Study on preparation of UV-CDs/Zeolite-4A/TiO2 composite photocatalyst coupled with ultraviolet-irradiation and their application of photocatalytic degradation of dyes

Jiaqi Guo; Yuping Fan; Xianshu Dong; Hongbo Zeng; Xiaomin Ma; Yuanpeng Fu

doi:10.1016/j.jenvman.2024.120342

Study on preparation of UV-CDs/Zeolite-4A/TiO₂ composite photocatalyst coupled with ultraviolet-irradiation and their application of photocatalytic degradation of dyes

J Environ Manage. 2024 Mar:354:120342. doi: 10.1016/j.jenvman.2024.120342. Epub 2024 Feb 20.

Authors

Jiaqi Guo¹, Yuping Fan², Xianshu Dong³, Hongbo Zeng⁴, Xiaomin Ma², Yuanpeng Fu²

Affiliations

¹ College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
² College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China.
³ College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China. Electronic address: dongxianshu@tyut.edu.cn.
⁴ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada. Electronic address: hongbo.zeng@ualberta.ca.

PMID: 38382431
DOI: 10.1016/j.jenvman.2024.120342

Abstract

In this work, ultraviolet irradiation was employed to assist in the preparation of a novel photocatalyst composite in the form of carbon dots/zeolite-4A/TiO₂, using coal tailings as the source of silicon-aluminum and carbon. The composite was designed for the degradation of methylene blue under 500 W of UV light irradiation. Zeolite-4A was used as a support for the well-dispersed carbon dots and TiO₂ nanoparticles. The as-prepared composites were subjected to thorough characterization, confirming the successful formation of zeolite-4A with a cube structure, along with the loading of TiO₂ and coal-based CDs in the composites. The experimental results demonstrated that the UV-CZTs nanocomposites exhibited a remarkable removal efficiency of 90.63% within 90 min for MB. The corresponding rate constant was exceptionally high at 0.0331 min^-1, surpassing that of the Dark-CZTs and pure TiO₂. This significant enhancement was possibly due to the synergistic effect of adsorption photocatalysis of the UV-CZTs, combined with the excellent electron-accepting capabilities of the coal-based CDs, which led to highly improved charge separation. An investigation of the spent photocatalyst's recyclability revealed that it retained a remarkable 82.94% MB removal efficiency after five consecutive cycles, signifying the stability of the composite. Trapping experiments also elucidated the primary reactive species responsible for MB degradation, which were identified as photo-generated holes and ⸱O₂^- species. By this process, the hydroxyl radicals generated in the system successfully promoted the transformation of coal tailings to coal-based zeolite and coal-based CDs. Coal-based zeolite served as an excellent carrier of titanium dioxide, which improved its dispersibility. The inhibition of e^--h⁺ recombination of titanium dioxide by introducing coal-based CDs improved the photocatalytic ability of titanium dioxide. Through this study, coal tailings, as a coal processing waste, were transformed into high-value materials, and relevant photocatalytic composite materials could be prepared with broad application prospects.

Keywords: Carbon dots; Methylene blue removal; TiO(2); UV-Irradiation; Zeolite-4A.

MeSH terms

Carbon
Catalysis
Coal
Coloring Agents
Titanium / chemistry
Ultraviolet Rays*
Zeolites* / chemistry

Substances

titanium dioxide
Coloring Agents
Zeolites
Titanium
Coal
Carbon