Diffusion coefficient of aqueous benzoic acid at 25.degree.C

Abstract

A conductometrlc technique has been used to measure precise blnary diffusion coeff lcients for aqueous benzoic acid solutions at concentrations from 0.0003 to 0.0153 mol dm-a at 25 OC. As the concentratlon drops, dlssociatlon of benzoic acid molecules Increases the overall rate of diffusion of the solute. The concentration dependence of the measured diffusion coefficients is In good agreement with predlcted behavior and yields 0.900 (k0.006) X lo-' m2 8-' for the limiting dlffuslon coefficient of the undlssoclated aqueous benzoic acid molecule. The new diffusion data can be used to model dissolution of the acld, a standard procedure for determlnation of mass-transfer coefflcients.

Molecular Diffusion Coefficients of Organic Compounds in Water at Different Temperatures

“…The experimental results are in excellent agreement with the experimental values of the molecular (or tracer) diffusion coefficient measured by other authors, [12][13][14][15][16][17][18] and repeated measurements of D m did not differ by more than 10%. Other experimental methods used to measure D m , such as Taylor dispersion technique, diaphragm cells and interferometry, [19,20] give a precision higher than 1%; however, the experimental method presented has the added interest of easily providing data at temperatures that differ significantly from ambient values.…”

“…Ghosh et al [7] Sahay et al [9] Dunker [6] Steele and Geankoplis [11] Wilke and Chang [18] Seidell [10] c* (kg/m 3 ) = 1. [12][13][14][15][16][17] at different temperatures, and this is an indication of the accuracy of the proposed method. Moyle and Tyner [15] propose the following equation to represent their data for 2-naphthol in water (see Fig.…”

Diffusion Coefficients of Three Organic Solutes in Aqueous Sodium Dodecyl Sulfate Solutions

“…C BH,t is the total concentration of benzoic acid in the solution. In our study, C BH,t = 2.0 × 10 −4 M, and the D ± can be calculated from limiting ionic conductances with the Nernst equation (40,42). Therefore, the value of D BH will be obtained by Eq.…”

“…Benzoic acid, a weak electrolyte, can partly dissociate into benzoate ion and hydrogen ion. Therefore, the measured diffusion coefficient (D) of benzoic acid in water is the joint contribution of the diffusion of the benzoic acid molecule and the corresponding benzoate ion, and it can be described by the following equation (40,41): [8] where D BH and D ± are the limiting diffusion coefficients of the molecular and the fully ionized forms of the benzoic acid in water, respectively. α is the degree of dissociation that can be calculated by the dissociation constant (40), and γ ± is the average activity coefficient in molarity.…”

Computational fluid dynamics modeling of immobilized photocatalytic reactors for water treatment

“…At 298 K, the following values were used: [42][43][44] The 228-mm-long white areas shown in both reactors correspond to the photocatalyst coatings. The cylinders inside the sleeves represent the UV lamps.…”