Effect of sodium dodecylsulfate on equilibria of copper complexation

Effect of sodium dodecylsulfate (SDS) on the complexation of copper(II) with iminodiacetic acid (IDA) and ethylene diamine (En) is investigated using pH-metric titration and NMR relaxation together with computer treatment of the results obtained. In the ternary system of Cu(II)-IDA-SDS the competition for Cu2+ ions between the complexing agent and surface active agent (SDS) was found, whereas in the presence of En the ternary associates with monomeric surfactant anions were observed

The formation of complexes of iron(III) with salicylic acid in the presence of cationic and nonionic surfactants

The effect of dodecylpyridinium bromide (DPB) and ethoxylated sorbitan palmitate (Tween 40) on the formation equilibrium of the complex of iron(III) with salicylic acid (H2L) in aqueous solutions was studied at 298 K by the spectrophotometry and NMR-relaxation techniques. It was found that an apparent decrease in the stability of [FeL]+ complex was associated with the solubilization of the ligand in its molecular form within simple and mixed micelles. Based on a mathematical description of the effect of surfactants within the frame-work of the model proposed, the binding constants of salicylic acid with micelles of cationic (logK = 2.0 ± 0.1) and anionic (logK = 2.4 ± 0.1) surfactants were determined. It was concluded that salicylic acid is solubilized in the boundary layer between the hydrocarbon core of micelles and head groups of surfactants

Binding of protonated forms of o-phenylenediamine and some other cations with the micelles of sodium dodecyl sulfate according to data from pH measurements

Binding of the protonated forms of o-phenylenediamine (oPn) with micelles in aqueous solutions of sodium dodecyl sulfate (SDS) was studied by potentiometric titration. The dependences of the apparent pro-tonization constant (log K1 app) for oPn on the content of surfactants and some ions (Na+, NH4 +, and Me4N+) were revealed. The micellar binding constants for the cations studied were obtained for the first time by computer simulation. The approach proposed is applicable for any other ions and surfactants. © 1996 MAK Haya/Interperiodica Publishing

The state of a paramagnetic probe in solutions containing mixed micelles of anionic and nonionic surfactants from data on nuclear magnetic relaxation

The state of Mn2+ ions in solutions of binary mixtures of anionic (sodium decyl, dodecyl, and tetradecyl sulfates) and nonionic (Tween 40 and Triton X-100) surfactants at 298 K was studied by the nuclear magnetic relaxation method. It was found that an increased spin-lattice relaxation rate of water protons is caused by formation of mixed surfactant aggregates. The method proposed previously for describing the micellization of anionic surfactants was extended to mixed aggregates containing a nonionic surfactant. A mathematical simulation revealed the formation of mixed micelles of alkyl sulfates and nonionic surfactants of two types: with 1 : 1 and 1 : 2 ratios. In the latter case, the mixed micelles are incapable of binding counterions, which is probably caused by the blocking of head sulfate groups by the ethylene oxide chains of the nonionic surfactants. The adequacy of the used approach was supported by the method of competing reactions between iminodiacetic acid and mixed micelles of sodium dodecyl sulfate and Tween 40 for binding with Mn2+ cations. © 1999 MAHK "Hayka/Interperiodica"

The formation of complexes of iron(III) with salicylic acid in the presence of cationic and nonionic surfactants

The effect of dodecylpyridinium bromide (DPB) and ethoxylated sorbitan palmitate (Tween 40) on the formation equilibrium of the complex of iron(III) with salicylic acid (H2L) in aqueous solutions was studied at 298 K by the spectrophotometry and NMR-relaxation techniques. It was found that an apparent decrease in the stability of [FeL]+ complex was associated with the solubilization of the ligand in its molecular form within simple and mixed micelles. Based on a mathematical description of the effect of surfactants within the frame-work of the model proposed, the binding constants of salicylic acid with micelles of cationic (logK = 2.0 ± 0.1) and anionic (logK = 2.4 ± 0.1) surfactants were determined. It was concluded that salicylic acid is solubilized in the boundary layer between the hydrocarbon core of micelles and head groups of surfactants. © 1998 MAK Haya/Interperiodica Publishing

Specific features of the complexation of copper(II), manganese(II), and gadolinium(III) with salicylic, benzoic, and sulfosalicylic acids in aqueous solutions of nonionic surfactant

