Reactive Dyes In Aqueous Solution Research Articles

Activity of laccase enzyme extracted from Malva parviflora and its potential for degradation of reactive dyes in aqueous solution

The use of enzymes, particularly laccase as a dye-degrading biogenic agent, is a significantly low carbon footprint, bio-inspired approach towards dye wastewater remediation, which not only decomposes and decolorizes the dyes but has also been reported to transmute dyes into less toxic by-products. The work presented herein utilizes both original and purified laccase extracted from Malva parviflora for decomposing pigments that adversely affect ecosystems. Extractions of enzymes from plants were designed by changing one variable at one time and by using response surface methodology (RSM). The optimum enzyme-specific activity of 420 units/mg protein from this flora occurred with extraction for 16.1 min at pH 5.0 with an extraction ratio of 0.17 in 0.42 M sodium acetate buffer. Sephadex G-150 was utilized to filter and purify the enzymes. An ultimate purity of 42% was thus achievable, which constituted a fourfold increase over that of the original extract. The extent to which both natural and purified laccases eliminated textile dyes was assessed under optimal conditions, which were considered to be 180 min at 37 °C. The enzyme extracted from Malva parviflora exhibited high removal efficiency and was able to transmute dyes into less toxic by-products. The extraction process was optimized using response surface methodology, resulting in an optimum enzyme-specific activity. The study found that unpurified enzymes exhibited a greater removal efficiency of dyes compared to purified enzymes. Overall, the findings suggest that laccase enzyme from Malva parviflora could serve as a practical biocatalyst for continuous decolorization of textile dyes with low carbon footprint.

Degradation of Reactive Dye in Aqueous Solution by Fenton, Photo-Fenton Process and Combination Process with Activated Charcoal and TiO2

In the present work, a comparative efficiency of photo-Fenton (PF) treatment process and its combined process with activated carbon (AC) and titanium dioxide (TiO2) have been investigated using reactive yellow 145 as a model compound. These processes are based on in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic dye until their mineralization into CO2 and H2O. The effect of different process parameters, such as initial dye concentration, pH of the solution, Fe2+ concentration, catalyst and adsorbent loadings, and effect of various systems and irradiation times have been studied. The degradation of the dye was monitored by decolorization and COD analysis and then analyzed by high-performance liquid chromatography and IR analysis. Obtained results showed that PF combined with titanium dioxide (PF-TiO2) for removal of TOC was more efficient than PF or combination with AC. About 73.7% of TOC removal was obtained after 240 min of UV–F–TiO2 process, whereas the PF and UV–F–AC process yielded TOC reduction of 61.5% and 54.8% after 240 min. Mineralization studied reveals that effectiveness of treatment processes for RY145 is UV–F–TiO2 > PF > UV–F–AC > F–AC > F–TiO2.

Mineralization of hetero bi-functional reactive dye in aqueous solution by Fenton and photo-Fenton reactions

This study focused on the advanced oxidation of the hetero bi-functional reactive dye Sumifix Supra Yellow 3RF (CI Reactive Yellow 145) using dark Fenton and photo-Fenton conditions in a lab-scale experiment. A 23 factorial design was used to evaluate the effects of the three key factors: temperature, Fe(II) and H2O2 concentrations, for a dye concentration of 250 mg L−1 with chemical oxygen demand (COD) of 172 mg L−1 O2 at pH = 3. The response function was the COD reduction. This methodology lets us find the effects and interactions of the studied variables and their roles in the efficiency of the treatment process. In the optimization, the correlation coefficients for the model (R2) were 0.948 and 0.965 for Fenton and photo-Fenton treatments, respectively. Under optimized reaction conditions: pH = 3, temperature = 298 K, [H2O2] = 11.765 mM and [Fe(II)] = 1.075 mM; 60 min of treatment resulted in a 79% and 92.2% decrease in COD, for the dye taken as the model organic compound, after Fenton and photo-Fenton treatments, respectively.

