Reactive Yellow Research Articles

Dissolvable layered double hydroxide nanoadsorbent‐based dispersive solid‐phase extraction for highly efficient and eco‐friendly simultaneous microextraction of two toxic metal cations and two anionic azo dyes in real samples

For the first time, a new mode of dispersive solid‐phase extraction is presented as a simple, rapid, adsorbent‐free and environmentally friendly method for the simultaneous microextraction and preconcentration of trace amounts of two metal ions (Pb2+ and Cr3+) and two anionic azo dyes (reactive yellow 15 (RY15) and reactive black 5 (RB5)). This method is based upon the in situ formation of a layered double hydroxide (LDH) nanosorbent through an electrostatic induction process. In this method, extraction of the analytes is performed simultaneously with the formation of the nanosorbent only by adding hydroxide ions. After extraction and separation of the sorbent from the sample solution through a syringe nanofilter, the analytes are eluted by dissolving the LDHs in an acidic solution. Finally, the extracted metal cations and anionic azo dyes are directly determined by micro‐sampling flame atomic absorption spectrometry and micro‐volume UV–visible spectrophotometry, respectively. Under the optimal experimental conditions including 20 μmol of hydroxide ions, 248.4:20.8 μg l−1 of M2+:M3+ ions, 12 cycles of air agitation and 200 μl of CF3COOH (2 M), good linearities were obtained for Pb2+, Cr3+, RY15 and RB5 in the concentration ranges 50–600, 5.0–280, 30–2500 and 30–2000 ng ml−1, respectively, with correlation of determinations higher than 0.995. The preconcentration factor for the target analytes was 50 in a 10 ml sample solution. The limits of detection were found to be 15, 1.5, 10 and 10 μg l−1 for Pb2+, Cr3+, RY15 and RB5, respectively. The intra‐day and inter‐day precisions were in the ranges 4.3–6.1 and 5.5–6.8%, respectively. Additionally, the presented method is applicable for the analysis of the target analytes in different water samples with reasonable recoveries (>87%).

Green synthesis of amorphous and gamma aluminum oxide nanoparticles by tragacanth gel and comparison of their photocatalytic activity for the degradation of organic dyes

The current study concentrates on Al2O3 nanoparticles (NPs) synthesis using tragacanth gel as a biotemplate source by the means of sol–gel method at different calcination temperatures. The synthesized catalysts were characterized by XRD, FTIR, FESEM, and EDX. The XRD analysis indicated that the catalyst calcined at 500 °C has amorphous and the one calcined at 900 °C has gamma phase. The comparison of photocatalytic activity of both amorphous and gamma Al2O3 NPs was investigated under visible light irradiation, considering their effects on the degradation of organic dyes, for instance direct black 122 (DB122) and reactive yellow 145 (RY145). The studied effects include initial dye concentration, photocatalyst dosage, and visible light irradiation on dye degradation. Comparison of photocatalytic activity of mentioned photocatalysts exhibited better degradation of a-Al2O3 than that of γ-Al2O3. The results stated that a-Al2O3 catalyst could remove 97% of the direct black 122, whereas with γ-Al2O3, only 30% dye was removed. Regarding RY145, 95 and 26% degradation was observed, respectively.

Ultrasound–assisted adsorption of toxic dyes by cottonseed cake: artificial neural networks, regression models and response surface optimization

In this study, dehydrated cottonseed cake as a low-cost and abundant byproduct in Turkey was utilized as an adsorbent for the decolorization of Reactive Blue 19 (RB19) and Reactive Yellow 145 (RY145) from aqueous solutions based on adsorption and ultrasound-assisted adsorption (UAA). Decolorization efficiency was optimized as a function of changes in process type, initial pH value, adsorbent concentration, temperature, reaction time, and initial dye concentrations of RY145 and RB19 based on response surface methodology (RSM) using Box-Behnken Design. The maximum decolorization efficiency of 99.9% for both RY145 and RB19 was obtained with ultrasound-assisted adsorption under the RSM-optimized conditions (with unity desirability) of 76.98 and 79.40 min reaction times, 233.20 and 254.29 mg L-1 initial dye concentrations, 1.37 and 1.44 g L-1 adsorbent concentrations, and 35.42 and 49.37 °C, respectively. The best-fit multiple non-linear regression models of decolorization efficiency with the highest adjusted coefficients of determination (R2adj) explained 99.52% and 99.48% of variations through adsorption of RY145 and RB19 and 98.14% and 98.01% of variations through UAA of RY145 and RB19, respectively, while artificial neural networks accounted for 99.82%.

