IN THIS WORK, THE RESULTS RELATING TO THE MEAN ACTIVITY COEFFICIENT MEASUREMENTS FOR NACL IN THE NACL+UREA+H2O SYSTEM USING POTENTIOMETRIC METHOD ARE REPORTED. THE POTENTIOMETRIC MEASUREMENTS WERE PERFORMED ON THE GALVANIC CELL OF THE TYPE: AG|AGCL|NACL (M), UREA (WT%), H2O (1−WT) %|NA-ISE, IN VARIOUS MIXED SOLVENT SYSTEMS CONTAINING 0, 10, 20 AND 30% MASS FRACTIONS OF UREA OVER IONIC STRENGTH RANGING FROM 0.001 TO 3.000 KGMOL-1 AT 298.2 K . SODIUM ION SELECTIVE ELECTRODE WAS MADE IN LABORATORY WITH MODIFIED CARBON NANOTUBE AS ELECTROCHEMICAL SENSOR. THE DEBY- HUCKEL AND PITZER ION-INTERACTION MODEL WERE USED FOR THE EXPERIMENTAL DATA CORRELATION AND CALCULATION OF THERMODYNAMIC PROPERTIES SUCH AS EXCESS FREE GIBBS ENERGY AND OSMOTIC COEFFICIENTS FOR UNDER INVESTIGATED SYSTEM. THE RESULTS CLEARLY INDICATE THAT A GOOD CORRELATION IS OBTAINED WITH THE PITZER MODEL TO DESCRIBE THIS SYSTEM

IN THIS WORK, THE RESULTS RELATING TO THE MEAN ACTIVITY COEFFICIENT MEASUREMENTS FOR NACL IN THE NACL+UREA+H2O SYSTEM USING POTENTIOMETRIC METHOD ARE REPORTED. THE POTENTIOMETRIC MEASUREMENTS WERE PERFORMED ON THE GALVANIC CELL OF THE TYPE: AG|AGCL|NACL (M), UREA (WT%), H2O (1−WT) %|NA-ISE, IN VARIOUS MIXED SOLVENT SYSTEMS CONTAINING 0, 10, 20 AND 30% MASS FRACTIONS OF UREA OVER IONIC STRENGTH RANGING FROM 0.001 TO 3.000 KGMOL−1 AT 298.2 K . SODIUM ION SELECTIVE ELECTRODE WAS MADE IN LABORATORY WITH MODIFIED CARBON NANOTUBE AS ELECTROCHEMICAL SENSOR. THE DEBY- HUCKEL AND PITZER ION-INTERACTION MODEL WERE USED FOR THE EXPERIMENTAL DATA CORRELATION AND CALCULATION OF THERMODYNAMIC PROPERTIES SUCH AS EXCESS FREE GIBBS ENERGY AND OSMOTIC COEFFICIENTS FOR UNDER INVESTIGATED SYSTEM. THE RESULTS CLEARLY INDICATE THAT A GOOD CORRELATION IS OBTAINED WITH THE PITZER MODEL TO DESCRIBE THIS SYSTEM

INTRODUCTION: RECENTLY, THERE HAS BEEN AN INCREASING AMOUNT OF WORK CONCERNING THE MEASUREMENTS OF THERMODYNAMIC PROPERTIES OF ELECTROLYTES IN MIXED SOLVENTS [1, 2], BECAUSE THEIR COMPOSITION IS IMPORTANT IN INDUSTRIAL, ENVIRONMENTAL CHEMISTRY AND BIOCHEMISTRY [3, 4]. FOR INSTANCE, ALCOHOLS ARE WIDELY USED IN PETROLEUM INDUSTRY TO FACILITATE TRANSPORT IN CERTAIN CIRCUMSTANCES. THE OPTIMIZATION OF THE CONDITION FOR PERFORMING SUCH PROCESSES IS IMPOSSIBLE WITHOUT THE CONSTRUCTION OF THERMODYNAMIC MODELS OF PHASES OF THE SYSTEM UNDER CONSIDERATION, WHICH, IN TURN, REQUIRES INFORMATION ABOUT THE PARTIAL AND INTEGRAL PROPERTIES OF LIQUID SOLUTION COMPONENTS. THEREFORE, THE PERFECT KNOWN OF PHYSICAL CHEMISTRY PROPERTIES OF THEIR MIXED SOLUTIONS IS NECESSARY. IN THIS WORK, THE THERMODYNAMIC PROPERTIES OF THE ELECTROLYTE IN MIXED SOLVENT SYSTEM (NACL+GLYCEROL+H2O), USING THE POTENTIOMETRIC METHOD WITH SURFACTANT MODIFIED ZEOLITE (SMZ) AS A NEW ION-SELECTIVE MEMBRANE ELECTRODE, ARE REPORTED.