Magnetic and photocatalytic response of Ag-doped ZnFeO nano-composites for photocatalytic degradation of reactive dyes in aqueous solution

To investigate the photocatalytic degradation of reactive dyes in aqueous solution, pure ZnO and Fe/Ag-doped magnetic photocatalysts having nominal compositions of Zn0.95−xFe0.05AgxO (x=0.0, 0.05 and 0.1) have been synthesized via self-consistent sol–gel based auto-combustion route. Thermally stable samples were subsequently confirmed to exhibit wurtzite type hexagonal structure, characteristic of ZnO. The nature of chemical bonding was elaborated by Fourier transform analysis. Electron microscopic techniques were employed to investigate the structural morphology and to evaluate the particle size. Ferromagnetic nature of the Fe/Ag doped samples was revealed by vibrating sample magnetometry, enabling the photocatalytic samples to be re-collected magnetically for repeated usage. The enhanced photocatalytic activity in the degradation of methylene blue under UV light irradiation with 5 and 10wt.% Ag/ZnFeO has been observed validating the potential applications of these materials in the field of photo-degradation of organic pollutants.

Removal of Reactive Dye by Adsorption over Chemical Pretreatment Coal based Bottom Ash

The coal based bottom ash from Thailand Power Plant has been used as the adsorbent for the removal of reactive dye in aqueous solution. The bottom ash was pretreated with 1N HCl, 1N HNO3, and 30% H2O2 before the adsorption tests. Adsorption of the pretreated bottom ash has been studied as a function of particle size, contact time, initial solution pH, and initial solution concentration. The ability to adsorb reactive dye (in terms of percentage dye removal) of these chemical treated bottom ashes are not significantly different. The adsorption reached an equilibrium state at about 15hours from the beginning of the experiments. The adsorption capacity at the equilibrium state increased as the size of the particles decreased. This was due to the increase in surface area of the adsorbents. The maximum adsorption occurred at the initial solution pH lower than 2 for all adsorbents with the highest percentage of dye removal and the highest amount dye adsorbed of 75.8 and 0.1mg/g adsorbents, respectively, for the H2O2 treated bottom ash. With varying the initial solution concentrations, the results showed that the adsorption capacity decreased as the initial solution concentration increased which was limited by the amount of the adsorbents in the system. Adsorption equilibrium data were fitted with both Langmuir and Freundlich adsorption isotherms with the correlation coefficient of 0.947 and 0.937, respectively.

Decolorization and Degradation of Reactive Dye in Aqueous Solution by Ozonation in a Semi-batch Bubble Column Reactor

The decolorization and degradation of anionic sulphonated azo dye (Reactive orange 16 (RO16)), which is suspected to be carcinogenic, were investigated using ozone. The decolorization process of the reactive dye was carried out by bubbling ozone at the bottom of a bubble column reactor containing the dye solution. The effect of pH, reaction time, dye concentration, ozone concentration, and decolorization time was studied. Also, degradation products and possible degradation mechanism were investigated. The results showed that ozonation was a highly effective way to remove color from wastewater. The color of a synthetic waste solution containing water-soluble reactive dye was reduced to 69.69 % under the basic condition (pH 12), with complete RO16 degradation occurring in 8 min. Ozone consumption continued for a further 16 min after which time most of the degradation reactions were complete. Kinetic studies showed that direct ozonation of the aqueous dyes represented a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with both the applied ozone dose and higher pH values and declined logarithmically with the initial dye concentration. Intermediates such as 6-acetylamino-3-aminonaphthalene-2-sulfonic acid, 2-(4-nitrosophenyl) sulfonylethyl hydrogen sulfate, and 6-acetamido-4-hydroxy-3-nitroso naphthalene-2-sulfonic acid were detected by gas chromatograph coupled with mass spectrometry in the absence of pH buffer, while nitrate and sulfate ions and formic, acetic, and oxalic acids were detected by ion chromatography.

Sequestration of Reactive Light-Yellow K-4G by Free <i>Mycobacterium phlei</i> Cells and its Extracellular Polysaccharide

Production of extracellular polysaccharide by the culture of Mycobacterium phlei were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the growth of the Mycobacterium phlei cell was 5000 mg•L-1, and inoculum size of 5%(v/v), 28°C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 95.5% and 5.0 g cell/L broth was obtained. The Mycobacterium phlei cell was effective in flocculating some soluble reactive dye in aqueous solution, reactive Light-Yellow K-4G with a decolorization efficiency of 93.5%, respectively, using 20 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

Optimization of Removal Conditions of Soluble Reactive Dyes from Aqueous Solutions by <i>Bacillus sp.</i> Biomass

The optimal conditions of by the culture of Bacillus sp.were examined, using beer wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in beer wastewater favorable for the growth of the Bacillus sp.was 5000 mg•L-1, and inoculum size of 5%(v/v), 30◦C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the Bacillus sp. biomass was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 93.8 and 95.5%, respectively, using 20 mL of the culture medium in 500 mL of 100 mg•L-1 dye solution.

