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1.
A UV–vis spectroscopic investigation has been made of the interactions of a specially synthesised series of o - and p -substituted, model arylazonaphthol dyes with the cationic and zwitterionic surfactants above and below their critical micelle concentrations at pH 10. Spectra of dyes incorporated in micelles of zwitterionic surfactant or cationic surfactant at pHs < 8 are similar to those found in nonionic micelles, i.e. dye substituents control its location similarly for all the micelle types. However, the common anion is selectively favoured in cationic micelle solutions at pH 10, due to electrostatic interactions within the micellar surface. Introduction of polar groups at either end of the molecule confines the dyes to the surface of either zwitterionic or cationic micelles and are characterised by atypical p K A shifts. Electrostatic complexes between dyes and cationic or zwitterionic surfactants were formed in sub-micellar regions, those with cationic surfactant being sparingly soluble.  相似文献   

2.
A spectroscopic study (UV–vis and adsorption) has been made of the interactions of select model azo dyes with a range of surfactant types or their mixtures both above and below their respective critical micelle concentrations. All surfactants inhibit adsorption of the dyes to cotton above their critical micelle concentrations due to incorporation in micelles. However, formation of 1;1 complexes between dyes and cationic or zwitterionic surfactants in sub‐micellar regions results in enhanced deposition on cotton. It is shown that attractive or repulsive electrostatic interactions play a key role in dye binding to micelles. Unusually, spectra of complexes formed between the dye and cationic surfactant are typical of those of the azo tautomeric form as opposed to the hydrazone form that is prevalent in aqueous media. Addition of anionic surfactant to micellar solutions of nonionic or zwitterionic surfactants results in successive displacement of dye from the respective micelles, i.e. binding is competitive.  相似文献   

3.
Optimal preparation of inkjet ink should be possible through the elucidation of the relationship between dye/additive interactions and ink performance. In the present study, the interactions between the dyes and surfactant additives were investigated. To investigate the physical properties of the surfactants used, the critical micelle concentration (cmc) and the aggregation number (N) were determined using electron spin resonance, static light-scattering, and fluorescence spectroscopy. On the basis of the cmc and N values, the visible absorption spectra of aqueous acid dye solutions (C. I. Acid Red 88, 13, and 27) containing surfactants (i.e., Surfynol 465 (S465), octaethylene glycol monododecyl ether (OGDE), and sodium dodecyl sulfate (SDS)) were measured. From the dependence of the spectra on the surfactant concentration, the binding constants, K(bind), of the acid dyes with the surfactant micelles were calculated: the K(bind) values decreased in the order of C. I. Acid Red 88 > C. I. Acid Red 13 > C. I. Acid Red 27, which correlates with the number of sulfonate groups. For all the dyes, the K(bind) values with the nonionic surfactants, S465 and OGDE, were much larger than those with the anionic surfactant, SDS. The thermodynamic parameters of the binding, i.e., the enthalpy change, ΔH(bind), and entropy change, ΔS(bind), were determined via the temperature dependence of the binding constants. The positive ΔH(bind) value for S465 indicates an endothermic binding process, while the negative ΔH(bind) values for SDS and OGDE indicate exothermic binding processes.  相似文献   

4.
Adsorption of dyes to cotton and inhibition by polymers   总被引:2,自引:0,他引:2  
This paper addresses some key factors that control the transfer of dyes between garments during detergency. It is shown that adsorption of a series of substituted arylazo-2-naphthol dyes to cotton under simulated detergency conditions is influenced by the log P fragment value of the dye substituent; this suggests that hydrophobic interactions make an important contribution to the binding free energy. The comparative effectiveness of nonionic, zwitterionic and cationic polymers in inhibiting adsorption of dye to cotton was also investigated. Increase in polymer concentration reduces dye adsorption to cotton; increase in polymer molecular weight at constant polymer concentration also inhibits dye adsorption up to a molecular weight of ca. 20000, above which there is no further change. Anionic surfactants reduce the efficacy of polymers by displacing dyes from polymers. Surprisingly, certain dyes become relocated in polymer/surfactant complexes; binding is much more effective than in corresponding surfactant micelles.  相似文献   

