Browsing by Author "de Luna, Mark Daniel G."

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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
(2019-06-15)
de Luna, Mark Daniel G.
;
Paragas, Larah Kriselle B.
;
Doong, Ruey-An
;
環境工程研究所
;
Institute of Environmental Engineering
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-, SO42-, Cl-, PO43-) on SMX removal were also examined. Lastly, the mechanism of SMX photodegradation was elucidated. (C) 2019 Elsevier B.V. All rights reserved.
Rapid removal of sulfamethoxazole from simulated water matrix by visible-light responsive iodine and potassium co-doped graphitic carbon nitride photocatalysts
(2018-11-01)
Paragas, Larah Kriselle B.
;
de Luna, Mark Daniel G.
;
Doong, Ruey-An
;
環境工程研究所
;
Institute of Environmental Engineering
An environment-friendly iodine and potassium co-doped g-C3N4 (IK-C3N4) photocatalyst was synthesized via the co-pyrolysis of urea and potassium iodate. Various characterization techniques were employed to evaluate the physical, thermal and chemical characteristics of the as-synthesized photo catalyst. Sulfamethoxazole (SMX) was used as a representative antibiotic pollutant. SMX removal by IK-C3N4 photocatalysts exceeded 99% (similar to 23 times higher than that of pure g-C3N4) within 45 min of visible light irradiation. The kinetics of SMX removal was analyzed with respect to solution pH, photocatalyst dosage and initial SMX concentration. Experimental data was found to fit the pseudo-first order kinetics and the Langmuir-Hinshelwood kinetics. The reuse of the photocatalyst up to 3 consecutive photo degradation cycles gave a minimal decline in SMX removal while the structure and the crystallinity of the nanomaterials remained unchanged. Overall, morphology engineering of conventional bulk graphitic carbon nitride can produce highly efficient photocatalysts for the decontamination of antibiotics in the aqueous environment. (C) 2018 Elsevier Ltd. All rights reserved.