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Tight ceramic ultrafiltration membranes have been proven to exhibit good rejection performance for reactive dye wastewater at high temperatures because of their high thermal and chemical resistance. However, the application of ceramic membranes for the treatment of cationic dye wastewater is challenging because of their surface charge. In this study, a ceramic membrane is modified by grafting aminosilane (KH-551) to enhance the positive charge of the membrane surface. The rejection performance of the charged modified ceramic membrane toward the methylene blue solution is significantly improved. The modification substance is bonded to the ceramic membrane surface via covalent bonding, which imparts good thermal stability. The modified ceramic membrane exhibits stable separation performance toward the methylene blue solution. Overall, this study provides valuable guidance for the adjustment of the ceramic membrane surface charge for treating industrial cationic dye wastewater.

In this work, the treatment efficiency of advanced oxidation processes H2O2/UV enhanced by the addition of a manganese catalyst complex (MnTACN) was investigated on a model dye solution and a real dye-house effluent. The experimental results were evaluated in terms of absorbance (A) and total organic carbon (TOC) reduction. The major degradation products of the model dye solution were identified by high resolution gas chromatography/mass spectrometry analyses. In addition, the toxicity of the final reaction solution after H2O2/UV/MnTACN treatment to Vibrio fischeri bacteria was determined. The results showed that the addition of the H2O2/UV/MnTACN system at in different concentrations of the catalyst solution increased enhance the decolourization rate compared to H2O2/UV for both the model dye solution and real dye-house effluent.

In the present study, calcium peroxide (CaO2) was used separately for potential application as an environmentally friendly and low-cost oxidant for the removal of a textile dye ‘Reactive Black 5’ (RB5) from simulated textile wastewater containing auxiliary chemicals of textile production. The specific morphology, elemental analysis, particle size distribution, specific surface area, identification of crystalline phases and surface functional groups of the synthesized CaO2 were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), laser diffraction (LD), Brunaure–Emmett–Teller method (BET), X-ray diffraction (XRD) and Fourier transmission infrared (FTIR), respectively. X-ray Diffraction analysis confirmed the synthesized oxidant as CaO2 with the tetragonal crystalline structure. The signal corresponded to a bending vibration of O–Ca–O was detected in the fingerprint region of the FTIR spectroscopy. The effects of various independent parameters such as contact time, pH, initial RB5 concentration and CaO2 dosage on decolorization were investigated. The results of the study showed that pH, initial dye concentration and the CaO2 amounts have significant effects on removal of the RB5. The optimum pH was determined 7 for the removal of RB5 by CaO2. 2.0 g CaO2 was found to be sufficient for the removal of 300 mg/L RB5 with 96.93% removal efficiency. Also 82.8% chemical oxygen demand (COD) removal efficiency from simulated textile wastewater (STW) was obtained by 2.0 g CaO2. The results of the present study showed that the CaO2 can be used as an environmentally friendly and low-cost oxidant for effective removal of reactive textile dyes.

Free radical graft polymerization of diallyldimethylammonium chloride (DADMAC) on cotton was employed to substantially improve the dyeability cotton with reactive dyes under salt-free conditions. The effects of plasma-induced graft polymerization of DADMAC on cotton, followed by dyeing with different reactive dyes, was characterized by Fourier transform infrared spectroscopy. A color fastness wash test was conducted to evaluate the effectiveness of cotton cationization on reactive dye fixing. The results show that the salt-free dyeing process with reactive dyes was effective after cationization modification, and the dye uptake rate and dyeing depth are higher than the conventional dyeing techniques.

Interest in insects as waste biomass bioconverters and their use as valuable resources for fat, proteins, and chitin has increased considerably in the last few years. In this study, proteins were extracted from defatted black soldier fly (BSF) (Hermetia illucens) exuviae by green hydrolysis using superheated water at 150 °C for 20 h, and the remaining chitin was deacetylated into chitosan and used as a finishing agent for polyester fabrics. A total amount of 7% fat, 40% proteins, and 20% chitin was obtained from BSF exuviae. Different hydrolysis times ranging from 1 to 20 h were tried until the complete purification of chitin. The purity of chitin and the obtained chitosan after deacetylation was assessed by Fourier transform infrared spectroscopy and thermal analysis. A preliminary study was successfully carried out to use the obtained chitosan as a finishing agent for polyester pretreated fabrics using citric acid as a grafting agent. The presence of chitosan on the fabric was verified by scanning electron microscopy and by dyeing of the pretreated polyester fabric using a reactive dye with sulfonated groups that are able to be absorbed by electrostatic attraction because of the created cationic nature of the fiber surface treated by chitosan.

This study analyzed the influence of operational conditions on the Direct Contact Membrane Distillation for synthetic effluents containing reactive and disperse dyes. Results of the permeate flux demonstrated different behavior of the process according to the class of dye. It was found a higher dependence of feed temperature to reactive dye and the analysis of temperature gradient between feed and permeate demonstrated the possibility of operation with higher temperatures in both streams to increase the permeate flux for both dyes. Feed flow rate influenced more the process with reactive dye, while the permeate flow rate determined this behavior for disperse dye. Energy factors showed that the gain output rate and energy efficiency enhanced with the increase of feed temperature, and the energy efficiency increased only with the permeate flow rate (and not with feed flow rate). The water distillation recovery rate was 97.3 % for reactive and 98.7 % for disperse dye; the color rejection of the dyes was over 98 %. These results indicated the adequate functionality of the process for water recovery of textile wastewater, providing an adequate permeate for possible reuse.

