Various sorbent/ion exchange materials have been reported in the literature for metal ion entrapment. We have developed a highly innovative and new approach to obtain high metal pick-up utilizing poly-amino acids (poly-L-glutamic acid, 14,000 MW) covalently attached to membrane pore surfaces. The use of microfiltration (0.2-0.6 μm) membrane-based sorbents containing multiple functional groups is a novel technique to achieve high metal sorption under convective flow conditions. For our studies, both commercial membranes and laboratory prepared cellulose membranes containing aldehyde groups were used for the attachment of poly-amino acids. Cellulose membranes were prepared by converting cellulose acetate microfiltration membranes to cellulose (using alkali treatment), subsequent oxidation of hydroxyl groups to aldehyde using sodium periodate, and attachment of poly-L-glutamic acid via Schiff base chemistry. Extensive experiments (pH 3-6) were conducted (under convective flow mode) with the derivatized membranes involving the heavy metals: lead, cadmium, nickel, copper, and selected mixtures with calcium in aqueous solutions. Metal sorption results were found to be a function of derivatization (aldehydes) density of membranes and degree of attachment of the polyfunctional groups, number of functional groups per chain, membrane surface area, and the type of metals to be sorbed. We have obtained metal sorption capacities as high as 1.5 g metal/g membrane. Of course, depending on the desired goals the membrane containing metal could be regenerated or stabilized for appropriate disposal.
|Number of pages||15|
|Journal||Journal of Membrane Science|
|State||Published - Apr 1 1998|
Bibliographical noteFunding Information:
The metal sorbent project was funded in part by DOD's Strategic Environmental Research and Development Program (SERDP), and by a grant from the National Science Foundation (CTS-9307518). The authors would like to thank Ed Barth of US EPA, Cincinnati for providing valuable suggestions throughout the course of this work. We would like to thank Stephen Ritchie for his contributions in the area of surface area determination. We would also like to thank Dr. Steve Kloos of Osmonics Corporation for providing the cellulose acetate composite membranes. P. Brushaber was supported by a NSF/REU grant through the Center of Membrane Sciences.
- Aldehyde derivatization
- Metal sorption
- Microfiltration membranes
- Poly-L-glutamic acid functionalization
ASJC Scopus subject areas
- Materials Science (all)
- Physical and Theoretical Chemistry
- Filtration and Separation