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The galvanising industry's wastewater treatment facilities generate waste metal hydroxide. These sludges have the potential to be used to remove textile dyes from effluents. In this study, three reactive dyes, which are frequently used in cellulosic textile materials' dyeing, Remazol Turquoise Blue G 133% (CI RB21), Remazol Red 3B (CI RR23), and Remazol Red 3BS 133% (CI RR239) were used to investigate the color removal efficiency of aluminum hydroxide sludge (AHS) depending on dye chromophore. Adsorption studies were conducted under varying conditions of pH, initial dye concentrations, and AHS doses. The characteristics of the AHS were examined by SEM (EDX and DX-Mapping), BET, XRD, and FTIR. The maximum dye removal was achieved at pH 3 for CI RB21, and at pH 5 for CI RR239 and CI RR23. Over 90% of dye removal was obtained for CI RR239 and CI RB21, when the adsorbent dosages were 8 g/l and 5 g/l, respectively. For CI RR23, the highest color removal percentage was only 72.7%, when the dosage of adsorbent was 10 g/l. It was also determined that at 500 mg/l initial CI RB21 dye concentration, the removal percentage of CI RB21 reached 95%, while the maximum removal percentages (95% for CI RR239 and 68.3% for CI RR23) were achieved at the 200 mg/l and 100 mg/l initial dye concentrations for CI RR239 and CI RR23, respectively. In the study, it was observed that the number of sulfo groups affecting the ionic charge of dye molecules and molecular weights of the dyes have a significant effect on the dye removal efficiency. Metal hydroxide is produced from treating wastewater from galvanising industry. Aluminium hydroxide sludge is cheap and efficient to remove dyes from textile wastewaters. Number of sulfo groups and molecular weights of dyes are significant for color removal efficiency. The highest dye removal by aluminium hydroxide sludge occurs in acidic conditions and dyes having higher molecular weight and higher number of sulfo groups. [ABSTRACT FROM AUTHOR]

As is known, color stripping can be done with oxidizing or reducing agents. Today, reactive dye stripping is conventionally carried out via reductive method using hydrosulfite. However, from an environmental point of view, the use of more ecological chemicals has gained importance. In this study, it is aimed to determine the performances of reducing and oxidizing chemical alternatives to hydrosulfite, depending on the reactive dye chromophore. On the other hand, it was also aimed to provide a color fading effect on reactive dyed cotton fabrics with a treatment applied after dyeing. For this purpose, color stripping and/or fading effect was investigated on cotton knitted fabrics dyed with four different reactive dyes having anthraquinone (Reactive Blue 19), phthalocyanine (Reactive Blue 21), monoazo (Reactive Red 239) and metal azo (Reactive Red 23) chromophores. Studies were carried out with hydrosulfite, sodium hydroxymethane sulfinate and potassium persulfate at five different concentrations. It can be said that sodium hydroxymethane sulfinate and potassium persulfate can be used as an alternative to hydrosulfite in red dyes and blue dyes, respectively. COD and BOD values of wastewater of potassium persulfate treatment was found to be lower than hydrosulfite, which indicates that it is an ecological alternative over hydrosulphite. [ABSTRACT FROM AUTHOR]

Today, innovative productions have gained great importance to meet customer expectations. In this study, color stripping in reactive dyed knitted cotton fabrics with ozone technology was investigated. Furthermore, it was also aimed to obtain vintage effect by fading the color with the ozonation process. For this purpose, fabrics were dyed into three primer colors, namely yellow, red and blue, and also black color, then they were subjected to ozonation at different durations and the resulting stripping efficiency was evaluated in comparison with conventional caustic-hydrosulfite stripping method. From the color fading values (%), it is possible to say that yellow is the hardest and blue is the easiest to fade among the three primer colors. It was observed that as the ozonation time increased, the color lightened, but the actual fading occurred within the first 15 minutes, after which the change in color was smaller. Besides, it has been shown that if the ozonation is done for a very short time such as 5 minutes on reactive dyed fabrics, the vintage effect can be obtained. On the other hand, color stripping can be achieved as an alternative to caustic-hydrosulfite treatment, if the ozonation is performed for 15 minutes or longer. [ABSTRACT FROM AUTHOR]

Aramid fabric was plasticized and modified with combination of carrier CWP-N and cationic gelatin protein auxiliary. The dyeing property of the treated aramid fabric dyed with reactive dyes was evaluated. And the modification mechanism of aramid fabric and its reactive dyeing mechanism were analyzed. Then, the structures of the treated aramid fabric were characterized with Fourier transform infrared (FTIR), scanning electron micrograph (SEM), surface friction properties and X-ray diffraction analysis, respectively. In addition, the glass transition temperature and the thermal properties of the treated aramid fabric were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), respectively. The results showed that the dyeing properties of the treated aramid fabric to reactive dyes were improved highly. Compared with the untreated aramid fabric, the dye uptake of the treated aramid fabric increased by more than 2.7 times, the color depth (K/S value) after soaping increased by more than 8 times, and the dye total fixation rate increased by more than 3.2 times. The chemical structure and surface morphology of the treated aramid fabric were changed significantly. And the glass transition temperature of the treated aramid fabric was reduced. The main reason for the significant improvement of reactive dyeing properties of the treated aramid fabric was the change of its structure. However, the crystallinity of the treated aramid fabric was almost unchanged. And the thermal stability of the treated aramid fabric was reduced. [ABSTRACT FROM AUTHOR]

