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India's domestic clothing and textile sector produce 5% of the country's GDP, 7% of industry output in value terms, and 12% of the country's export revenues. The primary threat faced by the textile industry is the color of the water that is left after dyeing. In the present study, water in oil nanoemulsion was used to remove the color from textile effluent. Nano-emulsion based on cyclohexanol was prepared using a high-speed homogenizer followed by ultrasonication. The emulsion, in general, was prepared using dye effluent water as the aqueous phase and cyclohexanol as the oil phase, and Beisol DEP as an emulsifier. The prepared emulsion was used to treat Reactive Blue 21 and Reactive Black 5. The treatment ratio of 1:1, 1:3,1:5, 1:7, 1:10 were tried. The treated effluent was tested for color removal efficiency, Chemical Oxygen Demand (COD), and Biological Oxygen Demand (BOD). Also, this study investigated the reusability of emulsion and solvent recovery. Emulsion characterization such as particle size and zeta potential was also carried out. It was found that there was about 95% decolourisation dye in effluent and the reusability of the solvent decreased by 7-10% after each cycle. [ABSTRACT FROM AUTHOR]

Recently, the products of dyes and phenols that effluent into water cause serious environmental complications where they cannot be controlled and sustained in the environment. In this study, a special type of bentonite clay was used to remove two types of reactive dyes (red, green) and 2,4-dichlorophenol from water by adsorption processes, under different operating conditions of pH values between (4-9) contact time (30-180) min, bentonite dose (0.2-1) g/200 ml, initial concentration (5-100) mg/L for reactive dyes, and (5-50) mg/L for 2.4-Dichlorophenol.The adsorption model has been applied to represent fit the experimental data of the adsorption process. The results showed that the Langmuir model was more suitable to represent the removal of reactive dyes (red, green) and the Freundlich model was more suitable to represent the removal of 2,4-dichlorophenol by bentonite clay.

A solid agricultural waste, coffee husk, was applied as an adsorbent for reactive dye-polluted wastewater treatment. Coffee husk biochar was pyrolyzed at 450 °C and then chemically activated using 50% ZnCl2 solution. The surface of activated coffee husk biochar was modified using a cationic surfactant, Cetyltrimethylammonium bromide (CTAB), to create CTAB-modified coffee husk biochar (MCH), to improve reactive adsorption of anionic dyes from synthetic wastewater. The selected reactive dyes were reactive yellow 145 (RDY145), reactive red 195 (RDR195), and reactive blue 222 (RDB222). The adsorption kinetics fit well using a pseudo-second order model for all three dyes. The adsorption isotherms matched well with the Langmuir model . The removal efficiency of RDY145 (83.7%) was the highest, followed by RDR195 (71.1%) and RDB222 (59.6%). The amount of RDY145 adsorbed by MCH was about 9-fold that adsorbed by conventional activated carbon. Additionally, the solution pH had no effect on reactive dye removal efficiency using MCH.

Abstract Potential use of living and non-living kefir grains (small, gelatinous white/yellow irregularly shaped masses consist of live bacteria and yeasts) on removal of reactive dye Remazol Navy RGB from aqueous solutions were investigated. Experiments were carried out under different process conditions in order to optimize and model the bioremoval processes. At all conditions the living kefir grains exhibited higher dye removal efficiencies than the non-living grains. In 180 min, 96.3% and 79.4% dye removal was obtained with living and non-leaving kefir grains respectively, at pH 2, 25 °C for 100 mg/L initial dye concentration by using 2.4 g/L kefir grain. Maximum adsorption capacities by living and inactivated kefir grains were obtained at 400 mg/L initial dye concentration as 134.59 and 56.92 mg/g respectively. Consecutive batch studies show that the living kefir grains could be reused over at least 5 cycles with high dye removal efficiency without any nutrition supplement. The biosorption kinetics both for living and non-living kefir grains were best described with pseudo-first-order kinetic model. On the other hand the biosorption equilibrium for living and non-living kefir grains were better defined by Temkin and Langmuir isotherm models respectively. Results suggest that the kefir grains could be used efficiently, eco-friendly and economically for removal of dyes from aqueous solutions.

Water pollution has already become a significant worldwide problem, especially in the textile dyeing industry. This paper describes decolorization of dye water modelled by textile dye wastewater. Decolorization was performed on an adsorbent made from physicochemically modified waste hemp fibers, obtained as a by-product from the production of ropes. The adsorbent is relatively dispersive and contains heterogeneous porous particles, with carbon as a dominant element. Obtained results have shown that the positive effect of adsorption directly depends on contact time, pH, temperature, and initial dye concentration. Dye concentration decreases in time, especially when the used concentration is the initial one. The effect of temperature below 40 °C is not significant, but adsorption gets more intensive when performed at 60 °C. The higher degree of decolorization is achieved at lower initial dye concentrations, although the highest initial dye concentration leads to higher dye adsorption. The experimental results of adsorption were described by using the Langmuir model. The maximum adsorption capacity ranges from 1.98 to 2.13 mg g-1 for linear and 2.03 to 2.12 mg g-1 for nonlinear form.

(1) Introduction: Natural polymers can be successfully used as a matrix to immobilize residual yeast-based biomass in a form that is easy to handle and can be used as biosorbent capable of removing persistent polluting species from different aqueous systems such as reactive azo dyes. (2) Experimental: Two types of new biosorbents were prepared based on residual Saccharomyces pastorianus yeast biomass immobilized in sodium alginate (using two different practice techniques) and studied in the biosorption process of reactive Brilliant Red HE-3B dye using certain experimental planning matrices according to the active central composite rotatable design of 23 order. The experimental data obtained under certain selected working conditions were processed considering the influence of three independent variables (biosorbent concentration—X1, initial dye concentration—X2 and biosorption time—X3) onto the dependent variable (Y = f(X1,X2,X3)) expressing the performance of reactive dye biosorption onto the new prepared biosorbents (i.e., dye removal degree, %). (3) Results: Two mathematical models were proposed for each prepared biosorbent. The maximum dye removal was 52.878% (Y1) when 18 g/L biosorbent 1 (micro-encapsulated form) was applied in 70 mg/L dye-containing solution for at least 8 h, and 75.338% (Y2) for 22.109 g/L biosorbent 2 (immobilized form) in 48.49 mg/L dye-containing solution for at least 8.799 h. (4) Discussion: The optimal values achieved for the two tested biosorbents were compared, and we investigated the possibility of using this residual biomass as a biosorbent for the reactive dye removal, supported by the experimental results with the recommended variation domains of each influencing variable. The results are sufficient to permit performing dye removal higher than 50% (biosorbent 1) or 70% (biosorbent 2), working with more than 18–22 g/L biosorbent after at least 8 h (as an exchange at work). (5) Conclusions: The proposed models are in good agreement with the experimental data and permit the prediction of dye biosorption behavior onto the experimental variation domain of each independent variable.

