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

Abstract

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 24h. 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.

Pertraction of Co(II) through Novel Ultrasound Prepared Supported Liquid Membranes Containing D2EHPA. Optimization and Transport Parameters

“…The liquid membrane phase was constituted by kerosene solutions of D2EHPA at concentrations between 0.2 and 0.8 M. The pores of the microporous support were filled with the membrane solution by applying ultrasound, using Labsonic M (Sartorius SA, Madrid, Spain) ultrasound equipment (titanium probe 10 mm diameter, sound rating density 130 W/cm 2 ), at 30 KHz, 150 µm, for 30 min (three times for 10 min, with 5 min intervals between them), and the active layer of the polymeric support at a distance of 16 mm from the ultrasound probe [24] (Figure 2a).…”

“…Transport studies were carried out using a permeation cell consisting of two identical compartments, containing 250 cm 3 (V) of feed or product phase, separated by the supported liquid membrane with an effective area (A) of 15 cm 2 [24] (Figure 2b). As feed phase, aqueous solutions of Co(II) between 0.010 M to 0.200 M (10 mol/m 3 to 200 mol/m 3 ) in 0.2 M acetate buffer, with pH ranging from 3 to 7, were used, and aqueous sulfuric acid solutions between 0.005 and 1 M were used as product phase.…”

“…All this makes the recovery of cobalt from raw materials and secondary sources very interesting from both environmental and economic reasons. Different techniques have been described for cobalt removal from aqueous solutions, including flocculation [5], adsorption [6][7][8][9], biosorption [10][11][12], phytoremediation [13], solvent extraction [14,15], ion exchange [16] capacitive deionization [17], electrowinning [18], micellar enhanced ultrafiltration [19], nanofiltration [20], reverse and forward osmosis [21,22], membrane distillation [23], liquid membranes [24][25][26][27] and combined methods [28].…”

Ultrasonic Mastering of Filter Flow and Antifouling of Renewable Resources

“…At present, the studies with ultrasound are limited to the preparation of supported liquid membranes …”

Ionic liquids supported by isoporous membranes for CO2/N2 gas separation applications

“…Four different ways to prepare SLMs with liquids are described in literature: immersion [49], pressure [50], vacuum [51] and ultrasound [52].…”