Efficient Oxidative Degradation of Azo Dyes by a Water‐Soluble Manganese Porphyrin Catalyst

Abstract

Dyes in wastewater severely affect the nature and quality of water by inhibiting the sunlight penetration into the stream, which thereby reduces the photosynthesis reaction. This poses a serious environmental threat in many developing countries. Recently, new methods for the treatment of colored dye effluent streams have attracted much attention. The [MnIII(tmpyp)]/H2O2 system (tmpyp=meso‐tetrakis(1‐methylpyridinium‐4‐yl)porphyrinato) was now found to degrade various azo dyes with remarkably high efficiency under ambient conditions in aqueous solution at certain pH values. Main products of the catalytic degradation of the dye amaranth by [MnIII(tmpyp)]/H2O2 were analyzed. The reaction mechanism was studied in more detail by using rapid‐scan stopped‐flow spectrophotometry as a function of pH, [catalyst], [H2O2], [dye], and [surfactants]. Spectral analyses and kinetic data suggested rapid formation of an intermediate [MnIII(tmpyp)(OOH)] (a compound 0‐type intermediate), followed by the formation of a relatively stable trans‐dioxomanganese(V) porphyrin complex, [MnV(O)2(tmpyp)] (a compound I analog). The one‐electron reduction of [MnV(O)2(tmpyp)] to [MnIV(O)(tmpyp)] (a compound II analog) was accelerated greatly by amaranth. On the basis of the kinetic and spectroscopic data, a reaction mechanism of the formation of reactive intermediates [MnIII(tmpyp)(OOH)], [MnV(O)2(tmpyp)], and [MnIV(O)(tmpyp)] was proposed.

Kinetics, Isotherm and Thermodynamic Studies of the Adsorption of Reactive Red 239 Dye from Aqueous Solution by Chitosan 8B

“…Rapid industrialization has led to increased various types of pollutants into aq- nogenic [2] [3]. Numerous technologies, such as adsorption [4] [5] [6] [7], membrane filtration [8], coagulation [9], ozonation [10], advanced chemical oxidation [11] [12], and biological processes [13], have been developed and applied worldwide for the scavenging and/or degradation of dyestuff wastewater.…”

Immobilized Lignin Peroxidase-Like Metalloporphyrins as Reusable Catalysts in Oxidative Bleaching of Industrial Dyes

“…A huge amount of papers reports the catalytic activity of metalloporphyrins in homogenous phase [33,127,136,137,138,139], even in the context of the treatment of textile dyes [140,141]. However, the heterogenization of the catalyst is a striking priority for the feasibility of a large scale process [29,142].…”

“…Acid Red 27 (amaranth, Scheme 13), once used as a food dye but withdrawn for its noticeable toxicity, has been recently studied [140] as the substrate for oxidation by H 2 O 2 in aqueous solution, in the presence of the Mn(III) complex of 5,10,15,20-tetrakis(1-methylpyridinium-4-yl) porphyrin MnT4MPyP. First, the mechanism of hydrogen peroxide with this cationic Mn porphyrin was studied.…”

Rational design of heme enzymes for biodegradation of pollutants toward a green future

“…To date, several physical and chemical methods have been developed for pollution controls of industrial dyes and halophenols, such as photo-induced degradation and chemical treatments [2,[5][6][7]. Meanwhile, their applications were limited due to the high costs and generation of secondary pollutions.…”