Background and objective: Wastewaters including dyes produced by various industries have serious destructive effects on the environment. Therefore, proposing analytical and numerical mathematics methods simulating dye removal process from industrial wastewaters are great of importance. Methods: In this research, the Fe3O4-activated carbon magnetic nanocomposite was synthesized and its crystalline structure, surface, and magnetic properties were characterized by XRD, SEM, and VSM techniques. Efficiency of the composite adsorbent for decolorization of Reactive Red dye in different conditions was investigated. Then, an artificial neural network was constructed by using Matlab program to predict the removal efficiency of dye onto magnetic activated carbon and the number of neurons in a hidden layer was optimized. pH, contact time, initial dye concentration, and temperature as input parameters and dye removal percentage as an output parameter were considered. Performance of network after its training was evaluated based on the correlation factor. The experimental data were analyzed by pseudo- first- order, pseudo- second- order , and intra-particle diffusion kinetics models.The Langmuir and Freundlich models were used to describe the sorption equilibrium isotherms. Results: . The high correlation factor for testing data showed that artificial neural network model can estimate the experimental data. The intra-particle diffusion kinetics and Freundlich isotherm models best describe the experimental data for the uptake of dye. A relatively low activation energy (34.6 kJ mol-1) suggests that the adsorption involve physio sorption. Maximum adsorption capacity decreased with increasing temperature. Conclusion: Use of network prediction resulted to eliminate experiments and to improve dye removal percentage.

Based on conventional pad-dry-pad-steam (PDPS) process, 3-chloro-2-hydroxypropyltrimethylammonium chloride was used as an etherifying agent to cationize cotton by the pad-irradiate process by microwave and then the cationized fabric was salt-free dyed by the pad-steam process. The results showed that the dyeability of the cationized fabric with salt-free reactive dye was nearly equivalent with conventional PDPS process. This study also developed a model to predict K/S value of dyed cotton fabric based on least squares support vector machine (LS-SVM). The simulation results based on actual run data demonstrated that the model using LS-SVM has high prediction accuracy and can be employed to predict the K/S value of dyed fabric using pad-irradiate-pad-steam process. [ABSTRACT FROM AUTHOR]

The decolorization and mineralization of Reactive Blue 222 dye was studied using UV/H2O2/ferrioxalate approach in combination with Pleorotus ostreatus. The dye was decolorized by UV/H2O2/ferrioxalate based advanced oxidation process (AOP) at different levels of process variables dye concentration, catalyst dose, pH, reaction time and resultantly, 80% decolorization was achieved. Pleorotus ostreatus treatment enhanced the dye degradation up to 92% at optimum levels of pH, temperature, inoculum size, carbon and nitrogen sources at specific concentration. Response Surface Methodology (RSM) was employed for optimization under face-centered central composite design (CCD). Although both treatments were found efficient for the removal of dye, but on applying the integrated approach, 96% dye removal was obtained which led to complete degradation of the dye. FTIR analysis confirmed the degradation of dye into low mass compounds. The water quality assurance parameters were measured to assess the mineralization efficiency. A significant reduction in COD (94%) and TOC (92%) were found when dye was degraded integrated approach. A phytotoxicity analysis on Pisum sativum plant revealed the non-toxic behavior of metabolites produced. Results revealed that the integrated approach is highly promising for the decolorization and mineralization of the Reactive Blue 222 dye and is also extendable to treat the dye in textile wastewater. [ABSTRACT FROM AUTHOR]

Reactive dye is widely used for cotton dyeing, but its low utilization results in vast amounts of colored effluent with high salinity discharge. Amino-modified Reactive Red 195/P(styrene-co-butyl acrylate-co-trimethyl(vinylbenzyl) ammonium chloride) nanospheres (Am-RPNs) are a kind of novel colorant that exhibit excellent dyeing ability for cotton fabrics and higher dye utilization than original reactive dyes. The colored polymer nanospheres demonstrated small size, high stability and dye content in the dispersion system when cationic polymer nanospheres were dyed at an optimal dye dosage of 100%. Transmission electron microscopy images showed that the polymer nanospheres have smooth spherical shapes. Am-RPNs with an average hydration diameter of 96.5 nm and zeta potential of −33.7 mV were fabricated after being modified with ethylenediamine at pH 11. Both analytical techniques, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, indicated the presence of –NH2 on the surface of Am-RPNs. The amino-modification mechanism of the Reactive Red 195/P(styrene-co-butyl acrylate-co-trimethyl(vinylbenzyl) ammonium chloride) nanospheres depended on the dyeing bath pH. The color depths of the cotton fabrics dyed with Am-RPNs reached up to 3.1 times higher than those with Reactive Red 195. Scanning electron microscopy images showed that Am-RPNs form stable deposits on the surface of the modified fibers. The cotton fabrics dyed with Am-RPNs possessed excellent rubbing and washing fastness, satisfactory light fastness, and desirable handle. This study provides an innovative method that employ Am-RPNs with high coloration performance to endow the cotton fabric with deep color and good colorfastness without using inorganic salt. [ABSTRACT FROM AUTHOR]

The colour quality assessment of reverse micelle-based (in octane or nonane medium) and conventional water-based dyed wool knitted fabric has been investigated using computer colour matching (CCM) approach. Both water-based and non-aqueous based dyeing methods exhibited no chromatic shift from the reflectance curves and established good linearity in the construction of calibration curves. The linearity of both calibration curves in terms of R2 value played a critical role in CCM. The colour yield obtained from reverse micellar dyed fabric samples was higher than the colour yield values from wool knitted fabrics dyed in water bath under different dye percentages. The CCM predicted concentrations were in good agreement to theoretical concentrations for both dyeing systems. To conclude, the results showed that reverse micellar dyeing in octane and nonane is capable of generating reliable colour recipes. The relative unlevelness indices (RUI) obtained from dyed wool knitted fabrics using reverse micellar approach reveal good to excellent levelness, which fulfills the requirements of the textile processing industry. TEM picture illustrated that reverse micelles are in nano-scale and this could enhance the dyeing effect of wool with reactive dyes. [ABSTRACT FROM AUTHOR]

