Degradation of Organic
Dyes via Bismuth Silver Oxide
Initiated Direct Oxidation Coupled with Sodium Bismuthate Based Visible
Light Photocatalysis
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Abstract
Organic dye degradation was achieved via direct oxidation
by bismuth
silver oxide coupled with visible light photocatalysis by sodium bismuthate.
Crystal violet dye decomposition by each reagent proceeded via two
distinct pathways, each involving different active oxygen species.
A comparison of each treatment method alone and in combination demonstrated
that using the combined methods in sequence achieved a higher degree
of degradation, and especially mineralization, than that obtained
using either method alone. In the combined process direct oxidation
acts as a pretreatment to rapidly bleach the dye solution which substantially
facilitates subsequent visible light photocatalytic processes. The
integrated sequential direct oxidation and visible light photocatalysis
are complementary manifesting <i>a</i> > 100% increase
in
TOC removal, compared to either isolated method. The combined process
is proposed as a novel and effective technology based on one primary
material, sodium bismuthate, for treating wastewaters contaminated
by high concentrations of organic dyes