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Electromotive force (emf) of the chemical cell without liquid-junction K-ISE | RbCl/CsCl ( m(E)) | ISE-Cl and K-ISE | RbCl/CsCl (m(E)), amide (m(N)) | ISE-Cl, have been measured at 298.15 K, where m(E)=(0.005 to 0.5) mol kg(-1) and m(N)= (0.05 to 3.0) mol kg(-1). The activity coefficients of RbCl/CsCl in amide (acetamide, propanamide, and n-butanamide) + water mixture can be obtained from these electromotive force data and in the mean time the Gibbs free energy interaction parameters of RbCl/CsCl + amide pair in water, g(EN), as well as the salt constant, k(S), can be evaluated. The results show that both g(EN)>0, k(S)>0 at 298.15 K, and all the activity coefficients of electrolyte in amide + water mixture increase with increasing the m(N), but it is a little complicated for the dependence of activity coefficients on m(E). These thermodynamic parameters were discussed in terms of a model of the structural interaction and electrostatic interaction and the dependence of them on the number of carbon atoms in amide as well as the radius of metal ions were interpreted by the group additivity principle.

Metsulfuron methyl is typical sulfonylurea herbicides. The degradation of metsulfuron-methyl has aroused research interests because it was mobile in natural media, and raising environmental concerns about contamination of metsulfuron-methyl to surface water. However, conventional methods cannot remove these herbicides from water efficiently. This work proposed a rapid and efficient enzymatic degradation of metsulfuron-methyl by chloroperoxidase (CPO). The effect of reaction conditions, including pH, concentration of oxidant and enzyme, and degradation time on the degradation efficiency (η) were studied and accordingly optimized. The optimum η of 93.2% for 16.7 μmol·L−1 metsulfuron-methyl was achieved after 10 min at 25 °C and weakly acidic pH. The required CPO is only 0.06 μmol·L−1. The degraded products of metsulfuron-methyl were identified by HPLC-MS. The results indicated that metsulfuron-methyl molecule was decomposed, and five smaller molecular fragments were detected. Moreover, it was found that if this enzymatic degradation was combined with following activated sludge treatment, then, this bio-cascade treatment was more effective in removal of metsulfuron-methyl in wastewater than by activated sludge alone (which was used in most municipal sewage plant). The COD removal increased from 12.09% to 74.27%. Ecotoxicity tests of 72 h EC50 for degraded solution using a green alga, Chlorella pyrenoidosa, as eco-indicator demonstrated the enzymatic degraded products had lower eco-toxicity than metsulfuron-methyl itself. Application of this bio-cascade treatment to real water sample and artificial wastewater containing metsulfuron-methyl was effectively. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of (RbF + RbCl + H 2 O) and (CsF + CsCl + H 2 O) systems were determined by the potentiometric method for different ionic strength fractions y B of RbCl/CsCl at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental values. The Pitzer mixing parameters and the Harned coefficients were evaluated. In addition, the mean ionic activity coefficients of RbF/CsF and RbCl/CsCl, the osmotic coefficients, and the excess Gibbs energies of the systems studied were calculated. [ABSTRACT FROM AUTHOR]

The (solid + liquid) equilibrium (SLE) and (liquid + liquid) equilibrium (LLE) of RbCl/CsCl + ethylene carbonate (EC) + H 2 O ternary systems were carefully investigated at 298.15 K. The SLE and LLE data were correlated by the corresponding equations respectively. Furthermore, the thermodynamic properties of RbCl/CsCl in the EC–water systems were determined by potentiometric method at T = 298.15 K. The experiment data were correlated by the Pitzer, modified Pitzer and the extended Debye–Hückel equations. The mean activity coefficients, osmotic coefficients and excess Gibbs free energies, standard Gibbs free energy of transfer and the standard solubility product of systems were calculated. The mean activity coefficient γ ± decreases with the increase of the molality of electrolyte at the fixed mass fraction of EC. But γ ± vary abnormally with the increase of the EC content. The result of Δ G t 0 reflects the spontaneously transfer of the electrolytes from water to the mixed solvents. [ABSTRACT FROM AUTHOR]

Activity coefficients of RbCl orCsCl in methanol + ethanol + water were determined at 298.15 K by the cells containing ion-selective electrodes (ISEs). The molalities of RbCl and CsCl are up to approximately 1 mol·kg–1in the mixed solvents, and the mass fractions offive aqueous MeOH/EtOH mixtures studied were (5/5, 10/5, 5/10, 10/10,and 15/15) %. The experimental data were optimized using the extendedDebye–Hückel, the Pitzer, and the modified Pitzer equations.The results of the apparent standard electromotive force E0* of the three equations are in good agreement. The meanactivity coefficients and the standard Gibbs energy of transfer ofRbCl or CsCl from pure water to mixed solvents (MeOH + EtOH + water)were also calculated. [ABSTRACT FROM AUTHOR]