Fabric ink-jet printing is a crucial technology of clean production in the textile industry. Reactive dyes and organic solvents are the important component of ink-jet printing ink. The structure, h...

A magnesium silicate polymeric coagulant (MgSiPC), which is an inorganic polymer for dye removal from wastewater, was prepared with different pH by copolymerization. The acidity was a key factor in the preparation of the MgSiPC. In the present research, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to analyze the characterization of optimum coagulants. Additionally, the response surface method (RSM) was applied to optimize the process of coagulation-flocculation. The results of FT-IR and XRD implied that the main components of the MgSiPC with pH 1.50-2.50 were almost the same. SEM images showed that MgSiPCs with pH 1.50-2.50 exhibited different structures including cluster and lamellar shape structure, compact rod-like and network structure, and a kind of irregular geometry shape structure. In the process of coagulation-flocculation, MgSiPCs with pH 1.50-2.50 showed highly efficient coagulation performance. The removal rate of reactive yellow 2(RY2) could reach above 90% at a dosage of 50-70 mg/L and initial pH 12.00, while the removal rate of reactive blue 2 (RB2) could attain above 93% at a dosage of 50-80 mg/L and initial pH 12.00. Moreover, MgSiPCs with pH 2.00 had the highest efficiency. The results of RSM showed that the optimum combination of the MgSiPC's dosage and initial pH was 62 mg/L and 12.08 for RY2 and 78 mg/L and 12.00 for RB2, respectively. Under optimum experimental conditions, the predicted data from this model were 96% for RY2 and 100% for RB2, which was consistent with the actual experimental data. Therefore, a pH of 2.00 is considered to be the optimal acidity for preparing MgSiPCs.

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.

This research aims at minimizing environmental pollution by effluents discharged from current textile dyeing processes. The reduction of pollution is approached with a nanofibrillated cellulose (NFC) dyeing method. In the commonly used exhaust reactive dye bath cotton dyeing process, water effluents are contaminated with unreacted dyes and dyeing formulation auxiliaries amid the consumption of 20 weight units of water per weight unit of colored textile products. It was recently demonstrated that using reactive dye-colored NFC hydrogels—an aqueous dispersion of the NFC pigment—a sustainable dye carrier—results in 6-fold reduction in consumption of water and auxiliaries. Here, we report further developments of this technology. Cotton fabrics and NFC hydrogels inherit a fraction of soluble polysugars that react and conjugate with the reactive dyes. These soluble dye-conjugated polysugars are released into the wastewater, thus resulting in water pollution and also in reduced efficiency of the dyeing process. We demonstrate here that post-treatment of NFC-colored cotton textiles with polycarboxylic acid secures permanent chemical grafting of the soluble dye-labeled polysugars and forms chemical cross-links with the NFC fibers on the cotton fabric via the esterification reaction. This combination leads to the improvement of dye fixation by 30% and reduces the dye discharge in the washing stage by 60%. This enhancement is approached without compromising the stiffness and breathability of the fabrics. The advanced textile method is tested for a series of reactive dyes covering the entire visual spectrum range.

One of the main drawbacks of heterogeneous photocatalysis is the high consumption of electrical energy generated by conventional lamps. This study proposes a methodology to find the best distribution of light emitting diodes (LEDs), i.e., the least amount of elements, and the optimum distance between them in order to substitute conventional lamps in photocatalytic processes, and a performance analysis in terms of energetic efficiency, using for this the Electric energy per order (EEO) Figure-of-merit and the cost results for the degradation of the textile reactive dye Orange PX-2R by means of UV/TiO2 process, using conventional lamps and different geometrical patterns of LED arrays. The obtained experimental results show that it is possible to replace sources of high-energy consumption by UV-LED arrays adapted to the specific needs for a given photocatalytic reactor obtaining suitable oxidation results, and the rate of decolorization obtained is similar to the results obtained with conventional lamps; however the UV-LEDs require 70% less electrical energy (178 vs 628 kWh/m3/order) than UV-lamps. Consequently, the use of UV-LEDs enables to degrade 3.5 times more dye with the current energy consumption of UV lamps. Finally, the proper choice for an array can generate additional energy savings.

This study aimed to develop a highly functionalized adsorbent material for the removal of persistent anionic reactive dye. The modification process was commenced via a wet oxidation method by using zirconium salt as an impregnating material. The process led to an increase in the overall porosity, thermal stability and its oxidative functionality. The newly synthesised material was named ZrAC. The morphological and textural images revealed the irregular and eroded structures with an increase in porosity of the modified adsorbent. The results of chemical and spectral analysis disclosed that the material had successfully gained the oxidative functionality over the surface that will favour the removal of anionic dye. Equilibrium isotherms and adsorption kinetics studies insinuate that the overall process of adsorption follows the Sips isotherm and pseudo-second order kinetic model, respectively. The monolayer adsorption capacity of ZrAC was found to be superior (506 mg g−1) to AC at 500 mg L−1 concentration of persistent reactive dye. Moreover, the desorption capabilities of ZrAC were found to be more prominent, which finally affirms its potential use in a continuous flow system as a reusable adsorbent. Additionally, the stability of zirconium, corroborated from ICP-MS and XPS data, revealed the stability of zirconium after adsorption cycles thus verified its reusability. Thus, the characterization and experimental results of ZrAC strongly advocated its potential as a future adsorbent for removal of reactive dyes.

