Photocatalytic Degradation of Disinfection By-Products (DBPs) Using Immobilized TiO2 Nanoparticles on Porous Foams: A Novel Approach for Water Treatment

Buenos días Presentamos los tres presupuestos necesarios para solicitar esta compra menor. Decidimos aceptar el primero ya que nos resulta más económico Un saludo y gracias Pobrano z https://repozytorium.bg.ug.edu.pl / Downloaded from Repository of University of Gdask 2025-11-19 11:47 4 th International Conference on Disinfection and Disinfection By-Products 352 P5. Photocatalytic Degradation of Disinfection By-Products (DBPs) Using Immobilized TiO2 Nanoparticles on Porous Foams: A Novel Approach for Water Treatment M. Miodyńska*†, O. Cavdar*, P. Mazierski*, A. Pieczyńska*, A. Zaleska-Medynska* * Department of Environmental Technologies, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland, [email protected] Abstract: Disinfection by-products (DBPs) are unintended chemicals formed during water treatment processes, posing health risks due to their carcinogenic and mutagenic properties. Photocatalysis, employing materials like titanium dioxide (TiO 2 ), offers a promising solution for DBP removal. This study introduces a novel method: immobilizing TiO 2 nanoparticles on a porous Al 2 O 3 matrix. Photocatalytic experiments were conducted on two DBP compounds, bromodichloromethane (BDCM) and monochloroacetic acid (MCAA), confirming high degradation efficiency. Minimal DBP adsorption on the photocatalytic layers was observed, with enhanced photolysis of BDCM compared to MCAA. Stability tests over five cycles demonstrated consistent effectiveness. These findings highlight the potential of TiO 2 -based photocatalytic layers for DBP removal. Keywords : Photocatalysis; Disinfection by-products; Water treatment INTRODUCTION Disinfection by-products (DBPs) are chemical compounds that form as unintended byproducts of disinfection processes in water treatment facilities. These compounds result from the reaction of disinfectants, such as chlorine or chloramine, with organic and inorganic matter present in the water (Xiao et al. 2023). While disinfection is crucial for preventing the spread of waterborne diseases, the presence of DBPs poses potential health risks due to their carcinogenic and mutagenic properties (Kimura and Ortega-Hernandez 2019). Efforts to mitigate the harmful effects of DBPs have led to the exploration of various removal methods (Mazhar et al. 2020). Among these methods, photocatalysis has emerged as a promising approach for the degradation of DBPs in water (Chang et al. 2019). Photocatalysis involves the use of photocatalysts, such as titanium dioxide (TiO 2 ), which can harness light energy to drive chemical reactions. When irradiated with light of appropriate wavelength, photocatalysts generate electron-hole pairs, initiating redox reactions that break down organic pollutants, including DBPs (Lee et al. 2023). The photocatalytic removal of DBPs offers several advantages, including high efficiency, environmental friendliness, and the ability to operate under ambient conditions. Moreover, photocatalysis can target a wide range of DBP compounds, making it a versatile solution for water treatment applications. In this study, we present a novel approach involving the immobilization of a photocatalyst in the form of TiO 2 nanoparticles through the deposition of a homogeneous and stable layer onto a porous Al 2 O 3 matrix. The conducted experiments corroborated the remarkable efficiency of photocatalytic degradation concerning two selected compounds classified as DBPs, namely, BDCM and MCAA, utilizing the resultant layers endowed with photocatalytic capabilities. MATERIALS AND METHODS A photocatalytic material, comprising a porous Al 2 O 3 matrix (pre-treated with isopropanol degreasing and subsequent drying), was utilized in conjunction with a photocatalytic paste (as detailed in patent application PCT/PL2021/050011). The paste incorporated TiO 2 particles (P25, Aeroxide) and was applied onto the Al 2 O 3 matrix via a conventional deep coating technique, with an application duration of 3 minutes. Following application, excess paste was eliminated by nitrogen blowing from all directions of the matrix. The resulting photocatalytic layers were then dried overnight at 60 ℃ and subsequently calcined at 450 ℃. As prepared photocatalytic foam is depicted in Figure 1a. Pobrano z https://repozytorium.bg.ug.edu.pl / Downloaded from Repository of University of Gdask 2025-11-19 11:47 4 th International Conference on Disinfection and Disinfection By-Products 353 Photocatalytic measurements were conducted within a teflon reactor (as shown in Figure 1b). The reactor contained