutant degradation Schematic diagram of photocatalytic reactor coupling with nanobubbles for organic pollutant degradation. The cylindrical reactor is made of stainless steel with a diameter of 210 mm and a height of 210 mm. Ti mesh (100 mm long, 100 mm wide and 0.5 mm thick) coated with TiO2 Array nanotubes installed inside the reactor. A 100 W high pressure mercury lamp (HPML) is placed in a quartz tube. In addition, the inlet and outlet are designed on the left and right side of the reactor respectively. The inlet is connected to the nanobubble generator. Wastewater is pumped into a bubble generator to prepare wastewater containing nanobubbles before entering the photocatalytic reactor. (Image: Han Group)

This reactor exhibited outstanding photocatalytic degradation capabilities, achieving a degradation efficiency of 95.39% for Rhodamine B after irradiation treatment. The reactor also succeeded in degrading other organic pollutants such as methylene blue, tetracycline and oxytetracycline hydrochloride, with respective efficiencies of 74.23%, 68.68% and 64.10%. Therefore, this study presents a promising strategy for wastewater treatment, combining photocatalysis and nanobubbles technologies.


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