Cumin seeds extract containing plant polyphenols was used as a reducing agent forthe preparation of iron-based magnetic nanoparticles. Then, functionalised magnetic nanoparticles (FMNPs) and chitosan were used to synthesise a novel magnetic polymeric nanocomposite (MPNC) with high efficiency and fast sorption kinetics for Reactive Black 5 removal. FMNPs and MPNC were characterised by Fourier transform infrared, vibrating sample magnetometer, field emission scanning electron microscopy, X-ray diffraction, and Zeta potential. The functionalised magnetic nanoparticles had a spherical shape with the size in the range of 22–38 nm that was covered with chitosan. The zeta potential of MPNC was +59.7 mV. Thepresence of Fe3O4 nanoparticles in MPNC sorbent and its crystalline structure was confirmed by FTIR and XRD, respectively. Results showed that the synthesised sorbent has an excellent sorption behaviour for Reactive Black 5 at room temperature and pH range of 5.5–6.5. The time required to reach equilibrium for various concentrations of Reactive Black 5 was ~ 100 seconds, and a 120 mg L−1of dye solution was 92% decolourised within this time. Experimental data were best fitted to the semi-first-order kinetics and Halsey thermodynamic models. The sorbent maximum capacity was 989.9 mg g−1. [ABSTRACT FROM AUTHOR]

Textile wet processing is one of the most water-consuming industries. The deficiency of soft water in some parts of the world urged the researchers to exert effort toward minimization of water consumption during textile wet processes. In this work, we bleach wool fabrics by hydrogen peroxide, followed by utilization of the discharged bleaching bath (DBB) in dyeing of wool with acid, reactive, and basic dyes. The residual H2O2 in the bleaching bath was decomposed into water and oxygen by adding low concentrations of potassium iodide (KI). Results of this investigation clarify that treatment of the DBB with KI is mandatory to make the bath appropriate for wool dyeing. The dyeability of wool toward the said dyes in KI-treated DBB is significantly higher than that upon dyeing with tap water. The fastness properties of the dyed fabric to washing, perspiration, and light were assessed. The turbidity, pH, total dissolved salts (TDS), total suspended salts (TSS), biological oxygen demand (BOD), and chemical oxygen demand (COD) of the bleaching effluent were assessed. Solubility of bleached/dyed wool fabrics in alkali and urea-bisulfite solutions assures the modification of some disulfide bonds along wool keratin macromolecules into cystine oxides/cysteic acid residues, and consequently the dyeability was enhanced. [ABSTRACT FROM AUTHOR]

Batik is an Indonesian traditional cloth which has been recognised as an Intangible Cultural Heritage of Humanity by UNESCO for more than a decade. Batik cloth is popular among Indonesian people for daily use, both for formal and informal occasions. Commonly, batik cloth is made from cotton, which has many advantages, however prone to bacterial growth, particularly in the tropical climate. Therefore, it is important to develop batik cloth with antibacterial properties. The antibacterial properties of batik cloth were achieved by applying ZnO nanoparticles as antibacterial agent. The nanoparticles were synthesised using precipitation-sonication method. The formed ZnO nanoparticles were in an average particle size of 54.76 nm and 99.77% ZnO content. The batik making process utilized a synthetic reactive dye of remazol-turquoise blue. The effect of process sequence, the level of antibacterial properties, the morphology of the ZnO coated fabric, and the effect of the application of nanoparticle on the dyeing process were investigated. The results showed that ZnO nanoparticle application on the batik fabric led to antibacterial properties. The process sequences in adding the ZnO nanoparticles were confirmed to significantly affect the antibacterial effectivity and the colour strength. The application of ZnO nanoparticles did not affect the colour fastness to washing as the test showed similar value to that of without ZnO treatment. In addition, the application of ZnO nanoparticles affects the mechanical properties by increasing the tensile strength and decreasing the elongation at break. The application of ZnO after batik making process was shown to have a greater effect on the mechanical properties. [ABSTRACT FROM AUTHOR]

The usability of natural fibers is increasing day by day to curtail the versatile applications of synthetic polymers that pollute the environment. In this research work, blended fibers from jute and cotton were utilized as reinforcing materials whereas unsaturated polyester resin (UPR) was chosen as a matrix to fabricate composite materials. Various reactive dye percentages (1, 2, 3, 4, 5, 6, 7, and 8%) and several gamma radiation doses (2.5, 5, and 7.5 kGy) were introduced to augment the properties of prepared composites where the 6% dye treatment and the 5 KGy gamma radiation dose presented paramount properties. Composites, fabricated by hand-lay-up technique, were characterized by mechanical properties (tensile strength, tensile modulus, and elongation at break), water uptake, Thermo-gravimetric analysis (TGA), Fourier Transformed Infrared (FTIR), and Scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

