Mordant Yellow 10 Research Articles

Integrated bio-chemo degradation of Mordant Yellow 10 using upflow anaerobic packed bed reactor (UAPBR) and tray type photo-Fenton reactor (TPFR)

Feasibility of the two stage anaerobic/photo-Fenton process to mineralize a mono-azo dye, Mordant Yellow 10 (MY10) in continuous mode of operation was demonstrated using an upflow anaerobic packed bed reactor (UAPBR) and a novelly-designed tray type photo-Fenton reactor (TPFR). The halotolerant Pseudomonas aeroginosa BRPO3 strain used in the UAPBR system demonstrated stable dye decolorization with almost 99% of dye removal efficiency up to 220 mg/L of dye concentration supported by glucose as co-substrate operated at 24 h retention time. Maximum dye removal rate was observed to be 933 ± 8 mg/day at 200 mg/L of dye concentration. The amines formed in the UAPBR were degraded almost completely (99%) using hydrogen peroxide (340 mM) in TPFR packed with iron shavings as the catalyst. Ecogenotoxicity studies with earthworm Eisenia fetida using alkaline comet assay revealed that the untreated and bio-treated dye water induced DNA damage in coelomocytes of earthworm whereas sequentially treated solution did not induce damage even after 72 h of exposure. This is probably the first study to investigate the detoxification efficiency of sequential treatment systems operated in continuous mode.

Fe0 catalyzed photo-Fenton process to detoxify the biodegraded products of azo dye Mordant Yellow 10

Inspired by the efficiency of the photo-Fenton process on oxidation of organic pollutants, we herein present the feasibility of visible light driven photo-Fenton process as a post treatment of biological method for the effective degradation and detoxification of monoazo dye Mordant Yellow 10 (MY10). Anaerobic degradation of MY10 by Pseudomonas aeroginosa formed aromatic amines which were further degraded in the subsequent Fe catalyzed photo-Fenton process carried out at pH 3.0, with iron shavings and H2O2 under blue LED light illumination. LC-MS and stoichiometric analysis confirmed that reductive azo bond cleavage was the major reaction in anaerobic bacterial degradation of MY10 producing 4-amino benzene sulfonic acid (4-ABS) and 5-amino salicylic acid (5-ASA) which were further degraded into hydroxyl amines, nitroso and di/tri carboxylic acids by the photo-Fenton process. Toxicity studies with human small cell lung cancer A549 cells provide evidence that incorporation of Fe0 catalyzed photo-Fenton step after anaerobic bacterial treatment improved the mineralization and detoxification of MY10 dye.

Carbon based materials as novel redox mediators for dye wastewater biodegradation

Due to their large-scale production and extensive application, dyes have turned serious pollutants when improperly handled and disposed, creating grave public health and environmental problems. One of the problems that textile industry is facing is related with the incomplete exhaustion of dyes onto textile fibres from an aqueous dyeing process, and the need to implement innovative and sustainable effluent treatment methods to remove colour. Additionally, legislation on the limits of colour discharge has turn increasingly rigid. Biological treatment systems have been shown as promising technologies. The main limiting factor of the reductive transformations by anaerobic sludge is the electron transfer, a slow process. This limitation can be overcome by making use of redox mediators, which are compounds that accelerate the electron transfer from a primary electron donor to a terminal electron acceptor, to speed up the process. Activated carbon (AC) has been shown as a feasible redox mediator. Samples of microporous thermal treated AC (ACH2) and mesoporous carbons: xerogels (CXA, CXB) and carbon nanotubes (CNT) were tested on azo dye and textile wastewater biodegradation. ∼85% Mordant Yellow 10 (MY10) and 70% of Reactive Red 120 (RR120) colour removal was obtained with all the carbon materials. Acid Orange 10 (AO10) is not biodegraded in the absence of carbon materials, but with CXB and CNT a 98% of colour removal was achieved. For MY10 and RR120, rates increased in the order: control<ACH2<CXA<CXB<CNT. HPLC analysis confirmed the reduction of dyes with the formation of corresponding aromatic amines. The effect of CNT was also observed in the biological treatment of real textile wastewaters.