Decolorization of Reactive Yellow 17 in aqueous solution by ozonation in a semi-batch bubble column reactor

In this study, the factors influencing the rate of chemical oxygen demand (COD) of a synthetic waste solutions containing water soluble reactive dye [Reactive Yellow 17 (RY17)] by ozone gas was investigated. The research was conducted using a semi-batch bubble column to take the advantage of the intensive back-mixing that prevails in bubble columns. As a result, the COD of disperse dyestuff wastewater was reduced to 78.58%, and decolorization was remarkable under the basic condition of pH 12, complete each dye degradation occurs in 12 min, ozone consumption goes on for a further 30 min after which time most degradation reaction is completed. Kinetic studies were exhibited that direct ozonation of the aqueous dyes were a pseudo-first-order reaction with respect to the dyes. The apparent rate constant increased with both applied ozone dose and higher pH values, declined logarithmically with the initial dye concentration.

Thin films containing oxalate-capped iron oxide nanomaterials deposited on glass substrate for fast Fenton degradation of some micropollutants

The main goal of the study was to evaluate the catalytic activity of two hybrid nanocatalysts consisting in Fe3O4 nanoparticles modified with either chitosan (CS) or polyethylene glycol (PEG)/ferrous oxalate (FO), and further deposited on solid substrate as thin films. X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) were employed for the structural and morphological characterizations of the heterogeneous catalysts. The degradation kinetic studies of two reactive azo dye (Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84)) as well as Bisphenol A (BPA) solutions were carried out using Fenton-like oxidation, in the presence of different concentrations of H2O2, at initial near-neutral pH and room temperature. The results indicated that a low amount of catalytic material (0.15g/L), deposited as thin film, was able to efficiently trigger dye degradation in solution in the presence of 6.5mmol/L H2O2 for RB5 and of only 1.6mmol/L H2O2 in the case of BPA and RY84. In the presence of complex matrices such as WWTP waters, the removal of BPA was low (only 24% for effluent samples). Our findings recommend the studied immobilized nanocatalysts as promising economical tools for the pre-treatment of wastewaters using advanced oxidation processes (AOPs).

Montmorillonite Nanoparticles in Removal of Textile Dyes from Aqueous Solutions: Study of Kinetics and Thermodynamics

Dyeing wastewaters are one of the most common pollutants that cause many problems for public health and environment due to dermatitis and skin rashes, cancer production, mutagenesis, etc. Thus, treatment of these wastewaters is necessary. The purpose of this study was to investigate the efficiency of montmorillonite nanoparticles as an adsorbent in adsorption process of Reactive Yellow 15 (RY15) and Reactive Yellow 42 (RY42) dyes from aqueous solutions. In this study, montmorillonite nanoparticles were used to remove RY15 and RY42 dyes. The effect of different variables such as pH, contact time, dye concentration and adsorbent dosage was studied. Finally, the effect of process temperature and thermodynamic was studied. Also, pseudo-first and second orders of kinetics were studied. The results showed that 3 is the best pH for the removal of both dyes. As contact time increases to 15 minutes, adsorption capacity increases and then reaches an approximately constant value. Adsorption capacity was also increased with increased dye concentration. By changing the adsorbent dosage from 0.2 to 0.6 g/L, adsorption capacity for RY15 and RY42 was reduced from 142and 166 to 63 and 59 mg/g, respectively. The results also showed that both dyes had the highest correlation with pseudo-second-order kinetics. The results of analyzing the process thermodynamics and temperature showed that values of DH, DS and DG are negative for both dyes.

