Transport of Thiourea through an Aliquat 336/Polyvinyl Chloride Membrane

Abstract

The transport of thiourea in acidic or neutral chloride solutions through a polyvinyl chloride (PVC) membrane containing immobilized Aliquat 336 was studied experimentally. No chemical interaction between thiourea and Aliquat 336 was observed. The acidity constant of thiourea at 1.0 ionic strength was 13.7 and its distribution constant for acidic solutions and neat 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 developed and used for the determination of the diffusion coefficient of thiourea in membranes with 30, 40, and 50 wt% Aliquat 336 content. The corresponding values are estimated to be 5.5 × 10⁻¹³ m²s⁻¹, 1.2×10⁻¹²m²s⁻¹ and 3.5 ×10⁻¹²m²s⁻¹, respectively. The transport properties of PVC membranes with other plasticizers [bis(1-butylpentyl) adipate, dioctylphenyl phosphonate, and n–decanol] were compared to the Aliquat 336/PVC membrane.

Keywords:

• Aliquat 336
• Thiourea
• Diffusion coefficient
• Membrane transport
• PVC membrane

ACKNOWLEDGEMENTS

We are grateful to the Australian Research Council for financial support. Yukio Sakai thanks Miyazaki University for a study visit.

Notes

^*Subscripts F, R, and m refer to the feed solution, the receiver solution, and the membrane, respectively, while H ⁺, T, and TH ⁺ refer to the protons, and the neutral and the protonated thiourea, respectively.