Effect of poly (sodium 4-styrenesulfonate) on the ionization constants of acid-base indicator dyes in aqueous solutions

Moskaeva, O. G.; Klochaniuk, Oleg R.; Marfunin, Mykyta O.; Mchedlov‐Petrossyan, Nikolay O.

doi:10.1016/j.colsurfa.2017.05.030

Cited by 7 publications

(16 citation statements)

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“…Such a coincidence is caused by the dependence of NR spectra on the concentration of NaPSS that by-turn depends on additives to water -NaPSS system. Thus, at the increase of P : D from 10 to 1500 λ max rises from 507 nm to 540 nm [28] in pure NaPSS solutions without salts. So, at some P : D values, which are different depending on the other compounds of solutions, λ max value can be equals 530 nm, but such a spectrum will not be the spectrum of NR in water.…”

Section: Dls Measurementsmentioning

confidence: 99%

“…Basing on our previous study [28], we consider both acidic and basic forms of NR as almost bound by the polyelectrolyte coils. Scheme 1.…”

Section: Methodsmentioning

confidence: 99%

“…Firstly, it should be noted that all app a pK values reported in this paper were obtained at polyelectrolyte : dye concentration ratio, P : D, equals 100. It allows avoiding polyelectrolyte-induced metachomatic effects [28,33,34]. The corresponding concentration of NaPSS was of about 0.003 M.…”

Section: Dls Measurementsmentioning

confidence: 99%

“…(3) and (4) may be applied to polyelectrolyte coils too. In our previous paper, the dependences of app a pK on log I for a set of indicator dyes were obtained in the presence of NaCl [28]. Indeed, these dependences are linear in the sufficient range of the ionic strengths.…”

Section: Dls Measurementsmentioning

confidence: 99%

“…As demonstrated in our previous work [28], the determination of the polyions size via the DLS method is difficult because of the non-sphericity of particles, which results in the apparent polydispersity. Nevertheless, the DLS method is widely used for determination of diffusion coefficients of NaPSS in water [29][30][31][32].…”

Section: Dls Measurementsmentioning

confidence: 99%

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Influence of the Ionic and Non-Ionic Additives on the Acid Strength of Neutral Red in the Aqueous Solutions of Poly (Sodium 4-Styrenesulfonate)

Moskaeva¹

2017

Chemical

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Polyions of poly (sodium 4-styrenesulfonate) in aqueous solution may be considered as colloidal pseudophase. Analogously to micelles, some species can be bind by the charged polyelectrolyte coils. In this paper, the colored acid-base indicator dyes were used for studying the penetration of ionic and non-ionic solution components in polyelectrolyte coils. Such analysis relies on alteration of the acid strength of dyes. The aim of this work was to determine the dependences of the apparent ionization constants of neutral red, app a K , on the ionic strength of solution, I, in different mixed systems containing poly (sodium 4-styrenesulfonate) (NaPSS) and tetraethylammonium bromide, tetra-n-butylammonium iodide, or 1-butanol with NaCl. Neutral red is fixed in the polyelectrolyte coils due to electrostatic and hydrophobic interactions. The polyelectrolyte : dye concentration ratio, P : D, an important parameter for spectophotometrical measurements, equals 100. It was found that tetra-n-alkylammonium salts display a stronger influence on the acid strength of neutral red as compared with that of NaCl. For instance, in the case of tetraethylammonium bromide app a pK = 7.90 ± 0.07 at I = 0.02 M whereas app a pK = 8.45 ± 0.04 with NaCl at the same ionic strength. It can be explained by specifical adsorption tetra-n-alkylammonium cations on polyions 'surface'. Introduction of 1-butanol significantly increases the acid strength of neutral red too, however its influence isn't monotonic with change of ionic strength. The dependences of app a pK on log I were discussed in terms of regularities which are well-known for surfactant micellar systems. All mentioned systems were also examined by dynamic light scattering measurements using Zetasizer Nano ZS Malvern Instruments apparatus. As it turned out, when the ionic strength is 3×10 -3 М or more the size (by number) of polyions in the presence of NaCl is of about 7 nm. Introduction of the additives results in somewhat higher size: in the case of 1-butanol the size of NaPSS is 10 nm.

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Section: Dls Measurementsmentioning

confidence: 99%

“…Basing on our previous study [28], we consider both acidic and basic forms of NR as almost bound by the polyelectrolyte coils. Scheme 1.…”

Section: Methodsmentioning

confidence: 99%