Effects of hydrating water molecules on the aggregation behavior of azo dyes in aqueous solutions

Hamada, Kunihiro; Nonogaki, Haruhiko; Fukushima, Yoshihiro; Munkhbat, Baljir; Mitsuishi, Masaru

doi:10.1016/0143-7208(91)85003-q

Cited by 64 publications

(16 citation statements)

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“…In order to determine the mode of aggregation, the aggregation constant in equilibrium and the aggregation number, the aggregation of dyes has been in-vestigated by a variety of methods, viz. polarography, 10,11 conductometry 12 UV-Vis spectrophotometry, [13][14][15][16][17][18][19] NMR, [20][21][22] light scattering 23 and electrolytic effect 24 measurements.…”

Section: Introductionmentioning

confidence: 99%

Association Equilibrium of Methylene Blue by Spectral Titration and Chemometrics Analysis: A Thermodynamic Study

Ghasemi

Miladi

2009

J Chinese Chemical Soc

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The monomer-dimer equilibrium of methylene blue (MB, Scheme I) has been investigated by means of UV-Visible spectroscopy in aqueous solutions. The self aggregation of MB in water has been investigated by recording absorption spectra in the wavelength range of 450-750 nm, and in different ionic strengths using concentrated KCl solutions in the temperature range of 20-90°C. Chemometrics analysis of the spectral data gave a dimerization constant, individual spectra of the monomer and dimer forms of the dye molecule. The quantitative analysis of the data of the undefined mixture was carried out by simultaneous resolution of the overlapping spectral bands in the whole set of absorption spectra. The dimerization constants of MB determined by mathematical deconvolution of the thermometric spectral titration data show dependency on temperature variations. The concentration range of MB was 6.00´10-5 -3.001 0 -4 M. Utilizing the van't Hoff relation, which describes the dependence of the equilibrium constant on temperature, the thermodynamics parameters DH°and DS°of the aggregation process were determined. The compensation effect was verified by the thermodynamics results of the dimerization process of the dye.

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Section: Introductionmentioning

confidence: 99%

Association Equilibrium of Methylene Blue by Spectral Titration and Chemometrics Analysis: A Thermodynamic Study

Ghasemi

Miladi

2009

J Chinese Chemical Soc

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“…So it is very difficult to calculate the thermodynamic parameters, as described in the previous paper [33,36]. The thermodynamic behavior for R-1 is less enthalpic and more entropic than that for R-2.…”

Section: Aggregation Of Dyes In Aqueous Solutionsmentioning

confidence: 99%

“…The aggregation number, n, of the dyes was determined by the procedure described in a previous paper [33], resulting in n = 2 for all the dyes. Therefore, for all the dye solutions, the following equilibrium between the dye monomer, D, and the dye dimer, D 2 , can be assumed:…”

Section: Aggregation Of Dyes In Aqueous Solutionsmentioning

confidence: 99%

Dye aggregation and interaction of dyes with a water‐soluble polymer in ink‐jet ink for textiles

Park

Hirata

Hamada

2012

Coloration Technology

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Detailed understanding of the interaction between dyes and additives and the aggregation behavior of the dye molecules in aqueous solutions is required to develop inkjet ink for textiles. In the present study, the aggregation behavior of three acid dyes (C. I. Acid Red 88, 13, and 27) containing different number of sulfonate groups in aqueous solutions was investigated by means of visible absorption spectroscopy. As a result, the higher the solubility of the dyes in water (the larger the number of sulfonate groups in the dyes), the lower are the aggregation constants of the dyes. For all the dyes, the aggregation constants decreased with increasing temperature, indicating the exothermic process of the dye aggregation. The thermodynamic process for C. I. AcidRed 88 having one sulfonate group is less enthalpic and more entropic than that for C. I. Acid Red 13 containing two sulfonate groups. C. I. Acid Red 27 including three sulfonate groups hardly form any aggregates. To elucidate the effects of the polymer additive, the binding constants of the dyes with the water-soluble polymer, poly(vinylpyrrolidone) (PVP), and the aggregation constants of the dyes in aqueous  Corresponding author. Tel.: +81 268 21 5411; fax: +81 268 21 5391 E-mail address: khamada@shinshu-u.ac.jp (K. Hamada) 2 polymer solutions were also estimated. The binding constants were also influenced by the number of the sulfonate groups in the acid dyes: the larger number of sulfonate groups diminished the binding constants. The aggregation constants in the presence of PVP were smaller than those in its absence at every temperature for all the dyes. This suggests that PVP has disaggregation effects. Furthermore, PVP makes the aggregation process less enthalpic with a greater entropic change. Thus, the aggregation process of the dyes in the polymer solutions is thermodynamically different from that in water, reflecting the interactions between the dyes and the polymer.