The methods of potentiometric titration and NMR relaxation were used to study the influence of the nonionic surfactant (NS), namely Triton X-100 (TX), on the acid-base and complexing properties of salicylic (H2L), benzoic (HR), and sulfosalicylic (H3X) acids. The influence of NS added on the titration curves of the examined acids was analyzed and it was established that salicylic and benzoic acids are bound by micelles to form species {H2L(TX)} and {HR(TX)} with logK equal to 2.12±0.03 and 1.57±0.03, respectively. The acidic properties of H3X are virtually the same in water and in the NS solutions. A significant (more than two-fold) increase in the proton relaxation rate is observed in the solutions of the mixtures of salicylic acid and TX in the presence of Cu2+, Mn2+, or Gd3+ ions. This effect was explained by the formation of ternary cation-ligand-surfactant species. For Cu(II) and Mn(II), compounds {M(HL)2(TX)2} with log K equal to 0.90±0.04 and 1.05±0.04, respectively, were detected. Complexes of composition {Gd(HL)3(TX)2} with logK=0.22±0.05 were discovered for Gd(III). The ternary species of benzoic acid are formed only in the presence of gadolinium: {GdR(TX)} with logK=-2.17±0.04. Sulfosalicylic acid does not form such mixed NS-containing compounds with the cations examined

Specific features of the complexation of copper(II), manganese(II), and gadolinium(III) with salicylic, benzoic, and sulfosalicylic acids in aqueous solutions of nonionic surfactant

The methods of potentiometric titration and NMR relaxation were used to study the influence of the nonionic surfactant (NS), namely Triton X-100 (TX), on the acid-base and complexing properties of salicylic (H2L), benzoic (HR), and sulfosalicylic (H3X) acids. The influence of NS added on the titration curves of the examined acids was analyzed and it was established that salicylic and benzoic acids are bound by micelles to form species (H2L(TX)} and (HR(TX)} with logK equal to 2.12 ± 0.03 and 1.57 ± 0.03, respectively. The acidic properties of H3X are virtually the same in water and in the NS solutions. A significant (more than two-fold) increase in the proton relaxation rate is observed in the solutions of the mixtures of salicylic acid and TX in the presence of Cu2+, Mn2+, or Gd3+ ions. This effect was explained by the formation of ternary cation-ligand-surfactant species. For Cu(II) and Mn(II), compounds {M(HL)2(TX)2} with logK equal to 0.90 ± 0.04 and 1.05 ± 0.04, respectively, were detected. Complexes of composition {Gd(HL)3(TX)2} with logK = 0.22 ± 0.05 were discovered for Gd(III). The ternary species of benzoic acid are formed only in the presence of gadolinium: (GdR(TX)} with logAT=-2.17 ± 0.04. Sulfosalicylic acid does not form such mixed NS-containing compounds with the cations examined. © 1998 MAK Haya/Interperiodica Publishing

Complexation in surfactant solutions: III. complexation of Ni(II), Cu(II), Gd(III), and Fe(III) in mixed solutions of anionic and nonionic surfactants

Complexation of Ni(II), Cu(II), Gd(III), and Fe(III) with chelating agents [iminodiacetic (H2IDA) and nitrilotriacetic acids (H3NTA)] and salicylic acid (H2Sal) in mixed solutions of anionic [sodium dodecyl (SDS) and tetradecyl sulfates (STS)] and nonionic surfactants [polyoxyethylene sorbitans Tween (Tw-20, Tw-40, Tw-60, and Tw-80) and Triton X100 (TX) polyoxyethylated adduct of octylphenol) is studied by the nuclear magnetic relaxation and spectrophotometry methods. Association of Cu2+, Ni2+, Gd3+, Fe3+, Na+, and H+ with mixed micelles is treated by computer simulation. It is demonstrated that chelating agents compete with mixed aggregates of surfactants in fixing multicharged metal ions. Salicylic acid forms mixed compounds with Fe(III), containing an alkyl sulfate and an oxyethylated adduct

Complexation in Surfactant Solutions: II. Complexation of Cu(II) and Fe(III) Salicylates in Sodium Alkyl Sulfate Solutions

The effect of sodium dodecyl sulfate and sodium tetradecyl sulfate on the composition and stability of Cu(II) and Fe(III) complexes with salicylic acid was studied by the NMR relaxation and pH-metric titration methods. For copper(II), it was found that micelles formed by the surfactants competetive with the complex for association with the cation without formation of mixed species. For Fe(III), the schemes of formation of metal-ligand-surfactant compounds were elucidated and the corresponding constants were evaluated by computer simulation. It was found that for two selected surfactants, the composition and stability of mixed species are the same

Association of dodecylsulfate ions with ethylenediamine dihydrochloride

The effect of sodium dodecylsulfate (SDS) on the acid-base properties of ethylenediamine (En) is studied at 308 K using potentiometric titration. Reduction of the acid function of EnH2 2+ cation (ΔpKmax ≃ 1.6) is found at the surfactant concentration Cs below the critical micellization concentration (CMC), while SDS micelles do not produce any additional effect. The effect found is accounted for by the formation of strong associates between the EnH2 2+ and DS-ions (logKas ≃ 6.5). © 1996 MANK Hayka/Interperiodica Publishing