5.
A wide-ranging investigation has been made of the adsorption of direct dyes to cotton and of inhibition by surfactants, polymers and polymer–surfactant mixtures. Generally, the selected polymers are extremely effective at inhibiting adsorption of most of the direct dyes to cotton but are less effective at inhibiting adsorption of small, model azo dyes. Micellar solutions of zwitterionic and cationic surfactants can inhibit adsorption of both small dyes and commercial dyes. It is shown that anionic surfactants at sub-micellar concentrations can inhibit polymer-dye interactions due to displacement of dye and/or relocation into micelle-like polymer–surfactant complexes. New insights have been obtained into the interactions of dyes with cotton and with polymers, surfactants or their mixtures, particularly into observed dye selectivities.  相似文献   

6.
A spectroscopic study has been made of the comparative effectiveness of nonionic, zwitterionic and cationic polymers in binding model dyes. Addition of polymer produces smaller changes in the UV–vis spectra than observed in micellar solutions. Upon binding to polymers, the measured pKA values of the model dyes decrease. The results of modelling and spectroscopic studies of the interaction between the model arylazonaphthol dyes are discussed in this paper. Addition of anionic surfactants, e.g. SDS, below their critical micelle concentrations disrupts polymer/dye binding, resulting in relocation of model dye to new sites formed from polymer/surfactant interactions. These sites are more apolar and produce spectra similar to those in corresponding micelles but with higher dye pKA values and binding affinities. For the previous paper in this series see page 140; for parts 1 and 2 see refs 1 and 2, respectively.  相似文献   

7.
In this study, the interaction of thionine, a cationic dye, with anionic [sodium dodecyl sulphate (SDS), lithium dodecyl sulphate (LiDS), and sodium dodecylbenzene sulphonate (SDBS)], nonionic (Tween 20 and Triton X‐100), and binary mixtures of anionic and nonionic surfactants was studied by conductometric and spectrophotometric measurements. The degree of ionisation, the counterion binding parameters, and the equilibrium constants in the premicellar region were obtained from conductivity data. Binding constants of thionine to anionic, nonionic, and mixtures of anionic and nonionic micelles were determined by spectrophotometric measurements. The binding tendency of thionine to anionic micelles followed the order SDBS > SDS > LiDS. The presence of nonionic surfactants increased significantly the binding affinity of thionine to anionic micelles, and the highest binding constant was calculated in the presence of Tween 20. The results obtained from conductometric studies correlated with those obtained from spectroscopic studies. Data concerning dye–surfactant interaction are important for a fundamental understanding of the performance of single and mixed surfactants and for their industrial application.  相似文献   

8.
Dye loss from unfixed dyed fabrics has been found to be insensitive to change in surfactant type or concentration. There was accompanying dye transfer to white fabric but this was reduced by Synperonic A7 in the case of fabrics dyed with CI Direct Green 26, due to solubilisation of the dye in nonionic micelles. The anionic surfactant, SDS, selectively displaced dye from fixed dyed fabrics, paralleling its behaviour with water soluble polymers. Similarly, dye loss was related to concentration of surfactant monomer, the effect increasing with SDS concentration up to its critical micelle concentration. Other anionic surfactants have been found to exhibit a similar trend, the effect increasing with their increasing surface activity. The commercial polymeric fixatives, Tinofix ECO and Indosol E50, were the most effective of those studied and the single-chain cationic surfactant, CTAB, was the least effective.  相似文献   