THIS RESEARCH PURPOSES ON THE THERMODYNAMICS MODELING OF THE TERNARY KBR+MANNITOL+ WATER AT 298.15 K BY ELECTROMOTIVE FORCE ( EMF ) MEASUREMENTS. ELECTROCHEMICAL CELLS WITH A POTASSIUM ION SELECTIVE ELECTRODE (K–ISE) VERSUS A BROMIDE ION SELECTIVE ELECTRODE (BR–ISE) AS A REFERENCE ELECTRODE WERE USED TO DETERMINE THE ACTIVITY COEFFICIENTS FOR KBR– MONOSACCHARIDE (MANNITOL) SYSTEMS IN WATER AT 298.15 K.

IN SOLUTIONS, THERE ARE INTERACTIONS BETWEEN ALL POSSIBLE SPECIES SUCH AS DISSOCIATED IONS, ION PAIRS, MOLECULES, ETC, THAT INTERFERE WITH THE BEHAVIOR OF THE SOLUTES ...

RECENTLY, THERE HAS BEEN AN INCREASING AMOUNT OF WORK ABOUT THE MEASUREMENT OF THERMODYNAMIC PROPERTIES OF ELECTROLYTES IN MIXTURES OF SOLVENTS, BECAUSE THEIR COMPOSITION IS IMPORTANT IN INDUSTRIAL CHEMISTRY, BIOLOGICAL AND OTHER FIELDS [1]. TO MEASURE THE THERMODYNAMIC PROPERTIES OF ELECTROLYTES IN MIXED SOLVENT, THERE ARE SOME METHODS LIKE ISOPIESTIC VAPOR PRESSURE, VAPOR PRESSURE LOWERING AND POTENTIOMETRIC METHOD [2]. IN THE LAST FEW DECADES, A SERIES OF ION-INTERACTION MODELS FOR ELECTROLYTE SOLUTIONS HAVE BEEN PROPOSED TO PREDICT THE ACTIVITY COEFFICIENT OF EACH SOLUTE AND THE OSMOTIC COEFFICIENT OF THE AQUEOUS SYSTEMS. ONE OF THE MOST FAMOUS AND USEFUL MODELS IS THAT PROPOSED BY PITZER [3]. PITZER EQUATION USE WITH MUCH ACCURACY, CORRELATE THE THERMODYNAMIC PROPERTIES OF MIXED AQUEOUS ELECTROLYTE SYSTEMS. IN THIS WORK, THE RESULTS RELATING TO THE MEAN ACTIVITY COEFFICIENT MEASUREMENTS OF KCL IN (KCL + MALTOSE + WATER) SYSTEM USING POTENTIOMETRIC METHOD ARE REPORTED. THE MEAN ACTIVITY COEFFICIENT OF KCL IN MIXED SOLVENT WAS DETERMINED ON A GALVANIC CELL CONTAINING A SOLVENT POLYMERIC (PVC) K-ISE AND AG/AGCL ELECTRODES AT T=298.15 K. THE RESULTING VALUES OF THE MEAN ACTIVITY COEFFICIENTS WERE CORRELATED WITH PITZER MODEL AND PITZER ION-INTERACTION PARAMETERS (B0, B1 AND CÆ) WERE DETERMINED. THEN THESE PARAMETERS WERE USED FOR CALCULATION OF OSMOTIC COEFFICIENT OF WATER AND EXCESS GIBBS FREE ENERGY FOR THE SERIES UNDER THE INVESTIGATED SYSTEM ARE REPORTED.

THERMODYNAMIC PRINCIPLES ARE APPLIED IN ANY SITUATION WHERE ENERGY TRANSFER IS DESIRABLE. THE COMPLEX FORMATION BETWEEN SOME HEAVY METAL CATIONS AND ETHYLENDIAMINE IN AQUEOUS MEDIA IS INVESTIGATED. THE INTERACTION BETWEEN CD+2 AND PB+2 CATIONS AND ETHYLENDIAMINE WAS STUDIED IN WATER MEDIA AT 10, 20, 30 AND 40OC ON A PT ELECTRODE USING SQUARE WAVE VOLTAMMETRIC METHOD. SODIUM CHLORIDE WAS USED AS SUPPORTING ELECTROLYTE. THE STOICHIOMETRY AND STABILITY OF THE FORMED COMPLEXES WERE DETERMINED BY MEASURING THE SHIFT IN POTENTIAL OF THE VOLTAMMETRIC PEAK OF METAL IONS AND COMPLEXES IN DIFFERENT CONCENTRATIONS OF ETHYLENEDIAMINE. EQUILIBRIUM CONSTANTS OF COMPLEX FORMATION BETWEEN LEAD AND CADMIUM IONS WITH ETHELTHNEDIAMINE IN THE STUDIED MEDIA WERE 5.735×1011 AND 2.170×1012 RESPECTIVELY. THERMODYNAMIC PARAMETERS (DG, DH AND DS) FOR CADMIUM COMPLEXATION WERE CALCULATED TO BE -69214 J MOL-1, -172207 J MOL-1, -352 J MOL-1 K-1 AND THAT OF LEAD WERE -65955 J MOL-1, -134736 J MOL-1, -235 J MOL-1 K-1. IN BOTH CASES THE MOLE RATIO OF LIGAND TO CATION WAS 3:1. OBTAINED DATA SHOWED THAT THE COMPLEXES ARE STABILIZED BY THE ENTHALPY TERM.