Metachromic interactions between azo and triphenylmethane dyes in aqueous solution

Interactions between dilute aqueous solutions of the triphenylmethane dye Crystal Violet and the disazo dyes Brilliant Orange or Brilliant Yellow at room temperature produce strong metachromic absorptions at 494 nm which are absent from the spectra of either component alone. The addition of acetone, ethanol or methanol to these solutions or raising their temperature reverses the interaction. It is suggested that these observations are consistent with a strong interaction occurring between adjacent molecules of crystal violet which are held together in a specific orientation by interacting with a stereoregular network of disazo dyes held together by hydrogen bonding.     

Kass-controlled Hg transport from Crystal Violet Lactone to Fluoran

We have investigated the Hg²⁺ transport from Crystal Violet Lactone to Fluoran dye based on the association constant, K_ass. Upon addition of Hg²⁺, the Crystal Violet Lactone shows a new peak at around 603 nm, and the color of the solution changed from colorless to blue. With the addition of Fluoran dye in this solution containing Crystal Violet Lactone and Hg²⁺, the absorption intensity of Fluoran dye at 447 nm and 586 nm was all increased. So the color of solution gradually became black from blue color. From the changes of the ratio A₅₈₆/A₄₄₇, it is apparent that the Hg²⁺ in Crystal Violet Lactone-Hg²⁺ was transported to colored Fluoran. The Hg²⁺ transport from Crystal Violet Lactone to Fluoran dye was also carried out by the calculation of the association constant: the binding ability for the complex formation of Fluoran dye and Crystal Violet Lactone-Hg²⁺ is much greater in CH₃CN solution (K_ass = 3.0 × 10⁴ M⁻¹) than that of the Crystal Violet Lactone with Hg²⁺ (K_ass = 1.2 × 10³ M⁻¹).     

Preparation and characterisation of silver‐ or copper‐doped TiO2 catalysts and their catalytic activity in dye degradation

In this study, silver‐ or copper‐doped TiO₂–Ce‐, TiO₂–La‐, and commercial TiO₂ (P25)‐supported catalysts were prepared. The catalysts and supports were characterised by powder X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption studies. UV‐light‐assisted heterogeneous Fenton‐like oxidation of two different‐structure dyes (anionic azo dye Orange II, CI Acid Orange 7 and cationic triphenylmethane dye Crystal Violet, CI Basic Violet 3) was investigated over the catalysts. Higher catalytic activity was observed in the oxidation of Orange II than in the oxidation of Crystal Violet. For both dyes, the TiO₂–Ce and TiO₂–La‐supported catalysts, which were in the form of anatase only, gave higher photocatalytic activity than the P25‐supported catalysts, which were in the form of anatase and rutile. Complete colour removal was observed during oxidation of Orange II over Cu/TiO₂–Ce and Cu/TiO₂–La catalysts, whereas the highest degree of decolorisation, 89.3%, was achieved by oxidation of Crystal Violet over Ag/TiO₂–Ce. The pH of the solution affected the surface state of the TiO₂, thus affecting the photocatalytic degradation of the dyes. The surface area of the catalysts is also a key parameter that influences their photocatalytic activity. It was observed that catalysts having higher surface areas brought about greater dye degradation.     

Dyeing of chemically modified cellulose. VII. Dyeability of cellulose bearing aromatic amino,nitro, and acrylamidomethyl groups

The effect of introducing aromatic amino, nitro, and acrylamidomethyl groups in the cellulose molecules on the dyeing properties of two direct dyes (Chlorantine Fast Red 6BLL and Solophenyl Orange T4RL) as well as two reactive dyes, (Procion Brilliant Red M5B and Procion Brilliant Orange MG) was investigated. The extent and rate of dyeing for cellulose bearing aromatic amino groups were lower than those of nonmodified cellulose irrespective of the dye used. In addition, the extent of dyeing decreased as the amount of aromatic amino groups increased. The opposite held true for cellulose bearing acrylamidomethyl groups, particularly with direct dyes where increasing these groups caused a substantial enhancement in the dye uptake. On the other hand, subjecting cellulose to nitration reaction prior to dyeing diminished significantly its dyeability with the dyes.     

