Hazardous Azo Dye Research Articles

Removal of hazardous azo dye Metanil Yellow from aqueous solution by cross-linked magnetic biosorbent; equilibrium and kinetic studies

In this study, glutaraldehyde cross-linked magnetic chitosan nanoparticles (GMCNs) were prepared through cross-linking modification of magnetic chitosan nanoparticles using glutaraldehyde as a cross-linker that exhibited excellent Metanil Yellow (MY) adsorption performance. The characterization of the GMCNs was performed by Fourier transform infrared spectroscopy, transmission electronmicroscopy, scanning electron microscopy, dynamic light scattering, and vibrating sample magnetometry analyses. Adsorption characteristics of MY from aqueous solution onto GMCNs have been studied. During the studies, various essential factors influencing the adsorption, like adsorbate concentration, amount of adsorbent, pH of the solution, and contact time have been monitored. The equilibrium was achieved within 17 h at pH 4, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 625 mg/g and a Langmuir adsorption equilibrium constant of 5.2 × 10−4 dm3/mg at 25°C. The adsorption kinetics of MY at different initial dye concentrations was evaluated by the first-order and second-order models. The kinetic studies of MY adsorption showed that the adsorption process followed a second-order kinetic model. Furthermore, the GMCNs can be regenerated and reused through dye desorption in alkaline solution at pH 10. Adsorption results for reusability were 100, 93, and 65%, respectively, for three repeats.

An Unusual Electrochemical Reductive Cleavage of Azo Dye into Highly Redox Active Copolymeric Aniline Derivatives on a MWCNT Modified Electrode Surface at Neutral pH and Its Electroanalytical Features

Developments of new decomposition or degradation methods of environmentally hazardous azo dyes from textile industries are very important. Usually, strong acid-based chemical/electrochemical and neutral pH-based bacterial decomposition methods were widely used. Here, we report a mild, simple, and facile electrochemical method for decomposition of azo dye (Sudan yellow; SY) into a highly redox active copolymer of polyanilines via aniline derivatives as intermediates on a MWCNT modified glassy carbon electrode (GCE/MWCNT) surface unusually in a neutral pH using phosphate buffer solution (PBS) (GCE/MWCNT@SY-CoPANIpH7). One of the intermediate products, aniline (Mw = 93 mol g–1, calculated) was identified by an in situ cyclic voltammetry-electrochemical quartz crystal balance experiment. No such SY electrochemical reaction was observed on a naked GCE surface. Physico-chemical characterizations by TEM, Raman, IR, and UV–vis spectroscopic methods supported the formation of polymeric product on MWCNT surface (GCE/MWCNT@SY-CoPANIpH7). Electroanalytical performance of this new electrode was tested using ascorbic acid (AA) and Fe(CN)63–, as models. Interestingly, a dilute solution of Nafion (Nf) casted modified electrode system (GCE/MWCNT@SY-CoPANIpH7/Nf) showed improved electroanalytical performance, unlike the conventional Nafion modified system (GCE/MWCNT/Nf) with vanished peak current response due to the electrostatic repulsive interaction between the anionic AA (pKa = 4.10), Fe(CN)63– ion, and anionic sulfonic acid groups in Nafion. A zwitter ionic complex between a polaronic copolyaniline and sulfonic acid of Nafion is proposed as a possible structure for the newly developed hybrid system. Using the GCE/MWCNT@SY-CoPANIpH7/Nf, a selective flow injection analysis of AA has been demonstrated as an analytical application with good recovery values.

Utilization of inactivated aerobic granular sludge as a potential adsorbent for the removal of sunset yellow FCF

Sunset yellow (SY) FCF is a hazardous azo dye pollutant found in food processing effluents. This study investigates the use of inactivated aerobic granular sludge (AGS) as a potential adsorbent for the removal of SY from water. Adsorption studies were carried out at varying pH values, dosages of adsorbent, initial dye concentrations, and temperatures. Optimal adsorption conditions were identified at pH 2.0, adsorbent dosage of 2.0g L−1, contact time under 120 min, and 35°C temperature. Equilibrium data of the adsorption process fitted very well to the Freundlich model (R2 > 0.99). Kinetics results showed that the experimental data fitted well to the pseudo-second-order model (R2 > 0.99). The thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°), and Gibbs free energy (ΔG°) were calculated. Thermodynamic testing demonstrated that the adsorption of SY was a spontaneous and endothermic process. Fourier transform infrared spectroscopy indicated that functional groups played an important role during the adsorption of SY. These results confirm that AGS can be used as an adsorbent for successful removal of SY dye from wastewater.

