Transport of thiourea through an Aliquat 336/polyvinyl chloride membrane

The transport of thiourea in acidic or neutral chloride solutions through a polyvinyl chloride (PVC) membrane containing immobilized Aliquat 336 was s tudied experimentally. No chemical interaction between thiourea and Aliquat 336 was observed. The acidity constant of thiourea at 1.0 ionic strength w as 13.7 and its distribution constant fur acidic solutions and near Aliquat 336 was 4.20. A mathematical model assuming ideal mixing in the solutions on both sides of the membrane and Fickian diffusion in the membrane was dev eloped and used for the determination of the diffusion coefficient or thiou rea in membranes with 30, 40, and 50 wt% Aliquat 336 content. The correspon ding values are estimated to be 5.5 x 10(-13) m(2)s(-1), 1.2 x 10(-12) m(2) s(-1) and 3.5 x 10(-12) m(2)s(-1), respectively. The transport properties o f PVC membranes with other plasticizers [bis(1-butylpentyl) adipate, diocty lphenyl phosphonate, and n-decanol] were compared to the Aliquat 336/PVC me mbrane.