Facilitated transport of Orange 3R was performed by means of emulsion liquid membrane (ELM) technique containing double extractants of Aliquat 336 and D2EHPA as extractant and synergist extractant, respectively. Cooking palm oil, sorbitan monooleate (Span 80), and sodium hydroxide were used as diluent, surfactant and stripping agent, respectively. Several parameters influencing the extraction of Orange 3R via ELM, namely effect of extraction time, agitator speed, Span 80 concentration and treatment ratio, were experimentally investigated and optimized using response surface methodology (RSM). Results demonstrated that about 91% of Orange 3R was successfully extracted under optimum conditions of 12 minutes of extraction time, 413 rpm of agitator speed, 3.2% (w/v) of sorbitan monooleate, and 1:9.8 of treatment ratio. Additionally, the aforementioned optimum conditions were found to be more suitable to treat low concentration of Orange 3R (less than 100 ppm) from simulated textile wastewater. The findings reveal that reactive Orange 3R dye is able to be selectively extracted using double extractants via sustainable ELM process as well as providing high potential application in the dye removal from industrial textile wastewater.

High chemical oxygen demand (COD) and a strong color, which primarily originates from desizing and dyeing operations, are two major removal objectives in textile wastewater treatment. In this study, crosslinking-induced precipitation via the covalent bonding between –OH groups of PVA and vinyl sulfone groups of reactive dyes is proposed to simultaneously remove poly(vinyl alcohol) (PVA) and reactive dyes. Due to the nucleophilic addition reaction under an alkaline condition, PVA polymers can be efficiently crosslinked by dye molecules and destabilized in the presence of alkali and Na2SO4. Additionally, due to the high coagulation efficiency under the alkaline conditions, MgSO4 was used as a coagulant to facilitate the removal of the residual color after precipitation. After a two-step process, whereby coagulation was followed by crosslinking-induced precipitation, the maximum efficiencies of the removal of COD, PVA, and color attained 88.9%, 86.3%, and 99.2%, respectively, when the PVA monomer/RB5 mole ratio was 400. We hope that this technically feasible, highly efficient, and cost-effective process provides a basis for the practical application of the simultaneous treatment of desizing and dyeing wastewater.

A straightforward method for imparting superhydrophobic character to cotton textiles using methods based in textile processing and organic synthesis was developed. Cotton fabric was first treated with a common dye anchor, cyanuric chloride, which was subsequently reacted with cysteamine to yield a thiol function on the surface. Thiol–ene click chemistry was employed to attach alkyl chains to render the surface hydrophobic. Effects of temperature and reaction time on the click reaction step were investigated to optimize the process, and a water contact angle exceeding 150° was obtained after reaction at 100 °C and 60 min. Furthermore, it was shown that both AIBN and hydrogen peroxide are effective initiators for the click reaction. The efficacy of the resulting textile in separating hydrocarbons from water was demonstrated. This straightforward preparation of a superhydrophobic textile is most promising in that it is accomplished without incorporating perfluorinated functional groups or nanoparticles.

Textile effluents contain a great variety of dye residues, their presence in the environment is undesirable since they cause a severe contamination in the aquifers. Different technologies are commonly used in the removal of these kind of dyes, which are often recalcitrant due to their anionic character, such as the sorption with activated carbon, zeolites and recently anionic clays (hydrotalcite-like compounds Al/Mg (HT-Al/Mg)) with relatively good results. The HT-Al/Mg can be synthesized by various methods assisted by treatments in the crystallization stage such as microwave and/or ultrasound irradiation, which allow the control of textural and morphological properties, in addition to reducing the synthesis times. The effects on the texture and morphology properties of HT-Al/Mg with an organic interlaminar anion (CH3COO-) synthesized by coprecipitation assisted with microwave irradiation, ultrasound and microwave-ultrasound in combined mode are studied. The synthesized materials were evaluated in the sorption of the reactive dye BEZAKTIV Red S-LF with reference to activated carbon. The solids were characterized before and after evaluation by known techniques described below. It was found that the HT-Al/Mg-CH3COO irradiated by the combined mode had the highest capacity of removal of the dyes compared to the reference material and when the materials were irradiated separately by microwaves or ultrasound.

For the first time, the ability of dyeing the montmorillonite (Mt) mineral with reactive dye aiming to prepare a new nanopigment was investigated and the optimum conditions were determined. The prepared nanopigment was characterized by Fourier-transform infrared spectra (FTIR), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), reflectance spectrophotometer (RS) and colorimetry analyses. The results showed that the dye molecules were attached to the hydroxyl groups of Mt plates through a covalent linkage. Also, the BET surface area values slightly increased after the dyeing process due to the separation of Mt plates and the reduction of particle size because of penetration of dye molecules among the plates. Colorimetry analysis revealed that the intercalation of dye molecules was depended on dye concentration and number of reactive sites on the Mt surface. The prepared nanopigment was used for dyeing the polyester fabric in high pressure and temperature conditions. The SEM, colorimetry, electromagnetic reflectance, flammability, and TGA tests were performed to investigate the properties of fabrics. Results indicated that intercalation of Mt nanopigment in the polyester fiber enhances the flame retardant, electromagnetic reflection and breathability of fabrics. Also, the optimum amount of nanopigment in the dyeing process was reported. It can be suggested that the prepared fabric can be a good candidate for utilizing in military and electronic aspects.