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]

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]

In the present investigation, date seed-derived biochar was applied as economic and effective sorbent for remediation of reactive dye from contaminated solutions. Biochar produced at 350°C through pyrolysis process exhibited reactive black 5 (REB5) sorption capacity 2.7 times higher than virgin date seeds. The surface of biochar was analyzed through Fourier transform infrared and scanning electron microscope data. The maximum REB5 uptake determined through the Langmuir model was found to be 113.4 mg/g. The REB5 sorption kinetics were accurately described by the pseudo-first-order model than pseudo-second-order model. Thermodynamic parameters indicated that REB5 sorption was spontaneous, feasible, and endothermic process. [ABSTRACT FROM AUTHOR]

In this work, a series of magnetic activated carbon/nanodiopside (Fe3O4/AC/Diop) nanocomposites were synthesised and used for the removal of reactive green KE-4BD dye from the aqueous solution. After preparation of nanodiopside by sol-gel method and activated carbon from coconut husk, first, Fe3O4/AC composite was prepared by in situ synthesis of Fe3O4 nanoparticles between activated carbon pores, and then, different percentages of Fe3O4/AC/Diop nanocomposites were prepared by simple mixing of Fe3O4/AC composite and Diop in ethanol. Formation of Fe3O4/AC and Fe3O4/AC/Diop composites was characterised by FTIR, field emission scanning electron microscopy, BET, XRD and vibrating sample magnetometer analyses. Thermogravimetric analysis was used to show the adsorption capacity of the adsorbent more accurately. Effects of amount of adsorbent, initial pH, contact time and dye concentration on reactive green dye removal were also studied using central composite design. Optimal conditions for maximum reactive green KE-4BD dye adsorption (98.35%) process were as follows: pH= 4.90, adsorbent amount: 0.015 g, dye concentration: 37.17 mg/L and contact time: 10.12 min, respectively. In addition, the adsorption kinetics, thermodynamics and isotherms were examined. Adsorption isotherms (qmax: 344.827 mg/g), kinetics and thermodynamics were demonstrated that the sorption processes were better described by the pseudo-second-order equation and the Langmuir equation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The removal efficiency of Reactive Blue 19 (RB19) by using surfactant-modified bentonite (MB) from aqueous solutions, and also textile wastewater samples was examined. Natural bentonite (NB) was firstly modified with didodecyldimethylammonium bromide (DDDAB) in order to increase the removal capacity of bentonite. MB was then characterized by Fourier Transformed Infrared Spectrophotometer (FTIR), x-ray diffractometry (XRD), x-ray fluorescence (XRF), Scanning Electron Microscope (SEM)/EDX, zeta potential, elemental, and thermal analysis techniques. The high adsorption capacity of MB was 407.7 mg g−1at pH = 1.5 and 20°C. The adsorption of Reactive Blue 19 onto MB agreed with the pseudo-second-order kinetic and Langmuir isotherm models. [ABSTRACT FROM AUTHOR]

The aim of the current research is to study the improvement of dyeability of silk fabrics using surface modification performed by corona discharge and chitosan pre-treatment. Effects of some operational variables such as corona treatment time, concentration of chitosan, time, and temperature on grafting process were examined through dyeability of silk fabrics using two commercial reactive dyes. Fourier transform infra-red and scanning electron microscopy spectroscopy data revealed the surface modification of the silk by corona discharge and grafting of chitosan onto the silk fabric. Optimal grafting values obtained were corona treatment time 30 min, concentration of chitosan 18% owf, time 2 h and temperature 60 °C. It was found that silk pretreatment with corona discharge and chitosan improved dyeability from 1.84 to 4.58 for RY and from 3.05 to 6.40 for RB. The results indicated that the color fastness and tensile strength of silk fabrics were not significantly affected irrespective of the grafting with corona and chitosan pre-treatment. The results of this study provide the potential making of eco-friendly modification and reactive dyeing of textile fibers using corona discharge and chitosan pre-treatment. [ABSTRACT FROM AUTHOR]

Mosquito repellent textile materials are being increasingly in demand as a preventive measure to protect the consumers from mosquito-borne diseases like malaria, dengue, etc. Many of these agents are applied in post-colouration operation to the fabric. Although initially they show good repellency against mosquitoes, upon repeated washing cycles, this effect gets diminished considerably. In the present work, nylon fabric is imparted mosquito repellent finish in one, single operation of dyeing cum finishing. This approach is based on the modification of commonly used mosquito-repellent N,N-diethyl-m-toluamide (DEET) and synthesizing a reactive dye based on this important ingredient. A reactive dye was synthesized in order to impart mosquito repellency to the nylon 6 fabric, DEET was first subjected to nitration using Potassium nitrate and dichloromethane (DCM). This nitrated product was reduced in the presence of water: ethanol (30:70) and the amine, thus, produced was then condensed with 2, 4, 6-trichloro-1, 3, 5-triazine (cyanuric chloride) a reactive group. The resultant product was finally reacted with an amino group present in 6-Amino-2-naphthalenesulphonic acid (Bronner’s acid) to obtain Sodium6-((4-(diethylcarbamoyl)-2-methylphenyl) amino)-1, 3, 5-triazin-2-yl) amino) naphthalene-2-sulfonate (reactive dye). This reactive dye was then applied on nylon 6 fabric by covalent bonding to provide mosquito-repellent material. The chemical structures of the dye were characterized using FTIR and1H-NMR spectroscopy. The melting point of the dye was characterized by Differential Scanning Calorimetry. The fastness properties of the dyed cum finished fabric were measured to evaluate the performance of the dye. Efficacy of mosquito repellency of the treated nylon 6 fabric was studied using standard methods. The nylon 6 fabric reacted with the mosquito-repellent dye and showed very good durable mosquito-repellent activity. [ABSTRACT FROM AUTHOR]

