			Home About us Contact

Supported Liquid Membrane (supported + liquid_membrane)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Supported liquid membranes in hollow fiber liquid-phase microextraction (LPME) , Practical considerations in the three-phase mode

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2007
Kari Folde Bårdstu
Abstract In this work, three-phase liquid-phase microextraction (LPME) based on a supported liquid membrane (SLM) sustained in the wall of a hollow fiber was investigated with special focus on optimization of the experimental procedures in terms of recovery and repeatability. Recovery data for doxepin, amitriptyline, clomipramine, and mianserin were in the range of 67.8,79.8%. Within-day repeatability data for the four basic drugs were in the range of 4.1,7.7%. No single factor was found to be responsible for these variations, and the variability was caused by several factors related to the LPME extractions as well as to the final HPLC determination. Although the volume of the SLM varied within 0.4,3.1% RSD depending on the preparation procedure, and the volume of the acceptor solution varied within 4.8% RSD, both recoveries and repeatability were found to be relative insensitive to these variations. Thus, the handling of microliters of liquid in LPME was not a very critical factor, and the preparation of the SLM was accomplished in several different ways with comparable performance. Reuse of hollow fibers was found to suffer from matrix effects due to built-up of analytes in the SLM, whereas washing of the hollow fibers in acetone was beneficial in terms of recovery, especially for the extraction of the most hydrophobic substances. Several of the organic solvents used in the literature as SLM suffered from poor long-term stability, but silicone oil AR 20 (polyphenyl-methylsiloxane), 2-nitrophenyl octyl ether (NPOE), and dodecyl acetate (DDA) all extracted with unaltered performance even after 60 days of storage at room temperature. [source]

Cobalt removal from waste-water by means of supported liquid membranes

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009
Kim Verbeken
Abstract BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste-water. In the present work, the removal of Co(II) from a synthetic CoSO4 solution containing initial amounts of cobalt(II) in the range 100,200 ppm (0.1,0.2 g dm,3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di-2-ethyl-hexylphosphoric acid (D2EHPA) and 5-dodecylsalicylaldoxime (LIX 860-I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid,liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui-Cel Extra-Flow 4 × 28) having a surface area of 19 m2, a steady Co(II) flux of 0.140 gm,2h,1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm,3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860-I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry [source]

Influence of temperature on mass transfer in an incomplete trapping supported liquid membrane extraction of triazole fungicides

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 7 2009
Luke Chimuka
Abstract The influence of temperature in a supported liquid membrane (SLM) extraction of triazole fungicides was investigated. The mass transfer parameters such as diffusion coefficient, flux and apparent viscosity were determined at temperatures ranging from 5 to 40°C. Increase in temperature led to an increase in diffusion coefficient and flux with a flowing acceptor solution. The apparent viscosity also decreased with an increase in temperature. However, the increase in mass transfer parameters did not result in an overall increase in extraction efficiency with a stagnant or circulation acceptor phase. Stripping of the analytes from the membrane into the acceptor phase as well as the configuration of the extraction unit could have limited the influence of temperature on mass transfer. The partition coefficient of analytes from the acceptor solution to the membrane, KA, was found to be much higher than that from the donor solution to the membrane KD, thus triazole compounds preferred to remain in the membrane even with an increased extraction temperature. [source]