Photocatalytic activity of electrospun MgO nanofibres: Synthesis, characterization and applications

One dimensional MgO nanofibres with high photocatalytic activity were fabricated using the electrospinning method via a polyvinyl alcohol (PVA)/magnesium precursor based system and the dye degradation efficacy of MgO nanofibres was compared with MgO nanospheres. Optimum electrospinning parameters including suitable magnesium precursors were investigated and the formation of MgO nanofibres were confirmed with scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) mapping. Furthermore, the crystalline lattice structure and surface roughness of fabricated nanofibres were evaluated using transmission electron microscopic-electron diffraction mode (TEM-SAED) and atomic force microscopy (AFM), respectively. Fabricated MgO nanofibres exhibited excellent photocatalytic degradation activity against widely used model reactive dye, Reactive Yellow (RY). In contrast to MgO nanospheres, electrospun MgO nanofibres completely degraded the reactive dye under UV irradiation. These photocatalytic MgO nanofibres show a great potential to be used in efficient treatment of industrial dye effluents.

Polyethylenimine-coated polysulfone/bacterial biomass composite fiber as a biosorbent for the removal of anionic dyes: Optimization of manufacturing conditions using response surface methodology

This study aim was to optimize the manufacturing conditions polyethylenimine-coated polysulfone/bacterial biomass composite fiber (PEI-PSBF) to remove anionic pollutants from aqueous solution. The contents of biomass, PEI, and glutaraldehyde (GA) were selected as independent variables, and the response was defined as Reactive Yellow 2 (RY2) uptake. The manufacturing conditions were optimized by response surface methodology (RSM) with the full factorial central composite design (CCD). The determined coefficient of determination (R2) value of the reduced quadratic model was 0.9551, and the optimal manufacturing conditions were predicted as 4.145 g of biomass, 1.104 g of PEI and 3.9 μL of GA, at where the predicted RY2 uptake was 543.78 mg/g. For validating the RSM-predicted results, the RY2 sorption capacity of the optimized PEI-PSBF was evaluated through isotherm experiments. The experimentally confirmed maximal uptake was comparable to predicted one. From these studies, the manufacturing conditions for PEI-PSBF were well optimized and its sorption capacity was 3.83 times higher than that of the PSBF.

Synthesis of silica gel modified with 2,2′-(hexane-1,6-diylbis(oxy)) dibenzaldehyde as a new adsorbent for the removal of Reactive Yellow 84 and Reactive Blue 19 dyes from aqueous solutions: Equilibrium and thermodynamic studies

In this study, a new sorbent was prepared by the chemical modification of silica gel with 2,2′-(hexane-1,6-diylbis(oxy))dibenzaldehyde (SiO2-NH2-BH) through a Schiff base bond formation by a normal method and a vice versa method. The structure and morphology of the synthesized materials were characterized by Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analyzes (TGA) and Ultraviolet Visible (UV–vis). The produced modified silica gel with normal method was used as an efficient adsorbent for the removal of two anionic reactive dyes, namely Reactive Yellow 84 (RY84) and Reactive Blue 19 (RB19) from their aqueous solutions by batch adsorption procedure. The effect of various operation parameters such as adsorbent dose, solution pH, solution temperature, initial dye concentration and contact time on the adsorption behavior of both the anionic dyes was investigated. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Based on the correlation coefficient values, it is observed that Langmuir isotherm is appropriate model to explain the adsorption isotherm of both the anionic dyes on SiO2-NH2-BH. The maximum adsorption capacities for Reactive Yellow 84 (RY84) and Reactive Blue 19 (RB19) dyes under room temperature were found to be 68.02 and 72.99mg/g, respectively. The optimized pH for the effective removal of Reactive Yellow 84 (RY84) and Reactive Blue 19 (RB19) dyes were obtained at 6 and 4, respectively. Meanwhile, different thermodynamic parameters such as the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were evaluated and the results indicated that the adsorption of both investigated dyes was a spontaneous and endothermic process in nature. Therefore, the silica modified with 2,2′-(hexane-1,6-diylbis(oxy))dibenzaldehyde can be employed as an effective and inexpensive adsorbent for the removal of anionic reactive dyes from aqueous solutions.

