A new separation method: combination of CO2 and surfactant aqueous solutions

Abstract

In this work, the effect of CO₂ on the cloud point temperature (CPT) of an aqueous solution of p-tert-octylphenoxy polyethylene (Triton X-100) was studied at different temperatures, pressures and surfactant concentrations. It was demonstrated that CO₂ could reduce the CPT of the micellar solutions considerably. On the basis of this finding, we proposed a new route to separate different substances from water by combination of Triton X-100 and CO₂. It was discovered that phenol or vanadium ion in aqueous solutions could be separated efficiently from water by combination of CO₂ and Triton X-100. Our study also showed that the gold nanoparticles synthesized in Triton X-100 micellar solutions could be recovered using CO₂ while the surfactant remained in the solution. This is attractive because recovery of gold nanoparticles is very convenient. This separation method has some unusual advantages, such as high separation efficiency, simple post-treatment process, and lower separation temperature, which is especially advantageous when temperature-sensitive substances are involved.