Visible light response photocatalytic activity appreciably enhanced by Dy incorporated KBiFe2O5 brownmillerite: An approach for wastewater remediation

Abstract

Dye effluents released from various factories and industries cause environmental contamination as well as health hazards, so it is highly necessary to take care of these issues. This work emphasizes the effective photodegradation of methylene blue (MB), a widely used industrial dye in Dy substituted KBiFe₂O₅. KBiFe₂O₅ is a brownmillerite structured promising multiferroic photoactive material favorable for photocatalytic and photovoltaic application. Solid state reaction method is adopted to synthesize Dy doped KBiFe₂O₅ (KBi_1-xDy_xFe₂O₅ (x = 0, 0.05, 0.075, 0.1)) and XRD analysis confirms the monoclinic structure with P2/c space group of the materials. Isothermal magnetic measurement reveals that magnetic moment increases with Dy incorporation by suppressing the canted spin structure of the pure compound. Through rigorous optimization, the photocatalytic performance of doped sample is enhanced from 72 % to 97 % MB degradation efficiency under direct sunlight in 180 min. Photo-generated holes are the primary active species for the degradation of MB in all samples. The enhancements in photocatalytic efficiency is ascribed to increased active sites, reduction in both particle size as well as pore diameter and band gap modification. The photodegradation of MB is also achieved around 90 % efficiency of 5 %-Dy doped KBiFe₂O₅ upon testing in river water as an industrial application.