One of the major problems in the household machine laundry process is dyes bleeding from coloured garments and then the re-depositing on lighter-coloured garments in the same wash load. Thus it creates staining on the light coloured cloth and also colour loss on the dark coloured cloth. Numerous attempts made to solve the issue but none of the remedies are completely successful. Improper loading of high quantity of dye transfer inhibitor (DTI) polymer also had severe negative effect on coloured garment in terms of colour striping, patchy and unsightly appearance. In this research, the amine based aromatic dye transfer inhibitor polymers pyridine N-oxide (PNO), used for the analysis. The performance of the polymer was optimized for better dye transfer inhibition property in the ‘in wash’ liquor against reactive dye. The findings of the research indicate that the performance pyridine N-oxide against reactive dye was excellent over the commercial DTI polymer polyvinylpyrrolidone (PVP). The addition of detergent diminishes the properties of the PVP, but the PNO overcomes that issues and acts well in presence of maximum quantity of the detergent. The research work optimized the amount of DTI polymer required for a single wash load, as 0.25 g. The level of detergent preferably 10 g/l and the pH value of 8. The findings revealed that the PNO polymer performs excellent against all the commercial dyes and also it is noted that the polymer overcomes the shortfalls of commercially available DTI polymers like PVP.

The Reactive Black 5 and Reactive Red dyestuffs have been synthesized in the laboratory. The synthesis was obtained by diazotization of 1-amino-phenyl-4-beta hydroxyethyl sulfone sulfate ester and coupling with 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid (H-acid) (mole ratio 2:1) (Reactive Black 5Na) and (mole ratio 1:1) (Reactive Red Na). The dye was purified-concentrated by ultrafiltration technology and the permeate (waste) was used as dye bath in the exhaustion of cotton and polyamide with the sodium salt of Reactive Black 5 (RB5Na) and the sodium salt of Reactive Red (RRNa). The same dyeing was also made with fresh water as dye bath. Fastness properties were also measured in both cases and the results were compared. Color measurement results of the dyeings were almost the same when the waste as dye bath was used.

The present paper investigates the effects of breed and age on the dye fixation on wool using a reactive dye. It also examines the optimization of the dyeing process realized using the response surface methodology. The dyeing step was carried out on raw wool using the bichromatic blue dye reagent Cibacron P-3R (C.I. Reactive Blue 49). The factors affecting the dyeing process, such as ammonia concentration, temperature, and the duration of the dyeing time, were studied using the response surface methodology. The performance of this dyeing process was evaluated by measuring the color yield (the dye fixation). The results have shown that the age and the breed of sheep have a significant effect (P

In this work, a new method for facile synthesis of covalently colored polyurethane latex was developed. A series of blue dye monomers were synthesized via one-step reaction of a reactive dye and amino compounds, and then employed as chain extenders to react with polyurethane prepolymer in the emulsification process to prepare the covalently colored polyurethane latexes. The chemical structures and the properties of dye monomers and the corresponding polymers were investigated, and the UV–Vis spectra of covalently colored polyurethane featured fairly consistent with dye monomers with maximum absorption wavelength at 620 nm and 580 nm, since the chemical structure of chromophore maintained unchanged. The conversion of dye monomer reached more than 92% with 1.0 wt% dye content, whereas the conversion decreased with the increase of the dye amount and the adding time. Compared with the noncovalently latex film, the light fastness of the covalently colored latex film was greatly promoted due to the chemical bonding of chromophores with polymer matrix.

A model is proposed to explain the manner by which the uptake of reactive dyes on cellulosic fibres is promoted by the addition of NaCl or Na2SO4 to the dyebath. The theoretical model invokes the concept of interstitial water in dyeing and suggest that increased dye uptake occurs because the added inorganic electrolyte promotes dye aggregation which reduces the solubility of the dye in the dyebath, so that the inherent preference of the highly soluble dye to favour the aqueous phase shifts towards the fibre phase. It is proposed that the same model can account for the promotion of direct dye uptake imparted by the reduction in the liquor ratio utilised for dyeing. As such, added inorganic electrolyte and reduced liquor ratio are considered to exert a combinatorial promotional effect on reactive dye uptake.

Reverse micelles using nonionic poly(ethyleneglycol) (PEG)-based surfactant as building block were introduced to encapsulate reactive dye for cotton dyeing. The morphological transition of reactive dyes from well-dispersive spherical form into highly agglomerated form via various surfactant-to-co-surfactant molar ratios and surfactant-to-water molar ratios have been preliminary investigated. The dyeing properties of cotton has been analyzed in terms of dispersion of reverse micelle structure from transmission electron microscopy, identification of chemical signatures of dye-cotton interaction from Raman spectroscopy, color strength and relative levelness. The reverse micellar structures under both highly dispersed and agglomerated forms are in good agreement with color strength and levelness data. The optimization of surfactant conditions can be considered as major parameters for investigating the quality of cotton dyeing including color strength and levelling conditions.

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 ...

The aggregation of dyes is a common phenomenon in solutions, particularly concentrated solutions, which seriously affects the dyeing and printing processes. In this study, the effects of alkylamine solvents on the reactive dye aggregation behavior in highly concentrated solutions was studied. Typical cases were conducted with two slightly toxic and environmentally friendly solvents, namely diethanolamine (DEA) and triethanolamine (TEA), and two reactive dyes, namely C. I. Reactive Red 218 (R-218) and C. I. Reactive Orange 13 (O-13). Aggregation states were studied by ultraviolet-visible (UV-Vis) absorption spectroscopy, Gaussian-peak-fitting method and fluorescence spectroscopy. The results showed that both the additives DEA and TEA could reduce the dye aggregation because the solvents, DEA and TEA, can break the iceberg structure and allow easy entry of the molecules into the dye aggregates. Also, the disaggregation caused by DEA was higher as compared with TEA, which may be caused by the weaker hydrogen bond and the relatively smaller steric hindrance effects of DEA. The schematic of disaggregation between R-218 and DEA was also discussed. For R-218, the dimers were disaggregated to monomer, while the higher-ordered aggregates were disaggregated to trimers and dimers for O-13. Moreover, physical properties such as viscosity and surface tension of the solutions were measured. This investigation is instructive for the further dyeing progress with organic bases in the textile industries.