the photocatalytic layer, along with 25 mL of an aqueous solution of DBP with an initial concentration of 20 mg/L, alongside a magnetic bar, and was hermetically sealed. Prior to irradiation, the reactor was stirred in darkness for 30 minutes to establish adsorption-desorption equilibrium between the photocatalytic layer and DBP molecules. Following this, a reference sample was collected, and the system was subjected to 1 hour of irradiation, with control samples (0.5 mL) withdrawn via a silicone septum every 20 minutes. The samples underwent filtration through a syringe filter (with a pore size of 200 µm) and were promptly analyzed using high-performance liquid chromatography (HPLC, Nexera XR SIL-20AC by Shimadzu) and ion chromatography (Metrohm AG 940 Professional IC Vario). To minimize the influence of temperature on DBP removal, the system was cooled to 16 ℃ during whole experiment. The evaluated DBPs included bromodichloromethane (BDCM) and monochloroacetic acid (MCAA). Additionally, the stability of the system was assessed over five photocatalytic cycles, with each cycle involving the removal of the DBP solution from the batch reactor and subsequent replenishment with a fresh 25 mL portion of DBP solution (C 0 =20 mg/L). These processes were conducted under identical conditions as described above, and sample analysis followed the same protocol. Figure 1 a) Photocatalytic layer, b) Teflon batch reactor for photocatalytic experiments. RESULTS AND DISCUSSION The obtained photocatalytic layers were applied in a photocatalytic reaction aimed at decomposing molecules of BDCM and MCAA. Figure 2 presents the results along with the photolysis of these compounds in the UV-Vis irradiation range (process without the photocatalytic layer) as well as conducted in darkness (90 minutes) to determine the ability of DBP molecules to adsorb. Pobrano z https://repozytorium.bg.ug.edu.pl / Downloaded from Repository of University of Gdask 2025-11-19 11:47 4 th International Conference on Disinfection and Disinfection By-Products 354 Figure 2 a) Photocatalytic degradation of BDCM (C 0 =20 mg/L), b) Photocatalytic degradation of MCAA (C 0 =20 mg/L). The degradation efficiency of BDCM and MCAA was registered at approximately 45 % and 90 % after 60 minutes of irradiation, respectively. In both cases, minimal adsorption of DBPs molecules on the photocatalytic layers in darkness was observed. However, increased photolysis of BDCM in the UV-Vis irradiation range (about 25 %) compared to the obtained photolysis of MCAA (about 13 %) was also noted. Nonetheless, the stability of the photocatalytic layers was investigated in five consecutive photocatalytic cycles using the degradation of BDCM as an example. Figure 3 presents the obtained results, clearly indicating the consistent effectiveness of employing the proposed photocatalytic materials in the degradation reaction of the DBPs representative, BDCM. Figure 3 Testing the stability of the photocatalytic layer in five BDCM (C 0 =20 mg/L) degradation cycles. The conducted experiments demonstrate a tremendous potential for the application of photocatalytic removal of DBPs in the presence of the proposed photocatalytic layers containing TiO 2 . Pobrano z https://repozytorium.bg.ug.edu.pl / Downloaded from Repository of University of Gdask 2025-11-19 11:47 4 th International Conference on Disinfection and Disinfection By-Products 355 ACKNOWLEDGEMENTS The research was financed 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”. REFERENCES Chang, Xueming, Xiaolong Yao, Ning Ding, Xiufeng Yin, Qinmin Zheng, Songliu Lu, Danmeng Shuai, & Yingxue Sun. 2019. Photocatalytic Degradation of Trihalomethanes and Haloacetonitriles on Graphitic Carbon Nitride under Visible Light Irradiation. STOTEN , 682 , 200–207. Hassaan, Mohamed A, Mohamed A El-Nemr, Marwa R Elkatory, Safaa Ragab, Violeta-Carolina Niculescu, & Ahmed El Nemr. 2023. Principles of Photocatalysts and Their Different Applications: A Review. Top. Curr. Chem. (Z).381 , 31. Kimura, Susana Y, & Alejandro Ortega-Hernandez. 2019. Formation Mechanisms of Disinfection Byproducts: Recent Developments. Current Opinion in Environmental Science & Health , 7 , 61–68. Mazhar, Mohd Aamir, Nadeem A Khan, Sirajuddin Ahmed, Afzal Husain Khan, Azhar Hussain, Rahisuddin, Fazlollah Changani, Mahmood Yousefi, Shahin Ahmadi, & Viola Vambol. 