Transport and relaxation of naphthalene in supercritical fluids

Abstract

The pressure dependence of diffusion coefficients of naphthalene in supercritical C02 and naphthalene-¿8 in supercritical ethylene has been measured by using the NMR fixed field gradient spin-echo Bessel function analysis technique. The pressure dependence of the reorientational motion of naphthalene-if8 in C02 and ethylene has been studied by measuring the deuteron spin-lattice relaxation time, 7), as a function of pressure at several isotherms. The temperatures were chosen to cover two regions of the naphthalene-supercritical solvent phase diagram. The experimental data allowed the molecular level test of the applicability of the Stokes-Einstein and Debye equations in the binary systems studied. The expression D(ij/7')0,75 = constant represents the experimental diffusion data well, and the modified Debye equation describes the reorientational motion of naphthalene in supercritical C02 and ethylene solvents.

Diffusion coefficients of naphthalene and dimethylnaphthalene in supercritical carbon dioxide

“…The diffusion coefficients of naphthalene obtained in this study are in good agreement with the literature data [8] in the high pressure range. The diffusion coefficients of naphthalene near the critical point decrease as shown in Figures 5 and 6.…”

“…The effective hard-sphere diameter of solute(2) was calculated by σ σ σ σ (8) where σ vw is the van der Waals diameter estimated by the method of Bondi [18]. The parameters of Schmidt number correlation are listed in Table 2 …”

“…Knaff and Schlünder [7] measured the diffusion coefficients for naphthalene and caffeine in supercritical carbon dioxide by using a pseudo-steady state solid dissolution technique. Lamb et al [8] measured the diffusion coefficients of naphthalene in supercritical carbon dioxide and ethylene by using the NMR fixed field gradient spin-echo Bessel function analysis technique. Funazukuri et al [9,10] were used the Taylor-Aris method to measure the diffusion coefficients of unsaturated fatty acid methyl esters and organic compounds in supercritical carbon dioxide.…”

Calculation of diffusion coefficient for supercritical carbon dioxide and carbon dioxide+naphthalene system by molecular dynamics simulation using EPM2 model

“…The calculated result of PVT relationship at 308.2 K and 323.2 K was shown in Figure 2 ( , , , , ) Experimental data [13][14][15][16][17] ( ) simulated by all atom model of naphthalene …”

Prediction of binary diffusion coefficients of solutes in supercritical solvents

“…(1) Sassiat et al (1987); (2) Swaid and Schneider (1979); (3) Umezawa and Nagashima (1992); (4) Suarez et al (1993); (5) Funazukuri (1996); (6) Funazukuri et al (1992); (7) Olesik and Woodruff (1991); (8) Mei et al (1995); (9) Akgerman et al (1996); (10) Lauer (1983); (11) Lamb et al (1989); (12) Knaff and Schliinder (1987); (13) Shenai et al (1993); (14) Lai and Tan (1995); (15) Liong et al (1992); (16) Funazukuri et al (1991); (17) Catchpole and King (1994); (18) Dahmen et al (1990a); (19) Wells et al (1992); (20) Noel et al (1994); (21) Eaton et al (1995); (22) Eaton and Akgerman (1997); (23 (11) x(rn2/rn,> As can be seen in Table 2, this work (Eqs. 10, 7 and 8) usually does well for predicting the diffusion coefficients of liquid and solid solutes in supercritical solvents, with a large density range ( p, 2 0.21).…”