ABSTRACT
A new class of high-performance nanoporous sorbents has been developed for heavy metal removal that overcomes the deficiencies of existing technologies. These novel materials are created from a combination of synthetic nanoporous ceramic substrates that have specifically tailored pore sizes (2 to 10 nm) and very high surface areas (-1000 m2/g) with self-assembled monolayers of well-ordered functional groups that have high affinity and specificity for specific types of free or complex cations or anions. These sorbents known as SAMMS™ (Self-Assembled Monolayers on Mesoporous Silica) are hybrids of two frontiers in materials science: molecular self-assembly techniques and nanoporous materials. One form of SAMMS™ containing monolayers of mercaptopropyl-trismethoxy silane has shown exceptional sorptive properties for mercury and other soft cations such as silver, cadmium, and lead. Another form of SAMMS™ with a functional monolayer consisting of ethylenediamine-Cu(II) complex (Cu-EDA) specifically adsorbs tetrahedral oxyanions such as arsenate, selenate, molybdate, chromate and pertechnetate even in the presence of high concentrations of sulfate. Separation of actinides can be addressed by SAMMS™ material synthesized with a set of monolayer functionalities consisting of hydroxypyridinones, acetamide and propinamide phosphonates. These nanoporous sorbents offer a better choice for efficient and cost-effective removal contaminants from diverse waste streams.
