Photocatalytic removal of phenazopyridine in a rotating disk photoreactor: Investigation of operational parameters

Subject Areas : Effective and expandable solutions to control and eliminate environmental pollution

Maryam Kamali-Alamdari ¹

1 - Department of Chemistry, Ta.C., Islamic Azad University, Tabriz, Iran

Received: 2025-11-01 Accepted : 2025-11-11 Published : 2025-11-26

Keywords: Heterogeneous photocatalysis, Rotating disk photoreactor, Phenazopyridine, Operational parameters, UV/TiO2 process,

Abstract :

In this study, the efficiency of a rotating disk photoreactor for the removal of phenazopyridine (PhP), a drug-resistant contaminant, using the UV/TiO₂ process was investigated. The effects of operational parameters – including the initial concentration of PhP, solution pH, solution volume, rotating disk speed, flow rate, and irradiation time – on PhP removal efficiency were examined. The results indicate that increasing the rotating disk speed up to 450 rpm enhances the removal efficiency, while further increasing it to 750 rpm produces no significant improvement. Higher flow rates and longer irradiation times also improve PhP removal efficiency, whereas higher initial concentrations of PhP reduce it. Moreover, the removal efficiency was higher at near-neutral pH (approximately 5.9) compared to acidic or alkaline conditions.

References:

[1] Dong, H., Zeng, G., Tang, L., Fan, C., Zhang, C., He, X., He, Y., 2015, An overview on limitations of TiO2-based particles for photocatalytic degradation of organic pollutants and the corresponding countermeasures. Water Research, 79, 128.
[2] Asiri, A.M., Al-Amoudi, M.S., Bazaid, S.A., Adam, A.A., Alamry, K.A., Anandan, S., 2014, Enhanced visible light photodegradation of water pollutants over N-, S-doped titanium dioxide and n-titanium dioxide in the presence of inorganic anions. Journal of Saudi Chemical Society, 18, 155.
[3] Naghdi, S., Moheb Shahrestani, M., Zendehbad, M., Djahaniani, H., Kazemian, H., Eder, D., 2023, Recent advances in application of metal-organic frameworks (MOFs) as adsorbent and catalyst in removal of persistent organic pollutants (POPs). Journal of Hazardous Materials, 442, 130127.
[4] Gharbani, P., 2024, Investigating the efficiency of graphene oxide in the adsorption of 2-chlorophenol from aqueous solutions as an environmental pollutant. Environmental Pollutions and Sustainable Urban Development, 1(3), 63. (in Persian)
[5] Sadeghi Farshi, F., 2024, Investigation of the efficiency of nickel oxide nanoparticles in removing C.I. Acid Red 97 as an environmental pollutant from aqueous environments. Environmental Pollutions and Sustainable Urban Development, 1(4), 71. (in Persian)
[6] Ghazi Tabatabaei, Z., 2024, Synthesis of zero valent iron loaded on carbon nanotubes and its effectiveness in removing a dye pollutant. Environmental Pollutions and Sustainable Urban Development, 1(2), 97. (in Persian)
[7] Hao, L., Yan, J., Li, M., Shao, W., Zeng, M., 2024, Coagulation-centered three-step approach for removing by-product organic pollutants from tetrabromobisphenol A industrial wastewater: Experimental and theoretic investigations. Environmental Research, 247, 118113.
[8] Elias, C., Ranque, S., Malleret, L., 2025, State of the art on fungal biodegradation of persistent organic pollutants in soils and innovative strategies for isolating relevant candidate strains. Environmental Technology & Innovation, 39, 104247.
[9] Eskandarloo, H., 2024, A review of new methods of removing environmental pollutants: Photolysis and UV/H2O2 processes. Environmental Pollutions and Sustainable Urban Development, 1(1), 1. (in Persian)
[10] Zafari, S.H., 2024, Removal of p-nitrophenol from aqueous environments by UV/S2O82- process in a continuous photoreactor: Optimization by Taguchi method. Environmental Pollutions and Sustainable Urban Development, 1(1), 33. (in Persian)
[11] Airemlou, L., 2024, Synthesis of ZnO/SnO2 nanocomposite loaded with silver via liquid impregnation method and investigation of its photocatalytic activity in removing an environmental pollutant under visible light irradiation. Environmental Pollutions and Sustainable Urban Development, 1(2), 85. (in Persian)
[12] Mohammadpour Koselar, Z., Ghazi Tabatabaei, Z., 2024, Design of multifunctional photocatalysts with g-C₃N₄ and its applications in sustainable technologies. Environmental Pollutions and Sustainable Urban Development, 1(3), 29. (in Persian)
[13] Swaminaathan, P., Saravanan, A., Yaashikaa, P.R., Vickram, A.S., 2024, Recent advances in photocatalytic degradation of persistent organic pollutants: Mechanisms, challenges, and modification strategies. Sustainable Chemistry for the Environment, 8, 100171.
[14] Cahill, J.D., Furlong, E.T., Burkhardt, M.R., Kolpin, D., Anderson, L.G., 2004, Determination of pharmaceutical compounds in surface- andground-water samples by solid-phase extraction and high-performanceliquid chromatography–electrospray ionization mass spectrometry. Journal of Chromatography A, 1041, 171.
[15] Fathinia, M., Khataee, A.R., 2013 Residence time distribution analysis and optimization of photocatalysis of phenazopyridine using immobilized TiO2 nanoparticles in a rectangular photoreactor. Journal of Industrial and Engineering Chemistry, 19, 1525.
[16] Hajesmaili, A., Bahrami, Z., 2016, Mesoporous titanium dioxide nanoparticles: Synthesis, characterization and application as photocatalyst for removing of phenazopyridine, Journal of Applied Chemistry, 11(41), 91.
[17] Eskandarloo, H., Badiei, A., Behnajady, M.A., Mohammadi Ziarani, G., 2016, Ultrasonic-assisted degradation of phenazopyridine with a combination of Sm-doped ZnO nanoparticles and inorganic oxidants, Ultrasonics Sonochemistry, 28, 169.
[18] Eskandarloo, H., Badiei, A., Behnajady, M.A., Afshar, M., 2015, Enhanced photocatalytic removal of phenazopyridine by using silver-impregnated SiO2–TiO2 nanoparticles: optimization of synthesis variables, Research on Chemical Intermediates, 41, 9929.
[19] Rahimpour-Javid, A., 2024, Removal of diclofenac from aqueous media by UV/TiO2 process in a fixed-bed batch photoreactor: Optimization by response surface methodology. Environmental Pollutions and Sustainable Urban Development, 1(4), 59. (in Persian)
[20] Behnajady, M.A., Dadkhah, H., Eskandarloo H., 2018, Horizontally rotating disc recirculated-photoreactor with immobilized TiO2-P25 nanoparticles onto HDPE plate for photocatalytic removal of p-nitrophenol. Environmental Technology, 39, 1061.
[21] Dadkhah, H., Behnajady, M.A., 2017, Photooxidative removal of p-nitrophenol by UV/H2O2 process in a spinning disk photoreactor: Influence of operating parameters. Chemical and Biochemical Engineering Quarterly, 31, 361.
[22] Shargh, M., Behnajady, M.A., 2016, Optimization of photocatalytic activity of immobilized TiO2-P25 nanoparticles in the removal of phenazopyridine using response surface methodology. Russian Journal of Applied Chemistry, 89, 1544.
[23] Shargh, M., Behnajady, M.A., 2016, A high-efficient batch-recirculated photoreactor packed with immobilized TiO2-P25 nanoparticles onto glass beads for photocatalytic degradation of phenazopyridine as a pharmaceutical contaminant: Artificial neural network modeling. Water Science & Technology, 73, 2804.