Copyright of Wool Textile Journal is the property of National Wool Textile Science & Technology Information Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• A novel UV/K 2 S 2 O 8 system for color stripping of reactive-dyed cotton was constructed. • The system has sustainable, low consumption and energy conservation characteristics. • Commercial reactive dyes fixed on cotton were efficiently stripped at low temperature. • Stripping reactions and attacks on substrate were raced and disclosed by FT-IR and SEM. • Possible working mechanism of the system for reactive-dyed cotton was also proposed. An efficient, sustainable and energy conservation system and method for color stripping of reactive dyes on cotton substrate in a dipping manner were constructed for the first time via a UV irradiation of potassium persulfate (K 2 S 2 O 8) in aqueous system to photocatalytically generate working species at an ambient temperature. The results show that the active species in the developed UV/K 2 S 2 O 8 system could efficiently attack and decolorize the model dye as well as other applied reactive dyes after being fixed on cotton substrate with high selectivity. An efficient and significant improvement of color stripping was available with a color stripping ratio higher than 90.0% even at a stripping duration of 30.0 min. High efficiencies in color stripping of 14 commercial reactive dyes involving various chromophoric matrixes on cotton substrate were also achieved in the stripping system with a recommended process, accompanied with commercially satisfactory tensile strength retentions of the substrate. The color stripping on the substrate in the UV/K 2 S 2 O 8 system was further traced and explored successfully by Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) analysis. Additionally, a possible working mechanism of the developed system for color stripping on the substrate was also proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

A new dye intermediate and novel reactive dyes containing both azo and benzsulfonamide auxochromic groups were synthesized. Their structures were characterized by 1H-NMR, 13C-NMR, MS, IR, and UV-Vis spectral analysis. The synthesized dyes were applied to dyeing of cotton fabrics and their dyeing parameters were assessed. The new dyes exhibited improved substantivity and fixation property on cotton fabrics compared with the dye C.I. Reactive Black 5 (RB5). The maximum exhaustion and total fixation values of the reactive dyes appeared when 2 % owf of the dye concentration was used. The wash fastness and rub fastness of the new dyes reached up to 4 grade and 4–5 grade, respectively. In addition, they showed excellent fastness to light. These new dyes seem to be promising candidates for application to dyeing of cotton fibers. [ABSTRACT FROM AUTHOR]

In this study, Reactive Orange 16, which is a reactive dye, was investigated by using magnetic poly (DVBVIM) to determine the effect of pH on adsorption. For this reason, the effect of pH on adsorption has been investigated in detail in pH: 2 and pH: 12. Magnetic poly (DVB-VIM) microbeads were characterized by scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR) studies and swelling studies. [ABSTRACT FROM AUTHOR]

Comparative results of color removal performances of Reactive Blue 198 (RB198), Reactive Yellow (RY145) and Reactive Blue 19 (RB19) by electrocoagulation process are presented. Our primary objective was to investigate whether the dye molecular weight affects color removal performance. Dye removal costs of each dye were calculated and compared. Experiments were performed at current densities of 1.04, 2.08, 4.17 and 10.42 A/m2 in electrocoagulation (EC) reactor with aluminum electrodes connected parallel monopolar configuration. Laboratory-scale experiments were run in batch mode with 0.5 L synthetic dye solution volume and 50 mg/L initial dye concentration. Results showed that the color removal efficiencies were directly influenced by the molecular weight of the dyes. The color removal efficiency of the dye with the greatest molecular weight (RB198) was the highest, whereas the color removal efficiency of the dye with the smallest molecular weight (RB19) was the lowest. Moreover, results indicated that the operating cost of RB198 was significantly lower (2.91 $ per kg dye removed) than RY145 (6.61 $ per kg dye removed) and RB19 ($6.72 per kg dye removed) at a current density of 4.17 A/m2. [ABSTRACT FROM AUTHOR]

The agricultural waste of orange peels (OPs) was utilized as a cheap biosorbent and then tested for its ability to treat the reactive red (RR) dye wastewater. Several experiments were done to get the equilibrium isotherm and kinetic-relevant data. In addition, several experimental factors such as solution pH, temperature, contact time, and initial RR dye concentration were studied, in light of their impact on the biosorption process. The utilized isotherm and kinetic models were evaluated by using the chi-square test and coefficient of determination parameters for their representation of real data. In addition, the obtained data of their biosorption capacities, at different conditions, were modeled by the artificial neural network (ANN) approach. The results of the isotherm study revealed that the experimental data can be best accounted by both the Langmuir and Temkin models, demonstrating that the RR molecules were sorbed to two or more different types of biosorption sites of OP. The kinetic study for determining the characteristics of the rate of diffusion demonstrated that the intraparticle diffusion process was not the sole rate-limiting step in the biosorption of the RR dye-OP couple. Furthermore, the biosorption process was chemisorption in nature, as the pseudo-second-order reaction proved to be the best representative model for the kinetic data. The outcome of modeling also assumed that using the ANN tool was useful to reproduce the data again and foretell the manner in which biosorption behaved. According to the results of the Langmuir model, it was found that the maximum OP uptake for the biosorption of the RR dye was up to 82 mg/g, observed at optimized values of the experimental parameters. Such prior results highlight that OP is an effective agent of biosorption in the elimination of RR dyes from polluted solutions, moreover, in a cost-effective manner. [ABSTRACT FROM AUTHOR]

Traditional dyeing usually consumes a large amount of water and chemicals, thus causing environmental problems. To alleviate these problems, non-aqueous dyeing technology appears as an alternative for improving dye fixation and reducing effluent discharge. Here we used silicone non-aqueous medium to dye a wool fabric. Continuous pad dyeing with reactive dyes was investigated. We optimized the type of penetrating agent, padder pressure and concentration of dye. Results show that the fixation and exhaustion reach 88% and 98%, respectively, which are higher than for water-based dyed samples. The rubbing fastness of the dyed wool fabric is improved 1–2 times, and the consumption of dye is reduced by 20% by comparison with acid or reactive exhaust dyeing. Other advantages include continuous salt-free dyeing, washing and drying; saving water and less water pollution. [ABSTRACT FROM AUTHOR]