A hybrid material obtained by blending &beta, chitosan (CS) with triethylenetetramine-functionalized graphene oxide (TFGO) (CSGO), was used as an adsorbent for a reactive dye (C.I. Reactive Blue 221 Dye, RB221), and the adsorption and removal performances of unmodified CS and mix-modified CSGO were investigated and compared systematically at different pH values (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12). The adsorption capacities of CS and CSGO were 45.5 and 56.1 mg/g, respectively, at a pH of 2 and 5.4 and 37.2 mg/g, respectively, at a pH of 12. This indicates that TFGO was successfully introduced into CSGO, enabling &pi, &ndash, &pi, interactions and electrostatic attraction with the dye molecules. Additionally, benzene ring-shaped GO exhibited a high surface chemical stability, which was conducive to maintaining the stability of the acid and alkali resistance of the CSGO adsorbent. The RB221 adsorption performance of CS and CSGO at acidic condition (pH 3) and alkaline condition (pH 12) and different temperatures was investigated by calculating the adsorption kinetics and isotherms of adsorbents. Overall, the adsorption efficiency of CSGO was superior to that of CS, thus, CSGO is promising for the treatment of dye effluents in a wide pH range.

In this study, we synthesized a novel N-halamine precursor, sulfuric acid mono-[2-(4-[4-chloro-6-(2-[4,4- dimethyl-2,5-dioxo-imidazolidin-1-yl]-ethylamino)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl)-ethyl] ester sodium (TB), which contains two reactive groups of monochloro triazine reactive groups and bis-sulphatoethylsolphone reactive groups. The structure of TB is similar to iso-bifunctional group reactive dyes and could be coated on cotton fabrics by covalent bonds through a reactive dyeing process. The cotton coated with TB was characterized by FTIR and SEM. After chlorination, the treated cotton fabrics showed excellent antibacterial efficacy and inactivated all inoculated S. aureus (ATCC 6538) and E. coli O157: H7 (ATCC 43895) within 1 min of contact. Over 85 % of tensile strength retained both in warp and weft directions after treatment and chlorination. Almost 80 % of active chlorine can be regained by treating with household bleach after extensive washing and long time storage.

Chloropyrimidine-based reactive dyes are reported as well suited to textile printing; however, nucleophilic aromatic substitution of chloropyrimidines with amino-containing chromophores is slow and often suffers from poor yields. In this study, a novel and simple method was developed for the synthesis of chloropyrimidine-based reactive dye under microwave irradiation. In addition, the dye was also synthesised by conventional heating for comparison, which took both the reaction time and yield into account. The progress of the synthesis reactions concerned were monitored using capillary electrophoresis and the purity of the dye obtained was assessed by thin-layer chromatography. The structure of the synthesised trichloropyrimidine dye was confirmed by Fourier Transform–infrared spectroscopy and elemental analysis. It was found that the reaction rate of the nucleophilic aromatic substitution carried out under microwave irradiation was 4-fold faster than that carried out under conventional heating, although the enhancement in product yield was modest. These results suggest that microwave irradiation is an effective technique for the synthesis of chloropyrimidine-based reactive dyes. The synthesised chloropyrimidine dye was formulated into an ink and applied onto a wool fabric by ink-jet printing. The printed fabrics were steamed at 102°C for 5-25 minutes at 5-minute intervals. Good K/S and rate of dye fixation were obtained, both of which improved with increasing steaming time. The prints obtained exhibited reasonably good light and wash fastness properties.

Pre-loading of monochlorotriazinyl β-Cyclodextrin (MCT-βCD) onto/within viscose/wool (V/W) and cotton/wool (C/W) blended fabrics provide hosting cavities that can form host-guest inclusion complexes with reactive dyes in postprinting as well as with triclosan derivative or silver nanoparticles/hyperbranched polyamide-amine (AgNPs/HBPAA) composite in subsequent final antibacterial finishing step. Coloration properties, antibacterial activity against (S. aureus) and (E. coli) pathogenic bacteria, durability of the obtained products, according to the above mentioned route, to wash, surface morphology and composition of selected samples were investigated. Results obtained signify that premodification of the nominated substrates with MCT-βCD (10 g/l), followed by reactive printing with mono-or bifunctional reactive dye (20 g/l), and subsequent post-finishing with triclosan derivative or AgNPs/HBPAA composite (15 g/l each) is an efficient treatments sequence for attaining reactive prints with significant antibacterial efficacy and noticeable durability to wash. Surface depositions of selected active ingredients were also confirmed using SEM and EDX analysis.