Cattle hoof and horn keratin hydrolysate from cattle hoofs and horns were successfully extracted and used to cationize cotton fabric. The effect of cationization was tested by dyeing the cationized cotton fabric using reactive dyes (cationized sample). The results were compared to conventionally dyed cotton fabric sample without cationization. The UV/VIS absorption result showed 6% improvement in exhaustion; the Color EyeK/Sresult gave 4.5% improvement in fixation and 6.8% in dye utilization for reactive dye (H-Reactive Red). Acceptable color fastness to washing (4/5) and light fastness (7) were achieved on cationized sample. [ABSTRACT FROM PUBLISHER]

Effectiveness of two strongly basic anion exchange resins of the gel (Dowex PSR-2) and macroporous structure (Dowex PSR-3) was compared in order to remove three hazardous dyes such as C.I. Acid Orange 7 (AO7), C.I. Reactive Black 5 (RB5), and C.I. Direct Blue 71 (DB71) contained in water and textile wastewaters. Batch adsorption experiments were carried out to analyze the effect of phase contact time, initial dye concentration, and the presence of auxiliary materials (anionic and cationic surfactants, Na2CO3, and Na2SO4). The Langmuir model better described the adsorption process of the dyes onto both resins than the Freundlich model. The monolayer adsorption capacities (qe) of Dowex PSR-3 were calculated as 336.4 mg/g for AO7, 317.9 mg/g for RB5, and 150.4 mg/g for DB71 at 25°C. Dowex PSR-2 of the gel structure is characterized by considerably lower values ofqe(50.1 mg/g for AO7, 17.2 mg/g for RB5, and 9.7 mg/g for DB71). Of special importance are high values of the working ion exchange capacities of Dowex PSR-3 determined from the breakthrough curves towards AO7 and RB5 equal to 127 and 85 mg/cm3, respectively. The pseudo second-order kinetic model described the experimental sorption data better than the pseudo first-order model. Methanol addition to the 1 M HCl and 1 M NaOH solutions improved the effectiveness of dye desorption. [ABSTRACT FROM PUBLISHER]

This paper includes the investigation on the dyeing performance of reactive and basic dyestuff regarding jute fiber and discusses their benefits and shortcomings. Plain woven jute fabric samples of 261 GSM were dyed with 0.5%, 1.0%, and 4.0% shade of basic and reactive dyes. Then the dyeing performance of both dyestuffs was analyzed. It has been found that exhaustion of basic dye is considerably greater than reactive dye, while this exhaustion decreases for basic dye and increases for reactive dye with the increment of respective shade percentages. This phenomenon has also been verified through the absorption curve, i.e.K/Svalue of fabric dyed with both dyestuffs in three different shade percentages. Again strong covalent bond is formed during the fixation of reactive dye with the cellulose of jute fiber, and at the same time no strong bond was created in case of basic dye. Finally the color fastness properties have been assessed through rubbing and washing. Both the dye classes have shown nearly similar ratings in case of dry rubbing. However, in case of wet rubbing and wash fastness to color change and color staining; the samples dyed with reactive dyes showed superior fastness ratings over the basic dyed samples. [ABSTRACT FROM AUTHOR]

The study describes the synthesis of modified immobilized activated alumina (MIAA) and its application for the removal of textile dye from aqueous media. Immobilization was carried out by using the sol--gel method while modifications were made during the synthesis by adding powder activated alumina. Batch adsorption experiments were carried out at 20±1 °C to see the effect of different parameters like contact time, stirring rate, initial concentration of the dye and dose of MIAA. The removal efficiency of Cibacron reactive yellow dye with an initial concentration of 400 mg/L was greater than 90% for 90 min contact time. Langmuir and Freundlich adsorption isotherms were applied which fitted the data with an R2 value of 0.99. The maximum adsorption capacity of MIAA was 25 mg/g at the initial dye concentration of 400 mg/L. MIAA can be regenerated thermally and chemically with the dye removal efficiency remained above 85% during the first 4 regeneration cycles. Thermal regeneration was achieved in a muffle furnace at 450 °C while chemical regeneration was done by immersing MIAA in 0.1 M NaOH solution for 2 h. MIAA also proved effective for the adsorption of dyes from actual textile wastewater giving a removal efficiency of 75%. [ABSTRACT FROM AUTHOR]

