Enhancing the Photocatalytic Degradation of Ciprofloxacin Contaminant Using a Combined Laser Irradiation (285/365 nm) and Porous g-C3N4

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C.R Garcia

Abstract
This work reports the use of porous graphitic carbon nitride (g-C3N4, gCN) for the photocatalytic
degradation of ciprofloxacion (CPX) contaminant using two laser wavelengths (285/365 nm).
The simultaneous irradiation with both wavelengths promoted the total degradation of CPX
dissolved in water. First, an aqueous solution of CPX + gCN was prepared and exposed to laser
irradiation with single wavelengths of 285, 365, 405 or 532 nm and no degradation of CPX was
observed after 3 h under of continuous irradiation. The solution of CPX + gCN was also exposed
to solar irradiation using solar simulated light (Xe lamp). In this case, the maximum degradation
percentage for CPX was 68% after 3 h. Afterwards, the aqueous solution of CPX+gCN was
irradiated with combined wavelengths of 285/365 nm, 285/405 nm, 285/532 nm and maximum
degradation percentages of 100, 62 and 27% were obtained after 3 h, respectively. The complete
degradation of CPX during the simultaneous irradiation of 285/365 nm was produced by the
following mechanism: the CPX was firstly protonated (charged positively as demonstrated by
DFT simulations) due to its direct interaction with 285 nm. Secondly, OH- radicals are generated
after photoexcitation of gCN by the two wavelengths and these radicals attacked the protonated
CPX by electrostatic attraction (the presence of such radicals was demonstrated by scavenger
experiments). The results presented here demonstrated that only two wavelengths are necessary
to produce total degradation of CPX (avoiding the use of lamps with full solar spectrum), which
could be one way to design more efficient and more compact photocatalytic systems able to
degrade organic contaminants.

Artículo-CEGR 10 2020


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