Supported liquid membranes with organic dispersion for recovery of Cephalexin

• Supported liquid membrane with organic dispersion was proposed and demonstrated.
• The mass transfer mechanism of the SLM-OD process was elucidated and modeled.
• A mathematic model was developed to calculate the mass transfer coefficient.
• Various operating parameters were investigated to identify the critical ones.
• The extraction reaction resistance was greatly reduced in SLM-OD.

Supported liquid membranes with organic dispersion (SLM-OD) have been proposed and investigated for simultaneous removal and recovery of Cephalexin from aqueous solutions by using the carrier Aliquat 336 and a commercially available hollow-fiber module (HFM). The organic dispersion, formed by dispersing a small amount of organic membrane solution in the feed solution with a mixer, flowed through the shell side of the HFM. Investigated various parameters including organic-to-feed volume ratio, Aliquat 336 concentration, initial Cephalexin concentration, KCl concentration, shell-side organic dispersion flow rate, and lumen-side strip solution flow rate. The mass transfer mechanism of the SLM-OD technique was elucidated, and a mathematical model was developed to calculate the overall mass transfer coefficient. The results showed that the overall mass transfer coefficient increased with an increase of organic-to-feed volume ratio or increase of Aliquat 336 concentration, but reduced with the increase of initial Cephalexin concentration. Furthermore, the results indicated that the lumen and shell side flow rates had little effects on mass transfer performance and that an excess amount of KCl was necessary for the facilitated transport. The fractional mass transfer resistances of SLM-OD were calculated based on the resistance-in-series model, showing that the extraction reaction resistance was greatly reduced. In addition, the SLM-OD was shown to be superior to the supported liquid membranes with strip dispersion (SLM-SD) in terms of the improvement of mass transfer performance and the reduced volume requirement of the organic membrane solution.