Water stable, flexible and ecological acceptance composite films were prepared by the solvent casting process using native, dealuminated (treated with HCl to affect the surface chemistry and pore structure) and/or surface modified (coated with a cationic surfactant PDADM of different molecular weights) H-ZSM-5 type zeolite of different shapes (spherical vs. rod) and Si/Al ratios (P26 vs. P371) as adsorbents and cellulose nanofibrils (CNFs) as a networking matrix (in a weight ratio of 4:1). The films were tested for removal of the black anionic reactive dye with the highest bleeding effect at the first rinsing cycle of textile laundering. The effects of zeolite structure and surface chemistry on films dye’ removal kinetics from a standardised rinsing bath were investigated for up to 140 min at room temperature and using 0.1 g/l of dye concentration, depending on the film-to-bath weight-to-volume ratios (from 1:10 to 1:1000), thus simulating different rinsing conditions. The results show that up to 80 % of the dye was removed in the first 20 min in the lowest weight-to-volume ratio (1:10), fitting the Langmuir isotherm, and the process followed the pseudo-second order kinetic, yielding a multi-layer adsorption mechanism with a monolayer capacity of ~11 mg/g and ~21 vs. ~30 mg/g by films prepared from native or HCltreated and PDADMA100 vs. PDADMA400 coated P371 zeolites, respectively. Such efficacy was due to the more densely and fully surface-covered longitudinal P371 with PDADM400, given the huge electrostatic attraction sites for dye molecules, compared to the partly interpenetrated PDADM into relatively larger pore-sized (~450 nm vs. 220 nm) of P26. The filtration performance of the films was also examined, be used for the removal of the dye from the rinsing bath, released from the washing drum. An ultra-high flux rate (11.000 kL/m2 h MPa) with 45 % of dye removal efficacy and capacity of ~24 mg/g was provided by films prepared from spherical and aggregated P26PDADMA-400, showing its high potential also as a filter membrane.

The controlling effect for dye exhaustion (adsorption) and diffusion (absorption) in a reactive dyeing of cotton is shown to be exerted by ionic strength in the dye solution rather than concentration of inorganic salts used as electrolytes. The study showed that the conclusion applies to both exhaust dyeing for dye exhaustion and pad dyeings for dye diffusion. Further, the addition of an alkali, even though it is not used as an electrolyte, increased the extent of exhaustion (in exhaust dyeing) and diffusion (in pad dyeing) due to increase in ionic strength of the dye solution. Hence, the total ionic strength of reactive dye solution for dye exhaustion and diffusion must be taken into account in order to ensure optimum reproducibility. Means for determining the total ionic strength of exhaust or pad dye solutions for different electrolytes are given.

In this study, we explored the dyeing behavior of cotton with reactive dyes in poly(ethylene glycol)-based reverse micelle system in nonaqueous alkane medium of nonane (C9H20). Calibration of dyeing databases for both conventional aqueous-based dyeing method and nonaqueous nonane reverse micellar dyeing method was initially established, along with simulated dyeing of standard samples with known concentrations. Several color difference formulae were used to conduct computer color matching (CCM), by matching the color between batch samples and the standard samples, for both dyeing methods. Excellent color matching results were achieved as both dyeing methods showed that the CCM-predicted concentrations were nearly the same as the known concentrations. It indicates that utilizing nonane as a solvent to facilitate reverse micellar dyeing of cotton can achieve good color matching when compared with that of the conventional aqueous-based dyeing system. Relative unlevelness indices were used to evaluate the evenness of the dyed samples. Good to excellent levelness results were obtained, comparable to that of the conventional aqueous-based dyeing system. Color fastness to laundering of nonane reverse micellar dyed samples was found to be good for industrial applications. In addition, during the reverse micellar dyeing process, only very low level of volatile organic compound content was detected and 98% nonane could be recovered simply by fractional distillation. The results in this study explored the practical usage of nonane nonaqueous reverse micellar approach on the dyeing of cotton with the use of reactive dyes.

The poly[2-hydroxy-3-(1-naphthyloxy)propyl] methacrylate [poly(NOPMA)] was used as a novel adsorbent for the removal of Remazol Brilliant Blue R (RBBR) known as a reactive dye. Physico-chemical properties of polymer were analyzed by FT-IR and SEM before and after dye adsorption. The Langmuir and Freundlich isotherms were used to explain the adsorption equilibrium, and when it was compared with each other it was seen that the adsorption process was well explained by the Langmuir isotherm model and showing a monolayer adsorption capacity for RBBR of 238.10 mg/g. Kinetic models known as pseudo-first-order, pseudo-second-order and intra-particle diffusion model were utilized to analyze the mechanism of adsorption, and results indicated that was an adsorption kinetic suitable with the pseudo-second-order. The thermodynamic parameters (∆ H o , ∆ S o , ∆ G o ) indicated that the adsorption process was spontaneous and endothermic. To optimize the study conditions, the effects of the concentration of RBBR, adsorbent amount and contact time on the adsorption were investigated by response surface methodology (RSM). According to RSM results, maximum RBBR removal was reached at the optimum initial dye concentration of 60.85 mg/L, adsorbent dosage of 0.04 g/50 mL and contact time of 59.91 min.

Reactive dye is a popular dye for dyeing cotton fiber due to its very good color fastness which is explained by the formation of covalent bond between dye and fiber. In this study, practicality of reuse of reactive dye by compensating for the hydrolyzed part of the dye solution is examined. A monofunctional dye (vinyl sulfone type) was used and it was found that dyeing cotton fiber with reused dyebath is possible. Since bifunctional dye can improve the chance of dye-fiber bond formation, vinyl sulfone based bifunctional reactive dyes were also selected in this study. Three types of bifunctional dyes were used and they basically share the same vinyl sulfone group; other reactive groups are monochlorotriazine, dichlorotriazine and vinyl sulfone. Such dyes were chosen in order to compare their respective efficiencies under the effect of one common reactive group. The aim of this study was to compare the effect of hydrolyzed and unhydrolyzed proportions of mono-and bifunctional reactive dyes on cotton fiber and study the possibility and efficiency of the two different reuse dyebath systems.