Adsorption equilibrium and thermodynamics of anionic reactive dyes from aqueous solutions by using a new modified silica gel with 2,2′-(pentane-1,5-diylbis(oxy))dibenzaldehyde

The 2,2′-(pentane-1,5-diylbis(oxy))dibenzaldehyde (BP) functionalized silica gel (Si-APTES-BP) was synthesized successfully by a normal method and a inverse method. These new materials were characterized by Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analyzes (TGA) and Ultraviolet Visible (UV–vis). The modified silica gel with normal method was used as a sorbent for removal of anionic reactive dyes Reactive Blue 19 (RB19) and Reactive Yellow 84 (RY84) from their aqueous solutions by batch adsorption procedure. The batch adsorption experiments were performed to study the effect of various experimental parameters such as the solution pH, contact time, initial dye concentration, adsorbent dose and temperature. The results showed that the adsorption capacity of RB19 and RY84 dyes were enhanced with increase temperature of solution. The maximum uptake value for RB19 and RY84 dyes were obtained at pH 5 and pH 8, respectively. The isotherm data of both investigated dyes were analyzed by the Langmuir and Freundlich adsorption models. Based on the correlation coefficient values, it has been deduced that the Langmuir model is better fitted to the experimental data. The Langmuir maximum adsorption capacity of the Si-APTES-BP at 298K was found to be 37.45 for RB19 and 32.36mg/g for RY84, respectively. In addition, thermodynamic studies were conducted to calculate the changes in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°). The negative values of ΔG° and the positive value of ΔH° indicated that the adsorption process of both investigated dyes was a spontaneous and endothermic process in nature. The reusability of Si-APTES-BP has proven that the adsorbent is durable and cost-effective. Therefore, the silica gel modified with 2,2′-(pentane-1,5-diylbis(oxy))dibenzaldehyde can be used as an effective adsorbent for the removal of anionic reactive dyes from aqueous solutions.

Textile wastewater treatment by AOPs for brine reuse

Abstract The most contaminated textile wastewater stream, dyeing discharge with a high residual salt content, was selected to undergo dedicated treatment by advanced oxidation processes (AOPs). A simulated mixture, based on an industrial recipe and containing Reactive Yellow 145 (RY145), Reactive Red 195 (RR195), and Reactive Blue 221 (RB221), was investigated. These dyes are used together in the trichromatic technique in industrial dyeing, and they occur together in wastewater. In this study, for the first time, several ozone-based AOPs (O3, O3/H2O2, O3/UV and O3/UV/H2O2) were tested under comparable conditions and assessed. Moreover, the roles of hydrogen peroxide and UV during the AOPs were determined. The influence of textile auxiliaries on the AOPs was also investigated. Due to the usage of multiple dyes in the same mixture, colour was evaluated based on whole UV–vis spectra by recalculating them as integrals. Extremely fast decolourization of the textile wastewater was observed during ozonation. Only 10% colour remained after 10 min of treatment, and satisfactory mineralization was also achieved. During the AOP experiments, it was found that ozonation is the best treatment method for implementation in the industry. Textile wastewater treated by AOPs could be reused as a source of ‘ready to use’ brine for the next textile dyeing operation.

Mass transfer phenomenon in photocatalytic cascade disc reactor: Effects of artificial roughness and flow rate

Photocatalytic process is a green technology that has been widely used in textile wastewater treatment. Mass transfer phenomenon plays an important role in photoreactor with photocatalyst immobilized on surface. In this study, a novel photocatalytic cascade disc reactor coated with ZnO nanoparticles was first applied to investigate the effect of two influential parameters, i.e. artificial roughness and flow rate on photocatalysis degradation of Reactive Yellow 81 (RY81). Mass transfer coefficients were then determined to describe the effect of those parameters on photocatalytic process based on benzoic acid dissolution method. Fluid flow and concentration fields were simulated to explore the characteristics of mass transfer process with OpenFOAM software. Based on the experimental and simulation results, it was found that as artificial roughness and flow rate value increase, Reynolds number and consequently the first order reaction rate constant of RY81 and mass transfer coefficients significantly increase.

