Sol-gel Materials for High Capacity, Rapid Removal of Metal Contaminants

Abstract

An environmental waste remediation method is presented where porous cylindrical monoliths are interposed as septa between a solution contaminated with metal ions and a solution of a precipitant. Precipitant and contaminant diffuse and generate precipitate nano- and micro-particles inside the monoliths. Two types of silica sol-gel monoliths were tested. One class of materials was prepared following a conventional base-catalyzed route which yielded fragile silica monoliths with pore diameters on the order of 7-10 nm. A second class of materials material consisted of templated silica macroporous monoliths that were cross-linked with diisocyanate. These materials had pore diameters on the order of microns and were mechanically extremely strong, having a Young modulus in excess of 400 MPa. Both types of silica gel monoliths proved very versatile, and allowed to precipitate a wide variety of metal ions, including toxic metals such as Cd2+, and fission by-products such as lanthanides and Sr2+. The capacity of the gel monoliths was also very high, at least 20 times higher than the capacity of conventional derivatized gels. Most importantly, precipitation inside the macroporous gels was a factor 7-8 more rapid than in microporous gels. The results indicate that macroporous cross-linked sol-gel monoliths are a promising material for the development of efficient, mechanically strong filter elements for environmental remediation.

Department(s)

Chemistry

Keywords and Phrases

Porous materials

International Standard Serial Number (ISSN)

0149-6395

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2007 Taylor & Francis, All rights reserved.

Publication Date

01 Jan 2007

Link to Full Text

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