反相高效液相色谱法测定红糖中碱性橙的含量

建立了高效液相色谱法测定红糖中碱性橙含量的测定方法。采用C18分离柱,以乙腈和水[V(乙醇)∶V(水)=60∶40]为流动相,检测波长为443 nm。检出限为0.10 mg/kg,回收率为84.0%~107.0%,测定结果标准偏差2.0%~5.3%。     

活性艳橙-KR的脱色和光催化氧化二步处理

对活性染料活性艳橙-KR的脱色、絮凝条件及光催化的条件进行了研究。活性艳橙-KR经过铁粉处理后,调节pH,絮凝沉降后,再经过光催化氧化降解,其COD的去除率可达到85％～92％,由于铁粉的加入．溶液中加入了铁离子,使得TiO2作为光催化氧化催化剂的催化作用增强,这是一种有效的降解方法,对实际生产有实用价值。     

The Fenton Chemistry and Its Combination with Coagulation for Treatment of Dye Solutions

Abstract

Aqueous solutions of Acid Blue 74, Acid Orange 10, and Acid Violet 19 were subjected to Fenton/Fenton‐like oxidation and its combination with lime coagulation. The analysis indicated no dependence of chemical oxidation efficacy on dye concentration in the range of 0.1–1 g L^?1. Complete or nearly complete (higher than 95%) color removal of all treated samples was observed. Dye:H₂O₂ weight ratio of 1∶2 proved optimal for treatment of all dye solutions by means of Fenton/Fenton‐like oxidation. Moderate doses of hydrogen peroxide led to the improvement of biodegradability of dye solutions. No formation of any toxic intermediates during the oxidation of Acid Orange 10 and Acid Violet 19 was detected. Only a slight toxicity increase was observed after Acid Blue 74 degradation by Fenton chemistry. H₂O₂/Fe³⁺ system with pH adjusted to 3 proved the most effective oxidation process. The combination of Fenton chemistry and subsequent lime coagulation was the most feasible treatment method of removing COD and UV₂₅₄ and UV_max absorbance of dye solutions. Combined oxidation and coagulation was more effective for Acid Blue 74 and Acid Orange 10 elimination than for Acid Violet 19.     

利用计算机配色拼混的分散黑染料

根据计算机配色软件对一黑色色样进行了测试,确定了一种了该分散黑染料的组成为C.I.分散橙73、C.I.分散橙44、C.I.分散紫93、C.I.分散蓝291∶1,用量比为1∶2.74∶2.51∶1.95。该复配分散黑具有稳定的色光,良好的染色提升性,各项色牢度均达到要求。     

The contribution of singlet oxygen to the photofading of triphenylmethane and related dyes

The contribution of singlet oxygen (¹Δ_gO₂) to the photofading of Crystal Violet in some solvents is examined. The rates of photofading in dichloromethane or acetone are accelerated in the presence of singlet oxygen sensitizers, e.g. Methylene Blue. The rates are retarded by adding effective singlet oxygen quenchers such as β-carotene or nickel dimethyldithiocarbamate. It seem shtat Crystal Violet is mainly photooxidized to give Michler's ketone and p-dimethylaminophenol via the reaction with singlet oxygen, which can be generated by the dye itself or by an added sensitizer. The effect of various singlet oxygen quenchers on the photostability of coloured materials derived from colour formers, such as Crystal Violet Lactone and 3-diethylamino-6-methyl-7-anilinofluoran, is examined also on silica gel.     

Adsorption of cationic dyes on Jalshakti®, super absorbent polymer and photocatalytic regeneration of the adsorbent

This paper presents a study on the batch adsorption kinetics of seven cationic dyes, namely, Methylene Blue, Safranine T, Rhodamine B, Crystal Violet, Malachite Green, Brilliant Green, and Basic Fuchsine onto Jalshakti^® (JS), a super absorbent polymer, from aqueous solution. The adsorption of dyes reaches equilibrium in 60–90 min. Equilibrium isotherms and intraparticle diffusion rate constants were measured for single component systems. It is found that uptake of dyes on JS follows the Langmuir and Freundlich isotherm models. The particle diffusion study showed that the initial boundary layer diffusion is followed by intraparticle diffusion effects. The flat and planar dye molecules are readily adsorbed as compared with the propeller shaped triphenylmethane dyes. Photocatalytic regeneration of spent JS using UV/TiO₂ is more effective compared to conventional methods. Further, the regenerated JS exhibits 90% efficiency for subsequent adsorption cycle with Methylene Blue and Safranine T aqueous solutions.     

