Photocatalytic remediation of methylene blue using hydrothermally synthesized H-Titania and Na-Titania nanotubes

Aderemi Timothy Adeleye; Kingsley Igenepo John; Joshua O Ighalo; Samuel Ogunniyi; Comfort Abidemi Adeyanju; Adewale George Adeniyi; Mohammed Elawad; Martins O Omorogie

doi:10.1016/j.heliyon.2022.e12610

Photocatalytic remediation of methylene blue using hydrothermally synthesized H-Titania and Na-Titania nanotubes

Heliyon. 2022 Dec 23;8(12):e12610. doi: 10.1016/j.heliyon.2022.e12610. eCollection 2022 Dec.

Authors

Aderemi Timothy Adeleye^{1

2}, Kingsley Igenepo John^{2

3

4}, Joshua O Ighalo^{5

6}, Samuel Ogunniyi⁵, Comfort Abidemi Adeyanju⁵, Adewale George Adeniyi⁵, Mohammed Elawad⁷, Martins O Omorogie^{8

9}

Affiliations

¹ Global Centre for Environmental Remediation (GCER), The University of Newcastle, Callaghan, Australia.
² Organization of African Academic Doctor (OAAD), Off Kamiti Road, P. O. Box 25305000100, Nairobi, Kenya.
³ College of Science, Health, Engineering and Education, Murdoch University, Murdoch 6150, Australia.
⁴ Department of Pure and Applied Chemistry, College of Natural and Applied Sciences, Veritas University, P.M.B. 5171, Abuja, Nigeria.
⁵ Department of Chemical Engineering, University of Ilorin, P. M. B. 1515, Ilorin, Nigeria.
⁶ Department of Chemical Engineering, Nnamdi Azikiwe University, P. M. B. 5025, Awka, Nigeria.
⁷ Faculty of Materials and Chemical Engineering, Yibin University, 64400, Yibin, China.
⁸ Department of Chemical Sciences, Redeemer's University, P.M.B. 230, Ede, 232101, Nigeria.
⁹ Environmental Science and Technology Unit, African Centre of Excellence for Water and Environmental Research (ACEWATER), Redeemer's University, P.M.B. 230, Ede, 232101, Nigeria.

Abstract

Although nanotube is among the most effective morphology of Titania due to its unilateral pathway for photo-generated charge transfer and mechanical stability, its performance is still hampered by high recombination. In the present study, to further improve the photocatalytic degradation performance of Titania, univalent elements of H and Na were respectively ion-exchanged into the Titania nanotubes (TNTs). The photocatalyst was characterized using XRD, TEM, ICP-AES, and FTIR. The modified samples displayed enhanced photocatalytic degradation performance over Degussa TiO₂ under UV-A light illumination of MB. The rate constants of NaTNT and HTNT were 16 and 13 times that of Degussa TiO₂. Specifically, the Na-TNTs showed better photocatalytic degradation activity than H-TNTs with a rate constant of 0.12 min^-1 while the latter showed 0.09 min^-1. The optimum adsorption and photocatalytic performance of NaTNT were determined at pH 6 achieving about 99% MB removal within 10 min of irradiation. The ion exchange NaTNT displayed excellent reusability after the fifth cycle of the photocatalytic tests and superoxide radicals were experimentally determined to be the main reactive oxygen species involved in the photocatalytic degradation of MB.

Keywords: Environmental protection; Methylene blue; Photocatalytic degradation; Titania.