Commercial Reactive Dyes Research Articles

Investigation of the stripping process of the reactive dyes using organic sulphur reducing agents in alkali condition

This paper focuses on the stripping application of the reactive dyes using different recipes set up with different reducing agents and working parameters. We tried to develop alternative stripping methods using two kinds of thioureadioxide because of several disadvantages of sodium dithionite. The pretreated woven fabrics were dyed at 0.25%, 1%, 4% owf% using five commercial reactive dyes by exhaust method. Totally, 180 specimens were dyed. Then, these specimens were stripped using alternative recipes. In these recipes, we investigated the effects of types of the reducing agents, the concentration of the reducing agents and caustic, process temperature and the presence of leveling agent on the stripping efficiency. In order to examine the efficiency of the stripping processes, we measured the colorimetric values (L*, ΔL, ΔE) of pretreated, dyed and the stripped samples using commercial spectrophotometer and international measurement method. The experimental results were statistically evaluated using analysis of variance (ANOVA) with significance level ofα=0.05. According to the measured and calculated spectral results, we achieved to develop alternative methods using thioureadioxide instead of sodium dithionite. In terms of ANOVA, we found out that only concentration of caustic itself did not have significant effects on the efficiency of stripping.

Assessment of degradation of eight commercial reactive azo dyes individually and in mixture in aqueous solution by ozonation

Degradation of eight commercial reactive azo dyes with different structures containing different substituted groups has been investigated in a semi-batch reactor by ozonation individually and in mixture. The results showed that pH 10 was effective for color and COD removal of these dyes. Different dyes needed different time of ozonation for decolorization. Dyes even if decolorized to 95–99%, COD removal was different for different dyes indicating that the complexicity of structures play a major role. Oxidation and cleavage of substituent groups were evidenced by the release of chloride, nitrate and sulfate during ozonation. Increase in biodegradability was observed after ozonation, as measured by the BOD 5/COD ratio. The ozonation reaction followed a pseudo first order kinetics. The study revealed that ozonation of reactive dye is a viable technique for dye containing wastewater treatment.

Environmental assessment of different photo-Fenton approaches for commercial reactive dye removal

An environmental study using life cycle assessment (LCA) has been applied to three bench-scale wastewater treatments for Cibacron Red FN-R hetero-bireactive dye removal: artificial light photo-Fenton process, solar driven photo-Fenton process and artificial light photo-Fenton process coupled to a biological treatment. The study is focused on electricity and chemicals consumption, transports and atmosphere and water emissions generated by the different processes involved. Results show that the artificial light photo-Fenton process is the worst treatment in terms of environmental impact. On the other hand, both solar driven and coupled to biological photo-Fenton processes reduce significantly the environmental damage, although none can be identified as the best in all impact categories. The major environmental impact is attributed to the H 2O 2 consumption and to the electrical energy consumption to run the UVA lamp. An economic analysis of the different photo-Fenton processes has also been performed and the results are discussed together with those obtained from the environmental assessment.

Adsorption of dyes and phenol from water on resin adsorbents: Effect of adsorbate size and pore size distribution

Batch adsorption runs of two commercial reactive dyes (methylene blue and reactive orange X-GN) and phenol from water onto two resin adsorbents (Amberlite XAD-4, a macroreticular adsorbent and ZCH-101, a hyper-cross-linked adsorbent) were carried out in the present study. Effect of adsorbate size and pore structure of the resin adsorbents on adsorption was discussed and Langmuir and Freundlich models were tested for the relevant adsorption isotherms. In the kinetic section concentration–time profiles were obtained to further elucidate the effect of adsorbate size and porous structure on adsorption mechanism. A pseudo-second-order model was proved to give a satisfactory description of the related kinetic results. Two-stage kinetic curve of methylene blue onto ZCH-101 was observed at a specific experimental condition and modeled schematically according to its specific pore size distribution. Furthermore, other kinetic experiments were performed at different ambient temperature to validate the proposed schematic model.