Dyeing of chemically modified celluloses. II. Effect of chemical modification of cellulose on the dyeing properties of some direct dyes

The behavior of partially acetylated cellulose, partially carboxymethylated cellulose, cyanoethylated cellulose, and cellulose grafted with polyacrylontrile toward three direct dyes, namely, Chlorantine Fast Red 6 BLL, Solophenyl Orange T4RL, and Diphenyl Brilliant Flavine 7GFF, was studied. Partially acetylated cellulose having 2.06% combined acetic acid showed higher dye uptake than the unmodified cellulose. The amount of dye uptake increased as the acetyl content increased up to 4% combined acetic acid. Beyond this, enhancement in the dye uptake was not significant. Whereas partially carboxymethylated cellulose showed a lower dye uptake than the control. The dye uptake decreased considerably as the carboxymethyl groups increased. The same holds true for cyanoethylated cellulose where increasing the cyanoethyl content caused a substantial reduction in the dye uptake. On the other hand, cellulose grafted with polyacrylonitrile up to 18.3% graft yield showed much higher dye uptake than the ungrafted cellulose.     

Absorption of Dyes by Keratin under Near Neutral Conditions*

The absorption by keratin of the monobasic dye Orange II (C.I. Acid Orange 7) and the dibasic dye Sunset Yellow FCF (C.I. Food Yellow 3) from a dyebath containing the sodium salt of the dye and different amounts of sodium chloride at two pH values (5.1 and 6 0) was studied. Salting-on and salting-off were observed with Orange II but not with Sunset Yellow. Theoretical curves were constructed to fit the empirical absorption isotherms. A constant affinity term enabled a fit with the Orange II curves to be obtained, but an affinity term that decreased with increasing salt concentration was required to obtain a fit with the Sunset Yellow curves. The effect of these factors on the diffusion coefficients of the dye anions in the presence of salt is discussed.     

Photoinitiated surface grafting of synthetic fibers,III. Photoinitiated surface grafting of poly(ethylene terephthalate) fibers

Photoinitiated surface grafting of acrylic acid (AA), acrylamide (AM) and 4-vinyl pyridine (VP) onto poly(ethylene terephthalate) (PET) fibers (a commercial textile yarn) has been studied using benzophenone (BP) as photoinitiator. A continuous process as previously described has been applied, which involves presoaking of the PET yarn in a solution of initiator and monomer in acetone and UV irradiation in nitrogen atmosphere. The resulting grafted polymer on the fiber surface has been analyzed by ESCA, titration of carboxy groups (grafted AA), and dye absorption. The relative ESCA intensities (RI) of O1s/C1s and N1s/C1s are used as measure for grafted AA, AM and VP, respectively, after recording the RI-values for ungrafted fibers. For grafting with AA, the RI-values increased from 32.8% (background) to 48.6% after 20 s irradiation time. The amount of carboxy groups measured by titration increased from 0.045 to 0.106 mmol/m². Assuming an even coverage of grafted AA polymer, this means a grafted layer of 4.8 nm thickness. After grafting, the adsorption of the dye Crystal Violet (CV) from aqueous solution increased by about 3 times. With AM as monomer, the RI-values increased from 2.6 (background) to 14.8% and the adsorption of a direct dye Sirius Lichtbordo B-LL increased by about 6 times. With VP as grafted monomer, the RI-values increased from about 2.6 (background) to 5.1% and the adsorption of the direct dye increased by about 4 times.     

Evaluation and mechanism of cationic/anionic dyes extraction from water by ionic liquids

Dispersive liquid–liquid micro-extraction (DLLME) using three different imidazolium-based ionic liquid (IL) was applied for extraction of recalcitrant dyes, Eriochrome black T (anionic azo dye), and Crystal Violet (cationic triphenylmethane dye) from aqueous solutions, not previously reported. Effects of process parameters such as initial dye concentration, pH of aqueous phase, amount and type of IL on fraction extracted, and distribution ratio of dyes were studied. Further, dyes interaction with ILs and extraction mechanism were explored. Considering the high cost of ILs, regeneration and reuse study for ILs was also performed using reverse DLLME. The fraction extracted for both the dyes with all the ILs varied significantly with pH change. Maximum dyes fraction extracted were observed nearly at neutral pH (pH =7). However, the fraction extracted were different for different IL.     

Role of unburnt carbon in adsorption of dyes on fly ash

Various fly ash samples with different unburnt carbon contents were collected, characterised and tested for adsorption of basic dyes, Methylene Blue and Crystal Violet, in aqueous solution. It was found that unburnt carbon plays a major role in dye adsorption. The mineral matter of fly ash has little adsorption capacity and most of the adsorption capacity of fly ash can be attributed to the unburnt carbon. The fly ash with higher unburnt carbon content will have higher adsorption capacity. For the carbon‐free fly ash, adsorption capacities for Methylene Blue and Crystal Violet are only 2 × 10^?6 mol g^?1 and 1.0 × 10^?6 mol g^?1, respectively, while the adsorption capacities for Methylene Blue and Crystal Violet on carbon‐enriched fly ash are 1.2 × 10^?4 mol g^?1 and 1.0 × 10^?4 mol g^?1, respectively. A two‐site Langmuir adsorption model best describes the adsorption isotherm. Copyright © 2005 Society of Chemical Industry     