At present, many well-known brands of washing machines in the market are equipped with dye transfer inhibition washing procedures. However, there is no standardized sample available for the evaluation of the dye transfer inhibition washing procedure, and there is no comparability and access standard of the high-quality washing machine with the related functions. In this article, the certified reference materials for the evaluation of the dye transfer inhibition function will be prepared, which consist of certified reference material of white cotton fabric and that of dyed cotton fabric. The certified reference material of white fabric is made of bleached plain fabric, and that of dyed fabric is made with different reactive red dyes and dyeing processes. The size and manufacturing process of the whole set of standardized samples for the evaluation of dye transfer inhibition are selected and determined through experiments. The preparation of the standardized sample for the evaluation of dye transfer inhibition will improve the research and design of the functional washing procedure, which can better solve the pain point when dark and light clothes are washed together. [ABSTRACT FROM AUTHOR]

Copyright of Tekstil: Journal of Textile & Clothing Technology is the property of Croatian Association of Textile Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The goat hair and chicken feather was steam exploded, frozen and disintegrated and further used for the adsorption of reactive blue 19 (RB19) dye. The effects of steam explosion,freezing and disintegration on the adsorption capacity of goat hair and chicken feather and their power were studied. As a result, the raw chicken hair (175 mg/g) had higher adsorption capacity than that of goat hair (55.24 mg/g); After steam flash explosion, freezing and disintegration, the scales of goat hair were broken, The crystallization indexes of EGHP and ECFP decreased, which were 8. 6% and 13.1%, respectively, its specific surface area, BJH adsorption pore cumulative specific surface area and pore volume are 1.64, 2.74, and 2.65 times of ECFP, respectively, their adsorption amount are 426. 7 mg/g and 440 mg/g. The combined treatment of steam flash explosion, frozen and disintegration improved the adsorption performance of goat hair and chicken feather effectively on RB19, and its adsorption capacity for goat hair is improved significantly. [ABSTRACT FROM AUTHOR]

Dye effluent is one of the most prominent source of water contamination. This study investigated the solar based photocatalytic decolorization of four commercial reactive dyes, which are Reactive Turquoise Blue G 133, Reactive Yellow M4g, Reactive Bordeaux B, and Reactive Red M8b using immobilized TiO2-Fe3O4 on three kind of binders as the support, specifically cyanoacrylate glue, oil-based paint, and white Portland cement on PVC plate. TiO2-Fe3O4 was synthesized using sol-gel method and placed in muffle furnace at 773 K. The composite of TiO2-Fe3O4 was characterized using SEM-EDX and XRD. White cement emerged as the best binder in term of the color removal efficiency of all four dyes compared to other binders, which were more than 90% color removal after 3 h of solar irradiation. Moreover, there was significant enhancement on color removal using immobilized photocatalyst on white cement compared to mobile photocatalyst. The kinetic of the decolorization performance followed the pseudo-first-order reaction. The apparent reaction rate constant was found to decrease along with the increase of the dye concentration. The photodecolorization kinetics fitted the Langmuir-Hinshelwood model. These protocols and results can be applied into textile industrial primary wastewater treatment using solar as a sustainable light and energy source.

Abstract The biosorption process using natural materials has found widespread applications than to their inexpensiveness, availability, and reusability. The aim of this research is to investigate the efficiency of psyllium seed powder in removal of reactive orange 16 dye. The impacts of various influential parameters such as initial pH, contact time, adsorbent dose, temperature and dye concentration were evaluated using a batch biosorption method. Data analysis was conducted by SPSS 19. The removal efficiency of reactive dye 16 using the natural adsorbent psyllium was obtained to be 94% in optimal conditions (pH 4, contact time = 40 min, and adsorbent dose = 2 g/L). Biosorption equilibrium experiments indicated that the best fit was achieved with Langmuir isotherm model. Maximum adsorption capacity was found to be 206.6 mg/g at 303 K. Kinetic analysis revealed that adsorption experimental data were best fitted by pseudo-second-order model. Free energy of adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were calculated to predict the nature of adsorption. Thermodynamic evaluation indicates that a spontaneous process has occurred. Inexpensive, locally available, and effective materials could be used for dye removal in wastewater treatment processes. Undoubtedly low-cost adsorbent benefits for commercial purposes in the future.

An eco-friendly dyeing of cotton fabrics with Reactive Golden Yellow K-2RA was carried out using supercritical carbon dioxide fluid with different humidity. Effect of dyeing temperature, pressure, time, dye concentration, and gas humidity on the dyeing properties of cellulose was investigated. The results indicated that good dyeing effect was achieved because of the nucleophilic substitution reaction of monochlorotriazine reactive group in Reactive Golden Yellow K-2RA and hydroxyl functional groups in cotton. The color strength of dyed samples was improved with the variation of dyeing conditions. An optimized eco-friendly dyeing of cellulose fabrics was recommended with a dyeing temperature of 90°C, a dyeing pressure of 20 MPa, a dye concentration of 5%, and gas humidity of 5% for 60 min in supercritical carbon dioxide fluid. Furthermore, acceptable washing, rubbing and light fastness rated over 4 were obtained.

A low cost activated carbon from corn straw was prepared by dry pyrolysis using the microwave, the SBET of activated carbon was 937 m2 g-1. The adsorption of Reactive Brilliant Yellow K-6G and Reactive Brilliant Red K-2BP on the activated carbon from corn straw were investigated. Four types of kinetic models and three types of isotherms were used to fit the experimental data. The results showed that the adsorption of RBY K-6G and RBR K-2BP on the activated carbon from corn straw both followed the pseudo-second-order kinetic model and Langmuir isotherm. The enthalpy change (ΔH°) and Gibbs free energy (ΔG°) are calculated, ΔH° > 0 and ΔG° < 0 suggested that the adsorption process was endothermic and spontaneous in nature. [ABSTRACT FROM AUTHOR]

An attempt was made to dye cotton fibres from non-aqueous system using anionic dyes. Dyeing from solvents systems has been attractive for the potential storage of water and low heats of vaporization of solvents as compared with that of water. Mostly solvents such as per-chloro ethylene, tri-chloro ethylene, acetone and DMF are used. [ABSTRACT FROM AUTHOR]