Characterization and evaluation catalytic efficiency of La0.5Ca0.5NiO3 nanopowders in removal of reactive blue 5 from aqueous solution

In the present study, nanoparticles of perovskite-type La0.5Ca0.5NiO3−δ (LCNO) were fabricated by sol–gel method in the presence of nitrate–metal–ethylene glycol (EG) polymerized complex. A series of analytical techniques were used to characterize the crystallinity, morphology, specific surface area and grain size of La0.5Ca0.5NiO3 powders. Thermal decomposition process of the complex precursor was examined by means of differential thermal analysis–thermal gravimetric analysis (DTA/TGA). X-ray diffraction (XRD) results showed that single perovskite phase has been completely formed after calcination at 750°C. In addition, transmission electron microscopy (TEM) images revealed that the average size of the particles is approximately 10–32nm in diameter. The surface morphology and composition of these nanopowders were also investigated using scanning tunneling microscopy (STM), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDX). LCNO nanoparticles showed the excellent adsorption efficiency towards reactive blue 5 (RB5) as a reactive dye in aqueous solution. The adsorption studies were carried out at different pH values, dye concentrations, various adsorbent dosages and contact time in a batch experiments. The dye removal efficiency was found to be decreased with increasing in initial pH of dye solution, and LCNO exhibited good dye removal efficiency at acidic pH specially pH 2. Experimental results indicated that the adsorption kinetic data follow a pseudo-second-order rate for tested dye. The isotherm evaluations revealed that the Langmuir model attained better fits to the experimental equilibrium data than the Freundlich model. Finally, the photocatalytic degradation of RB5 using LCNO under solar light and UV irradiation at pH 2 was also investigated. The results showed that the nanoparticles cannot act as pure photocatalyst and the degradation of RB5 dye follows only an adsorption process.

Biosorption Applications of <i>Flavobacterium sp.</i> Biomass for Decolorization of Soluble Reactive Light-Yellow K-4G Solutions

The optimal conditions of production of flocculant by the culture of Flavobacterium sp. were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the growth of the Flavobacterium sp.was 5000 mg•L-1, and inoculum size of 5%(v/v), 30°C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 95.0% and 4.0 g biomass /L broth was obtained. The Flavobacterium sp. biomass was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G with a decolorization efficiency of 98.5, using 20 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

Adsorption Applications of <i>Bacillus sp.</i> Biomass for Decolorization of Soluble Reactive Dyes Contaminated Solutions

The optimal conditions of production of biopolymer by the culture of Bacillus sp.were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the growth of the Bacillus sp.was 4500 mg•L-1, and inoculum size of 6%(v/v), 28◦C, initial pH 7.0 and shaking speed of 160 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 97.5% and 4.0 g biomass /L broth was obtained. The Bacillus sp. biomass was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 98.5 and 92.5%, respectively, using 20 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

Effective NH 2-grafting on attapulgite surfaces for adsorption of reactive dyes

The amine moiety has an important function in many applications, including, adsorption, catalysis, electrochemistry, chromatography, and nanocomposite materials. We developed an effective adsorbent for aqueous reactive dye removal by modifying attapulgite with an amino-terminated organosilicon (3-aminopropyltriethoxysilane, APTES). Surface properties of the APTES-modified attapulgite were characterized by the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption. We evaluated the impact of solvent, APTES concentration, water volume, reaction time, and temperature on the surface modification. NH 2–attapulgite was used to remove reactive dyes in aqueous solution and showed very high adsorption rates of 99.32%, 99.67%, and 96.42% for Reactive Red 3BS, Reactive Blue KE-R and Reactive Black GR, respectively. These powerful dye removal effects were attributed to strong electrostatic interactions between reactive dyes and the grafted NH 2 groups.