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 23factorial design was used to evaluate the effects of the three key factors: temperature, Fe(II) and H2O2concentrations, for a dye concentration of 250 mg L−1with chemical oxygen demand (COD) of 172 mg L−1O2at 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. [ABSTRACT FROM PUBLISHER]

Batch and fixed bed experiments were carried out for the removal of Reactive Turquoise Blue Q-G125% (TB) dye from aqueous solution using cashew apple bagasse (CAB) as non-conventional adsorbent. CAB, a lignocellulosic material, used in this study contained 20.56% ± 2.19% cellulose, 10.17% ± 0.89% hemicellulose, and 35.26% ± 0.90% lignin and was characterized as nonporous material and its surface area cannot be determined by nitrogen adsorption at 77 K. Kinetic and equilibrium study were performed in batch systems, evaluating the effects of pH, contact time, initial concentration, adsorbent loading, and temperature on the adsorption. The pseudo-second-order model best described the adsorption kinetic data. The adsorption isotherms of TB onto CAB were well fitted by the Freundlich model. The maximum adsorption capacity of the biomass was 145.10 mg/g and high levels of dye removal (> 90%) at 60°C. According to thermodynamic results, the adsorption of TB onto CAB is a spontaneous endothermic process. Dynamic adsorption behavior was studied in fixed bed system. The highest bed adsorbed quantity of 32 mg/g with 100 mg/L TB initial concentration at 1 mL/min flow rate and 1.4 cm bed-height was obtained. The results showed that CAB is a promising adsorbent for the adsorption of the dye. [ABSTRACT FROM AUTHOR]

An inorganic–organic composite material (MCPAM) consisting of magnesium chloride and polyacrylamide, was applied to remove reactive dye (Cibacron Red FN-R) from aqueous solution through coagulation–flocculation process. MCPAM with the ratio of 90% MgCl2/10% PAM was the best ratio in removing reactive dye. Kinetics of reactive dye removal was investigated using pseudo-kinetics model and it fits pseudo-second-order reaction model. The mechanism of reactive dye removal was investigated through physicochemical properties of supernatant, flocs, and sludge. The change of conductivity and pH denotes the interactions between reactive dye and MCPAM. The chemical structure, settling, and microstructure of sludge indicate the formation of sludge during coagulation–flocculation process. The settled sludge volume and sludge volume index (SVI) that of MCPAM was lower than that of MgCl2. The flocs formed using MCPAM was also relatively compact and larger in size compared to that of MgCl2. The reactive dye removal was optimized through central composite design whereby color removal (%) and chemical oxygen demand (COD) reduction (%) were optimized by five operating factors, namely, concentration of dye, pH, dosage of MCPAM, agitation speed, and agitation time. The optimal values reported for color removal (%) and COD reduction (%) were of 97–98% and 60–81%, respectively. [ABSTRACT FROM AUTHOR]

In the present study, simultaneous reactive dyeing and easy care finishing of cotton with a non-formaldehyde and environment-friendly compound (citric acid [CA]) was successfully optimised using a statistical model. An optimised recipe was formulated based on the half factorial central composite design and numerical optimisation solution by Design-Expert 6.0 software. The optimised conditions were investigated for the concentration of CA, catalyst, reactive dye, alkali and urea. Evaluation of the recipe was made with respect to K/S, percent fixation of reactive dye, dry crease recovery angle and tensile strength. The simultaneous dyeing and finishing using theoretical optimised recipe was carried out and performance of the sample was compared with the sample using conventional two-step dyeing and finishing process. [ABSTRACT FROM AUTHOR]

To achieve the silk transfer printing with reactive dye, novel transfer printing paper was prepared by coating the special paste. The impacts of each ingredient in the paste on the printing property of transfer paper were investigated. Results showed that hot-melt adhesive agent (soluble polyester, ES-1) influenced the extent of dye transfer during the hot-press process significantly; thickener (sodium alginate, SA), fixing alkaline agent (NaHCO3), and humectants (urea, glycerin and dicyandiamide) had their own contributing effects to the extent of dye fixation during the steaming. Optimal printing property was achieved when using the paste containing ES-1 6%, SA 3%, NaHCO3 1%, glycerin 2·5%, urea 2·5% and dicyandiamide 2%. The paste displayed a shear thinning behaviour and low thixotropy. The transfer paper had a good storing stability and can absorb the dye ink evenly and rapidly. The printed silk possessed a good colour fastness but its handle decreased slightly. [ABSTRACT FROM AUTHOR]