Traditional dyeing of cotton fabrics with reactive dyes has produced many environmental problems. Therefore, it is important to investigate the relationship between dye molecular structures and dyeing properties for cleaner procedures. Here, the properties of five azo-based reactive dyes with different substituents and reactive groups were studied. The dyes had similar molecular shapes, sizes, and chromophore structures. Differences were in the aromatic rings, the number of sulfonate groups, and the position of vinyl sulfonate on the benzene ring. The dye substantivity (S%), exhaustion (E%), reactivity (R%), fixation (F%), color strength, salt effects, alkali effects, and color fastness were investigated and analyzed. Different substituents on the dyes had a little effect on the ultraviolet-visible absorption maximum wavelength. In addition, the requirements of salt and alkali to produce the maximum color strength varied for different dye structures. The dye containing a naphthalene ring, three sulfonate groups, and a vinyl sulfonate at the para-position of the benzene ring produced the highest color strength and fixation values. Color fastness was almost the same for each dyed sample, except for the wet-rubbing fastness. The results should be useful for developing new dyes and environmentally friendly dyeing techniques. [ABSTRACT FROM AUTHOR]

The present study shows sorption capacity of the metallurgical dust, for the anionic dye—Reactive Blue 19, from aqueous solutions and real textile wastewater. The sorption processes were carried out in batch method at six doses of: 2, 5, 10, 20, 50, and 100 g/L. The highest maximum sorption capacity of the dust in relation to the dye from aqueous solution has been estimated for sorbent dose of 2 g/L, it was 319.2 mg/g, and the removal efficiency (RE) was at the level of 62.7%. The experimental data have been analyzed by the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models, using nonlinear regression. To determine the best fit isotherm 3 error functions were used. Reactive Blue 19 from aqueous solutions was probably bound by the electrostatic attraction between the anionic dye and positively charged surface of the dust. Comparing sorption of the Reactive Blue 19 dye from aqueous solution and textile wastewater, it was observed that for all doses of the metallurgical dust the dye was removed in higher amounts from wastewater, probably due to the presence of the auxiliary substances used in dyeing processes. The RE of the dye was very high both from aqueous solution and textile wastewater, in the range of 84.90–99.92% and 96.48–99.99%, respectively. The results showed that dust from a steel plant, containing iron oxides, can be used as low-cost and effective sorbent to remove reactive dye from aqueous solution and textile wastewater. [ABSTRACT FROM AUTHOR]

Treatment of the dyehouse effluent is essential to minimize the environmental pollution. Extensive literature is available on the adsorptive treatment of dyes using activated carbon prepared from low-value materials. But, the treatment of dyes using biochar provides two benefits: ease of biodegradability and use as a soil amendment. The main aim of the present study is to investigate the feasibility of the cassava stem biochar (CSB) for the removal of mixed reactive dyes from simulated effluent. Biochar was produced by slow pyrolysis under an argon atmosphere at 200°C–400°C at varying time and their yields were compared. In this work, batch trials were performed to study the adsorption of mixed reactive dyes [Reactive Red (RR) and Drimarene Turquoise (DT)] on CSB. The parameters examined for batch adsorption are pH, temperature, contact time, adsorbent dosage, initial dye concentration, and agitation speed. The maximum dye removal of 88.47% was found at an equilibrium time of 10 min and the optimum pH of 3. The mathematical models for isotherm, kinetics, and thermodynamics were analyzed to calculate maximum adsorption capacity, rate constant, and thermodynamic parameters, respectively. Adsorption followed Langmuir, Dubinin–Radushkevich (D–R) and Temkin isotherms. Pseudo-first-order model fitted well with the experimental data. Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray diffraction of biochar were characterized before and after adsorption studies. Thus, the results showed that CSB could be utilized effectively for the removal of mixed reactive dyes from simulated effluent. [ABSTRACT FROM AUTHOR]

To enhance the dye fixation of pad-steam dyeing with reactive dyes, we used five kinds of dyes and water–ethanol dyeing medium to investigate the hydrophobic effect in dyeing process. The results indicated that the higher the molecule weight per water soluble group, i.e. the stronger dye hydrophobicity, the higher the dye fixation rate. When dyed with hydrophobic dye, both the alkali and steaming time can be reduced to realize the saving of chemicals and energy. For the more hydrophobic C.I. Reactive Orange 16 (RO16), the appropriate sodium carbonate concentration is 20 g/L, which is 10 g/L lower than the 30 g/L of C.I. Reactive Violet 5 (RV5). Similarly, RO16 just needed 2 min of steaming time to obtain the maximum K/S value, while RV5 needed 3 min. Enhancing the hydrophobicity of dyeing medium can also increase the dye fixation rates and K/S values. The K/S values and fixation rates of fabrics dyed with RV5 increased up mostly by 31.2% and 14% via using ethanol instead of 32 vol.% water in dyeing medium, respectively. All the dyed fabrics exhibit good color fastness. [ABSTRACT FROM AUTHOR]

Decreasing the temperature for dyeing wool fiber with reactive dye using a laboratory based ultrasonic machine was investigated as a way to obtain good quality dyed samples. Ultrasonic irradiation was used to reduce dyeing time and temperature whilst increasing dye migration and fastness. The ultrasonic machine was set at a 40 kHz frequency level, with effective power of 130 W and heating power of 350 W to carry out the dyeing process of the wool fiber within the temperature range 60-80 °C. The dyeing processes used both ultrasonic dyeing and without ultrasonic dyeing to obtain the laboratory results. At every dyeing stage from 60 °C to 80 °C, the exhaustion rate of dyeing was measured. Ultrasonic dyeing yielded better results compared to without ultrasonic dyeing. The diffusion coefficient, partition ratio, and standard affinity increased with the increased dyeing temperature and the use of an ultrasonic bath. The efficiency of ultrasonic dyeing was measured and the absorption rate constant was at least 55 % greater than without ultrasonic dyeing at every dyeing temperature i.e. 60 °C, 70 °C, and 80 °C. The color fastness to washing and rubbing was better for samples dyed with ultrasonic dyeing. Scanning electron microscopy (SEM) was used to measure the surface changes of the fiber. SEM analysis showed no evidence of scale damage on the wool fiber surface. [ABSTRACT FROM AUTHOR]

Response surface methodology is widely used in the optimization of dyeing conditions. Herein, the color strength and dye fixation rate of the cotton fabric dyed by pad‐irradiate‐pad‐steam (PIPS) process were determined and compared to by conventional pad‐dry‐pad‐steam (PDPS) process. Then the response surface methodology and central composite design were used to optimize the cationizing conditions during the pad‐irradiation step of the process to obtain high color strength during the subsequent salt‐free reactive dyeing of the cotton fabric via a pad‐steam process. The obtained experimental data were fitted to the second‐order polynomial equation, and response surface plots and contour plots were used to identify the optimal cationizing condition, the 3‐chloro−2‐hydroxypropyltrimethylammonium chloride concentration of 104 g/L, the microwave irradiation power of 537 W, the treatment time of 6 min, and the molar ratio of sodium hydroxide to 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride of 1.02. The results showed that the experimental color strength of the cotton fabrics was in close agreement with the value predicted by the model and the optimal cationizing condition was obtained precisely. [ABSTRACT FROM AUTHOR]