2020. Chlorination Disinfection By-Products in Municipal Drinking Water – A Review. J. Clean. Prod. 273 , 123159. Lee, Dong-Eun, Mo-Keun Kim, Mohtaram Danish, and Wan-Kuen Jo. 2023. State-of-the-Art Review on Photocatalysis for Efficient Wastewater Treatment: Attractive Approach in Photocatalyst Design and Parameters Affecting the Photocatalytic Degradation. Catal. Comm. 183 , 106764. Pobrano z https://repozytorium.bg.ug.edu.pl / Downloaded from Repository of University of Gdask 2025-11-19 11:47 Photocatalytic Degradation of Disinfection By-Products (DBPs) Using Immobilized TiO2 Nanoparticles on Porous Foams: A Novel Approach for Water Treatment Magdalena Miodyńska-Melzer, Onur Cavdar, Paweł Mazierski, Aleksandra Pieczyńska, Adriana Zaleska-Medynska Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 Street, 80-308 Gdańsk, e-mail: magdalena.miodynska-melz[email protected] Disinfection by-products (DBPs) are chemical compounds formed unintentionally during water treatment when disinfectants like chlorine or chloramine react with organic and inorganic matter [1]. While disinfection prevents waterborne diseases, DBPs pose health risks due to their carcinogenic and mutagenic properties [2]. To reduce DBP levels, various removal methods have been explored [3], with photocatalysis showing promise for DBP degradation [4]. Using photocatalysts like titanium dioxide (TiO2), photocatalysis harnesses light to drive reactions that break down DBPs [5]. In this study, we propose immobilizing TiO2 nanoparticles on a porous Al2O3 matrix, demonstrating effective photocatalytic degradation of selected DBPs. 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] R. Xiao et al., Disinfection Byproducts and Their Precursors in Drinking Water Sources: Origins, Influencing Factors, and Environmental Insights, Engineering., 36 (2024)36–50. [2] Kimura et al.,Formation Mechanisms of Disinfection Byproducts: Recent Developments. Current Opinion in Environmental Science & Health, 7 (2019)61–68. [3] Mazhar et al., Chlorination Disinfection By-Products in Municipal Drinking Water –A Review. Journal of Cleaner Production, 273 (2020)123159. [4] Chang, et al., Photocatalytic Degradation of Trihalomethanes and Haloacetonitriles on Graphitic Carbon Nitride under Visible Light Irradiation. Science of The Total Environment, 682 (2019)200–207. [5] Lee, et al., State-of-the-Art Review on Photocatalysis for Efficient Wastewater Treatment: Attractive Approach in Photocatalyst Design and Parameters Affecting the Photocatalytic Degradation. Catalysis Communications, 183 (2023)106764. Figure 3 – Efficiency of photocatalytic degradation of different type of DBPs compound in the presence of photocatalytic layers. RESULTS Label Name BDCM Bromodichloromethane MCAA Monochloroacetic acid CSA 5 -Chlorosalicylic acid CP 4 -Chlorophenol DCP 2,4 -Dichlorophenol TCP 2,4,6 -Trichlorophenol CNP 4 -Chloro-3-nitrophenol METHODOLOGY Photocatalytic foams preparation Photocatalytic experiments Figure 1 – Scheme of photocatalytic foam preparation. ➢Source of light: 1000 WXe lamp ➢Light intensity: 100 mW/cm² ➢Reactor volume: 25 mL ➢Initial concentration of pollutant solution: 20 mg/L ➢Volume of pollutant solution: 25 mL ➢Process temperature: 16 °C ➢Equilibrium time: 30 minutes ➢Irradiation time: 60 minutes (samples were collected every 20 minutes) ➢Concentration analysis of DBPs: The concentrations of BDCM, CSA, CP, DCP, TCP, and CSA in the collected samples were analyzed using HPLC/DAD, while MCAA was analyzed using IC. ➢Filter: ABK7 filter was used to block radiation below 300 nm, preventing excessive photolysis of the tested DBPs. ➢Photocatalytic foam size: 2 x 2 x 1 cm The exact content of the photocatalytic paste with TiO2particles and parameters of photocatalytic layers preparation is patented (no PL433102A1) 1. Cleaning ceramic foam 2. Drying the ceramic foam in the dryer 3. Dipping the foam into the photocatalytic paste containing TiO2 particles 4. Removing the photocatalytic layer from the paste and removing the excess paste with an air stream 5. Drying the photocatalytic foam in a dryer 6. Calcination of the foam Figure 2 – Phototalytic foam and the photoreactor used for experiments of DBPs photodegradation. INTRODUCTION ➢A stable photocatalytic paste containing TiO₂ nanoparticles with effective photocatalytic properties was successfully formulated. ➢A reliable procedure was developed for applying this paste onto the surface of commercially available porous Al₂O₃ ceramic matrices. ➢The resulting photocatalytic layers were effectively utilized in the degradation of selected DBPs under photocatalytic conditions, demonstrating excellent process efficiency. ➢The highest efficiency of photodegradation was observed for haloacids (MCAA and CSA). ➢The weakest efficiency of photodegradation was determined for halomethanes (BDCM). ➢These findings provide a solid foundation for further advancement in the application of the developed photocatalytic materials, particularly from a process engineering perspective.