SYNTHESIS AND PHOTOCATALYTIC ACTIVITY OF HIERARCHICAL FLOWER-LIKE ZNO FOR METHYLENE BLUE DEGRADATION UNDER UV LIGHT

In this study, a porous, hierarchical flower-like zinc oxide (ZnO) structure was successfully synthesized via a hydrothermal method using urea and CTAB as shape-directing agents to optimize photocatalytic efficiency for environmental remediation. Structural characterization via scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the formation of a highly crystalline, pure hexagonal wurtzite phase assembled from ultrathin nanosheet building blocks. The photocatalytic performance of the synthesized ZnO was evaluated through the degradation of methylene blue (MB) dye under UV light illumination (365 nm). The catalyst achieved a (98.7 ± 0.5)% degradation efficiency within 40 minutes, following a pseudo-first-order kinetic model with a reaction rate constant of 0.109 min-1. Optimization studies identified a catalyst dosage of 0.2 g/L as near-optimal, while coexistence tests demonstrated that the system maintains high stability and excellent removal efficiency in the presence of various competing environmental anions (Cl- , NO3 - , HCO3 - , CO3 2-). Radical scavenger investigations revealed a clear inhibition hierarchy, establishing that the degradation mechanism is predominantly driven by hydroxyl radical-mediated oxidation alongside secondary contributions from photogenerated holes. These findings highlight the prepared porous ZnO architecture as an efficient, stable, and sustainable candidate for the degradation of persistent organic pollutants in municipal wastewater.

1. Masuleh, M.T., Hasheminiasari, M., Ashiri, R. Enhanced Photocatalytic Efficiency of Eco-Friendly Synthesized ZnO for Rapid Full Degradation of Methylene Blue Dye. Materials Advances, 6(8), 2611–2621 (2025). https://doi.org/10.1039/d5ma00026b

2. Saraee, M., Maleki, B., Kikhavani, T., Mansouri, M. Investigating the Process of Photocatalytic Removal of Methylene Blue from Wastewater Utilizing ZnO-Mn-Ce/Biochar Nanocomposites under Visible Light. Iranian Journal of Chemistry and Chemical Engineering, 43(12), 4360–4377 (2024). https://doi.org/ijcce.2024.2026808.6552

3. He, X., Yang, Y., Li, Y., Chen, J., Yang, S., Liu, R., Xu, Z. Effects of Structure and Surface Properties on the Performance of ZnO towards Photocatalytic Degradation of Methylene Blue. Applied Surface Science, 599, 153898 (2022). https://doi.org/10.1016/j.apsusc.2022.153898

4. Rustembekkyzy, K., Sabyr, M., Kanafin, Y.N., Khamkhash, L., Atabaev, T.S. Microwave-Assisted Synthesis of ZnO Structures for Effective Degradation of Methylene Blue Dye under Solar Light Illumination. RSC Advances, 14(23), 16293–16299 (2024). https://doi.org/10.1039/d4ra02451f

5. Qian, S.; Bao, E.; Chen, H. Facile Preparation of Porous ZnO Microflowers with Large Surface Area. Materials Letters, 330, 133347 (2023). https://doi.org/10.1016/j.matlet.2022.133347

6. Zhu, C., and Wang, X. Nanomaterial ZnO Synthesis and Its Photocatalytic Applications: A Review. Nanomaterials, 15(9), 682 (2025). https://doi.org/10.3390/nano15090682

7. Ferreira, S.H., Morais, M., Nunes, D., Oliveira, M.J., Rovisco, A., Pimentel, A., Águas, H., Fortunato, E., Martins, R. High UV and Sunlight Photocatalytic Performance of Porous ZnO Nanostructures Synthesized by a Facile and Fast Microwave Hydrothermal Method. Materials, 14(9), 2385 (2021). https://doi.org/10.3390/ma14092385

8. Li, L., Han, L., Han, Y., Yang, Z., Su, B., Lei, Z. Preparation and Enhanced Photocatalytic Properties of 3D Nanoarchitectural ZnO Hollow Spheres with Porous Shells. Nanomaterials, 8(9), 687 (2018). https://doi.org/10.3390/nano8090687

