Insights into the rapid elimination of antibiotics from aqueous media by tunable C3N4 photocatalysts: Effects of dopant amount, co-existing ions and reactive oxygen species

Mark Daniel G de Luna; Larah Kriselle B Paragas; Ruey-An Doong

doi:10.1016/j.scitotenv.2019.03.003

Insights into the rapid elimination of antibiotics from aqueous media by tunable C₃N₄ photocatalysts: Effects of dopant amount, co-existing ions and reactive oxygen species

Sci Total Environ. 2019 Jun 15:669:1053-1061. doi: 10.1016/j.scitotenv.2019.03.003. Epub 2019 Mar 1.

Authors

Mark Daniel G de Luna¹, Larah Kriselle B Paragas², Ruey-An Doong³

Affiliations

¹ Department of Chemical Engineering, College of Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines; Environmental Engineering Program, National Graduate School of Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines. Electronic address: mgdeluna@up.edu.ph.
² Environmental Engineering Program, National Graduate School of Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines.
³ Institute of Environmental Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan; Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan. Electronic address: radoong@nctu.edu.tw.

PMID: 30970454
DOI: 10.1016/j.scitotenv.2019.03.003

Abstract

Conventional photocatalytic nanomaterials are not environmentally sustainable since these are usually produced from scarce mineral and metal precursors. Moreover, high pollutant removal efficiencies by conventional photocatalysts are only attained after several hours of reaction with light. In this study, novel visible light-active photocatalysts were synthesized from environment-friendly carbon precursors and applied for the rapid degradation of sulfamethoxazole (SMX) in aqueous solutions. The photocatalysts were prepared via the co-pyrolysis of urea with varying doping temperature and dopant amount. These variations played a vital role in improving the performance of the photocatalysts and resulted in up to >99% SMX removal within 45 min of visible light irradiation. Characterization of the photocatalysts showed that potassium and iodine dopants were responsible in the red shift and broadening of the light absorption spectrum to the visible region. In addition, the band gap energy narrowed by 0.23 eV resulting in faster charge transfer but slower recombination of the photo-generated electron and hole pairs. Effects of varying concentrations of inorganic salts (NO₃^-, SO₄^2-, Cl^-, PO₄^3-) on SMX removal were also examined. Lastly, the mechanism of SMX photodegradation was elucidated.

Keywords: Antibiotics; Heterogeneous catalysis; Pharmaceuticals; Photocatalytic degradation; Sustainable nanomaterials; Wastewater treatment.

MeSH terms

Anti-Bacterial Agents / analysis*
Environmental Restoration and Remediation / methods*
Ions / chemistry
Nitriles / chemistry*
Photolysis*
Reactive Oxygen Species / chemistry*
Water Pollutants, Chemical / analysis*

Substances

Anti-Bacterial Agents
Ions
Nitriles
Reactive Oxygen Species
Water Pollutants, Chemical
cyanogen