9.
The photophysics of the phenoxazin-3-one dyes resazurin and resorufin was studied in a micellar solution of cetyltrimethylammonium chloride and in reverse micelles of 1,4-bis(2-ethylhexyl)sulfosuccinate and benzylhexadecyldimethylammonium chloride. Absorption and fluorescence emission spectra, as well as fluorescence lifetimes and T–T transient absorption spectra were determined as a function of surfactant concentration. In the presence of direct micelles of cetyltrimethylammonium chloride, both dyes displayed red shifts in the absorption and fluorescence spectra together with a simultaneous fluorescence lifetime increase. The electrostatic attraction between the anionic dyes and the positive micellar interface favors the location of the dyes closer to the head groups of the surfactant molecules. In reverse micellar systems the spectral properties depended upon the charge of the surfactant and water content. In the case of 1,4-bis(2-ethylhexyl)sulfosuccinate, at low water content both dyes were incorporated into the interface; as the water content increased their spectral properties tended to those in pure water. In contrast, in the case of cationic surfactant, the dyes were located in the interfacial pseudophase as a result of electrostatic interactions.  相似文献   

10.
A spectrophotometric method has been used to study the interactions of some monoazo anionic dyes with a series of nonionic surfactants of different ethylene oxide chain length. The interaction between the dyes and the surfactants has been shown to be hydrophobic in nature with the extent of interaction increasing with increasing hydrophobicity of alky I side–chains on the dyes.  相似文献   

11.
As a class of novel surfactants, Gemini surfactants usually exhibit fairly excellent interfacial properties in aqueous solutions on account of the unique structure. They have significant application and development potential for industrial production. However, the mixing properties of Gemini surfactants with conventional surfactants are the key to their application. The equilibrium surface tension curves of anionic/nonionic surfactant mixtures based on the sulfonate Gemini surfactant (SGS-12) were measured using the Wilhelmy Plate method. The parameters of surface adsorption, the interaction parameters between anionic and nonionic surfactants, and the thermodynamic parameters of micelle formation were calculated from the corresponding equations. In addition, the dynamic surface tension (DST) curves of anionic/nonionic surfactant mixtures were examined through bubble profile analysis, and the diffusion performance parameters were acquired from empirical formulas. The solubilization of pyrene in micelle solutions was studied using UV–vis absorption spectroscopy. The results show that the interaction parameters of all anionic/nonionic surfactants are negative, indicating that there is a synergistic effect on reducing the surface tension. For the SGS-12/OP-10, SGS-12/Tween 80, SGS-12/AEO9, and SGS-12/APG0810 mixtures, the optimum mixing ratios are 6:4, 7:3, 7:3, and 8:2, respectively. The thermodynamic data of micelles show that the formation of mixed micelles for SGS-12/APG0810 mixtures is an enthalpy-driven process. The tendency of DST curves of the SGS-12/APG0810 mixture is similar to that of SGS-12. In comparison with single-surfactant solutions, the anionic/nonionic surfactant mixtures show stronger solubilization capacity toward pyrene.  相似文献   

12.
The complex-forming interaction between two direct dyes, CI Yellow 106 and CI Blue 78, and two nonionic surfactants, namely, polyoxyethylene nonyl phenyl ether (NP-12) and polyoxyethylene stearylamine (R-11), in aqueous solutions was studied. The estimation was made by measuring surface tension and critical micelle concentration (CMC) changes as a function of dye concentration. A decrease of NP-12 surface tension at low concentration and an increase of R-11 surface tension in the presence of both dyes were observed along with a significant decrease of NP-12 CMC values. A difference in the spectrophotometric absorbance of dye solutions in the presence of both surfactants, indicating a change in the environment of the dye chromophore, was also visible. These results confirm the formation of hydrophobic complexes of NP-12 and hydrophilic complexes of R-11 with both dyes.  相似文献   

