Distribution of Picric Acid into Various Diluents

Abstract

Extraction constants, defined as ex = [HPic] o /[H + ][Pic − ], for picric acid (HPic) into ten diluents were spectrophotometrically determined at 298 K, where the subscript "o" refers to an organic (o) phase which is composed of the diluent. Their values for the HPic extraction into benzene and chloroform were fairly consistent with those reported before. From the ex values, distribution constants (D,HPic) of HPic into the o phases were estimated using the thermodynamic relation ex = D,HPic HPic , where HPic corresponds to a protonation constant of Pic − in water. Thereby, contributions of functional groups, such as-Cl and-CH 3 , involved in the diluents molecules to D,HPic were discussed. The same discussion was also applied for the distribution of the ion pair, composed of CdPic 2 and 18-crown-6 ether, into the diluents.

Solvent Extraction of Cadmium Picrate by 18-Crown-6 Ether into Several Less-polar Diluents and Nitrobenzene: Re-evaluation of the Corresponding Overall Extraction Systems

“…Also, using the average log K HPic value (=0.55 ± 0.03) [8], we evaluated log K D,HPic to be 0.51 ± 0.03. This log K D,HPic value was the smallest of those (=0.89-1.97) [7] reported previously by the authors on the HPic extraction into various diluents.…”

“…Water amount of used 18C6 (>98.0%, Wako) was determined by the KarlFischer titration to be 0.062 ± 0.029% at N=4. The H(I) amount of an aqueous solution prepared from a commercial HPic (>99.5%, Wako) was determined by an acid-base titration [7]. Other reagents were the same as or similar to those employed previously [1,4].…”

“…Also, the procedures for the HPic extraction into DBE were the same as those reported before [7]. Total amounts of Pic(−I) extracted into DBE were back-extracted into aqueous solutions with 0.1 mol dm 3 NaOH from the DBE phases and then were determined at the wavelength of 355.0 nm spectrophotometrically [7].…”

“…By there-determination of K ex , the authors will eliminate a problem on the large deviation [1] of the Bz system from the plot of log K ex,ip versus log K D,18C6 . (5) in which the K HA value averaged in the experimental I range (=0.00043-0.022 mol dm −3 at HA=HPic) was introduced, was employed for the analysis [7]. The symbol D A refers to the distribution ratio of species with A − .…”

Equilibrium Data on the Reactive Extraction of Picric Acid from Dilute Aqueous Solutions Using Amberlite LA-2 in Ketones

“…The researchers added that extraction efficiency was positively affected from the existence of ammonium nitrate in the solution due to the salting out effect, while it decreased with the sulfates . At another study, Kudo et al evaluated ten different low-polar diluents and showed the positive effect of the functional groups in the structure of the organic diluent for the recovery. However, recovery efficiencies obtained with organic diluents in these studies were significantly low and need to be improved.…”