Continuous flow Reactor Based on UV LEDs and TiO2 Supported on Alumina Ceramic Foam for Photocatalytic Degradation of DBPs

Continuous flow Reactor Based on UV LEDs and TiO2 Supported on Alumina Ceramic Foam for Photocatalytic Degradation of DBPs P. Mazierski, M. Miodyńska-Melzer, O. Cavdar, A. Pieczyńska, A. Zaleska-Medynska Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 Street, 80-308 Gdańsk, e-mail: [email protected] Disinfection by-products (DBPs) are a group of chemical compounds formed when disinfectants, particularly chlorine, are used to eliminate harmful organisms such as bacteria, viruses, and parasites during water treatment (Richardson, 2003). This disinfection process is essential to ensure the safety and potability of drinking water (Srivastav et al., 2020). However, when disinfectants react with organic and inorganic materials naturally present in the water, they can unintentionally create DBPs, which may pose potential health risks (Sadiq & Rodriguez, 2004). Among the various technologies developed to mitigate or remove DBPs, photocatalysis using TiO2 has gained attention for its high efficiency, low energy consumption, and environmentally friendly approach in degrading organic pollutants (Gora et al., 2018). In this study, photocatalytic degradation of DBPs was investigated for the first time using a continuous-flow reactor equipped with low-cost UV LEDs and TiO2-coated alumina ceramic foams. CONCLUSIONS 4th International Conference on Disinfection and DBPs | October 21st –24th 2024 | Almería, Spain Acknowledgement: The research was funded by the Horizon Europe Program of the European Union as part of the project No. 101081963 “Innovative Integrated Tools and Technologies to Protect and Treat Drinking Water from Disinfection Byproducts (DBPs)”, acronym “H2OforAll”.https://h2oforall.eu/ References: 1. Richardson, S. D. 2003 Disinfection by-products and other emerging contaminants in drinking water. TrAC Trends in Analytical Chemistry, 22,666–684. 2. Srivastav, A. L., Patel, N., & Chaudhary, V. K. 2020 Disinfection by-products in drinking water: Occurrence, toxicity and abatement. Environmental Pollution, 267, 115474. 3. Sadiq, R., & Rodriguez, M. J. 2004 Disinfection by-products (DBPs) in drinking water and predictive models for their occurrence: a review. The Science of the Total Environment, 321,21–46. 4. Gora, S. L., Liang, R., Zhou, Y. N., & Andrews, S. A. 2018 Photocatalysis with easily recoverable linear engineered TiO2 nanomaterials to prevent the formation of disinfection byproducts in drinking water. Journal of Environmental Chemical Engineering, 6, 197–207. RESULTS AND DISSCUSIONMETHODOLOGY INTRODUCTION •The TiO₂-coated alumina ceramic foams, with nanoparticle sizes ranging between 30-60 nm, created a highly active surface for photocatalysis, contributing to the system's overall efficiency. •The continuous-flow reactor equipped with UV LEDs and TiO₂-coated alumina ceramic foam demonstrated significant photocatalytic degradation of DBPs, with noticeable reductions in the concentration of all tested compounds. •Among the tested DBPs, monochloroacetic acid (MSAA) and 2,4,6-trichlorophenol (TCP) exhibited the highest degradation rates. •This study confirms that the combination of low-cost UV LEDs and TiO₂-coated materials can serve as an effective, scalable, and environmentally friendly solution for mitigating the presence of harmful DBPs in water treatment processes. Synthesis of photocatalytic layers: •TiO2 was coated on the surface of alumina ceramic foam (Fig. 1) according to our patent application (PCT/PL2021/050011). •Briefly, commercial alumina ceramic foam (100x100x22 mm, porosity 20 ppi) was immersed for 5 min in TiO2 paste composed of commercial TiO2 (P25Degussa), water, PEG 400, Triton X-100 and isopropanol. After that excess paste was removed by blowing with a stream of nitrogen, dried for 12 h at 60˚C and finally calcined at 450˚C for 3 h. Figure 1 – Image of the porous photocatalytic layer, prepared in accordance with our patent application (PCT/PL2021/050011) Photocatalytic experiments: •Continuous flow reactor (volume 2L) with internal chamber dimensions of 200x100 mm, containing maximum three photocatalytic layers with dimensions of 100x100x22 mm and LED modules (max = 360 nm) was designed (Fig. 2). •Continues flow reactor was 3D printed using ABS filament and connected to a system (Fig. 2) enabling the degradation process to be carried out under flow conditions (5L tank and peristatic pump). •The processes of photocatalytic degradation of monochloroacetic acid, 4chloro-3-nitrophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4, 6trichlorophenol and 5-chlorosalicylic acid in a continues-flow reactor was carried out up to 4 h. •DBPs concentration was tested using a high-performance liquid chromatograph (HPLC, Nexera XR SIL-20AC by Shimadzu) and ion chromatograph (Metrohm AG 940 Professional IC Vario). Figure 2 – Visualization of continuous flow reactor and system enabling the degradation process to be carried out under flow conditions Figure 3 – SEM images of TiO2 coated on alumina ceramic foam with porosity 20 ppi •As can be seen from Fig. 3 the surface of alumina ceramic foams was effectively coated with TiO2 nanoparticles enabling developed surface for conducting degradation processes. •The size of TiO2 nanoparticles varied in the range of 30-60 nm. •The efficiency of photocatalytic degradation process of selected DBPs in a continues-flow reactor is presented in Fig. 4. Figure 4 – Photocatalytic degradation of monochloroacetic acid, 4-chloro-3-nitrophenol, 4-chlorophenol, 2,4dichlorophenol, 2,4, 6-trichlorophenol and 5-chlorosalicylic acid in a continues-flow reactor