Equilibrium and kinetics study of reactive dyes removal from aqueous solutions by bentonite nanoparticles

Today, environmental pollution by various pollutants such as dyes is one of the most important issues of the world. Colored wastewaters are entering to the environment by many industries (for instance, textile and paper industries). Various technologies have been used to remove these pollutants. In this study, we have demonstrated the effectiveness of bentonite nanoparticles as a low cost adsorbent for removal of Reactive Yellow 15 (RY15) and Reactive Yellow 42 (RY42). The effects of variables such as pH, contact time, dye concentrations, adsorbent dosage and solution temperature, on the removal process have been studied. Residual of RY15 and RY42 dyes concentration was measured using a spectrophotometer set in 420 and 430 nm wavelengths, respectively. Also, the bentonite nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Brunauer-Emmett-Teller. Finally, the data were examined by isotherms of Langmuir, Freundlich, pseudo-first-order and pseudo-second-order kinetics and thermodynamic parameters. The maximum amount of adsorption for both dyes was at the pH = 3. With increasing the contact time and concentration of dye, adsorption capacity increased as well. Also, increasing the adsorbent dosage resulted decreasing the adsorption capacity. In optimum conditions, the maximum absorption capacity was 156.9 mg/g for RY15 and 170.7 mg/g for RY42. It was shown that removal of dyes of RY15 and RY42 follow, respectively, Freundlich isotherm and Langmuir isotherm and pseudo-second-order kinetics. The results of examining temperature and thermodynamics of the process showed that Delta S degrees and Delta H degrees are negative for both dyes. However, Delta G degrees was positive or negative for different temperatures. Since bentonite nanoparticles of this research were effective, cheap and available, so it can be used as an effective adsorbent for removal of RY15 and RY42.

Extraction and quantification of phenolic compounds from Prunus armeniaca seed and their role in biotransformation of xenobiotic compounds

The current research project has been devoted to isolating new low cost and eco-friendly phenolic compounds from fruit seeds, peels and vegetables to reduce the atmospheric pollution. Natural phenolic compounds were extracted from different fruit seeds and agriculture waste: P. armeniaca, P. persica, P. domestica and Triticum aesativum. The total phenolic content was quantified, and the maximum value (1 mL extract having 1,933 μg) was found in P. armeniaca seed extract. Phytochemical screening showed that P. armeniaca seeds contain higher amount of alkaloid, tannins, saponins and flavonoid. P. armeniaca seeds enhanced the biotransformation of reactive yellow dye up to 69.89% with maximum laccase (322.45 IU/mL) production. Biodegradation of reactive yellow was only 23.34% without natural redox mediator at sixth day of incubation. Use of P. armeniaca seed stimulators resulted in maximum laccase activity (894.4 IU/mL) with 99.5% rate of removal. UV-Vis, HPLC & FTIR analysis confirmed the transformation of parent dye into various new products. Phytotoxicity study indicated 0% germination index of Avena sativa seeds with reactive yellow, whereas 83% germination index having 100% seed germination while 83% root elongation with treated sample. Thus, the study revealed that the natural phenolic compounds could serve as high potential redox mediators for enhanced laccase-mediated decolorization of reactive yellow dye.