The feasibility of using sodium oxalate in the dyeing of cotton fabrics with reactive dyes in place of inorganic salt (sodium sulfate or sodium chlorate) was studied. Sodium oxalate was compared with sodium formate and sodium citrate in cotton dyeing with reactive dyes. The results showed that sodium oxalate could be a suitable exhausting agent in the reactive dyeing process. The effect of sodium oxalate to enhance a photochemical reaction is also researched by measuring the color removal of the reactive dye solution. The results revealed that color removal of the dye solution containing sodium oxalate is 5.62% higher than that containing sodium sulfate after irradiation for 30 min. The overall results suggested that sodium oxalate has the potential not only as an exhausting agent for reactive dyeing of cotton but also as an accelerant for photochemical reaction in the treatment of dyeing wastewater. [ABSTRACT FROM AUTHOR]

Cotton was modified with hydrolysed sericin fraction of silk in the presence of trisodium citrate as the esterification catalyst following a pad–dry–cure technique. The treatment of cotton fabric with 5% hydrolysed sericin in the presence of 7.5% catalyst followed by drying at 95°C for 5 min and curing at 140°C for 5 min produced optimum results with respect to exhaustion and fixation of reactive dyes having chlorotriaznyle and vinyl sulphone reactive groups when dyeing was accomplished in the absence of salt. Colour fastness to wash, light and rubbing of cotton for the application of reactive dyes remain unaltered for such prior modification with hydrolysed sericin. IR spectroscopy indicated the incorporation of amino acid residues of sericin fraction of silk in polymeric chains of cotton via establishment of ester linkages between carboxylic group of the amino acid moiety and hydroxyl groups of the cotton cellulose on pad–dry–cure. [ABSTRACT FROM AUTHOR]

Narrow-leaved cattails (Typha angustifolia L.) show higher efficiency in the removal of colour and reduction of pH, TDS, and conductivity from synthetic reactive red dye wastewater (Rw) when silicon is added to the wastewater. The efficiency of the colour removal was increased from 86% within 12 days to 93% within 9 days with the addition of silicon. Furthermore, the TDS was also decreased when adding silicon in the wastewater. In addition, calcium and proline accumulation in the plant leaf increased in response to increasing Rw concentrations in the absence of added silicon. Higher salinity was also observed with increasing Rw concentrations. Plants attempt to balance their water potential by secreting proline as an osmotic adjustment. But both calcium and proline levels decreased when silicon was added to the wastewater. This result implies that the plant uses silicon as primary element for responsibility under salt stress condition by increasing growth of plant. In addition, silicon can be used instead of calcium, resulting in decreased proline and calcium production in the plant. [ABSTRACT FROM PUBLISHER]

In this study, the possible use of canola stalks, which are agricultural residues available in large quantities, for the removal of Remazol Black B (RBB) was investigated. Batch adsorption studies were carried out to examine the influence of various parameters. The results indicated that adsorption was strongly pH-dependent but slightly sorbent dose- and contact time-dependent. The Freundlich and Langmuir adsorption models were used for the mathematical description of adsorption equilibrium and isotherm constants at 25°C. Both models were applicable for the description of dye adsorption isotherm in the concentration range studied. However, the Langmuir model showed a higher correlation coefficient than the Freundlich model. According to the Langmuir model, the highest adsorption capacity was found to be 32.8 mg/g. Kinetic models, pseudo-first order and pseudo-second order were employed to describe the adsorption mechanism. The adsorption data followed the pseudo-second order kinetic model with regression coefficient (R2 ) higher than 0.999. In conclusion, the results showed that canola stalks could be used as a promising and cost-effective biosorbent for treatment of wastewater containing dye. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to explain how colour fastness results are improved as a result of increasing the degree of fixation of reactive dyes on wool, polyamide and wool-polyamide blend fabrics. Wool-polyamide blend fabrics were printed with two different types of reactive dyes, e.g. monochlorotriazine and vinylsulphone. Trichloroacetic acid (TCAA) was added to the printing paste for controlling the pH level during the fixation process to get a maximum colour yield and a maximum dye fixation on the two components of the blend, e.g. wool and polyamide. In order to accelerate the reaction rate, a quaternising agent, e.g. triethylamine (TEA) was also added to the printing paste. The factors that may affect the efficiency of printing method, e.g. the concentration of TCAA, urea, wetting agent, TEA, steaming time and temperature were studied in detail. [ABSTRACT FROM AUTHOR]

The potential of burhead (Echinodorus cordifolius L.) for the treatment of textile wastewater has been investigated. Reactive red 2; RR2 [MW=615], reactive red 120; RR120 [MW=1469] and reactive red 141; RR141 [MW=1775] were studied in order to determine the effect of molecular size on the efficiency of dye removal by plants in batch systems of constructed wetlands under soil and soil-free conditions. Dye concentrations, total dissolve solids (TDS), conductivity and pH in the effluents, and the relative growth rates (RGR) of plants were measured. The highest efficiency of dye removal during 7 days under soil-free conditions was RR2 (33.09 μmolRR2kg-1FW), followed by RR120 (13.35 μmolRR120kg-1FW) and RR141 (10.57 μmolRR141kg-1FW), respectively. This suggests that the structure and size of dye molecule strongly affects the efficiency of dye removal by plant. The results from a synthetic wetland experiment found that dye removal was 96 % at 4 days and 6 days under soil and soil-free conditions, respectively. Furthermore, plants were able to decrease TDS (42 %), conductivity (50 %) and pH (from 9.5 to 7.4) within 2 days in the synthetic reactive red141 dye wastewater (SRRW141) under soil-free conditions, thus demonstrating the potential of burhead for textile wastewater treatment. [ABSTRACT FROM AUTHOR]