Production of a Novel Biopolymer by Culture of <i>Bacillus cereus</i> B-11 Using Molasses Wastewater and its Use for Dye Removal

The optimal conditions of production of biopolymer by the culture of Bacillus cereus B-11 were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the production of the biopolymer was 5000 mg•L-1, and inoculum size of 5%(v/v), 28◦C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 98.5% and 3.55 g biopolymer /L broth was obtained. The biopolymer was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 97.5 and 94.7%, respectively,using 25 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

Production of a Novel Biopolymer by Culture of <i>Pseudomonas fluorescens</i> Using Brewery Wastewater and its Use for Dye Removal

The optimal conditions of production of biopolymer by the culture of Pseudomonas fluorescens were examined, using brewery wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in brewery wastewater favorable for the production of the biopolymer was 6000 mg•L-1, and an optimal culture condition of inoculum size of 5%(v/v), 28°C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 97.5% and 3.67 g biopolymer /L broth was obtained. The biopolymer was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 95.8 and 96.2%, respectively，using 25 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.The decolorization efficiency was dependent on the flocculant dosage and solution pH.

Preparation of bioadsorbents for effective adsorption of a reactive dye in aqueous solution

AbstractThe surface of barley straw, an agricultural waste, was modified chemically using a cationic surfactant hexadecylpyridinium chloride monohydrate (CPC) and used as an adsorbent for removal of Reactive Blue 4 (RB4) from aqueous solution. The raw and surfactant‐modified barley straws (SMBS) were characterized by Fourier transform infrared and elemental analysis. The stability of CPC adsorbed on straw surface was evaluated by exposing to water and organic solvents. The adsorption was performed on removing RB4 from wastewater in a batch adsorption system. The effects of contact time, initial concentration of dye and pH of solution on RB4 uptake were investigated and discussed. It was found that the removal percentage of RB4 increased with the increase in contact time. Adsorption was favorable at acidic condition and the maximum removal of 100% was obtained at pH 3. Dye‐loaded SMBS was stable and percentage of desorption was less than 7% in water. The kinetic studies revealed that the kinetic data fitted well to the pseudo‐second‐order model. The isotherm study also indicated that RB4 adsorption on SMBS matched well with the Langmuir model other than the Freundlich model. The maximum adsorption capacity determined from the Langmuir isotherm was 29.2 mg g−1 at 25 °C. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Dark-degradation of reactive brilliant blue X-BR in aqueous solution using α-Fe2O3

The precursor of Fe2O3 was prepared by chemical precipitation method with sodium hydroxide (NaOH) and iron chloride hexahydrate (FeCl3·6H2O). The samples annealed at different temperature were characterized by means of X-ray diffraction (XRD) and infrared absorption spectroscopy (IR). Degradation of reactive dye in aqueous solution was used to evaluate the catalytic performance of the Fe2O3. The experiments of degradation had been done in dark place. The experimental results indicated that the catalytic property of the precursor of α-Fe2O3 was excellent. The mechanism of the degradation of reactive dye in aqueous solution was investigated by comparing the data in the absence and presence of oxygen. The precursor of α-Fe2O3 annealed at 300°C was the best. The degradation rate of reactive brilliant blue X-BR could exceed 95% in 8min at 25°C when the concentration of the precursor of α-Fe2O3 was 0.1g/L. The mechanism of the catalytic oxidation reaction was investigated by comparing the X-BR catalytic oxidation data in the absence and presence of oxygen.

Radiation-induced decomposition and decoloration of reactive dyes in the presence of H 2O 2

The dyeing wastewaters represent a large input of hazardous compounds to the environment and these compounds are usually non-biodegradable. In this study, electron beam irradiation-induced decoloration and decomposition of reactive dyes in aqueous solution were investigated. Two different reactive dyes (reactive red KE-3B and reactive blue XBR) solutions were irradiated with electron beam at different doses in the absence and presence of H 2O 2. The changes of absorption spectra and pH value were described and analyzed as well as the degree of decoloration and COD removal. The influences of absorbed doses, H 2O 2 additions and initial dye concentrations are discussed. The experimental results show that reactive dyes in aqueous solutions can be effectively degraded by electron beam irradiation, especially in the presence of hydrogen peroxide.