Textile wastewater is considered one of the most polluting effluents for ecosystems. Despite the various treatment methods used, its treatment still imposes a challenge on these industries especially with the increase in industrial activities. The electrochemical treatment of textile wastes has emerged as a promising solution, with almost no sludge production in comparison to other methods. In this paper, in house-fabricated electrochemical microfluidic systems were investigated for the electrochemical, indirect oxidation, decolorization of reactive dye solutions. Reactive Blue 19 and Reactive Yellow 181 dyes as single or mixed solutions were selected as models. Three effective electrochemical microfluidic chips designs were successfully fabricated: (1) a two-electrode cell (2E), (2) a three-electrode cell with reference electrode mounted on the top (3E-M), and (3) a three-electrode cell with an integrated reference electrode (3E-B). The electrochemical cells were characterized by their simple fabrication and effective performance. In all designs, 300 μm diameter carbon pencils were used as working and counter electrodes, along with an Ag/AgCl reference electrode. An experimental approach, using fractional factorial design, was used to study the optimum conditions for the degradation of each dye. The optimized factors were current density, pH, electrolyte concentration, dye concentration, and decolorization time. The percentage decolorization of the Reactive Blue was almost 100% in all of the microfluidic systems, while that of Reactive Yellow and the mixed solution were the highest in the 2E microfluidic chip, with efficiencies of 89% and 95%, respectively. Moreover, in optimum conditions, the performance of the three designs was investigated for the chemical oxygen demand (COD) removal in all dye solutions. Among the three designs, the 3E-M microfluidic chip was found to have the best capability for the COD removal, followed by 3E-M and then 3E-B. The reaction kinetics for the degradation process of each dye was found using the integrated method, and the results revealed pseudo-first-order reaction, with rate constants of 0.0545 and 0.0206 min–1 for Reactive Blue and Reactive Yellow, respectively. [ABSTRACT FROM AUTHOR]

In the present work, an ultrasound-assisted reverse-precipitation method was applied as a new approach for the synthesis of CuxO/Fe2O3/MoC. In the sonication method, a bath type sonicator as a simple, cost-effective, and low intensity sonicator was used. To determine the influence of ultrasonic waves on the morphology and application of nano-hybrid as nano-sorbent, it was also synthesized using the reverse precipitation method. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), Zeta-potential measurement, and vibrating sample magnetometer (VSM) techniques. The XRD analysis confirmed that the sono-synthesized sample has higher crystallinity than the conventional one and CuO/Cu2O/MoC/Fe2O3 phase was obtained under ultrasound. According to the TEM and FESEM, sono-synthesized nanoparticles were rod-like with a width and length of 3 nm and 40 nm, respectively. Also, a well-dispersed shape and uniform morphology of nanoparticles were obtained using sonication. In comparison with the conventional nano-hybrid, this structure results in more void and accessible sites for adsorption of pollutants. The efficiency of resulting nanoparticles in adsorption of reactive dyes as a model of the pollutant was evaluated by sorption and sono-sorption processes. The sono-synthesized sample removed the pollutants more efficient than the conventional sample. The removal efficiencies were about 99% for the removal of reactive dyes using the sono-synthesized sample and sono-sorption method. Besides, determining factors including pH, pollutant concentration, temperature, and contact time were optimized in the sono-sorption and sorption processes. A colorimetric method based on RGB value was used to determine dye concentration in aqueous media. The images were taken by a smartphone and analyzed by ImageJ software. The accuracy of RGB results was confirmed by a UV–Vis spectrophotometer. [ABSTRACT FROM AUTHOR]

• This study shows that MBR has the potential to decolourize textile wastewater. • IKH22 consortium is able to remove 80–90 % of organic matter under MBR conditions. • Under high biomass concentration of 8 g.L−1 a total MBR decolourization is obtained. • MBR leads to an almost total MLVSS removal whatever the biomass concentration. Textile industry is being a very demanding consumer of high-quality water with highest wastewater discharge. Membrane bioreactor (MBR) was employed widely to treat dying effluents due to its distinct advantages over conventional techniques. This study investigated the potential of biological treatment employing a microbial community 'IHK22′ under MBR laboratory-scale conditions to decolourize reconstituted textile wastewater in order to be reused. First, the bioreactor was conducted at a low biomass concentration of 4 g MLVSS ⋅L−1. Decolourization performances were maintained at very high rates (91–100 %) for dye mass loading rates in the range of 1.25–2.5 mg⋅g MLVSS -1⋅d-1. Then, the dye concentration was increased to 7.5 mg⋅g MLVSS -1⋅d-1, the decolourization performances of the MBR have been affected (80–87 %). When the biomass concentration has been increased to 8 g MLVSS ⋅L−1, thus, a total MBR decolourization was then observed (100 %). Under 320 mg⋅g MLVSS -1⋅d-1 and regardless of the operating period of the MBR, all the microorganisms and microfiltration membrane allow the elimination of most soluble organic matter of the treated effluent (80–90 %). Obtained results indicate that the dye mass loading rate can influence the efficiency of dye removal through an MBR. The use of an appropriate biomass concentration significantly improves the MBR performances for an effective textile wastewater treatment. [ABSTRACT FROM AUTHOR]

