Increasing stability and transport efficiency of supported liquid membranes through a novel ultrasound-assisted preparation method. Its application to cobalt(II) removal

A novel ultrasound assisted method for preparing supported liquid membranes is described in this paper. The stability and efficiency of the supported liquid membrane obtained was tested by removing cobalt(II) from aqueous solutions through a facilitated countertransport mechanism using CYANEX 272 as carrier and protons as counterions. The results are compared with those obtained using supported liquid membranes prepared by soaking the polymeric material in the organic solution of the carrier at atmospheric pressure and under vacuum, both for 24 h. Higher transport efficiency (>5%), flux (∼18%), permeability (∼20%) and stability (>6% in the second run and ∼10% in the third run) were obtained by the supported liquid membrane prepared using the ultrasound assisted method. These findings can be explained by the effects of cavitation and acoustical streaming – which result from the ultrasound passing through the organic solution of the extractant – on the porous structure of the polymer support and on the pore filling.

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► A novel ultrasound assisted method (UAM) for preparing supported liquid membranes (SLMs) is described.
► The SLMs obtained are tested by removing cobalt(II) from aqueous solutions using CYANEX 272 as carrier.
► SLMs prepared by UAM are compared with those prepared by soaking (SM) and vacuum (VM) methods.
► Higher transport efficiency, flux, permeability and stability are obtained by SLMs prepared by UAM than by SM or VM.
► Cavitation and acoustical streaming are suggested to be responsible of the higher efficiency of the UAM.