Using protein nanofibrils to remove azo dyes from aqueous solution by the coagulation process

The ever-increasing applications of hazardous azo dyes as industrialized coloring agents have led to serious remediation challenges. In this study, proteinaceous nanofibrils were examined as coagulants for decolorization of azo dyes in aqueous solutions. The results provided some insight regarding the mechanism of dye removal. The strength of nanofibrils to remove dyes from solution was evaluated by remediation of acid red 88, Bismarck brown R, direct violet 51, reactive black 5, and Congo red. However, the efficiency of nanofibrils to coagulate with different dyes was variable (60–98%) and dependent on the structures of dyes and the physicochemical conditions of the solutions. Increasing the temperature or ionic strength declined the coagulation time and induced the rate of dye removal. Changing pH had contradictory effects on the dye removal efficiency which was more affected by the chemical structure of the dye rather than the change in stability of the coagulant. The efficiency of nanofibrils to remove dyes was more than that of charcoal, which is considered as one of the most common substances used for azo dye remediation which may be due to its well dispersion in the aqueous solutions, and slower rates of the coagulation than that of the adsorption process. Furthermore, cytotoxicity was not detected after treating cell cultures with the decolorized solutions. Accordingly, by integrating biological and biophysicochemical processes, proteinaceous nanofibrils can be promising candidates for treatment of colored wastewaters. Ease of production, proper and quick dispersion in water, without the production of dangerous dye by-products and derivatives, are some of the main advantages of nanofibrils.

Adsorption of Ponceau 4R from aqueous solutions using alkali boiled Tilapia fish scales

Tilapia fish scale, which facilitates both surface adsorption by hydroxyapatite and electrostatic interaction by collagen after boiling in alkaline environment, was used to prepare an adsorbent for the removal of the hazardous azo dye, Ponceau 4R. The prepared adsorbent was characterized by SEM, FT-IR and physical adsorption studies. Adsorption of Ponceau 4R by the prepared adsorbent was achieved under different initial Ponceau 4R concentrations, fish scale adsorbent doses, temperatures and pH conditions. The Freundlich isotherm model represented the experimental data very well. Kinetic studies indicated that the adsorption process followed the pseudo-second-order model and the theoretical maximum adsorption capacity of the fish scale adsorbent was 134.40 mg g−1. The adsorption thermodynamics study indicated that the adsorption process was a spontaneous and exothermic process.

Evaluation of adsorption characteristics of an anionic azo dye Brilliant Yellow onto hen feathers in aqueous solutions

PURPOSE AND AIM: Removal of an anionic azo dye Brilliant Yellow has been carried out from its aqueous solutions by using hen feathers as potential adsorbent. Hen feathers procured from local poultry were cut, washed, and activated. Detailed chemical and physical analysis of hen feathers and its characterization through scanning electron microscopy, X-ray diffraction, and infrared measurements have been made. Procured dye has been adsorbed over under batch measurements and adsorption process is monitored using UV spectrophotometer. Optimum parameters for the adsorption of Brilliant Yellow over hen feathers have been determined by studying the effect of pH, temperature, concentration of dye, and amount of adsorbent. On the basis of Langmuir adsorption, isotherms feasibility of the ongoing adsorption has been ascertained and thermodynamic parameters have been calculated. Attempts have also been made to verify Freundlich, Tempkin, and Dubinin–Radushkevich adsorption isotherm models. It is found that during adsorption, uniform distribution of binding energy takes place due to interaction of the dye molecules and the ongoing adsorption process is chemisorptions. The kinetic measurements indicate dominance of pseudo-second-order process during the adsorption. The mathematical treatment on the kinetic data reveals the rate-determining step to be governed through particle diffusion at 8 × 10−5 M and involvement of film diffusion mechanism at higher concentration at temperatures at all the temperatures. The developed process is highly efficient and it can be firmly concluded that hen feather exhibits excellent adsorption capacity towards hazardous azo dye Brilliant Yellow.

Design and mechanism of iron catalyzed carbon–carbon bond cleavage and N-oxidation processes of hazardous dyes for selective synthesis of nitroarenes and aminoarenecarboxylic acids