Ginger fiber(GF) is not suitable for textile due to its coarseness and it is usually disposed as wastes. This paper introduces a technology to make ginger fiber a valuable adsorbent of dyes in dyeing wastewater. The new technology is to explode the ginger fiber first by steam, and then frozen and disintegrate it to powder. We investigated the impact of a variety of factors in processing the ginger fiber on its ability to adsorb the dye RB19 in dyeing wastewater, which included the conditions under which the stream explosion was conducted, concentration of NaCl, and pH value. The surface morphologies and crystallization indexes of the ginger fiber before and after steam explosion were analyzed to elucidate the mechanisms underlying the improved adsorption of ginger fiber after steam explosion. Experimental results showed that steam explosion conducted under pressure1.9 MPa and lasting 150 s increased the adsorption from 48.8 to 115.12 mg/g. It was also found that several RB19 molecules aggregated to an ellipsoid with three axes: 33.4 Å×11.4 Å×8.8 Å. Breaking the ginger fiber surface enhanced the movement of RB19 molecules into the exploded ginger fiber powder(EGFP) and steam explosion made EGFP much richer in GF than in crystal index (CI). Increasing the pressure under which the steam explosion was conducted from 1.3 to 1.9 MPa reduced CI in EGFP from 35% to 20%, indicated that the steam explosion opened the amorphous region in the ginger fiber and that the expansion increased with pressure. As such, it enhanced the adsorption of RB19. The increased adsorption was mainly due to the broken surface. In addition, EGFP became small particles with a diameter of 80 μm, thereby enlarging the pores. Such structural changes made it easy for the dye molecules to move into the amorphous region of EGFP and improved its adsorption consequently. The steam explosion also increased the adsorbing rate, reducing the time required from the adsorption to reach equilibrium from 12 h to 8 h. The adsorption of RB 19 by the processed ginger fiber followed a second-order kinetic and the Langmuir thermodynamic model. After five cycles of adsorption-desorption, the adsorption capacity of the ginger fiber was still 80% of its original capacity. It is concluded that that steam explosion can effectively improve the adsorption capacity of ginger fiber. As a biomass adsorbent, EGFP can not only ameliorate the detrimental impact of dyeing wastewater on environmental but also turns a waste into a decontaminant amendment. It has potential applications in environmental engineering. [ABSTRACT FROM AUTHOR]

The traditional cotton fabric light coloring process was divided into two processes, which is bleaching and dyeing, and the process is long and the water consumption is large. To solve the problem, a new cotton fabric bleaching and dyeing one-bath process was used to dye the light-colored phase. The experimental results show that the optimal process for SR dyeing with reactive dyes of Norwegian clones is 1% H2O2, 65 °C, 40 min, and 7.5% solid soda, which not only shortens the operation process, but also improves production efficiency, the objective of energy saving and emission reduction as well as production costs reduction can be reached. [ABSTRACT FROM AUTHOR]

A solid agricultural waste, coffee husk, was applied as an adsorbent for reactive dye-polluted wastewater treatment. Coffee husk biochar was pyrolyzed at 450 °C and then chemically activated using 50% ZnCl2 solution. The surface of activated coffee husk biochar was modified using a cationic surfactant, Cetyltrimethylammonium bromide (CTAB), to create CTAB-modified coffee husk biochar (MCH), to improve reactive adsorption of anionic dyes from synthetic wastewater. The selected reactive dyes were reactive yellow 145 (RDY145), reactive red 195 (RDR195), and reactive blue 222 (RDB222). The adsorption kinetics fit well using a pseudo-second order model for all three dyes. The adsorption isotherms matched well with the Langmuir model. The removal efficiency of RDY145 (83.7%) was the highest, followed by RDR195 (71.1%) and RDB222 (59.6%). The amount of RDY145 adsorbed by MCH was about 9-fold that adsorbed by conventional activated carbon. Additionally, the solution pH had no effect on reactive dye removal efficiency using MCH. [ABSTRACT FROM AUTHOR]

In this study, real wastewater from a dyeing factory and previously treated by biological processes was decolorized by Fenton oxidation. Direct and reactive dyebaths and the related auxiliaries constituted the polluted effluents. A synthetic wastewater was also prepared in the same way in order to compare degradation performance. The study was performed with a systematic approach, searching optimum values of H2O2 and FeSO4 concentrations, pH, temperature and the chemical structure of each tested dye. Depollution results showed that the oxidation behaviour of synthetic and real wastewaters was very similar, especially during the first stage where the breaking of chromophore groups allowed fast colour removal. However, it was found that higher ratios of [H2O2]/[FeSO4] must be engaged in the case of real wastewaters. Results also showed that the catalytic oxidation yielded a fast and complete depollution at [H2O2]/[FeSO4] = 70, pH 3 and temperature 40°C. For experiments with direct dye, colour and COD removals were, respectively, 90% and 87% in the case of real wastewater. Reactive real wastewater showed non-stable oxidation evolution due to the hydrolysed dyestuff and this led to 83% and 45% decolourization and COD removal, respectively. Better depollution results were noted for the synthetic wastewater experiments. This finding was related to the non-stable composition of the real wastewater and the unknown chemical and physical interferences between its compounds. After sedimentation, reuse of the treated wastewater for new dyeing experiments was also investigated. For this purpose, the whole process was run under complete recycling mode and the previously treated effluent was re-used as fresh dyebath. Results in terms of colour depth and fastness showed that dyeing performances were very similar, and an important opportunity is offered by reusing wastewater treated by Fenton oxidation process. [ABSTRACT FROM AUTHOR]

At present, many well-known brands of washing machines in the market are equipped with dye transfer inhibition washing procedures. However, there is no standardized sample available for the evaluation of the dye transfer inhibition washing procedure, and there is no comparability and access standard of the high-quality washing machine with the related functions. In this article, the certified reference materials for the evaluation of the dye transfer inhibition function will be prepared, which consist of certified reference material of white cotton fabric and that of dyed cotton fabric. The certified reference material of white fabric is made of bleached plain fabric, and that of dyed fabric is made with different reactive red dyes and dyeing processes. The size and manufacturing process of the whole set of standardized samples for the evaluation of dye transfer inhibition are selected and determined through experiments. The preparation of the standardized sample for the evaluation of dye transfer inhibition will improve the research and design of the functional washing procedure, which can better solve the pain point when dark and light clothes are washed together. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the decolorisation effect of atmospheric pressure plasma treatment on knitted fabrics dyed with reactive dyes under different processing parameters, ie, air concentration, treatment duration and water content. The fabrics were dyed with reactive dye of a blue colour, and the colour depths were 0.5%, 1.5% and 3.0% on weight of fabric. The colour properties of untreated and plasma‐treated fabric samples were evaluated by means of reflectance, K/S and relative unlevelness index. The colour properties were evaluated instrumentally and quantitatively in order to study the decolorisation effect induced by atmospheric pressure plasma treatment. Experimental results revealed that the desired decolorisation effect was heavily influenced by the atmospheric pressure plasma treatment processing parameters. Although the desired decolorisation effect could be obtained by controlling the processing parameters of the atmospheric pressure plasma treatment, the treatment did not provide any significant reduction in the bursting strength of the fabric. [ABSTRACT FROM AUTHOR]

