Jalel Mhalla

University of Monastir | UTM · Department of Chemistry

Abstract: All current theories concerning the conductivity of polyelectrolytes ignore the dielectric friction effect undergone by the polyion chains according to their conformation. Indeed, Manning’s theory is limited to the case of stretched chains and only takes into account hydrodynamic, electrophoretic and ionic frictions; while scaling approac...

In this study, we investigate the aggregation of an ionic liquid (IL), 1-allyl-3-methylimidazolium bromide ([AMIM][Br]) in aqueous solution containing variable amounts of poly(diallyldimethylammonium) chloride (PDADMAc), using conductivity, density, and viscosity techniques in combination with the molecular dynamics simulation approach.

In this study, we investigate the aggregation of an ionic liquid (IL), 1-allyl-3-methylimidazolium bromide ([AMIM][Br]) in aqueous solution containing variable amounts of poly(diallyldimethylammonium) chloride (PDADMAc), using conductivity, density, and viscosity techniques in combination with the molecular dynamics simulation approach. The critica...

In this paper, we propose a new approach in order to interpret the dependency of the conductibility of carboxymethylated cellulosic polyelectrolytes XCMC1, XCMC2, XCMC3 in water at 25°C, with their alkali counterions (X ≡ Li⁺, Na⁺ and K⁺) or ammonium counterions (X ≡ Et4N⁺ and Bu4N⁺). The 750 ring-blocks of each CMCi chain are randomly substituted...

Translational dielectric friction effect on polyions is ignored by the literature. However, its contribution to the polyion conductibility is very sensitive to the configuration of the polyion chain, so that transition from coiled configurations to completely stretched configuration gives generally rise to a gap of the dielectric friction coefficie...

Conductivity measurements in water and at 25 °C show that the variation of the equivalent conductivity ΛPX with the counter ion concentration CX of some PDDPX polyelectrolytes, poly(1,1-dimethyl-3,5-dimethylene piperidinium, X), for X ≡ Br⁻, Cl⁻, \({\text{NO}}_{3}^{ - }\) and F⁻, is characterized by an inversion in Kohlraush’s law (i.e., \(\forall\...

In this contribution, we propose a new simple and fast computing approach to model liquid water and water-1,4 dioxane mixture, which is intermediate between molecular dynamics calculation and lattice fluid H-bonding theory in which water molecules are arranged according to a fluctuating hexagonal Ih network. It generalizes the interstitial mixture...

In this paper we have generalized on the basis of the superposition principle, the Debye-Hückel model in the case of a spatial distribution of “n” fixed ions surrounded by an ionic atmosphere. According to this approach, the mean electrostatic potential at a position M is written as a sum of individual screened Coulomb potentials: ∑ni = 1(Zie/ε)Aie...

The main object of this paper is to give a new interpretation of the dependence of the conductibility of a polyion with the nature of its counterions. For this, we analyzed in detail while comparing several models, the various physical factors influencing the mobility of a polyion (ionic condensation, hydrodynamic and electrophoretic frictions, ion...

In this paper, we propose a new approach in order to interpret the variation of the conductibility of the PSS polyion with the nature and the concentration of the alkaline counter-ions Li+, Na+ and K+, and the hydrophobic cations Et4N+ and Bu4N+. This approach is based on a recent model in which the stretched polyion is represented by a chain of su...

We have proved in details that the dielectric friction remains the principal frictional effect for a stretched polyion modeled as a chain of charged spheres, whereas, in the case of Manning's model (infinite thread with a continuous distribution of charge), this friction effect is nonexistent. According to this chain model, it is therefore possible...

We present a general description of conductivity behavior of highly charged strong polyelectrolytes in dilute aqueous solutions taking into account the translational dielectric friction on the moving polyions modeled as chains of charged spheres successively bounded and surrounded by solvent molecules. A general formal limiting expression of the eq...

Above the cmc, aqueous solution of sodium dodecyl sulfate SDS is an ionic mixture constituted of micelles of apparent charge number Zap, free counterions Na+ and free monomers SD-. The degree of micellization and the degree of condensation of Na+ on the micelles are calculated according to the mass-action model and by the generalization of the Fuos...

In this study, we develop new analytical and numerical speciation calculations corresponding to all kinds of combinations of complexation constants and hydrolysis constants given by more or less reliable literature data, and associated to fifteen probable uranyl-citrate species: M p L n , (with: M  (UO 2) 2+ , L  (HCit) 3-and p = 1, 2; n = 1, 2,...