Ultrasound-assisted Fenton process using siderite nanoparticles prepared via planetary ball milling for removal of reactive yellow 81 in aqueous phase

Nano-sized siderite was used as catalyst for the heterogeneous Fenton process combined with ultrasonic irradiation to degrade reactive yellow 81 (RY-81) in the aqueous phase. As the most efficient process, nano-sized siderite prepared via ball milling was chosen to carry out the experiments. 6h milled siderite at initial pH of 3.0 led to the highest removal efficiency of 92.09% within the reaction time of 30min. At a short reaction time of 20min, increasing siderite nanoparticles dosage from 0.3 to 0.75g/L resulted in increasing removal efficiency from 49.82 to 79.86%, respectively, while further increase in the dosage caused a substantial decrease in the efficiency. In the case of the effect of solute concentration, increasing the dye up to 400mg/L led to a significant decrease in the removal efficiency (65.77%). The presence of 0.01M Na2CO3 and C2H5OH significantly diminished the decolorization efficiency of RY-81 (<10%) with initial concentration of 100mg/L. The intermediates produced during the treatment process were also identified using GC–MS analysis. This research suggested that ball milled siderite is a potential catalyst for the efficient decolorization of textile effluents via ultrasound-assisted Fenton process.

Characterization of a salt resistant bacterial strain Proteus sp. NA6 capable of decolorizing reactive dyes in presence of multi-metal stress.

Microbial biotechnologies for the decolorization of textile wastewaters have attracted worldwide attention because of their economic suitability and easiness in handling. However, the presence of high amounts of salts and metal ions in textile wastewaters adversely affects the decolorization efficiency of the microbial bioresources. In this regard, the present study was conducted to isolate salt tolerant bacterial strains which might have the potential to decolorize azo dyes even in the presence of multi-metal ion mixtures. Out of the tested 48 bacteria that were isolated from an effluent drain, the strain NA6 was found relatively more efficient in decolorizing the reactive yellow-2 (RY2) dye in the presence of 50gL(-1) NaCl. Based on the similarity of its 16S rRNA gene sequence and its position in a phylogenetic tree, this strain was designated as Proteus sp. NA6. The strain NA6 showed efficient decolorization (>90%) of RY2 at pH 7.5 in the presence of 50gL(-1) NaCl under static incubation at 30°C. This strain also had the potential to efficiently decolorize other structurally related azo dyes in the presence of 50gL(-1) NaCl. Moreover, Proteus sp. NA6 was found to resist the presence of different metal ions (Co(+2), Cr(+6), Zn(+2), Pb(+2), Cu(+2), Cd(+2)) and was capable of decolorizing reactive dyes in the presence of different levels of the mixtures of these metal ions along with 50gL(-1) NaCl. Based on the findings of this study, it can be suggested that Proteus sp. NA6 might serve as a potential bioresource for the biotechnologies involving bioremediation of textile wastewaters containing the metal ions and salts.

Photocatalytic Removal of Bismarck Brown G and Reactive Yellow 145 over Prepared (Co, Ni)&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Spinel Catalyst

Background/Objectives: The current study is focused on the synthesis of spinel catalyst (Co, Ni) 3 O 4 . This catalyst was used in removal of two textile dyes from wastewater that are charged from local textile factory. Methods/Statistical Analysis: This catalyst was synthesized using co-precipitation method. The obtained materials was calcinated in a furnace oven at temperature of 600⁰C for four hours. Then produced catalysts were investigated using different techniques such as Powder X-Rays Diffraction (PXRD), Atomic Force Microscopic (AFM). The treated industrial wastewaters that were used in this study were collected from the local textile factory in Hilla city (Iraq). Findings: The photocatalytic activity of the synthesized catalysts was investigated by following the photo catalytic removal of both Bismarck Brown G, (BBG) dye and Reactive Yellow145 dye (RY145) from the industrial wastewaters at normal atmospheric conditions. After one hour of reaction, the efficiency of dye removal was 94.60% and 31.11% for Bismarck Brown G and Reactive Yellow 145 dye respectively. Applications/Improvements: This study gives promising results in concern with treatment of industrial wastewaters before they are charged into the nearest water streams or in some cases they can be recycled to be used for industrial purposes at the same factory or at any other industrial unit.

Use of RSM modeling for optimizing decolorization of simulated textile wastewater by Pseudomonas aeruginosa strain ZM130 capable of simultaneous removal of reactive dyes and hexavalent chromium.