Azo dyes, possessing a primary aromatic amino group, on diazotisation in presence of cotton followed by treatment with soda ash at 60–65 °C were found to ‘reactively’ dye cotton with varying degrees of fixation depending on the chemical structure of the azo dye. Evidence of dye-fibre reaction is indirectly inferred from poor to fair colour values obtained in absence of added soda ash. Dyed cotton retained significant colour even after three treatments with boiling dimethyl formamide (DMF). Coloured cellulose precipitated when a solution of dyed cotton in 85% w/w phosphoric acid was diluted with dimethyl sulfoxide (DMSO). The phosphoric acid-DMSO mixture was colourless. These two tests prove the existence of a dye-fibre covalent bond. A new class of reactive dyes without an externally attached reactive system is therefore, in principle, available. It will have the advantage of reduced raw material and manufacturing costs.

Dyeing processes are highly important for differentiation of textile products, and in general, they use a huge amount of water and chemical additives, generating a great environmental impact. In the last years, the interest in finding alternative environmentally friendly solvents for these processes has increased, with a double aim: to decrease the quantity of water used and to improve the dyeing quality. In this work, we analyze an alternative procedure to dye cotton fabrics with only two dyeing agents, a polyfunctional reactive dye and a protic ionic liquid (PIL) as an alternative solvent, avoiding the need for common chemical additives into the conventional process, thus reducing the amount and concentration of pollutants. The proposed procedure allows PIL recycling with no appreciable loss of efficiency, since after dyeing, the unfixed dye remains active in the bath, following the known exhaustion dyeing method. A collection of 13 PILs were studied with the aim of analyzing their effectiveness as dyei...

In order to produce deep shades of colour, ramie fibre was subjected to pretreatment by cationization, caustic mercerization (slack and tension condition), and liquid ammonia mercerization. The untreated and pretreated samples were dyed with 0.5 to 7 % concentrations (on mass of fiber (o.m.f)) of Liyuansol Red FL-2BL reactive dye. The dyeing properties of dye exhaustion, fixation, colour uniformity, wash fastness, and rubbing fastness were investigated. The results indicated that these pretreatments improved dye exhaustion and fixation on ramie fibre, with no loss of fastness. For the untreated and treated substance, the amount of dye mass absorption increased linearly with increased dye o.m.f. Cationic treatment improved performance, with 89 % and 98 % for exhaustion and fixation, respectively, and the maximum K/S values of all fibers receiving pretreatment. The colour uniformity was acceptable and similar for the untreated and treated ramie fibers, with the exception of cationic-treated fabric dyed at 7 % dye o.m.f that showed a high standard deviation value of colour uniformity. The Freundlich and Langmuir adsorption isotherm models were also used to study the adsorption of dye on ramie fibre; all of the adsorption processes fit the Freundlich model.

To achieve textile dyeing and functional finishing in one process, a bleach-resistant reactive dye precursor to anti-bacterial N-halamine was synthesised by reacting a type of dichlorotriazine reactive dye with 4-amino-2,2,6,6-tetramethylpiperidine. The synthesised compound, which can be transformed to an N-halamine molecule by exposure to dilute bleach solution, was used to dye cotton fabrics. After exposure to a dilute sodium hypochlorite solution, dyed cotton fabrics showed excellent anti-bacterial properties against Staphylococcus aureus and Escherichia coli O157:H7, facilitating a ca. 6-log reduction in bacteria within a short period of contact. Compared with the dichlorotriazine reactive dye, the reactive dye precursor demonstrated comparable dyeing properties including exhaustion and fixation values. No differences in rub fastness, wash fastness or bleach fastness were detected between fabrics dyed with, respectively, dichlorotriazine reactive dye and the reactive dye precursor to N-halamine.

Jute fabric was treated with mixed natural amino acids obtained from waste soya bean seed extract for chemical modification of jute for its cataionization and to enhance its dyeability with anionic dyes (like direct, reactive and acid dye) as well enabling soya modified jute for salt free dyeing with anionic reactive dyes maintaining its eco-friendliness. Colour interaction parameters including surface colour strength were assessed and compared for both bleached and soya-modified jute fabric for reactive dyeing and compared with direct and acid dye. Improvement in K/S value (surface colour strength) was observed for soya-modified jute even in absence of salt applied in dye bath for reactive dyes as well as for direct and acid dyes. In addition, reactive dye also shows good dyeability even in acid bath in salt free conditions. Colour fastness to wash was evaluated for bleached and soya-modified jute fabric after dyeing with direct, acid and reactive dyes are reported. Treatment of jute with soya-extracted mixed natural amino acids showed anchoring of some amino/aldemine groups on jute cellulosic polymer evidenced from Fourier Transform Infra-Red (FTIR) Spectroscopy. This amino or aldemine group incorporation in bleached jute causes its cationization and hence when dyed in acid bath for reactive dye (instead of conventional alkali bath) showed dye uptake for reactive dyes. Study of surface morphology by Scanning Electron Microscopy (SEM) of said soya-modified jute as compared to bleached jute was studied and reported.

