Azo dye degradation by recycled waste zero-valent iron powder

Abstract

Neste trabalho é apresentado um método eficiente para a degradação de corantes, usando uma fonte de pó de ferro zero ambientalmente amigável (resíduo de um processo industrial). A influência de vários fatores experimentais (tais como: pH, massa de ferro, tamanho de partícula, concentração do substrato, atmosfera inerte ou oxidante) sobre a eficiência do ferro zero em reduzir o grupo cromóforo e o teor de carbono orgânico total de um azocorante (Preto Remazol B) foi avaliada. O processo de degradação do corante apresentou uma cinética de primeira ordem com uma constante de 0,153 min -1 . Nas condições otimizadas (pH=3, [Fe] = 5 g L -1 , tamanho de partícula ≤ 250 μm), este processo promoveu uma descoloração de 95% e redução de 70% na concentração de carbono orgânico total de uma solução 100 mg L -1 do corante. Este processo também foi empregado na degradação de um efluente industrial têxtil apresentando bons resultados e demonstrando capacidade para ser uma alternativa para a remediação de sistemas aquáticos poluídos.In this paper an efficient method for azo dye degradation using an environmentally friendly zero-valent iron powder source is presented (iron particles discarded from a manufacturing process). The influence of several experimental parameters (such as pH, iron mass, particle size, substrate concentration, oxidizing and inert atmospheres) on the ability of zero-valent iron to reduce the chromophoric groups and total organic carbon content of the azo dye Remazol Black B was evaluated. Kinetic studies revealed that the azo degradation by Fe 0 appeared to be first-order with respect to substrate, with an observed rate constant (k obs ) of 0.153 min -1 . Under the optimized operational conditions (pH 3, [Fe] = 5 g L -1 , iron particle size ≤ 250 μm), the iron-based process produced net a reduction in color and total organic carbon of about 95% and 70%, respectively. The process was also evaluated for the degradation of textile effluent. The studied process showed good characteristics, which can make it an effective alternative for polluted aquatic system remediation.Keywords: reductive degradation process, dye degradation, effluent treatment, Fenton´s reagent IntroductionOver the last decades, the increasing demand for dyes by the textile industry has shown a high pollutant potential. It is estimated that around 10 -15% of the dyes are lost in the effluent during the dyeing processes. 1,2 The discharge of highly colored synthetic dye effluents can be very damaging to the receiving water bodies, since these dyes in the water strongly absorb sunlight, which decreases the intensity of light absorbed by water plants and phytoplankton, reducing photosynthesis and the oxygenation of water reservoirs. 3 Also, public perception of water quality is greatly influenced by its color. The presence of unnatural colors is esthetically unpleasant and tends to be associated with contamination. 4 In addition, dyes used in the textile industry may be toxic to aquatic organisms and can be resistant to natural biological deg...

Dynamic and equilibrium studies of the RDX removal from soil using CMC-coated zerovalent iron nanoparticles

“…The degradation reaction stops when all the available Fe(0) is consumed. This finding also agrees with the results obtained by Pereira and Freire (2006) when using ZVI for azo dye removal in aqueous solution. The Fe/RDX molar ratio of 55 resulted in 90% RDX removal.…”

Degradation of food dyes by zero-valent metals exposed to ultrasonic irradiation in water medium: optimization and electrospray ionization mass spectrometry monitoring

“…[12][13][14][15][16][17][18] Several metals (such as Zn, Sn, Pt) can be used as reduction agents, but iron has received the foremost emphasis due to its high efficiency in addition to its low cost and toxicity. [19][20][21][22][23][24][25][26][27][28][29] Mass spectrometry (MS) has been used for a long time for the measurement of isotopes and to determine the structure of organic molecules. Currently the major advances in mass spectrometry have occurred in the ionization sources.…”

Rapid decolorization of water soluble azo-dyes by nanosized zero-valent iron immobilized on the exchange resin

“…Zero valent iron (ZVI), an environmentally friendly strong reducing agent, has been widely studied for environmental remediation in recent years. Now, it has been used in treating and remedying waste waters contaminated with chlorinated compounds [8,9] , nitro aromatic compounds [10] , nitrates [11] and heavy metals [12] , and even for the deoxidization of more complex anthropogenic chemicals including pesticides [13] and dyes [14][15][16][17][18][19] . Among these compounds, azo dyes are easier to be deoxidized than to be oxidized.…”