05/02272 Decolorization and mineralization of commercial reactive dyes under solar light assisted photo-Fenton conditions

05/02272 Decolorization and mineralization of commercial reactive dyes under solar light assisted photo-Fenton conditions

Decolorisation and mineralisation of homo‐ and hetero‐bireactive dyes under Fenton and photo‐Fenton conditions

The degradation of two commercial reactive dyes, CI Reactive Red 141 (homo‐bireactive) and CI Reactive Red 238 (hetero‐bireactive), using Fenton's reagent in the dark and under either artificial or solar irradiation, has been investigated. The main parameters that govern the complex reactive system, i.e. type of irradiation, temperature and initial concentrations of iron(II) and hydrogen peroxide, have been studied at pH 3. Temperature and the use of light have beneficial effects on the removal of colour, aromatic compounds, total organic carbon, acute toxicity, given as changes in EC50 values (against the marine photobacteria Vibrio fischeri) and changes in the biodegradability. The advanced oxidation processes used in this study have proven to be highly effective for the treatment of such types of reactive dyes and several advantages concerning the technique application arise from the study. The possibility of a combined advanced oxidation process‐biological treatment is proposed.

Decolorization and mineralization of commercial reactive dyes under solar light assisted photo-Fenton conditions

The degradation of different commercial reactive dyes: a monoreactive dye (Procion Red H-E7B), an hetero-bireactive dye (Red Cibacron FN-R) and a Standard Trichromatic System, by using solar light assisted Fenton and photo-Fenton reaction is investigated. The reaction efficiencies have been compared with the ones obtained for the same system in the dark or under the assistance of an artificial light source. The use of solar light is clearly beneficial for the removal of color, aromatic compounds (UV 254), total organic carbon (TOC), and the increase of the BOD 5/COD ratio. The possibility of a combined advanced oxidation process (AOP)/biological treatment based on the use of sunlight is suggested.

The photofading mechanism of commercial reactive dyes on cotton

The photofading mechanism of 16 commercial dyes (8 Procion, 8 Remazol) reactively dyed on cotton is investigated. All 16 dyes fade at similar rates, with Δ E's of 2.7–6.1 after 15 h irradiation in simulated Florida sunlight. By removal of UV, it is shown that fading is caused by both visible and UV light, with visible light being the dominant factor for azo dyes and UV for phthalocyanines. By removal of oxygen, it is shown that oxygen is critical for fading by visible but not UV light. Quenching experiments with DABCO show that singlet oxygen is unimportant, and therefore the key reaction in visible fading is an electron transfer from the excited state of the dye to oxygen. Water in the pH range 3–8 increases fading by only 36% compared to dry and at more extreme pH's, larger increases in fading are seen.

Azo-hydrazone tautomerism of phenylazonaphthol sulfonates and their analysis using the semiempirical molecular orbital PM5 method

The enthalpy of formation for the azo and hydrazone tautomers (A & H Ts) of 1-phenylazo-2-naphthols, 2- and 4-phenylazo-1-naphthols and 4-phenylazo-1-naphthol-2-sulfonic acids was estimated both in the gaseous phase and in water using a semi-empirical molecular orbital PM5 and COSMO method. Substituent effects on the solvation energies for these phenylazonaphthols were analysed in detail. The A & H Ts of azo dyes have small enthalpies of transformation which are the same as heterocyclic tautomers in heterocyclic compounds such as nucleic acid bases and heterocycles of amino acids. The hydroxyazo dyes examined exist mostly as the hydrazone tautomer (HT) in water, since the HTs possess usually larger (minus) values of solvation energy than the azo tautomers (ATs). Dyes whose A & HTs possess comparable energy of solvation result in higher stability of the ATs in water than the HTs since the ATs are more stable in the gas phase. Sulfonic acid groups ortho ( o) to the azo group have unusual solvation energies resulting in dyes whose ATs have higher stability than the HT's in water. Examples of such azo dyes examined are the 4- and 2-( o-sulfophenylazo)-1-naphthols and their derivatives. In general, electron-withdrawing substituents have a small effect on the azo-hydrazone tautomerism (AHT) of phenylazonaphthols with the exception for sulfonic acid groups at certain positions in the structures. Examples of commercial reactive azo dyes showing such a tendency are C.I. Reactive Red 1, Red 194 and Red 227. Chloride substituents in the triazine ring imparted strong effects on the AHT of C.I. Reactive Red 1.