An ionic liquid, choline hydroxide, was synthesised and used in a mixed alkali system for fixation of homobifunctional reactive dyes. Its molecular structure was confirmed using FTIR, 1H NMR, and 13C NMR spectroscopy. Response surface methodology was employed to optimise the dyeing conditions for reactive dyes using a sodium carbonate–choline hydroxide mixed alkali system. A Box–Behnken design with three variables, namely sodium carbonate concentration, choline hydroxide concentration, and fixation time, was used to design the experimental runs. Analysis of variance was used to estimate the statistical parameters and to evaluate the quality of the statistical model fit. The quality and model terms were evaluated using Fisher's F-test, the coefficient of determination, and probability values. The interactive effect of operating variables on the response (K/S) was studied using three-dimensional response surface plots. The results obtained from the solutions of highest desirability were found to be comparable with conventionally used alkali systems, namely sodium carbonate alone and sodium carbonate–sodium hydroxide mixed alkali. The ionic liquid choline hydroxide could be effectively used along with sodium carbonate for fixation of reactive dyes, with the advantage of reductions in pollution load, total dissolved solids, and chemical oxygen demand.

A new anthraquinonoid disperse reactive dye containing a dichlorotriazine reactive group was successfully synthesised on the basis of the Ullmann reaction in a ligand-free system by employing a copper(i) iodide as catalyst, in combination with a subsequent condensation reaction. The parameters of the cross-coupling reaction between 1-chloroanthraquinone and 2,5-diaminotoluene sulphate were investigated and optimised, such as the molar ratio of the reactants, the dosage of potassium carbonate and copper(i) iodide, the reaction temperature, and the reaction time. The results demonstrate that the dosage of potassium carbonate and the reaction time had significant impacts on the yield of the dye precursor, and an optimum synthesis process was also recommended. Moreover, the achieved dye was successfully characterised and confirmed from chemical structure and colour characteristics by employing Fourier transform infrared analysis, nuclear magnetic resonance spectroscopy, UV-vis absorption spectroscopy, elemental analysis, and liquid chromatography–mass spectrometry (LC-MS). Furthermore, a successful application of the obtained dye was achieved, with satisfactory coloration properties on silk and wool.

Benzenesulfonic acid-doped polyaniline nanorods were synthesized by oxidative polymerization of aniline and were subsequently used for the decolorization of simulated reactive dye bath effluent. Transmission electron micrograph showed that the size of the nanorods varied from 60 to 90 nm. Fourier transform infrared pattern of nanorods indicate that sulfonic acid was successfully doped on polyaniline nanorods. Under optimized conditions, sulfonic acid doped polyaniline nanorods decolorized 78% of simulated reactive dye bath effluent. The modified Freundlich model and modified pseudo-first-order model showed satisfactory fit for dye decolorization. The crystalline nature of the nanorods was modified after adsorption of dyes. The results of the study indicate that benzenesulfonic acid doped polyaniline could be used for the treatment of textile wastewaters. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1383–1389, 2017

In this research, SBA-15/polyaniline mesoporous composite was synthesized, characterized, and applied for the adsorption of Reactive Orange 16 (RO 16) as a reactive dye from aqueous media. Fourier transform infra-red spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and BET were used to examine the structural characteristics of the obtained adsorbent. The input parameters including pH, dosage, temperature, and contact time were investigated and optimized. The obtained optimized conditions are as follows: pH=2, time=60 min, and adsorbent dose=0.4 g/l. Moreover, predictive models based on MLP (Multi-Layer Perceptron) and RBF (Radial Basis Function) networks were presented to predict the adsorption amount according to the input parameters including pH, dosage, temperature, time, and dye concentration. Two criteria, namely, correlation coefficient (CC) and root mean square error (RMSE) are used between the observed and predicted amounts to validate the models. Comparison of the obtained results using these two models showed that the prediction based on the MLP network model is better than the RBF network.

A simple, efficient and scalable approach was developed for the fabrication of highly fouling resistance nanocomposite hollow fiber membranes with the aim of effective removal of environmentally detrimental reactive dyes. The naturally occurring halloysite nanotubes were functionalized via facile self-polymerization of m-aminophenol in mild acidic condition and employed as a hydrophilic additive. The chemical modification was confirmed by FTIR, TEM and energy dispersed X-ray (EDX) analysis. The hybrid nanocomposite membrane was prepared by dry–wet spin technique with different additive dosage. The resultant membrane was characterized in terms of contact angle, surface energy, porosity, zeta potential, elemental mapping and morphology. The permeation experiments illustrated superior water flux of 104.9 Lm−1 h−1 and 9.6% of irreversible fouling with more than 90.3% of flux recovery by the simple hydraulic cleaning. Most importantly, prepared membrane was subjected for hazardous reactive dye removal application with different experimental parameters. The hybrid membrane with 2 wt. % of additive concentration showed more than 97% and 94% for the Reactive Red 102 and Reactive Black 5 dyes respectively. This approach may also be very useful in developing high flux, fouling resistant ultrafiltration hollow fiber membranes for the other similar type applications such as hemodialysis membranes.

Natural sawdust of Calabrian pine was explored as low-cost industrial by-product for a hetero-bireactive dye removal from aqueous solution in this study. Batch experiments were carried out to investigate the effects of contact time and dye concentration on biosorption efficiency. Maximum biosorption amounts were achieved almost in the 20-30 min of contact for the studied dye range (50-200 mg l -1). An increase in the dye concentration resulted in decrease in the percent dye removal and increase in the biosorption capacity of biosorbent. Different kinetic and isotherm models were used to examine the biosorption experimental data for elucidating the dye removal mechanism. The equilibrium data were best represented by Freundlich isotherm model confirming multilayer coverage. The kinetics of dye biosorption best obeyed the pseudo-secondorder equation. The negative value of standard Gibbs free energy change (-3.61 kJ mol-1) indicated that physical forces were involved in the spontaneous dye biosorption. Thus, the sawdust as a possible non-conventional biosorbent presented an interesting option for bioremediation of contaminated environments by such unsafe dyes.