SIT Parameters for the Dependence of (Poly)carboxylate Activity Coefficients on Ionic Strength in (C₂H₄)₄NI_aq (0 ≤ I ≤ 1.2 mol·kg^-1) and (CH₃)₄NCl_aq (0 ≤ I ≤ 3.9 mol·kg^-1) in the Temperature Range 278 K ≤ T ≤ 328 K and Correlation with Pitzer Parameters

Abstract

Parameters for the dependence on ionic strength of activity coefficients for several protonated and unprotonated mono-hexacarboxylates in (C 2 H 5 ) 4 NI and (CH 3 ) 4 NCl aqueous solution were calculated from protonation data [31 polycarboxylates, 613 protonation constants at T ) 298 K, 1244 at T * 298 K, in (C 2 H 5 ) 4 NI; 16 polycarboxylates, 433 protonation constants at T ) 298 K, 308 at T * 298 K (T ) 278 K to 328 K), in (CH 3 ) 4 NCl], at different ionic strengths [0 mol‚kg -1 e I e 1.2 mol‚kg -1 , for (C 2 H 5 ) 4 NI and 0 mol‚kg -1 e I e 3.9 mol‚kg -1 , for (CH 3 ) 4 -NCl)] using a modified SIT model. In this model, the interaction coefficients are considered as dependent on ionic strength according to the equation ) ∞ + ( 0 -∞ )/(I + 1). The analysis of protonation data showed that the parameters for the dependence on both ionic strength and temperature are a simple function of the charge of carboxylate species. Mean values of interaction coefficients are given by the relationships ) jz 2 ; j ∞ ) -0.0188 and -0.0063; j 0 ) 0.2420 and 0.1642 for (C 2 H 5 ) 4 NI and (CH 3 ) 4 NCl, respectively. For the activity coefficients of neutral species, a simple relationship as a function of the number n of carboxylic groups was found: log γ N ) k m I (k m ) Setschenow coefficient); k m ) k h m ‚n, k h m ) -0.0198 and 0.0055, for (C 2 H 5 ) 4 NI and (CH 3 ) 4 NCl, respectively. Mean values of interaction coefficients were also reported for some synthetic and natural polyelectrolytes in (C 2 H 5 ) 4 NI ( j ∞ ) -0.007; j 0 ) 0.199). Furthermore, calculations were made to find the parameters of Pitzer equations. Also in this case, we found a simple relationship between (0) and (1) parameters and species charges. A comparison is given between the SIT and Pitzer models. An almost perfect correlation was found between the SIT and Pitzer coefficients.

Thermodynamic Parameters for the Interaction of Amoxicillin and Ampicillin with Magnesium in NaCl Aqueous Solution, at Different Ionic Strengths and Temperatures

“…The dependence of the formation constants of the two systems on the ionic strength was modeled by the Debye–Hückel type equation (eq ) and the Specific ion Interaction Theory (SIT), by using both one- (eq ) and two-parameter (eq ) approaches. − In the first case (eq ), both the ionic strength and stability constants used were in the molar concentration scale.…”

“…A modified version of the SIT equation was proposed in the past, − where the specific interaction coefficient ε is dependent on the ionic strength, following the relationship: where Δε ∞ and Δε 0 are parameters for the dependence on ionic strength for Δε NaCl → ∞ and Δε NaCl → 0, respectively.…”

Protonation Constants, Activity Coefficients, and Chloride Ion Pair Formation of Some Aromatic Amino-Compounds in NaClaq(0 mol·kg–1 ≤ I ≤ 3 mol·kg–1) at T = 298.15 K

“…Equation can be considered equivalent to eq , if the molal concentration scale was used, so that Δε = C . The dependence on ionic strength of Δε i can be studied using a similar approach ,− used in eq : normalΔ ε = normalΔ ε ∞ + normalΔ ε 0 − normalΔ ε ∞ 1 + I or eq normalΔ ε = normalΔ ε false( 0 false) + normalΔ ε false( 1 false) nobreak0em0.25em⁡ ln ( 1 + I ) Table reports the protonation constant values at infinite dilution, calculated using eqs and , and , and and , while Table reports all of the parameters for the dependence on ionic strength.…”

Activity-based analysis of potentiometric pH titrations

“…In this contribution, in addition to the original Debye-Hückel equation (Equation 3), we use the Davies equation (4), and the Specific Interaction Theory (SIT), equation ( 5) [11,12,13,14].…”