RESUME: Dans ce travail nous montrons d'après la comparaison entre les conductibilités expérimentales et théoriques de l'héparine de sodium dans les solutions aqueuses diluées et en adoptant le modèle ellipsoïdal que, pour la longue chaîne (héparine RB21055, L S = 160 A°, Z S =-55), la transition entre la configuration étirée et celle enroulée se p...

We present an accurate generalization of the Zwanzig's approach in order to calculate the translational dielectric friction ξD and the effective mobility ueff of an ellipsoidal polyion of ZSe charge, R minor axis and (γ = L/2R) eccentricity. ξD = (2/3)τ(ε0 − ε∞)ε0− 2(αcZSe)2(Rapp)− 3, τ is the dielectric relaxation time, ε0 and ε∞ are the static an...

The capillary electrophoresis method has been applied to the speciation study of uranium(VI) at room temperature, in 0.02M citrate buffer solutions, at pH values between 2.5 and 5.5 and at citrate/U ratios between 20 and 40. No negatively charged species have been pointed out at pH values lower than 3. For a pH value higher than 5, the electrophero...

In a previous work, we have verified that sodium chondroitin sulfate in water at 25 °C, presents a correct Manning behavior (αM=0.81). In contrast, we expect that the rate of condensation α is shifted from its Manning value (αM=0.36) in water–dioxane (50% wt) mixture at 25 °C, (α≅0.47). In order to verify this dioxane effect, we have compared exper...

In this work, we generalized the (Bjerrum–Debye–Fuoss–MSA) double layer model to an ellipsoidal polyion (chondroitin sulfate) of (∣Zs∣e) structural charge, Ls structural length, R minor axe and (R² + L²/4)1/2 major axe. With L ⩽ Ls. Na⁺ counter ions are distributed on the contact (or condensed) layer and on the Debye layer (ionic atmosphere). Both...

Calorimetric measurements of heats of dilution: QDC→0=−nsφL,sexp, of aqueous solutions of NaBPh4 are determined at 25 °C in the concentration range: . Results show a large positive deviation between experimental φL,sexp and φL,sMSA calculated from exact MSA theory. This deviation can be interpreted as an indirect solute–solute attraction due to the...

ABSTRACT : In this work we experimentally studied the variation of partial molal volumes and partial molal enthalpies of mixture of water and dioxane with the molar fraction XD of dioxane at T = 298°K and P = 1atm. We also studied the liquid-vapor diagram in order to determine the variation of activity coefficients of water and dioxane with XD. It...

Because of the incompatibility of the Manning model with the principle of Ostwald dilution and because it does not take into account the dielectric friction effect, we present in this work another simple but realistic model in order to establish limiting laws of salt-free polyelectrolyte solutions in conformity with the principles of equilibrium an...

In this work, we experimentally studied the variation of partial molal volumes and relatives partial molal enthalpies of NaB(Ph)4, water and dioxane with the weight-fraction P(D) of dioxane (0 ≤ P(D) ≤ 20 %) and with the molality m of the salt (0 ≤ m ≤ 0.4) at 25°C and P = 1atm. We also partly achieved the same work for some binary and ternary syst...

In this work, we experimentally studied the variation of partial molal volumes and relatives partial molal enthalpies of NaB(Ph)$_4$, water and dioxane with the weight- fraction $P_D$ of dioxane (0 = $P_D = 20$%) and with the molality m of the salt (0 = m = 0.4) at 25 $^{\circ}$C and P = 1atm. We also partly achieved the same work for some binary a...

A new type of HNC calculation is proposed in which the variation of the solvation energies with salt and solvent concentration is taken into account. This is done by means of a self-consistent calculation of the distance dependent permittivity function around a central ion. The theory yields ion-ion as well as ion-solvent correlation functions and...

The conductivities of Am3+(aq) and Cf3+(aq) were determined from 0.001 equimolar AmCl3-HCl and CfCl3-HCl aqueous solutions. The solutions were prepared from milligram—scale samples of pure 243Am(OH)3 and hydrated 249CfCl3. Concentrations of Am3+ and Cf3+ in the solutions were determined by a counting. Two conductivity runs were carried out with ali...