The sensitivity and impact of dye structure and fibre micronaire on the increased dyeability of bioengineered cotton fibres

Previous research reported on a screening method to assess the functionalisation of bioengineered cotton fibres through the absorption of CI Acid Orange 7. The aim of the present paper is to extend this study to different dye classes. Thus the dye absorption of bioengineered cotton fibres containing oligochitin is studied for a series of dye classes. Statistically significant differences were found between cotton lines designed to produce oligochitin in the fibre and their respective controls for all tested dyes, confirming previous results with CI Acid Orange 7. Further, although variations in micronaire influenced dye absorption, it was confirmed for all dyes tested as well as for CI Acid Orange 7 that the oligochitin production had a larger impact on the exhaustion values than the differences in micronaire. The method described in this paper can be applied as a screening tool to meet the challenge of working with small quantities of fibrous materials. Moreover it shows the potential that the incorporated oligochitin has for increasing dyeability with a wide range of dyes and creating fibres with more versatile reactivity.     

Effects of anions on the photocatalytic and photoelectrocatalytic degradation of reactive dye in a packed‐bed reactor

The effects of various anions, Cl^?, ClO₄^?, SO₄^2?, NO₃^?, HCO₃^?, H₂PO₄^? and C₂O₄^2?, on the photocatalytic and photoelectrocatalytic degradation of reactive Brilliant Orange K‐R have been investigated in a packed‐bed photoelectrocatalytic reactor. It was found that the nature and concentrations of these inorganic anions significantly affected the photocatalytic and photoelectrocatalytic degradation performance of the reactive dye. The results indicated that the external electric field was successfully applied to improve the photocatalytic efficiency of reactive Brilliant Orange K‐R in the presence of Cl^?, especially at higher concentrations, while other inorganic anions displayed more or less negative effects on the degradation of the dye. The strongest inhibition effect on photocatalytic and photoelectrocatalytic degradation of the dye was observed in the presence of HCO₃^? ions. Copyright © 2004 Society of Chemical Industry     

The use of Jatobá bark for removal of cationic dyes

In this work, the application of Jatobá bark (the waste product of medicinal plant processing) in removal of the cationic dyes Methylene Blue, Crystal Violet and Rhodamine B from aqueous solution was studied in a batch system. The effect of contact time, pH and temperature on dye removal was investigated. An increase in pH from 2 to 10 was accompanied by an increase in the amount of dye adsorbed. The equilibrium sorption data fitted to the Langmuir, Freundlich and Langmuir–Freundlich equations were investigated. The Langmuir–Freundlich isotherm exhibited the best fit with the experimental data and the maximum adsorption capacities at room temperature being 211.5, 89.5 and 69.4 for Rhodamine B, Methylene Blue and Crystal Violet, respectively. The kinetic sorption was evaluated by the pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion models. It was observed that sorption follows the pseudo‐second‐order kinetic model. The thermodynamic parameters for the sorption process were also determined. The spontaneous and endothermic nature of adsorption was obtained based on the negative value of free energy (ΔG) and the positive value of enthalpy (ΔH). The results indicate that Jatobá bark could be used as a low‐cost material for the removal of cationic dyes from wastewater.     

Fenton试剂氧化降解结晶紫的动力学研究

探讨了Fenton试剂在光照条件下对结晶紫模拟印染废水进行氧化处理的动力学规律,讨论了H2O2初始浓度、FeSO4初始浓度、反应温度及草酸的络合作用对结晶紫氧化降解的影响,确定了最佳降解条件,建立了Fenton试剂氧化降解结晶紫的动力学方程,为光照条件下利用Fenton试剂处理含结晶紫类的印染废水提供了依据.     

Urea/alkali-free printing of cotton with reactive dyes

Urea reduction or elimination in reactive dye print pastes is of ecological interest. Sodium edetate is presented as a complete substitution of urea in the conventional print paste of reactive dyes, namely CI Remazol Black B and Remazol Brilliant Orange 3R using a constant amount of sodium alginate as the thickening agent. Three different print pastes containing urea/NaHCO₃, sodium edetate/NaHCO₃ and sodium edetate were thoroughly investigated. Different factors that may affect the printability of cotton, such as the concentrations of sodium edetate, urea, dye, absence or presence of alkali and steaming time in the prints obtained were evaluated with respect to the dye fixation, colour strength, dye penetration, levelling and the fastness properties. Excellent to good fastness was obtained for all samples irrespective of the print paste used.