Comparative Study on the Decolorization of Orange II by Zero-valence Tin in Citric and Hydrochloric Acids

Abstract

Zero-valence tin reductively degraded a persistent azo dye, Orange II to produce colorless aromatic amines. The effects of acid concentrations and initial Orange II concentrations on the decolorization of Orange II by tin in citric and hydrochloric acids were investigated. The decolorization reaction in citric acid was faster than that in hydrochloric acid at 2.5 and 5 mM acid concentrations. The faster reaction would be related to the characteristic dissolution reaction of tin in citric acid. The first-order kinetic was applicable in citric acid over the examined range of 0.1 -0.4 mM initial Orange II. However, at more than 0.2 mM initial Orange II the first-order kinetic was not applicable in hydrochloric acid and thus the relaxation first-order reaction kinetic was applied. The result that zero-valence-tin/citric acid system demonstrated successful decolorization in repeated use supports the possibility of its application for azo dye wastewater.

Biphasic reduction model for predicting the impacts of dye-bath constituents on the reduction of tris-azo dye Direct Green-1 by zero valent iron (Fe 0 )

“…These H 2 bubbles can cause convection in the system providing better mixing conditions which may facilitate removal of iron-organic acid complexes from the iron surface active sites, thus, improving dye reduction rate (Nishide and Shoda, 2012). Also, this H 2 gas may itself act as a reducing agent depending on the surface condition of Fe 0 (Siantar et al, 1996;Bruzzoni et al, 2000).…”

Homogeneous Palladium Nanoparticles Surface Hosts Catalyzed Reduction of the Chromophoric Azo (-N=N-) Group of Dye, Acid Orange 7 by Borohydride in Alkaline Media

“…Since most of the biochemical and biophysical processes require a large amount of adsorbents along with other means, such as intricate reactors and intensive power supply , researchers have put much emphasis on the chemistry of different metals or metal composites (containing mostly iron, nickel, copper, etc.) mediated reduction of azo dyes . Although these reduction processes are efficient but one serious concern lies in the usual practice of large usage of metal dosages, which generate metal sludge as secondary wastes .…”

“…mediated reduction of azo dyes [36][37][38][39][40][41][42]. Although these reduction processes are efficient but one serious concern lies in the usual practice of large usage of metal dosages, which generate metal sludge as secondary wastes [31].…”

“…To confront this major challenge to degrade these wastewater pollutants, different biochemical and physiochemical techniques, mainly fungal and bacterial decomposition [19][20][21], enzymatic degradation [22], coagulation [23,24], adsorption [25][26][27], photocatalytic oxidation [28][29][30], Fenton oxidation [30][31][32][33], advanced oxidation processes [34,35], and chemical reduction [36][37][38][39][40][41][42], have been frequently employed to decolorize and scavenge these colorants from waste water.…”