Remediation of colored wastewater loaded with dyes and metal ions is a matter of interest nowadays. In this study, 220 bacteria isolated from textile wastewater were tested for their potential to decolorize each of the four reactive dyes (reactive red-120, reactive black-5, reactive yellow-2, and reactive orange-16) in the presence of a mixture of four different heavy metals (Cr, Zn, Pb, Cd) commonly found in textile effluents. Among the tested bacteria, the isolate ZM130 was found to be the most efficient in decolorizing reactive dyes in the presence of the mixture of heavy metals and was identified as Pseudomonas aeruginosa strain ZM130 by 16S rRNA gene analysis. The strain ZM130 was highly effective in simultaneously removing hexavalent chromium (25mgL(-1)) and the azo dyes (100mgL(-1)) from the simulated wastewater even in the presence of other three heavy metals (Zn, Pb, Cd). Simultaneous removal of chromium and azo dyes ranged as 76.6-98.7% and 51.9-91.1%, respectively, after 180h incubation. On the basis of quadratic polynomial equation and response surfaces given by the response surface methodology (RSM), optimal salt content, pH, carbon co-substrate content, and level of multi-metal mixtures for decolorization of reactive red-120 in a simulated textile wastewater by the strain ZM130 were predicted to be 19.8, 7.8, and 6.33gL(-1) and a multi-metal mixture (Cr 13.10mgL(-1), Pb 26.21mgL(-1), Cd 13.10mgL(-1), Zn 26.21mgL(-1)), respectively. Moreover, the strain ZM130 also exhibited laccase and nicotinamide adenine dinucleotide (reduced)-dichlorophenolindophenol reductase (NADH-DCIP reductase) activity during the decolorization of reactive red-120. However, the laccase activity was found to be maximum in the presence of 300mgL(-1) of the dye as compared to other concentrations. Hence, the isolation of this strain might serve as a potential bio-resource required for developing the strategies aiming at bioremediation of the wastewater contaminated with dyes and heavy metals.

Adsorptive characteristics of the polyurethane-immobilized Corynebacterium glutamicum biosorbent for removal of Reactive Yellow 2 from aqueous solution

Polyurethane (PU) was evaluated for its possibility as an immobilization matrix for the raw biomass of Corynebacterium glutamicum. Initially, different blending ratios of the raw biomass to PU weight were tested, and the ratio of 7: 3 was identified as the optimal condition. PU-immobilized biosorbent (PUIB) with a particle size ranging from 0.425 to 0.18mm was selected for the adsorption of Reactive Yellow 2 (RY2). The uptake of RY2 on the PUIB was favorable at acidic pH, especially below 3. According to the Langmuir model, the maximum RY2 uptakes were estimated to be 104.0, 93.3, and 87.3mg/g at pH 2, 3, and 4, respectively. The pseudo-first-order and pseudo-secondorder models were applied to fit the biosorption kinetic data; the latter model fitted the data well with a high coefficient of determination (R2) and low average percentage error (e) values. The RY2-sorbed PUIB was able to be regenerated and reused for five cycles of the adsorption and desorption processes.

Textile Dye Removal Using a Photocatalytic Cascade Disc Reactor Coated by ZnO Nanoparticles: Effects of Hydraulic Parameters

AbstractHydraulic parameters play an important role in mass transfer phenomena in photocatalytic reactors. These fundamental hydraulic parameters are flow rate, relative roughness, and Reynolds number. This research experimentally evaluates the effects of flow rate and artificial relative roughness in order to determine the factors influencing the removal efficiency and reaction rate constant of Reactive Yellow 81 (RY81). For this purpose, a cascade photocatalytic reactor is constructed which consists of similar polymethylmethacrylate plates coated by ZnO nanoparticles and with various types of roughness. Dye removal efficiency is calculated for different flow rates with and without considering relative roughness. Furthermore, this study also reveals main effective parameters increasing the mass transfer rate, and uses a decision tree model called M5-Pruned (M5P) for predicting dye removal efficiency. Therefore, simple relations are provided for calculation of dye removal efficiency that consider importan...