13.
The apparent thermodynamic parameters of ionisation and the association constants of the two forms of Methyl Orange were evaluated in the presence of different surfactants (TX-100 as nonionic, CTAB as cationic and SDS as anionic). The enthalpy of ionisation of the dye in aqueous solution and at different surfactant concentrations is obtained from a novel thermochromic method and is found to decrease in aqueous medium in CTAB and TX-100 micelles and to increase in the case of SDS micelles. The apparent ionisation constant of the dye is evaluated spectrophotometrically for each surfactant concentration and type. The apparent Gibbs free energy, entropy of ionisation and association constants are also calculated. The results are discussed in light of the stabilisation of the two forms of the dye in the micellar core of the different surfactants and their effect on properties of the bulk solution is examined.  相似文献   

14.
To preserve the environment for civilization, we should remove the pollutants like toxic dyes by friendly and cost efficacious method. In this study, the effect of surfactants or mixed surfactants on physicochemical, optical and adsorption properties of ternary mixed oxide CeO2-ZrO2-Al2O3 (CZA) are investigated. The ternary mixed oxide CZA was prepared by surfactants or mixed surfactants assisted ultrasonic co-precipitation method. The physicochemical and optical properties are estimated by different techniques like XRD, TEM, EDX, FTIR, SBET and UV–Vis/DR. The CZAT and CZAC have hybrid shapes and high surface area. The adsorption properties of ternary mixed oxides adsorbents were characterized by sono-removing anionic dyes such as Congo red (CR) and Remazol red RB-133 (RR). The different factors like contact time, different dye concentrations and temperatures also studied. The kinetics and isotherms applications showed that, the adsorption process was followed pseudo second order kinetics and the Freundlich isotherm model. Also, the adsorption is spontaneous and endothermic process through the thermodynamic study. Finally, the results showed that the ternary mixed oxide nano-adsorbent (CeO2-ZrO2-Al2O3) is promising and functional materials for anionic dye sweep from wastewater.  相似文献   

15.
The acid-base equilibria of three anionic sulfonephthalein dyes, viz., bromothymol blue (BTB), thymol blue (TB), and cresol red (CR), were studied spectroscopically in aqueous media containing the water-soluble noninonic polymers polyvinyl alcohol (PVA) and polyethylene glycol (PEG) in the presence of an anionic surfactant, sodium dodecyl sulfate (SDS). A partition equilibrium method was used to determine the equilibrium constant of partition of the dyes between the micellar pseudo phase and aqueous phase in the presence of PVA and PEG. The critical aggregation concentrations (CAC) of the surfactants in buffered aqueous systems containing the neutral polymers were also determined. The CAC of the polymer-surfactant systems were found to be lower than the critical micelle concentration of such systems in the absence of polymer, in otherwise identical conditions. The pH-dependent association constants, K ass, of the sulfonephthalein dyes with the SDS-PVA system increased with the increase in molecular weight of the polymer. The interactions of the dyes with the buffered aqueous SDS-PVA and SDS-PEG systems were found to be endothermic and entropy oriented. In the polymer domain, the head group region of the micelles was more exposed at lower concentrations of the polymer, but under excess polymer concentration they were increasingly shielded, which impaired their electrostatic interaction with the dyes.  相似文献   

16.
《Dyes and Pigments》2013,96(3):502-511
To design adequate ink composition for textile printing, the relationship between the dye/additive interaction and ink performance is investigated. In the present study, the three acid dyes C. I. Acid Red 88, 13, and 27, a water-soluble polymer poly(vinylpyrrolidone) (PVP) and three surfactants, sodium dodecyl sulfate (SDS), octaethylene glycol monododecyl ether (OGDE), and Surfynol 465 (S465) were used and the dye/additive interaction was investigated by means of visible absorption measurements. The visible absorption spectra of aqueous dye solutions changed with the addition of the nonionic surfactants, but further addition of PVP had little effect on the spectra, indicating that the strong binding of the dye molecules with the nonionic surfactant micelles is maintained even in the presence of PVP. In contrast, in the case of SDS, the spectra changed with the addition of the surfactant as well as with further addition of PVP. This indicates that the behavior of the acid dyes in the three-species system depends on the dye structure, the surfactant structure, and the molecular weight of PVP. Furthermore, to estimate the ink performance, the physical properties of the ink, such as viscosity, surface tension, and ink droplet formation were determined. Ink solutions with favorable physicochemical properties and low molecular weight PVP showed good ink droplet formation. In the optimized ink composition (PVP-1/S465: 1.4/0.004 mol dm−3) most of the dye molecules are strongly bound to the PVP chain, but the binding is not significantly affected by the addition of S465.  相似文献   