9. Modi, S., Yadav, V.K., Amari, A., Alyami, A.Y., Gacem, A., Harharah, H.N., Fulekar, M.H. Photocatalytic Degradation of Methylene Blue Dye from Wastewater by Using Doped Zinc Oxide Nanoparticles. Water, 15(12), 2275 (2023). https://doi.org/10.3390/w15122275

10. Lei, A., Qu, B., Zhou, W., Wang, Y., Zhang, Q., Zou, B. Facile Synthesis and Enhanced Photocatalytic Activity of Hierarchical Porous ZnO Microspheres. Materials Letters, 66(1), 72–75 (2012). https://doi.org/10.1016/j.matlet.2011.08.011

11. Ejsmont, A. and Goscianska, J. Hydrothermal Synthesis of ZnO Superstructures with Controlled Morphology via Temperature and PH Optimization. Materials, 16(4), 1641 (2023). https://doi.org/10.3390/ma16041641

12. Guzmán-Carrillo, H.R., Rivera-Muñoz, E.M., Cayetano-Castro, N., Herrera-Basurto, R., BarqueraBibiano, Z., Mercader-Trejo, F., Manzano-Ramírez, A. Facile Control of ZnO Nanostructures by Varying Molar Concentration of Zinc Acetate. Materials Research Bulletin, 90, 138–144 (2017). https://doi.org/10.1016/j.materresbull.2017.02.034

13. Kadau, A.T., Kalkozova, Z.K., Gritsenko, L.V., Markhabayeva, A.A., Abdullin, K.A. Influence of Parameters of Low-Cost Synthesis Methods on Zinc Oxide Morphology. Herald of the Kazakh-British Technical University, 22(3), 290–301 (2025). https://doi.org/10.55452/1998-6688-2025-22-3-290-301

14. Kanafin, Y.N., Rustembekkyzy, K., Seiilbek, A., Kutzhanova, K., Atabaev, S., Kaikanov, M., Atabaev, T.S. ZnO/WO3 Composite for Efficient Photocatalytic Degradation of Methylene Blue Dye under Solar Light. Scientific Reports, 16, 8702 (2026). https://doi.org/10.1038/s41598-026-40207-0

15. Negash, A., Mohammed, S., Weldekirstos, H.D., Ambaye, A.D., Gashu, M. Enhanced Photocatalytic Degradation of Methylene Blue Dye Using Eco-Friendly Synthesized RGO@ZnO Nanocomposites. Scientific Reports, 13, 22234 (2023). https://doi.org/10.1038/s41598-023-48826-7

16. Khao, T.; Gembo, R.O.; Odisitse, S.; King’ondu, C.K. Fabrication of ZnO Nanoparticles Using Marula (Sclerocarya Birrea) Leaf Extract for Catalytic Degradation of Rhodamine 6 G and Methylene Blue Dyes under UV Light Irradiation. Next Materials, 7, 100366 (2025), https://doi.org/10.1016/j.nxmate.2024.100366

17. Saadi, H., Atmani, E.H., Fazouan, N. Enhanced Photocatalytic Degradation of Methylene Blue Dye by ZnO Nanoparticles: Synthesis, Characterization, and Efficiency Assessment. Environmental Progress and Sustainable Energy, 44(1), e14529 (2025). https://doi.org/10.1002/ep.14529

18. Krobthong, S., Rungsawang, T., Wongrerkdee, S. Comparison of ZnO Nanoparticles Prepared by Precipitation and Combustion for UV and Sunlight-Driven Photocatalytic Degradation of Methylene Blue. Toxics, 11(3), 266 (2023). https://doi.org/10.3390/toxics11030266

19. Atta, D., Wahab, H.A., Ibrahim, M.A., Battisha, I.K. Photocatalytic Degradation of Methylene Blue Dye by ZnO Nanoparticle Thin Films, Using Sol–Gel Technique and UV Laser Irradiation. Scientific Reports, 14, 26961 (2024). https://doi.org/10.1038/s41598-024-76938-1