Treatment of organic pollutants in water using TiO2 powders: photocatalysis versus sonocatalysis

The scope of this work was to explore the application of different TiO2 powders (P25, PC105, PC500 and their calcined forms) for the photocatalytic and sonocatalytic treatment of model wastewaters containing single pollutants and their mixtures; dyes: C.I. Reactive Violet 2 (RV2), C.I. Mordant Yellow 10 (MY10) and oxalic acid. The influence of the applied catalyst type on the photocatalytic and sonocatalytic efficiency was explored with the emphasis on crystalline form and granulometric properties of powders. Generally, TiO2 powders, which were applied as obtained, demonstrated higher photocatalytic activity (~20 % of organic content oxidized in the mixture of dyes and oxalic acid in 30 min) while their calcined forms were shown to be more prominent as sonocatalysts (up to 13 % of organic contents oxidized in 30 min). The XRD analysis of calcined TiO2 powders confirmed the predominant crystal form of rutile. The degradation and mineralization kinetics of dyes RV2, MY10, oxalic acid and their mixtures was studied. In general, experimental results fitted well (R2 > 0.94) to the half and first order reaction rate model, pointing at the two ongoing mechanisms, i.e. reaction with ·OH radicals and direct electron transfer between adsorbed molecules and catalyst surface. A certain deviation is observed for the model solution containing dye MY10. MY10 serve as a filter for the UV-A irradiation (λmax = 365 nm). A detailed kinetic study confirmed the two simultaneous kinetic pathways and the comparable mechanisms for oxalic acid and dyes photocatalysis. The performed study confirmed the similarity of occurring mechanisms in photocatalysis and sonocatalysis due to sonoluminescence, with the extent of acoustic cavitation in ·OH radical generation.

DFT Study of Binding and Electron Transfer from a Metal-Free Dye with Carboxyl, Hydroxyl, and Sulfonic Anchors to a Titanium Dioxide Nanocluster

We report results of density functional theory (DFT) calculations of a metal-free dye, 5-(4-sulfophenylazo)salicylic acid disodium salt, known as Mordant Yellow 10 (MY-10), used as sensitizer for TiO2dye-sensitized solar cells (DSSCs). Given the need to better understand the behavior of the dyes adsorbed on the TiO2nanoparticle, we studied various single and double deprotonated forms of the dye bound to a TiO2cluster, taking advantage of the presence of the carboxyl, hydroxyl, and sulfonic groups as possible anchors. We discuss various binding configurations to the TiO2substrate and the charge transfer from the pigment to the oxide by means of DFT calculations. In agreement with other reports, we find that the carboxyl group tends to bind in bidentate bridging configurations. The salicylate uses both the carboxyl and hydroxyl substituent groups for either a tridentate binding to adjacent Ti(IV) ions or a bidentate Ti-O binding together with an O-H-O binding, due to the rotation of the carboxyl group out of the plane of the dye. The sulfonic group prefers a tridentate binding. We analyze the propensity for electron transfer of the various dyes and find that for MY-10, as a function of the anchor group, the DSSC performance decreases in the order hydroxyl + carboxyl &gt; carboxyl &gt; sulfonate.

Role of energy level alignment in solar cells sensitized with a metal‐free organic dye: A combined experimental and theoretical approach

AbstractWe report results of combined experimental and theoretical studies of dye‐sensitized solar cells (DSSCs) using 5‐(4‐sulfophenylazo)salicylic acid disodium salt, known as Mordant Yellow 10 (MY‐10), as TiO2 sensitizer. We focus on a single dye but vary the solvent and the pH of the solution as well as the photoelectrode preparation conditions to determine the conditions for best photovoltaic conversion efficiency. We found experimentally that the efficiency, measured under standard air mass 1.5 global (AM 1.5G) conditions, was higher in solutions of ethanol than of water, but still small (up to 0.174%), although the fill factor (FF) was large (up to 0.73). Of the dyes in ethanol, MY‐10 in alkaline solution showed the best matching of the solar spectrum but displayed the lowest efficiency. Density functional theory (DFT) calculations provided the optimized geometry, electronic structure, and electronic spectrum of the dye in fully protonated as well as partially and totally deprotonated forms, in solution. The calculated optical spectra are consistent with the experimental data, with strong absorption in the visible range only for the alkaline dye solution. The low device efficiency is very likely related to the weak optical absorption in the visible range. The much higher photovoltaic conversion efficiency of the DSSCs fabricated using acid or roughly neutral pH solutions, corresponding to the protonated and partially deprotonated forms of MY‐10, respectively, is likely caused by the better alignment of the ground state of the dye with the redox level of the electrolyte. The decrease with pH of the dye solution of the short‐circuit current was linked to a weaker charge injection from the excited state of the dye to the conduction band of the oxide, which is correlated with the shifting of the excited state of the dye deeper into the CB edge of the semiconductor. The variation of the open‐circuit voltage with the pH of the solution was linked to the adjustment of the conduction band edge of TiO2, depending on the number of protons transferred from the dye to the oxide surface. Based on our results, we analyze the relative importance of the main criteria that should be met by a dye to be used in a DSSC.