Gray jute fabric has been bleached by three different processes—gray-bleach, scour bleach, and gray ambient bleach—to produce white fabric. These processes produce different optical and physical properties. All the bleached jute fabrics were dyed with direct and reactive dyes. Bleached and dyed jute fabrics were padded with finishing formulation comprising resin, softener, and nonionic surfactant, subsequently dried and cured. An evaluation of the bleached jute fabric reveals that the finishing treatment resulted in very good creasing characteristics without much deterioration of tensile strength. There is no alteration in color of the bleached and dyed jute fabrics before and after the finishing treatment. Washing fastness of the finished fabric is also good. Therefore, this combined finishing treatment can be applied to jute fabric to produce diversified and value-added jute products. [ABSTRACT FROM AUTHOR]

The photochemical degradation of C. I. Reactive Blue 2 (RB2) in aqueous solution has been studied using a homogeneous UV/Fenton process. The effects of applied H2O2, Fe2+ salt and RB2 concentrations at constant UV irradiation characteristics, the pH, and temperature were determined. By the application of 0.5 mM Fe2+ and 2.5 mM of H2O2 the complete color removal and mineralization extent of 73.8% were achieved. According to the color and TOC removal, it could be suggested that the studied UV/Fenton type process appeared as a viable technique for the treatment of wastewater containing such types of reactive dyes. [ABSTRACT FROM AUTHOR]

Chemical modification of cellulose fabric with the emulsion of the triazine derivative containing the tertiary and quaternary amino groups was investigated. Chemical modified cellulose fabric could catalyze itself with reactive dyes containing chorotriazine group. Compared with unmodified cellulose, the modified cellulose could be dyed with reactive dyes under neutral or weakly acidic condition without the addition of salt. The color yield was higher than that of the unmodified cellulose, despite of the addition of large amounts of salt and alkali in the latter case and the modified cellulose got better wash fastness. [ABSTRACT FROM AUTHOR]

Cotton fabrics dyed with reactive dyes were treated with composite silicon sol by traditional pad-dry-cure process in order to investigate the colour fixation properties. The results show that the hue values of the fabrics change little and the dry and wet rubbing fastnesses are improved by more than half a grade. The fade rate of washing at 60°C decreased by ∼30% due to the protection of composite silicon sol thin film on the surface of cotton fabric. The ΔE value of the fabric dyed with reactive red dye exposed in the Xenotest could be decreased from 17·6 to 7·4. The data demonstrate that the composite silicon sol treatment has no important effect on the handle of fabrics, indicating that the composite sol method is an effective way to improve the colour fastness of cotton fabrics. [ABSTRACT FROM AUTHOR]

The binding processes of Reactive Red K-2BP (K-2BP) and Reactive Violet K-3R (K-3R) onto poly(epicholorohydrin-diamine)(PEPIDA) in solution and film were investigated by spectrophotometric and quartz crystal microbalance (QCM) methods, respectively. By using a multiple linear regression technique, the concentrations of the colored components in the mixtures of dye+PEPIDA were measured simultaneously from the absorbance spectra. The binding equilibrium constants for K-3R and K-2BP onto PEPIDA in solution were estimated to be 9.31×106 and 1.86×106 L · mol-1, respectively. The difference in the color removal between K-3R and K-2BP by PEPIDA was discussed. The binding processes of K-3R and K-2BP onto PEPIDA film were followed by the QCM. The binding equilibrium constants were evaluated to be 1.27×106 and 3.28 ×105 L · mol-1 for K-3R and K-2BP onto PEPIDA film, respectively. They are less than those determined in PEPIDA solutions. The binding rate constants for K-3R and K-2BP onto PEPIDA film were estimated to be 1.43×105 and 1.72×105 L · mol-1 · s-1, respectively. [ABSTRACT FROM AUTHOR]

This paper was intended to study decoloration of azo C.I. Reactive Red 243 under UV radiation in the presence of hydrogen peroxide. The H2O2/UV oxidation process is a feasible and effective alternative in the treatment of effluents that contain such recalcitrant substances as reactive dyes. A statistical factorial design at 2n was used to evaluate how the variables pH (3 and 11), H2O2 concentration (5 and 20 mM), urea concentration (5 and 15 g I-1), and NaCl concentration (2.5 and 3.5 g l-1) affected the decoloration process efficiency. The results were expressed as percent colour removal from the solution by using absorbance measurements. The H2O2/UV process proved to be effective in degrading reactive dyes, with approximately 99% colour removal being achieved under specific conditions. Hydrogen peroxide concentration had a positive effect and influenced a great deal. Sodium chloride (NaCl) concentration presented a negative effect on the experiments in which it reduced the percent colour removal from the reactive dye solutions. Solution pH and urea concentration did not present any significant effect on the decoloration process. [ABSTRACT FROM AUTHOR]

