Membranes, sensors, and other functional materials
Besides catalysts, we also design and develop a number of other
types of functional materials, including ion exchangers
for ion trapping, inorganic membranes and chiral membranes for gas or liquid separations, and nano-scale molecular sensors.
Ion exchangers for ion trapping
Sponsor: DOE/EM
Contact: Jim Miller
In a collaborative effort with Texas A&M University, Sandia
researchers have invented and developed a new crystalline silicotitanate
ion exchanger that is capable of removing parts-per-million levels
of cesium from highly alkaline solutions containing molar concentrations
of sodium (see Figure 4). They are also highly effective at removing
cesium from neutral and acidic solutions and at removing strontium
from basic and neutral solutions. The materials have been commercialized
through a cooperative research and development effort with UOP
as IONSIV® IE-910 and IE-911 ion exchangers. This project
was the recipient of an R&D 100 Award in 1996.
IONSIV® IE-910 and IE-911 are ideal materials for
separating radioactive cesium and strontium from the millions
of gallons of waste such as those found at the Hanford Nuclear
Reservation in Washington state, Oak Ridge in Tennessee, Savannah
River in South Carolina and other Department of Energy (DOE) sites.
At the Hanford site, 177 underground storage tanks are currently
being used to store approximately 65 million gallons of radioactive
waste containing more than 165 million curies of radioactivity.
Sixty seven of the tanks are presumed to have leaked or be leaking.
Much of the radioactivity in the waste is due to the presence
of isotopes of cesium and strontium. An independent review team
has estimated that over 300 million dollars could be saved by
applying CST technology rather than the baseline technology to
the Hanford cleanup.
A novel antimony titanate material, with high selectivity for
the adsorption of strontium under extreme conditions (pH 0.5 -
14) has been synthesized and characterized. Comparisons between
the titanate and doped titanate phases reveals a phase change
that is necessary for the enhanced selectivity toward strontium
in highly acidic conditions. Results have been obtained for the
material in batch ion exchange tests conducted at various solution
pH values and in the presence of a number of competing cations.
Promising results from a continuous flow column ion exchange
experiments in both HNO3 and Hanford waste simulant
(B-110) have led to further investigations.
Molecular model of crystalline silicotitanate showing pore structure |  |
Designed Molecular Recognition Materials for Chiral Sensors, Separations and Catalytic Materials
Sponsor: LDRD (internal Sandia R&D support)
Contacts: Tina Nenoff , John Shelnutt
Our goal is the development of materials that are highly sensitive
and selective for chiral chemicals and biochemicals (such as insecticides,
herbicides, proteins, and nerve agents) to be used as sensors,
catalysts and separations membranes. Computer molecular modeling
methods are used in the design of these materials, especially
in the chiral surface-modifying agents. Molecular modeling is
also being used to predict the catalytic and separations selectivities
of the modified mesoporous materials. Synthetically, we are using
chiral organic molecules as templating agents, around which we
will build inorganic frameworks, with the predetermined size,
shape and chirality incorporated. Furthermore, we are successfully
ìattachingî designed chiral metalloporphyrins to
substrates of various controlled pore size and dimension for separations
studies.
Engineered mesoporous structure with functionalized molecular coating for chiral separations |  |
Selective Inorganic Thin Films
Sponsor: DOE/EERE/OTT
Contacts: Tina Nenoff
In this project we synthesize and model permeability of shape-selective
molecular sieve membranes for xylene separation, and continue
in our development of inorganic molecular sieve membranes for
light gas separations. In addition, we are augmenting the project
to include investigating catalytic properties of xerogel- and
aerogel-supported metal nanoclusters, and synthesizing high surface
area catalyst supports with improved stability at high temperatures
(> 1000°C).
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Last modified: April 23, 1997