An efficient iron catalyzed oxidative degradation process has been developed for selective conversion of environmentally hazardous azo and indigo dyes into nitroarenes and aminoarenecarboxylic acids (anthranilic acids) respectively, using polymer supported tribromide reagent at an alkaline pH. The in situ generated and the isolated (defined) chloro-iron(II)-terpyridine–pyridine carboxylate [Fe(tpy)(pic)Cl] catalyst system has been developed and its catalytic function was invented for the degradation process. The different nitrogenous and oxygen ligands have been screened out for the development of best catalyst system, and eventually we explored pyridine 2-carboxylic acid and terpyridine ligands together, were found to be the best. Notably, the in situ generated and the defined catalyst systems have found to be more effective with similar catalytic activities towards the oxidative degradation of both the dyes. As a result, the whole oxidative degradation process has been carried out with Fe(tpy)(pic)Cl catalyst system and the general process utilizes the efficient catalytic method for the selective oxidation of –N N– and –C C– bonds of azo and indigo dyes respectively. The detailed catalysis, mechanistic and kinetic investigations have been made for the reactions. Interestingly, both the dyes proceed with a common oxidative degradation mechanism under identical kinetic patters. A common oxidative degradation mechanism which operates in both the dyes has been proposed and an identical related kinetic model was designed. The main interesting aspect of the present work pertains to the catalytic conversion of environmentally hazardous compounds into useful molecules; such are anthranilic acids and nitrobenzenes. Other special aspect related to catalytic activity of iron and potentially, iron catalyst accelerates the reaction rates with 15–20-fold faster. The reactions were also carried out with different polymer supported trihalide and inter-halide reagents. Notably, trichloride and inter-halide regents were found to be more reactive. The catalytic method developed for the degradation process was found to be very efficient and the involvement of cost-effective reagents makes the reaction simple, and can be conveniently scalable to industrial/technological operations with suitable modifications.

A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dye—Acid Blue 113

A mesoporous carbon developed from waste tire rubber, characterized by chemical analysis, FTIR, and SEM studies, was used as an adsorbent for the removal and recovery of a hazardous azo dye, Acid Blue 113. Surface area, porosity, and density were determined. The adsorption of the dye over the prepared adsorbent and a commercial activated carbon was achieved under different pH, adsorbate concentration, sieve size, adsorbent dosage, contact time and temperature conditions. Langmuir and Freundlich adsorption isotherm models were applied and thermodynamic parameters were calculated. Kinetic studies indicated that the adsorption process follow first order kinetics and particle diffusion mechanisms are operative. By percolating the dye solution through fixed-bed columns the bulk removal of the Acid Blue 113 was carried out and necessary parameters were determined to find out the percentage saturation of both the columns. Recovery of the dye was made by eluting 0.1M NaOH through the column.

Removal of a hazardous azo dye (Basic Red 46) from aqueous solution by princess tree leaf

Batch biosorption experiments were carried out for the removal of Basic Red 46 (BR 46) from aqueous solution by using princess tree leaf (PTL) as a potential biosorbent. The effects of solution pH, biosorbent dosage and size, dye concentration, temperature and contact time on the biosorption of BR 46 onto the PTL were investigated. The experimental results showed that maximum pH for efficient BR 46 biosorption was about 8.0. The equilibrium was attained in 70 min. The amount of BR 46 sorbed onto the PTL increased with the increase of dye concentration, in contrary, it decreased with increases of temperature, biosorbent dosage and size. The equilibrium sorption was best described by the Langmuir isotherm model. The maximum monolayer sorption capacity was found as 43.10 mg g − 1 at 25 °C. Kinetic studies indicated that the pseudo-second order model fitted to the experimental data well. Thermodynamic parameters demonstrated that the biosorption process was spontaneous and exothermic. The results revealed that the PTL could be used as a low-cost alternative biosorbent for the dye removal from wastewater.

A novel magnetically separable γ-Fe 2O 3/crosslinked chitosan adsorbent: Preparation, characterization and adsorption application for removal of hazardous azo dye

A novel magnetically separable adsorbent, namely magnetic γ-Fe 2O 3/crosslinked chitosan composites (Mγ-Fe 2O 3/CSCs), was prepared by miroemulsion process and characterized by XRD, FT-IR, TGA, DSC, SEM and VSM. Adsorption of methyl orange (MO), used as a model pollutant, from aqueous solution on Mγ-Fe 2O 3/CSCs was investigated. Characterization results indicated that magnetic γ-Fe 2O 3 nanoparticles have been introduced in Mγ-Fe 2O 3/CSCs and kept intrinsic magnetic properties. The saturated magnetization ( σ s) of Mγ-Fe 2O 3/CSCs can be expediently adjusted by changing additive dosage of γ-Fe 2O 3. Adsorption results showed that both nanocomposite adsorbents with weight ratio of γ-Fe 2O 3 to chitosan of 1:10 and 2:5 exhibited higher adsorption capacities and attained adsorption equilibriums in shorter time compared with crosslinked chitosan. After adsorption, Mγ-Fe 2O 3/CSCs were effectively separated from reaction solution in 10 s by applying an adscititious magnetic field. Adsorption kinetics of MO on 1:10 Mγ-Fe 2O 3/CSCs followed the pseudo-second-order kinetic model. Effects of both initial pH and adsorbent dosage on the adsorption of MO were remarkable in experimental conditions.