17.
Laccase (benzenediol, oxidoreducase; Enzyme Commission Number) is a multi‐copper oxidase from biomass. Laccase enzyme recycling on molecular oxygen as an electron acceptor can be applied for the decolorisation of synthetic dyes. The decolorisation of 49 commercial reactive dyes using laccase was investigated. The effects of diverse structure surfactants on decolorisation are discussed. The absorption spectra of reactive dyes after a laccase biodegradable reaction were analysed. Reactive dyes based on anthraquinone and azo structures could be decolorised using the enzyme and their chemical structures broken. Reactive dyes based on an anthraquinone structure were easier to decolorise than those based on an azo structure. Surfactants could affect the decolorisation of dyes with an enzyme. The effect of nonionic surfactant on the decolorisation of anthraquinone dyes was the reverse. The cationic surfactant could improve the decolorisation rate of diazo dye. The effect of the anionic surfactant on dye decolorisation was small. Most commercial reactive dyes could be decolorised and biodegraded using a laccase enzyme under mild conditions. Laccase enzyme biotechnology has potential applications in the decolorisation of reactive dye wastewater.  相似文献   

18.
The ability of reactive dye molecules (CI Reactive Red 180 and CI Reactive Yellow 23) to undergo self-association and to associate with different surfactants has been examined spectrophotometrically. The stability constants KDS of the dye-surfactant complexes were calculated at dye:surfactant ratios varying from 1:0 to 1:10 and for different surfactant types (anionic, zwitterionic, nonionic and cationic). Dye uptake on viscose fibre observed for a dye:surfactant molar ratio of 1:0.5 was found to be related to KDS values.  相似文献   

19.
For improved surface properties, nonwoven fabrics of polypropylene and poly(ethylene terephthalate) were treated with several kinds of surfactants, including anionic, cationic, and nonionic types. The adsorption isotherms of the anionic, cationic, and nonionic surfactants on the nonwoven fabrics were different. The adsorption isotherm of the cationic surfactant (dodecyl dimethylbenzyl/ammonium chloride) exhibited a maximum. The adsorption isotherm of the anionic surfactant (sodium dodecylbenzene sulfonate) was in the shape of the fifth Brunauer adsorption isotherm, and that of the nonionic surfactant (alkylphenol/ethylene oxide condensate) was similar to the fourth Brunauer adsorption isotherm. The time of the adsorption equilibrium was constant for the same types of adsorbate and adsorbent, and it was not related to the initial concentration. The specific surface resistance of the nonwoven fabrics decreased substantially after the adsorption of ionic surfactants. The nonwoven fabrics with the surfactants were characterized with scanning electron microscopy and X‐ray photoelectron spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3210–3215, 2003  相似文献   

20.
The interactions between anionic dye (tartrazine) and cationic surfactants (dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide) have been studied by conductometric, spectrophotometric, and tensiometric techniques. The conductance and surface tension of dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide in pure water as well as in aqueous tartrazine when plotted with surfactant concentration gave values of the critical micelle concentration at different temperatures. As well as increasing the length of the carbon chain of surfactants, the presence of tartrazine reduces the critical micelle concentration. From specific conductivity data, the counterion dissociation constant, standard free energy, enthalpy, entropy of micellisation, surface excess concentration, surface tension at critical micelle concentration, minimum area per molecule, surface pressure at critical micelle concentration, and Gibbs energy of adsorption were evaluated. Spectroscopic studies reveal that the binding of dye to micelles brings a bathochromic shift in dye absorption spectra that indicates dye–surfactant interaction.  相似文献   

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