Oxidation of commercial reactive azo dye aqueous solutions by the photo-Fenton and Fenton-like processes

This paper evaluates the degradation of two azo reactive dyes, C.I. Reactive Yellow 84 (RY84) and C.I. Reactive Red 120 (RR120) by photo-Fenton and Fenton-like oxidation. All experiments were performed on a laboratory scale set-up. The effects of different reaction parameters such as initial pH, contact time, effect of light and hydrogen peroxide concentrations on the oxidation of the dye aqueous solutions have been assessed. Effective system conditions were found to be pH of 3, hydrogen peroxide-to-iron molar ratio of 20:1 and UV or solar irradiation. The color removal efficiency at the optimum conditions during different Fenton-like processes was also evaluated. The results show that the color removal of RY84 after 15 min reaction time follows the decreasing order: solar/Fe(II)/ H 2O 2>UV/Fe(II)/ H 2O 2>UV/Cu(II)/Fe(III)/ H 2O 2>UV/Fe(III)oxalate/H 2O 2>UV/Fe(III)/ H 2O 2>dark/Fe(II)/ H 2O 2>solar/Fe(III)oxalat/H 2O 2>UV/H 2O 2>UV/Fe(II)=UV. During the same reaction period the relative order for RR120 removal rate was slightly different: solar/Fe(II)/ H 2O 2>UV/Fe(II)/ H 2O 2>UV/Fe(III)/ H 2O 2=UV/Cu(II)/Fe(III)/ H 2O 2>UV/Fe(III)oxalate/H 2O 2=UV/H 2O 2>UV. The toxic potential of the dye’s degradation was investigated by the bioluminescence test using the LUMIStox 300 instrument and results were expressed as the percentage inhibition of the luminescence of the bacteria Vibrio fisheri. Formate and oxalate, identified as fragmental oxidation products of investigated dyes, could also be detected after 15 min irradiation time.

Reactive dyeing systems for wool fibres based on hetero‐bifunctional reactive dyes. Part 2: Investigation of dyeing properties during the dyeing cycle

The dyeing behaviour during the dyeing cycle of a Sumifix Supra dye and some other commercial reactive dyes under various dyebath pH conditions was investigated. Studies of the dyeing of wool serge fabric indicated that the diffusion properties of hetero‐bifunctional Sumifix Supra dyes generally lie between those of b‐sulphatoethylsulphone (Remazol dyes) and monochlorotriazine (Procion H dyes).

Reactive dyeing systems for wool fibres based on hetero‐bifunctional reactive dyes. Part 1: Application of commercial reactive dyes

The wool dyeing properties, such as exhaustion and fixation parameters, of selected hetero‐bifunctional Sumifix Supra dyes and some other commercial reactive dyes were quantified under various dyebath pH conditions. Studies of the dyeing of wool serge fabric indicated that Sumifix Supra dyes could produce reasonably high fixation values. However, remarkably improved fixation values were obtained when these dyes were pre‐activated to the vinylsulphone form and dyed in this form, especially at low pH values (pH 4 or lower).

Process of dyeability modification and bleaching of cotton in a single bath

Graft polymerisation of the cationic monomer, methacryloylaminopropyltrimethylammonium chloride (MAPTAC), onto scoured cellulose was carried out in the bleaching process, aiming at modifying the fibre using a single bath. The extent of MAPTAC fixation on cellulose was measured. The bleaching performance of hydrogen peroxide in the presence of the modifying agent was found to be slightly reduced. The modified bleached cotton fabric was then dyed with a commercial reactive dye in the absence of salt. The dye uptake and colour strength of the modified fabric was markedly increased with an increase in the concentration of MAPTAC. This was attributed to the presence of the cationic groups of the MAPTAC which played a crucial role in attracting the anionic dyes from the dyebath. The results suggest that the dyeing properties of the modified fabric are closely dependent on the efficiency of MAPTAC fixation on cellulose during concurrent modifying and bleaching of cotton.

Co‐application of hydroxyalkyl dyes and polyphosphonic acids to cotton to achieve dye—fibre covalent bonding

The dyeing of cotton to a high standard of wet‐fastness with hydroxyalkyl dyes and a polyphosphonatecrosslinker system has been investigated. Dyes containing hydroxyalkyl groups were prepared, by the reaction of commercial reactive dyes with ethanolamine, and applied to cotton fabric in the presence of polyphosphonic acid crosslinking agents using cyanamide as a catalyst. The application was carried out using a pad‐thermosol method. The effects of cyanamide concentration, the nature of the crosslinker and the type of hydroxyalkyl dye were studied in detail. It was concluded that multifunctional polyphosphonates are capable of producing dyeings on cellulosic fibres exhibiting a high degree of covalent bonding (fixation). The efficiency of dye fixation at ca. 2% pure dye (owf), obtained from this method, was greater than 90%.

