Applications of Surfactant-Modified-Zeolites (SMZ) to Environmental Remediation - Robert S. Bowman, New Mexico Tech Earth & Environmental Science

Surfactant-Modified-Zeolites (SMZ) and Their Applications to Environmental Remediation

Robert S. Bowman , Professor of Hydrology

For list of SMZ publications and ordering information, click here .

Zeolites are naturally occurring hydrated alumniosilicates characterized by cage-like structures, high surface areas (hundreds of m²/g) and high cation exchange capacities (hundreds of meq/kg). There are more than 40 distinct natural zeolites, which occur in massive deposits throughout the world. The most common natural zeolite is clinoptilolite. As shown at left, clinoptilolite has a two-dimensional 8-ring and 10-ring channel structure with the largest cavity dimension measuring 4.4 by 7.2 Angstroms.


Zeolite surface chemistry resembles that of smectite clays. Unlike clays, however, natural zeolites can occur as millimeter- or greater-sized aggregates and are free of shrink-swell behavior. As a result, zeolites exhibit superior hydraulic characteristics and are suitable for flow-through applications. Treatment of natural zeolites with large cationic surfactants (quaternary amines) dramatically alters their surface chemistries. These large organic cations exchange selectively with native inorganic cations to form a stable, organic-rich coating on the external surfaces of the zeolite. Surfactant modification allows the zeolites to sorb nonpolar organic solutes and anions, for which untreated zeolites have little affinity. The following pages describe the properties of clinoptilolite, surfactants, and surfactant-modified zeolite (SMZ), and our research into environmental applications of SMZ.


SMZ Preparation and Properties
Properties of zeolites Zeolite-surfactant interactions Sorption of anions, cations, and neutral organics by SMZ Mechanisms of surfactant and contaminant sorption by SMZ


Environmental Applications of SMZ
For Contaminant Sorption SMZ permeable barrier test facility SMZ permeable barrier test results SMZ for treatment of oil field wastewaters SMZ for removal of pathogens from sewage For Contaminant Sorption/Destruction SMZ/ZVI pellets for combined sorption/reduction SMZ/ZVI permeable barrier test results SMZ + microorganisms for combined sorption/biodegradation

References
Bowman, R.S. 2002. Applications of surfactant-modified zeolites to environmental remediation. Micoporous Mesoporous Mat. (submitted). For list of SMZ publications and ordering information, click here .

Last Updated: May 5, 2003 by Webmaster.