The limiting conductivity of Dy3+(aq) has been determined for the first time by linear extrapolation of conductivity measured in dilute aqueous solutions of (DyCl3 + HCI) at 25-degrees-C as lambda-degrees(Dy3+ , aq) = (62.9 +/- 0.7) S-cm2-eq-1. A second set of conductivity measurements in dilute aqueous solutions of DyCl3 has given evidence of very...

The study of the variation of the self-diffusion D+ of (Cs) ion in the isobutyric acid-water critical mixture (Xc = 0.38 in acid), with temperatures T shows that D+ presents no anomaly in the vicinity of the critical temperature (Tc = 300 K). However Ln D+ is linear with 1/T only for T > 306.65 K.

In analogy to Feynman’s approach we define the propagator P(r0, t0; r, t) = a.Exp( -S/b) as the probability density for a brownian particle at position r0 to follow any path α up to position r. From the principles of : finite precision, non-elementarity, and noninstantaneousness we introduce the concepts of effective mass m, and free action S = - m...

Dans le present travail nous etudions la variation du coefficient d'autodiffusion D de l'ion Cs + dans le melange «eau-acide isobutyrique» en fonction de la composition massique de l'acide, et en fonction de l'ecart a la temperature critique (T-Tc). Pour les regions riches en eau et en acide isobutyrique, cette variation peut etre interpretee en te...

The use of radioactive isotopes of ions, of **1**4C labeled molecules of solvents, and of tritiated water, makes it possible to follow the migration of all individual components in a mixed electrolyte solution. Even if these results could be qualitatively interpreted in terms of ion-ion and ion-solvent interactions, the best formalism to represent...

The self diffusion coefficients of the 152Eu3+ ion aqueous nitrate solution and the 241Am3+ ion in neodymium perchlorate solution are determined by the open end capillary method (OCM). The aim of this work is as follows: Verification of the Onsager limit law concerning the relative variation of the self diffusion coefficient with the ionic strength...

To get basic information on the complete actinide series radiochemical measurements are necessary. Since the structure of the aqueous trivalent ions is not known, we undertook a study of transport properties. These properties, like limit diffusion coefficient, are related to the size of the hydrated ion and therefore its variations along the 5f ser...

Conductance measurements by Spedding et al. [1] were obtained with halide solutions at pH ≅ 6.4 without taking into account hydrolysis of M3+ ions: 3×− + Ln3+ + H2OLnOH2+ + H+ + 3 X−.Since the aqueous solution should contain several ions (and small quantities of carbonate) we developed [2] a generalized Robinson-Stokes equation which is applicable...

In this work, we confirm the fact that in the case of rare earth ions, the hydration process has an electrostatic character. We calculate with our theoretical model the local electrostatic field, which is equivalent to an electrostatic pressure. The local density around an Ln3+ ion is obtained from the state equation of pure water at high pressure....

We have generalized the Robinson-Stokes conductivity equation to the case of the mixed ions solution by the use of the Onsager-Kim equation. We have used this new equation to fit the conductivity data of LaCl3 in aqueous solution taking into account the hydrolysis phenomenon. We have the obtained the values of the thermodynamic hydrolysis constant...

We have measured Washburn number of NaBPh4 by emf method in 20% wf% dioxan-water in order to obtain individual preferential solvation number of BPh4. Results show that junction potentiel is about 41 mV, and that BPh4- anion carries about 5 molecules of dioxan at high dilution in NaBPh4.

In a complete discussion of transport properties in terms of the formalism of irreversible thermodynamics, we have described the diffusion of ions in non-homogeneous solvent mixture; the ion–solvent coupling terms lij play an important role as a result of the preferential solvation phenomenon. Moreover, it is concluded that the determination of the...

Transient concentration gradients, for initially homogeneous species, in electrolyte solutions, are experimentally observed and theoretically analyzed. These heterogeneous regions are mainly produced by transient diffusion potentials induced by multicomponent diffusion in electrolyte solutions. Similar effects can be produced by gradients of activi...

In this study, we derive the general solution of the diffusion equation for multicomponent systems, even with non-constant diffusion coefficients, in the case of limiting conditions corresponding to the open-end capillary method. For this purpose, it was necessary to obtain the complete expression of the diffusion coefficients Dij by a detailed ana...

The coupling between tracer and mutual diffusion in electrolyte solutions is experimentally realized and theoretically analyzed. The essential coupling terms are the electrical diffusion potential gradient, and the activity coefficient gradient, arising from the individual excess chemical potential of each ion.