Photo-oxidation of Mordant Yellow 10 in aqueous dispersions of ferrihydrite and H 2O 2

To investigate the effect of ferrihydrite on the degradation of azo dyes, Mordant Yellow 10 (MY10) was selected as a model azo dye. The photodegradation of MY10 was studied in the presence of both ferrihydrite and hydrogen peroxide under UV irradiation. The results showed that no degradation of MY10 was detected in the H 2O 2/UV system without ferrihydrite. When a small amount of ferrihydrite (0.5 g L −1) was introduced into the reaction system, it was found that the degradation of MY10 with H 2O 2 occurred even in the dark, and UV irradiation could significantly accelerate the degradation rate. Hydroxyl radicals ( OH) generated through the catalytic decomposition of H 2O 2 by ferrihydrite play a major role in the oxidation of MY10. In addition, the effect of key operating parameters such as initial pH of the solutions, initial concentration of H 2O 2 and temperature was studied on the photo-oxidation of the dye. The results indicated that the degradation rates increase with decreasing initial pH values (from 9 to 3) and increasing concentration of H 2O 2 (from 1 to 5 mM) and temperature (from 288 to 318 K).

The microstructure of ferrihydrite and its catalytic reactivity

Ferrihydrites were prepared by different mixing procedures of ferric and sodium hydroxide solutions. The microstructure of ferrihydrites was characterized by XRD, TG-DTA, BET surface and EXAFS. The catalytic activity of ferrihydrites toward degradation of Mordant Yellow 10 (MY10) and decomposition of hydrogen peroxide was evaluated. The results show that ferrihydrites, prepared by different procedures, display various physico-chemical properties, which can be well explained by the standard multiphase structural model of ferrihydrite.

Modeling the mineralization and discoloration in colored systems by (US)Fe 2+/H 2O 2/S 2O 82− processes: A proposed degradation pathway

The scope of this experimental research was to study the kinetics of dye mineralization and discoloration in miscellaneous dye systems by advanced Fenton degradation, Fe 2+/H 2O 2/S 2O 8 2−, with and without ultrasound (US) employment. Reactive azo dye C.I. Reactive Violet 2 (RV2) and C.I. Reactive Yellow 3 (RY3) as well as mordant azo dye C.I. Mordant Yellow 10 (MY10) were used as model pollutants for composition of 7 different types of model dye wastewater, i.e. MY10, RV2, RY3, MY10 + RV2, MY10 + RY3, RV2 + RY3 and MY10 + RV2 + RY3 in the concentration of 50 mg L −1. The molar ratio of Fe 2+, H 2O 2 and K 2S 2O 8 (equimolar) of 1:5 was used, since it was shown as optimal. Mineralization of studied systems was enhanced by simultaneous application of Fenton and US. Mineralization extents obtained after 60 min of treatment varied from minimal 49% for RV2 + RY3 system up to maximal 73% for MY10 + RV2 + RY3 system. Almost 100% of discoloration was achieved in all studied systems within few minutes of applied process. A degradation pathway of studied azo dyes was proposed and 14 variations of mathematical model describing each system and particular process have been developed.

Influence of iron on degradation of organic dyes in corona

In this work application of AOPs such as Fenton process, aqueous phase high voltage electrical discharge (corona) and their combination have been studied for colored wastewater treatment. Experiments were conducted on water solutions of four different organic dyes, two azo dyes C.I. Mordant Yellow 10 (MY10) and C.I. Direct Orange 39 (DO39), and two reactive of azo type C.I. Reactive Red 45 (RR45) and C.I. Reactive Blue 137 (RB137). The efficiency of studied AOPs has been estimated on the bases of UV–vis spectrophotometric and TOC measurements. The rate constants in the kinetic model have been determined. Experimental data have been compared with the developed mathematical model.