Removal and recovery of Chrysoidine Y from aqueous solutions by waste materials

This article describes the use of bottom ash [a power plant waste] and de-oiled soya [an agricultural waste] as effective adsorbents for the removal of a hazardous azo dye [Chrysoidine Y] from its aqueous solutions. This paper presents an experimental study and discussion of the adsorption characteristics of this dye on the two adsorbents. The adsorbents have been characterized, and also the effects of time, temperature, concentration, pH, and sieve size on the extent of adsorption have been evaluated. Batch adsorption measurements, kinetic studies, and column operations have been performed to elucidate the dye uptake capacity of the adsorbents. The monolayer adsorption capacities at 30 °C have been found from Langmuir analysis to be 7.27 × 10 −5 mol g −1 and 3.35 × 10 −5 mol g −1 for bottom ash and de-oiled soya, respectively. Adsorption kinetics experimental data are indicative of pseudo-second order kinetics during these processes. Column experiments indicate practical utility of the adsorbents for eradicating hazardous dyes from effluents. The recovery of the adsorbed dye from bottom ash and de-oiled soya, have been found to be 85% and 99%, respectively.

Process development for the batch and bulk removal and recovery of a hazardous, water-soluble azo dye (Metanil Yellow) by adsorption over waste materials (Bottom Ash and De-Oiled Soya)

Bottom Ash and De-Oiled Soya have been used as adsorbents for the removal of a hazardous azo dye—Metanil Yellow from its aqueous solutions. Adsorption of Metanil Yellow on these adsorbents has been studied as function of time, temperature, concentration and pH. Batch adsorption studies, kinetic studies and column operations enabled extraction of lethal dye from wastewaters. Adsorption equilibrium data confirms both Langmuir and Freundlich isotherm models and monolayer coverage of dye over adsorbents. Kinetic data have been employed to calculate specific rate constants, indicating thereby involvement of first order kinetics in the on-going adsorption and activation energy was determined as 0.813 and 1.060 kJ mol −1 for Bottom Ash and De-Oiled Soya, respectively. For both adsorbents, the adsorption process has been found governing by film diffusion, over the entire concentration range. Column operations have also been performed for the bulk removal of the dye and also to examine the practical utilization of fixed bed adsorption technique in elimination of dangerous effluent. Saturation factors for Bottom Ash and De-Oiled Soya columns have been calculated as 99.15 and 99.38%, respectively. Attempts have also been made to regenerate the dye from the exhausted columns using aqueous sodium hydroxide as eluent.

Removal and Recovery of the Hazardous Azo Dye Acid Orange 7 through Adsorption over Waste Materials: Bottom Ash and De-Oiled Soya

An azo dye, Acid Orange 7 [p-(2-hydroxy-1 naphthylazo)benzene sulfonic acid] was removed by adsorption over two waste materials, namely, bottom ash, a power plant waste, and de-oiled soya, byproduct obtained during the processing of soybean in soya oil extraction mills. Both waste materials showed excellent adsorption abilities and can be treated as low-cost adsorbents. The adsorbents were characterized through IR spectroscopy and differential thermal analysis (DTA), and preliminary investigations were carried out by batch adsorption to examine the effects of pH, adsorbate concentration, sieve size, adsorbent dosage, contact time, and temperature. A plausible mechanism for the ongoing adsorption process and thermodynamic parameters were also obtained from Langmuir and Freundlich adsorption isotherm models. The kinetic measurements helped in determining the specific rate constant, confirming the applicability of the first-order rate expression. To identify whether the ongoing process is particle diffusion ...

Use of waste materials—Bottom Ash and De-Oiled Soya, as potential adsorbents for the removal of Amaranth from aqueous solutions

Bottom Ash, a power plant waste material and De-Oiled Soya, an agriculture waste product were successfully utilized in removing trisodium 2-hydroxy-1-(4-sulphonato-1-naphthylazo)naphthalene-3,6-disulphonate—a water-soluble hazardous azo dye (Amaranth). The paper incorporates thermodynamic and kinetic studies for the adsorption of the dye on these two waste materials as adsorbents. Characterization of each adsorbent was carried out by I.R. and D.T.A. curves. Batch adsorption studies were made by measuring effects of pH, adsorbate concentration, sieve size, adsorbent dosage, contact time, temperature etc. Specific rate constants for the processes were calculated by kinetic measurements and a first order adsorption kinetics was observed in each case. Langmuir and Freundlich adsorption isotherms were applied to calculate thermodynamic parameters. The adsorption on Bottom Ash takes place via film diffusion process at lower concentrations and via particle diffusion process at higher concentrations, while in the case of De-Oiled Soya process only particle diffusion takes place in the entire concentration range.