Thesolubility, density, refractive index, and viscosity data forthe ethylene glycol + CsBr + H2O, 1,2-propanediol + CsBr+ H2O, and glycerin + CsBr + H2O ternary systemshave been determined at (288.15, 298.15, and 308.15) K. In all cases,the solubility of CsBr in aqueous solutions was decreased significantlydue to the presence of polyhydric alcohol. The liquid–solidequilibrium experimental data were correlated using the NRTL (nonrandomtwo-liquid) activity coefficient model, considering nondissociationof the dissolved salt in the liquid phase, and new interaction parameterswere estimated. The mean deviations between calculated and experimentalcompositions were low, showing the good descriptive quality and applicabilityof the NRTL model. The refractive indices, densities, and viscositiesfor the unsaturated solutions of the three ternary systems have alsobeen measured at three temperatures. Values for all of the propertieswere correlated with the salt concentrations and proportions of polyhydricalcohol in the solutions. [ABSTRACT FROM AUTHOR]

Abstract: The thermodynamic properties of CsF in the ROH (R=methyl or ethyl)+water mixtures were determined using potentiometric measurements at 298.15K with the mass fraction of ROH varying from 0.00 to 0.30. The Pitzer, extended Debye–Hückel and Pitzer–Simonson–Clegg equations were successfully utilized to fit the experimental data based on the molality and mole-fraction-composition scale. Except for the standard cell potentials and Pitzer parameters, the mean activity coefficients, osmotic coefficients and standard Gibbs energies of transference of CsF from water to the methanol+water or ethanol+water mixtures have also been discussed herein. [Copyright &y& Elsevier]

This article deals with the meanactivity coefficients of RbF orCsF in the glycine + water mixed systems. The Pitzer, the modifiedPitzer, and the extended Debye–Hückel equations areused to describe the nonideal behavior of the electrolyte. The osmoticcoefficients, the excess Gibbs free energy, and the standard Gibbsenergies of transfer were calculated with the corresponding parameters. [ABSTRACT FROM AUTHOR]

In this paper, the mean activity coefficients for CsBr,as wellas the osmotic coefficients, the excess Gibbs free energies, the Gibbsenergies of transference, and the primary hydration in different MeOH–waterand EtOH–water mixtures at 298.15 K are calculated by potentiometricmeasurements. The cell used in this work contains two ion selectiveelectrodes (ISEs): Cs-ISE|CsBr(m), ROH(w), H2O(1 – w)|Br-ISE (R = Me andEt), and the mass fraction of ROH in the mixture (w) was varied between 0 and 0.3 in 0.1 unit steps. The experimentaldata were correlated very well by the thermodynamics equations ofPitzer, modified Pitzer, and Debye–Hückel models. [ABSTRACT FROM AUTHOR]

Activity coefficients for RbCl in different ethylene glycol water and glycerol water mixed solvents were determined at 298.15 K using potentiometric measurements. The Pitzer and extended Debye−Hückel equations were applied to describe the nonideal behavior of the electrolyte, and the corresponding coefficients were determined for each mixed solvent system. [ABSTRACT FROM AUTHOR]

• MCl + TMU + H 2 O systems (M = Na, K, Rb, Cs; TMU = tetramethylurea). • LLE systems of CsCl + TMU + H 2 O at 298.2 and 308.2 K. • SLE system of CsCl + TMU + H 2 O at 288.2 K. • SLE systems of NaCl/KCl/RbCl + TMU + H 2 O at 288.2, 298.2 and 308.2 K. • Affecting factors of temperature, solubility and solvent properties are discussed. For this article, we investigated the phase behavior and physicochemical properties of the ternary systems MCl (M = Na, K, Rb, Cs) + tetramethylurea (TMU) + H 2 O at temperatures of 288.2, 298.2 and 308.2 K. For (solid–liquid) equilibrium (SLE) systems (NaCl/KCl/RbCl + TMU + H 2 O at three temperatures and CsCl + TMU + H 2 O at 288.2 K), the density, solubility and refractive index about the saturated solutions was obtained. About (liquid–liquid) equilibrium (LLE) systems (CsCl + TMU + H 2 O at 298.2 and 308.2 K), the binodal curves and tie lines were obtained. The three parameter equation, Othmer-Tobias and Bancroft equations were used to correlate the SLE and LLE data. [ABSTRACT FROM AUTHOR]