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“…Boer's law analysis of individual dyes. changes in the dye solubility state due to aggregation and other dye-dye interactions are not as easily characterized [ 5 ] . Therefore, it is insufficient to state that for some wavelengths, the effects of increasing dye or salt concentration will decrease the absorptivity of the dye in solution; changes in absorptivity may be negative or positive depending on which wavelength is being observed.…”

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confidence: 99%

Using Neural Networks to Predict Dye Concentrations in Multiple-Dye Mixtures

Jasper

Kovacs

Berkstresser

1993

Textile Research Journal

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A neural network is used to predict the concentrations of three dyes from their spectrophotometric absorbances. With this technique, the network achieves a peak of 5% and an average of 2.6% error over a range of dye concentrations of 0 to 0.15 g/l.The neural network is evaluated against two other models based on Beer's law, and performs significantly better over the entire range of concentrations measured. ' Assistant Professor, College of Textiles. 2 Graduate Student, IMSEI. 3 Graduate Student, College of Textiles.The Dye Applications Research Group ( DARG ) at North Carolina State University is currently investigating approaches to an optimized control system for dyeing fabrics. In order to achieve this goal, the system ( dyebath ) must be closely and accurately monitored to feed information in real-time to the controller [ 1 ] . This paper discusses the use of a neural network to predict concentrations in a multiple dye mixture from spectrophotometric absorbance measurements. ' Discussion of Beer's Law A plot of absorbance versus concentration, often called a &dquo;Beer's law plot,&dquo; is given as where A is the absorbance at a specified wavelength (normally ~m~ ) , a is the specific absorbance or extinction coefficient, I is the path length, and c is the concentration of the dye. This linear behavior is shown graphically in Figure 1 for the three dyes used in the experiment. It is important to remember that the absorbance value A assigned to each dye from this plot is given at one wavelength for each dye-425 nm for yellow, 520 nm for red, and 595 nm for blue dye-the Àmax values for these three dyes. DEVIATIONS FROM BEER'S LAW As the mean particle size of a single absorbing species increases ( usually as the result of increasing the dye or inorganic salt concentration), the solution absorbs less light, and the absorptivity usually decreases at the . wavelength of maximum absorbance [6]. However, fIGURE 1. Boer's law analysis of individual dyes. changes in the dye solubility state due to aggregation and other dye-dye interactions are not as easily characterized [ 5 ] . Therefore, it is insufficient to state that for some wavelengths, the effects of increasing dye or salt concentration will decrease the absorptivity of the dye in solution; changes in absorptivity may be negative or positive depending on which wavelength is being observed. The temperature of the dye solution can also affect the absorptivity of any given dye [ 6 ] .Previous studies have not accounted for heterogeneous dye interactions or changes due to different dye particle sizes increasing at different rates with respect to dye concentration or salt concentration. Classical at Kungl Tekniska Hogskolan / Royal Institute of Technology on August 21, 2015 trj.sagepub.com Downloaded from 546 analytical models predict that the spectrum for a mixture of absorbing species in a solution is equal to the sum of the individual spectra [ 2 ] . ' For mixtures of dyes, however, this assumption cannot be made; the spectra of mixtures of dyes in solutio...

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Effects of hydrating water molecules on the aggregation behavior of azo dyes in aqueous solutions

Cited by 64 publications

References 12 publications

Association Equilibrium of Methylene Blue by Spectral Titration and Chemometrics Analysis: A Thermodynamic Study

Association Equilibrium of Methylene Blue by Spectral Titration and Chemometrics Analysis: A Thermodynamic Study

Dye aggregation and interaction of dyes with a water‐soluble polymer in ink‐jet ink for textiles

Using Neural Networks to Predict Dye Concentrations in Multiple-Dye Mixtures

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