The present work aims to the study of the increase of pick-up, together with uniformity degree, concerning the application of reactive dyeing baths by padding in a dry cotton fabric previously treated with CORONA discharge. Dyeing recipes, with and without wetting agent, are compared and advantages of CORONA discharge are analysed. Reactive dyes are used, expecting also to increase washing fastness of the difficult dark colours due to higher penetration of the dye into the core of the fibres when submitted to plasmatic treatment. The use of CORONA discharge intends to modify hydrophility of cotton fabrics even when they are presented to padding in hydrophobic state. A good alternative to wetting agent presence in recipes is found and more uniform and intense dyeings are performed in all cases. [ABSTRACT FROM AUTHOR]

In this study high voltage pulsed corona electrical discharge advanced oxidation processes (AOPs) were applied to bleach and degrade C.I. Reactive Green 8 and C.I. Reactive Red 45 organic dyes in water solutions. Two types of hybrid gas/liquid high voltage electrical discharge (corona) reactors, known as hybrid series and hybrid parallel were studied. The difference between these reactors relates to electrode configuration, which affects the amounts of ozone, hydrogen peroxide and hydroxyl radicals produced. Experiments were conducted using dye concentrations of 20 mgl-1 and 75 mgl-1, with and without NH4ZSM5 zeolite addition in order to determine possible effects of added solid particles to total process efficiency. The role of ozone in combination with zeolites was assessed through comparative direct ozonation experiments with ozone supplied by an ozone generator. UV/VIS spectrophotometric measurements and measurements of total organic carbon (TOC) were used for the determination of decolorization and mineralization rates. [ABSTRACT FROM AUTHOR]

Synthetic dyes are more available than natural dyes were in the past, because of lower prices and wider ranges of bright shades with considerably improved color fastness properties. In current years, concern for the environment has created an increasing demand for natural dyes, which are friendlier to the environment than are synthetic dyes. The aim of this work is to study the effect of dyeing cotton fabrics with both a natural dye (henna) and a synthetic dye (Remazol blue) on some mechanical properties and those of stability to light exposure. The undyed and dyed cotton fabrics were tested for their mechanical behaviors expressed as tenacity (N), elongation %, and work-breaking (N · m). They were also tested for shrinkage and crease recovery angle. The stability to light before and after 100 h exposure was examined by investigating the microstructure [using x-ray diffraction (XRD)] and macrostructure [using a scanning electron microscope (SEM)] and the reflection spectra. The results proved that the cotton samples dyed with Henna dye have higher mechanical properties than those dyed with “Remazol” reactive dye. Moreover, the light fading behaviors of both synthetic and natural dyes were studied in terms of the reflection spectra (400–800 nm), microstructure, and macrostructure of the sample's fibers. [ABSTRACT FROM AUTHOR]

The aqueous solution of a model reactive dye, C.I. Reactive Blue 5, was ozonated in the presence of a heterogeneous catalyst, CuS. It was found that CuS was very effective for catalyzing the decolorization so that both treatment time and ozone consumption were significantly reduced. For 1 g/L of the reactive dye, the stoichiometric ratios of ozone to dye in catalyzed and noncatalyzed ozonations were 2.7 and 10.6 (moles of ozone consumed)/(moles of dye oxidized), respectively, and the optimum catalyst load was 0.4 g/L. Although the noncatalytic ozonation was pseudo-first-order and the apparent pseudo-first-order rate constant declined with initial dye concentration logarithmically, in contrast, the experimental results showed that the catalytic ozonation was pseudo-second-order and the apparent pseudo-second-order rate constant decreased with initial dye concentration semilogarithmically. It was observed that the efficacy of ozone decolorization was higher at low pH and a scavenger test revealed that the amount of free radicals were negligible during ozonation. The experimental data further indicated that increase in temperature would increase the rate of the catalytic ozonation, however, the increment in the rate was not significant beyond 20°C. [ABSTRACT FROM AUTHOR]

The two-step reaction of the C.I. Reactive Red 120 (RR120) production was monitoring by thin-layer chromatography with densitometry. The obtained intermediate C. I. Reactive Red 1 (RR I), hydrolized by-products and final product RR120 were separated and quantificated. The production costs and the pollution of wastewater were significantly decreased by optimization of the RR120 process. [ABSTRACT FROM AUTHOR]

Coconut husk modified through the use of N-(3-chloro-2-hydroxypropyl)-trimethylammonium chloride was evaluated for its ability to remove reactive dyes from aqueous solution. Sorption of dyes was pH dependent and favorable sorption occurred at low pH. In contrast, natural coconut husk showed very little uptake of these reactive dyes. The maximum sorption capacities of the modified coconut husks for Reactive Blue 2, Reactive Yellow 2, Reactive Orange 16 and Reactive Blue 4 were 128.9, 182.2, 254.5 and 423.7 mg/g respectively. Column experiments using textile effluent showed that the reactive and disperse dyes in the effluent could be successfully removed. [ABSTRACT FROM AUTHOR]