In the present study the polyacrylic anion exchanger Amberlite IRA 478 (IRA 478) was used for removal of textile dyes such as C.I. Acid Red 18 (AR18), C.I. Reactive Blue 21 (RB21) and C.I. Direct Yellow 142 (DY142) from aqueous solutions. Sorption of the above-mentioned dyes was carried out by the static and dynamic methods. The obtained results were analyzed by determining the adsorption isotherm parameters using the Langmuir and Freundlich models. Kinetic parameters of dyes sorption were calculated from the pseudo-first order, pseudo-second order and intraparticle diffusion models. The monolayer sorption capacities of IRA 478 determined from the Langmuir isotherm were found to be 1098.5 mg/g for AR18 (R²=0.994), 46.8 mg/g for DY142 (R²=0.820) and 23.5 mg/g for RB21 (R²=0.987). Kinetic studies revealed that effectiveness of AR18, DY142 and RB21 uptake increases with increasing phase contact time and initial dyes concentration. The kinetics of the dyes sorption process on the anion exchanger is best described by the pseudo-second order model (PSO) due to the high values of the determination coefficients R² (linearity condition of the plot t/qt vs. t). The rate constants of the pseudo- second order kinetics k2 are reduced from 0.1001 to 0.0008 g/mg·min for AR18, from 0.0147 to 0.0112 g/mg·min for DY142 and 0.0489 to 0.0072 g/mg·min for RB21 with an increase of initial concentration of dyes. The presence of salts and surfactants had an impact on the retention of direct and reactive dyes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical oxidative degradation can degrade reactive dyes. • The porphyrin ring structure of Reactive Blue 21 is more stable. • Box-Behnken designs can successfully optimize the operating parameters. • The combination of high degradation and low energy consumption is realized. • The electrochemical degradation system is installed in the washing machine. At present, organic wastewater containing dyes has become one of the main threats to the environment, and wastewater pollution caused by dyes released from fabrics during home washing also accounts for a large proportion. In this study, Ti/IrO 2 electrodes for dye waste degradation were designed and prepared with Reactive Yellow 210 (RY 210), Reactive Blue 19 (RB 19) and Reactive Blue 21 (RB 21) solutions, and a laboratory electrochemical reactor was constructed. Secondly, in the reactor, the effects of current density (20–60 mA cm−2), electrolyte concentration (NaCl, 0.01–0.03 M L−1), and initial dye concentration (30–70 mg L−1) on the COD degradation rate and energy consumption of the dye solution were explored, and the parameters were optimized by the Box-Behnken design, and the equipment was realized in the washing machine. The results showed that the effect of degradation parameters on the degradation of the three groups of dyes was: current density > initial dye concentration > electrolyte concentration. Through parameter optimization, the average COD degradation rates of the three groups of dyes, Reactive Yellow 210 (RY 210), Reactive Blue 19 (RB 19) and Reactive Blue 21 (RB 21), reached 50.71%, 41.65%, and 33.12%, respectively, and the degradation energy consumption decreased by the same trend as 29.91%, 26.49%, and 65.91%, respectively. [ABSTRACT FROM AUTHOR]

Decolorization of red azo dye (Cibacron Red FN-R) from synthetic wastewater has been investigated as a function of solar advanced oxidation process. The photocatalytic activity using ZnO as a photocatalysis has been estimated. Different parameters affected the removal efficiency, including pH of the solution, initial dye concentration and H2O2 concentration were evaluated to find out the optimum value of these parameters. The results proved that the optimal pH value was 8 and the most efficient H2O2 concentration was 100mg/L. Toxicity reduction percent for effluent solution was also monitored to assess the degradation process. This treatment method was able to strongly reduce the color and toxicity of reactive red dye-238 to about (99 and 80) % respectively. It can be concluded, from these experiments, that the using of ZnO as a photocatalysis was exhibited as economical and efficient treatment method to remove reactive red dye-238 from aqueous solution.

Bacteria were isolated from effluents of textile industries and screened by their capability to decolorize at least one of eight reactive dyes used in the textile industries. Three isolates having the capability to decolorize the highest number of dyes with more than 25% of decolorization were identified as Alcaligenes faecalis AZ26, Bacillus cereus AZ27 and Bacillus sp. AZ28 based on morphological, cultural, biochemical characteristics, and 16S rDNA sequence analysis. The decolorization capability of these three bacterial isolates was optimized under different physicochemical conditions by using Novacron Super Black G (NSB-G), one of the eight reactive dyes commonly used in textile industries. These bacterial isolates grew well in the presence of up to 500 mg L−1 of NSB-G and showed decolorization of approximately 90% at 200 mg L−1 of NSB-G after 96 h of cultivation at 37 °C and pH 8.0 under static condition. Decolorization of NSB-G by the bacterial isolates was investigated using UV-VIS spectrophotometry and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The UV-visible absorbance spectra and the FTIR spectrum of the decolorized NSB-G significantly differed from those of the parent dye, indicating that the NSB-G was degraded by the bacterial isolates. High decolorization extent supports the notion that the bacterial isolates reported herein might have potential in the biological treatment of dyeing mill effluents.

The study explores the efficacy of indigenously isolated halo-alkaliphilic bacterium Nesterenkonia sp. for decolorization of reactive violet 1(RV1) dye at alkaline pH. Dye decolorization by the microbe was tested first in nutrient broth by varying initial dye concentration (50-3000 mg/L), pH (7.0-12.0), inoculum size (1-10%) and temperature (4-45 C) by spectrometric determination of absorbance at 550 nm, using single parameter approach. Box Behnken Design model of Response Surface Methodology (RSM) was then used to obtain optimized combination of process parameters for best dye degrading response of the microbe, based on 46 experiments. The microbe is found effective under a wide range of conditions and showed excellent reusability up to 6 batch cycles. Short term acclimatization in repeated cycles made decolorization faster and greater. Growth of the microbe was favored at high pH (11.5) and in the presence of salts (2.5-5%), decolorizing 94-100% of the dye. Decolorization of the dye by the microbe was also studied in simulated and real textile wastewaters under the optimized process conditions using 1% starch as carbon supplement. The bacterium degraded the dye and also bioremediated the wastewaters by successfully moderating the pH, removing toxic metal Cr (VI) and chemical oxygen demand (COD) during treatment. [ABSTRACT FROM AUTHOR]

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