Metal Rejection by Nanofiltration from Diluted Solutions in the Presence of Complexing Agents

Nanofiltration (NF) of solutions containing low levels of metal ions, in the absence and presence of complexing agents, using three polyamide membranes was investigated. For a given membrane, metal rejection increased with decreasing ion concentration and valence of metal ion in the absence of compl...

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Bibliographic Details
Published in:Separation science and technology 2005-01, Vol.39 (2), p.363-376
Main Authors: Lin, Su-Hsia, Wang, Tsung-Yuan, Juang, Ruey-Shin
Format: Article
Language:English
Subjects:
Complexing agents
Metal ions
Nanofiltration
Rejection
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Summary:Nanofiltration (NF) of solutions containing low levels of metal ions, in the absence and presence of complexing agents, using three polyamide membranes was investigated. For a given membrane, metal rejection increased with decreasing ion concentration and valence of metal ion in the absence of complexing agents. The rejections of 20 mg/L of Co 2+ , Ni 2+ , Mn 2+ , Sr 2+ (pH 4) were above 90% at an applied pressure of 65 psi with DK (MWCO, 150) and DL (MWCO, 300) membranes and near 15 to 20% with a GE (MWCO, 1000) membrane. In the presence of complexing agents, the rejection of metals was generally higher than those obtained in their absence. The rejection of metals increased with increasing solution pH and finally, reached a plateau beyond each certain pH value. Such pH-dependent rejections could be satisfactorily related to the overall formation constants between metal ions and complexing agents.
ISSN:0149-6395
1520-5754
DOI:10.1081/SS-120027563