Removal of malachite green dye from contaminated aqueous solutions using WO₃/Eu₂O₃-visible-light-assisted photocatalysis

ABSTRACT

Aqueous solutions contaminated with malachite green (MG) organic water-soluble dye were treated with a series of novel europium oxide-doped tungsten oxide photocatalysts (WO₃/Eu₂O₃) under visible light illumination. First, the photocatalyst series was prepared via a simple preparation procedure. Second, the produced photocatalyst series was investigated using different physical characterisation techniques, including: XRD, FTIR, FESEM, EDX and diffuse reflectance (DR). Characterisation results confirmed the successful and homogeneous doping of europium oxide particles within tungsten oxide. As a result, the photocatalytic activity of the synthesised Eu-doped WO₃ samples was assessed at 425 nm. Finally, malachite green contaminated aqueous samples were treated with both un-doped- and doped-tungsten oxide photocatalysts under visible light illumination. Results indicate that doping of tungsten oxide with just 1 mole% europium oxide enhanced the photocatalytic activity of the doped-tungsten oxide, compared with the un-doped photocatalyst, by 4 folds, from 10% to 40%, with a slight decrease in the photocatalysts band-gap energies from 2.76 to 2.65 eV. The first-order rate constants for the photocatalysis of malachite green dye using samples W1-W4 were calculated to be 0.13, 0.61, 0.55, and 0.5, respectively.

KEYWORDS:

• Organic dye removal
• contaminated aqueous solutions
• photocatalysis
• tungsten oxide
• europium oxide-doping

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through General Research Project under grant number (G.R.P-114-40).