ION-PAIR EXTRACTION OF MULTI-OH COMPOUNDS BY COMPLEXATION WITH ORGANOBORONATE

Ion-pair extraction with organoboronate has been investigated as a regenerable means of removal and recovery of multi -OH compounds from aqueous solution. The extractant utilized was 3-nitrophenylboronate (NPB-), paired with Aliquat 336 as cation (A336+). The solubility of 3-nitrophenylboronic acid (NPBA) in water at 25-degrees-C was measured as 0.45 +/- 0.02 g/100 g H2O. The 1:1 complexation stability constant for 1,2-propanediol with NPB- was measured by the buffer-capacity method through the Antikainen model as 3.2, 2.3 and 1.95 mol/l-1 at 25-degrees. 35-degrees and 44.8-degrees-C, respectively. The A336+NPB- ion pair was prepared by repeated washing of a mixture of Aliquat 336, NPBA and diluent with aqueous NaOH and then water. Equilibria were measured for extraction of fructose, glycerol, and sorbitol from aqueous solution into the ion-pair extractant in a diluent of 2-ethylhexanol.