Homogenous and Heterogenous Advanced Oxidation of Two Commercial Reactive Dyes

Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l-1 by titanium dioxide mediated photocatalytic (TiO2/UV), dark and UV-light assisted Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were quite effective in terms of colour, COD as well as TOC removal. Moreover, the relative growth inhibition of the azo dye towards the marine algae Dunaliella tertiolecta that was initially 70%, did not exhibit an increase during the studied advanced oxidation reactions and complete detoxification at the end of the treatment period could be achieved for all investigated treatment processes. However, for Reactive Blue 21, abatement in COD and UV-VIS absorbance values was mainly due to the adsorption of the dye on the photocatalyst surface and/or the coagulative effect of Fe3+/Fe2+ ions. Although only a limited fraction of the copper phythalocyanine dye underwent oxidative degradation, 47% of the total copper in the dye was already released after 1 h photocatalytic treatment.

Biodecolorization screening of synthetic dyes by four white-rot fungi in a solid medium: possible role of siderophores.

Four selected fungi were screened for their ability to decolourize a textile effluent and commercial reactive dyes in a solid medium. Ligninolytic enzymes activities (lignin peroxidase, manganese peroxidase and laccase) and siderophores presence were monitored in decolourized plates. The results showed low lignin peroxidase activity and no manganese peroxidase activity was detected for all fungi. Laccase activity was observed in Reactive Blue 19 decolourized plates by Trametes versicolor and Trametes villosa. Siderophores presence was observed in Trametes versicolor, Phanerochaete chrysosporium and Lentinus edodes decolourized plates. Lentinus edodes displayed the greatest decolourization ability both in terms of extent and rapidity of decolourization. The transformation observed for dyes open the possibility to study siderophores to treat dyes and textile effluents.

Kinetic modeling of liquid-phase adsorption of reactive dyes and metal ions on chitosan

The rates of adsorption of three commercial reactive dyes and Cu(II) from water in the absence and presence of complexing agents using chitosan were measured at 30°C. Three simplified kinetic models, i.e., pseudo-first-order, pseudo-second-order, and intraparticle diffusion, were tested to investigate the adsorption mechanisms. It was shown that the adsorption of reactive dyes and Cu(II) in the absence of complexing agents could be best described by the intraparticle diffusion model, whereas that of Cu(II) in the absence of complexing agents such as EDTA, citric acid, and tartaric acid by the pseudo-second-order equation. Kinetic parameters of the three models and the normalized standard deviations between the measured and predicted results were also calculated and discussed.

The fastness, to repeated washing, of reactive dyes and pre-metallised acid dyes on nylon 6,6

Standard depth dyeings were prepared using three, unsulfonated 1:2 pre-metallised acid dyes as well as three reactive dyes on knitted nylon 6,6 fabric and the fastness of the dyeings to 20 repeated wash tests was determined. In the case of the three pre-metallised acid dyes, while aftertreatment with a commercial syntan/cation system as well as a modification of this commercial system reduced both the rate and extent of dye loss during repeated washing, the extent of dye loss which occurred was not unsubstantial. In contrast, the dyeings obtained using the three commercial reactive dyes suffered considerably lower dye loss during repeated washing.

Comparative adsorption of metal and dye on flake- and bead-types of chitosans prepared from fishery wastes

The adsorption capacities and rates of Cu(II) and a commercial reactive dye RR222 on flake- and bead-types of chitosans prepared from three fishery wastes (shrimp, crab, and lobster shells) were compared at 30°C. It was shown that all equilibrium isotherms could be well fitted by the Langmuir equation. The adsorption capacity of Cu(II) on flake- and bead-types of chitosans appeared to be comparable, but the adsorption capacity of RR222 on bead type was much larger than that on flake type by a factor of 2.0–3.8. The rates of dye adsorption on both types of chitosans indicated different controlling mechanisms. In addition, the bead type of chitosans exhibited a greater rate compared to the flake type.

Dye–fibre bond stabilities of some reactive dyes on cotton

Cotton fabric dyed with commercial reactive dyes of the monochloro-s-triazine, bis(monochloro-s-triazine), and bis(monofluoro-s-triazine) type was treated in buffer solutions pH 10 and 12 at 60, 85 and 98°C. Hydrolysis has been investigated using spectrophotometrical measurements of hydrolysed dye at λ max. The percent of hydrolysed dye was calculated.