Riboflavin as a redox mediator accelerating the reduction of the azo dye Mordant Yellow 10 by anaerobic granular sludge

Azo dyes are important persistent pollutants of textile industry effluents. Reduction of these dyes to their corresponding aromatic amines under anaerobic conditions can be used to initiate biodegradation. Since electron transfer is suggested to be rate limiting, redox mediators are being considered to improve dye reduction kinetics. This study evaluates the use of riboflavin, the redox active moiety of common occurring enzyme cofactors, as a redox mediator to accelerate the reduction of the azo dye, mordant yellow 10 (MY10). Dye reduction was found to follow zero order kinetics, the total rate constant (Vtotal) could be separated into two components: the rate of reduction due to direct contact between enzymes in the sludge with the dye (Vdirect); and the rate of reduction mediated by riboflavin (Vmediated). Riboflavin increased the Vtotal by 61% at extremely sub-stoichiometric concentrations of 9.1 micromol l(-1), which corresponded to a molar riboflavin:dye ratio of 1:60. The accelerating effect of riboflavin displayed saturation kinetics at higher concentrations, with a maximum increase of Vtotal of approximately 2-fold. A model is presented which assumes that Vmediated depends on the activity of riboflavin reductase (RR) and thus follows Michaelis-Menton kinetics with respect to the riboflavin concentration. The half-velocity constant (Km) was very low (6.3 micromol l(-1)), indicating a high affinity of the sludge RR for riboflavin. Both Vdirect and Vmediated were found to be proportional to the assay sludge concentration. The results taken as a whole indicate that vitamin levels of riboflavin can be utilized to improve the kinetics of azo dye reduction during anaerobic treatment.

Photooxidation of azo dye in aqueous dispersions of H2O2/α-FeOOH

The photodegradation of an azo dye, Mordant Yellow 10 (MY10), in aqueous dispersions of goethite (α-FeOOH)/H2O2 at neutral pHs under UV irradiation was studied in comparison with the dark reaction. It was found that UV irradiation could significantly accelerate the degradation of MY10. This provides an alternative approach to the treatment of non-biodegradable azo dye pollutants. The degradation process were investigated by infrared (IR), 1H NMR, total organic carbon (TOC) and gas chromatography–mass spectroscopy (GC–MS) analysis. Evidence for enhancement of OH radical generation by UV irradiation was obtained using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin-trapping EPR spectroscopy. A possible degradation mechanism of MY10 by α-FeOOH/H2O2 under UV irradiation was proposed, which involves the photolysis of the surface complex of H2O2 with the oxide surface metal centers to produce OH radicals, leading to the decomposition of organic compounds.

Heterogeneous Photo-Fenton Degradation of an Azo Dye in Aqueous H2O2/Iron Oxide Dispersions at Neutral pHs

Abstract The photodegradation of Mordant Yellow 10 (MY10), a kind of azo dye, in aqueous dispersions of H2O2/hematite (α-Fe2O3), goethite (α-FeOOH) and akaganeite (β-FeOOH) at neutral pHs under UV-light irradiation was examined. The fastest degradation rate of MY10 was obtained with goethite. The formation of •OH in the photoreaction process was detected by ESR spin-trapping technique. A possible mechanism of heterogeneous photo-Fenton reaction was proposed.

Degradation of azo dye Mordant Yellow 10 in a sequential anaerobic and bioaugmented aerobic bioreactor

Complete biodegradation of azo dyes requires an anaerobic and aerobic step, in the anaerobic step sulfonated azo dyes (SADs) are reduced, yielding (sulfonated) aromatic amines ((S)AAs) which can be degraded aerobically. The complete biodegradation of the SAD Mordant Yellow 10 (MY10) was studied in a sequential anaerobic and aerobic bioreactor. Anaerobically, MY10 was reductively cleaved and the resulting aromatic amines, 5-aminosalicylic acid (5-ASA) and sulfanilic acid (SA), were both recovered in high stoichiometric yields. One of the AAs, 5-ASA, was readily degraded under aerobic conditions. However, SA was not degraded aerobically in the continuous experiment because no SA-degrading bacterial activity was present in the system. Therefore, a SA-degrading enrichment culture derived from Rhine sediment was used as an inoculum source. This enrichment culture was bioaugmented into the aerobic reactor by increasing the hydraulic retention time (HRT), thus enabling SA-degrading activity to develop and maintain in the aerobic reactor. After decreasing the HRT, the SA-degrading activity remained in the bioreactor and the stoichiometric recovery of sulfate (a SA biodegradation product) indicated the mineralization of SA after bioaugmentation. Batch experiments with aerobic reactor sludge confirmed the biodegradation of SA and 5-ASA. The sequential anaerobic and aerobic bioreactor was able to completely remove the sulfonated azo dye MY10 at a maximum loading rate of 210 mg MY10 (lreactor d)-1 after the appropriate microorganisms for aerobic degradation of SA were bioaugmented into the aerobic bioreactor.