Adsorption behavior of reactive dye in aqueous solution on chemical cross-linked chitosan beads

A batch system was applied to study the adsorption of reactive dye (reactive red 189) from aqueous solutions by cross-linked chitosan beads. The ionic cross-linking reagent sodium tripolyphosphate was used to obtain more rigid chitosan beads. To stabilize chitosan in acid solutions, chemical cross-linking reagent epichlorohydrin (ECH), glutaraldehyde and ethylene glycol diglycidyl ether was used and ECH shows a higher adsorption capacity. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms at different particle sizes and isotherm constants were determined. The Langmuir model agrees very well with experimental data and its calculated maximum monolayer adsorption capacity has very large value of 1802–1840 (g/kg) at pH 3.0, 30 °C. The kinetics of the adsorption with respect to the initial dye concentration, temperature, pH, ionic strength, and wet/dry beads were investigated. The pseudo-first-order, second-order kinetic models and intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The dynamical data fit well with the second-order kinetic model, except for the dry beads fitting better with the first-order model. The adsorption capacity increases largely with decreasing solution pH or with increasing initial dye concentration. Thermodynamic parameters such as change in free energy (Δ G 0), enthalpy (Δ H 0), entropy (Δ S 0) and activation energy were also determined. The adsorption mechanism is shown to be the electrostatic interactions between the dye and chitosan beads. The desorption data shows that the removal percent of dye RR 189 from the cross-linked chitosan beads is 63% in NaOH solutions at pH 10.0, 30 °C. The desorbed chitosan beads can be reused to adsorb the dye and to reach the same capacity as that before desorption.

Reactive Dyes Removal from Wastewaters by Adsorption on Eucalyptus Bark - Adsorption Equilibria

As research previously carried out with eucalyptus bark to remove reactive dyes in aqueous solution showed that it had interesting adsorption capacities [1, 2], it was decided to continue this investigation. Adsorption equilibria studies in order to optimize the experimental conditions were done. As it was already known that the highest adsorption capacities were observed at room temperature and that among all the other studied parameters that could influence the equilibrium (pH, temperature and both initial dye, sodium chloride and bark concentration) pH had a high significance level (1% in the Fisher test) [2] and was an easily adjustable variable in industrial practice, it was decided to carry out adsorption equilibria studies parametered by initial pH. Because the above mentioned studies [1, 2] had shown that there should be a maximum adsorption capacity near initial pH 2 for the chosen values of the selected parameters that influence adsorption equilibria besides initial pH, the last variable, initial pH (pHi), was explored for pH 1.50-2.50. Confirmation that, under these circumstances, the maximum adsorption capacity occurred at initial pH 2.0 was demonstrated. Langmuir model fitted the isotherms individually very well. A trial to generalize this model to all the isotherms having Langmuir parameters expressed as a function of the initial hydrogen ion activity, a Hi +, only succeeded forpH range, (1.50, 1.89) that is to say, just for one of the sides of the curve adsorption capacity = f (a Hi +) As the parameters of Langmuir equation, Q and KL, vary in opposite senses with initial pH, it is thought that for the successful side of the curve, Q probably has predominant influence, while on the other side KL may have greater importance.

The aggregation of triphenodioxazine reactive dyes in aqueous solution and on cellulosic and nylon substrates

Monomer–dimer equilibriums of triphenodioxazine (TPDO) reactive dyes with vinylsulfone anchors (PVS-TPDO) and monochlorotriazine anchors (MCT-TPDO) were investigated in water, in aqueous organic solvent, and on a cellulosic substrate. The aggregation tendency of PVS-TPDO in water was promoted by the addition of neutral electrolyte and suppressed by that of 1-methyl-2-pyrrolidone (MP). The dimerization constants, K, for PVS-TPDO were estimated in water and in aqueous sodium chloride solution; PVS-TPDO showed also aggregation on a cellulosic substrate. The apparent value of K on dry cellulose was two orders of magnitude smaller than that in water, and was increased by about ten times by water. The aggregation of PVS-TPDO in aqueous sodium chloride solution was suppressed by the addition of both MP and poly(vinylpyrrolidone). Four TPDO dyes examined showed the same order of aggregation tendency on cellulosic and nylon substrates as that in aqueous solution.