ENHANCED PHOTODEGRADATION OF METHYL ORANGE VIA TiO₂/g-C₃N₄ PHOTOCATALYST UNDER LOW-INTENSITY UVC IRRADIATION

Muhammad Aqil Asyraaf Mohd Mahadi; Nurul Amirah Abdullah; Hamizah Mokhtar; Hartini Ahmad Rafaie; Sazlinda Kamaruzaman; Umar Kalmar Nizar; Zul Adlan Mohd Hir

Muhammad Aqil Asyraaf Mohd Mahadi Faculty of Applied Sciences, Universiti Teknologi MARA Pahang Branch, 26400 Bandar Tun Abdul Razak Jengka, Pahang, Malaysia.
Nurul Amirah Abdullah Faculty of Applied Sciences, Universiti Teknologi MARA Pahang Branch, 26400 Bandar Tun Abdul Razak Jengka, Pahang, Malaysia.
Hamizah Mokhtar Faculty of Applied Sciences, Universiti Teknologi MARA Pahang Branch, 26400 Bandar Tun Abdul Razak Jengka, Pahang, Malaysia.
Hartini Ahmad Rafaie Centre of Foundation Studies, Universiti Teknologi MARA Selangor Branch, Dengkil Campus, 43800 Dengkil, Selangor, Malaysia.
Sazlinda Kamaruzaman Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
Umar Kalmar Nizar Chemistry Department, Universitas Negeri Padang, West Sumatra, Indonesia.
Zul Adlan Mohd Hir Faculty of Applied Sciences, Universiti Teknologi MARA Cawangan Pahang, 26400 Bandar Tun Abdul Razak Jengka, Pahang, Malaysia

Keywords: Graphitic carbon nitride, methyl orange, photocatalysis, titanium dioxide, water remediation

Abstract

Synthetic anionic azo dyes, such as methyl orange (MO), represent substantial environmental issues because of their persistence and toxicity in water ecosystems. The presence of this dye in water bodies tends to pose significant risks to human health and the ecological systems under long-term exposure. Previous research has shown that the synergistic heterojunction formation between TiO₂ and g-C₃N₄ may reduce electron-hole recombination rate and enable the material to absorb more light, due to its extended absorption range, hence, significantly improving photoactivity. Thus, in the present work, TiO₂/g-C₃N₄ composite photocatalysts were prepared via a facile mixing procedure, with varying g-C₃N₄ ratios. The photodegradation performance was evaluated against the MO dye under a very low UVC light intensity (9 W). The surface morphology, composition, functional groups, recombination behaviours and band gap energy were characterised using SEM-EDX, FTIR, PL and UV-Vis-NIR, respectively. The fabrication of TiO₂/g-C₃N₄ composites has resulted in a significant enhancement in the photodegradation performance of pure TiO₂and g-C₃N₄. The TiO₂/g-C₃N₄ with a ratio of 0.5:0.15 (TG2) demonstrated a rapid removal efficiency (~72 %) within 180 min under normal conditions, which was 1.4 times higher than that of pure TiO₂. The enhanced photoactivities were attributed to the outstanding separation of charge carriers (e_CB^-/h_VB⁺) as demonstrated by the band gap and photoluminescence spectra studies. The kinetic display pseudo-first-order kinetics with a rate constant of 7.3 × 10^-3 min^-1. This work revealed that the TiO₂/g-C₃N₄ composite photocatalysts exhibit promising potential for degrading dye molecules via the heterojunction mechanism.