Abstract: Extraction of platinum-group elements, e.g. Pd, by adsorption from acidic aqueous solutions, using chelating acrylic fibers having amidoxime substituents followed by recovery by elution with an HCl-thiourea solution. From about 10% to 100% of the acrylic fiber CN are converted to amidoxime by reaction with NH2OH (hydroxylamine) in H2O/MeOH solution in the range of 30° C.-90° C. for from 15 min to 72 hrs. The adsorptive loading of elements onto the fiber and the efficiency of elution therefrom is substantially 100%, in multiple cycles of adsorption/elution. The novel fiber/extraction process is rapid, lending it to a continuous recovery operation. A portion of the CN groups of may be converted to carboxylate groups by reaction with NaOH. Short lengths of fiber are loaded into a vertical column and the pregnant solution introduced. Upon breakthrough, the fibers may be eluted, washed and recycled hundreds of times without removal from the column.

Abstract: A metals-adsorbent PAN fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. No ester groups are present. The inventive fiber is used for removing metals, including toxic metals, from fresh water, including rivers, streams, lakes, ponds, drinking water from wells and other sources, and industrial discharge waste waters, in a pH range of 3-10, and preferably at slightly acidic conditions in the range of pH 5-6. Metals that can be removed include heavy and toxic metals, such as Sc, V, Mn, Fe, Co, Ni, Cu, Sr, Yb, Cd, Cs, Pb, La, Ce, Nd, Eu, Zn, Tb and U. The adsorbed metals can be removed from the fiber by acidic elution and recovered. The fiber can be rinsed and reused.

Abstract: Extraction of platinum-group elements, e.g. Pd, by adsorption from acidic aqueous solutions, using chelating acrylic fibers having amidoxime substituents followed by recovery by elution with an HCl-thiourea solution. From about 10% to 100% of the acrylic fiber CN are converted to amidoxime by reaction with NH2OH (hydroxylamine) in H2O/MeOH solution in the range of 30° C.-90° C. for from 15 min to 72 hrs. The adsorptive loading of elements onto the fiber and the efficiency of elution therefrom is substantially 100%, in multiple cycles of adsorption/elution. The novel fiber/extraction process is rapid, lending it to a continuous recovery operation. A portion of the CN groups of may be converted to carboxylate groups by reaction with NaOH. Short lengths of fiber are loaded into a vertical column and the pregnant solution introduced. Upon breakthrough, the fibers may be eluted, washed and recycled hundreds of times without removal from the column.

Abstract: A metals-adsorbent PAN fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. No ester groups are present. The inventive fiber is used for removing metals, including toxic metals, from fresh water, including rivers, streams, lakes, ponds, drinking water from wells and other sources, and industrial discharge waste waters, in a pH range of 3-10, and preferably at slightly acidic conditions in the range of pH 5-6. Metals that can be removed include heavy and toxic metals, such as Sc, V, Mn, Fe, Co, Ni, Cu, Sr, Yb, Cd, Cs, Pb, La, Ce, Nd, Eu, Zn, Tb and U. The adsorbed metals can be removed from the fiber by acidic elution and recovered. The fiber can be rinsed and reused.

Abstract: A fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. The fiber may be used for removing uranium from seawater and toxic metals from drinking water.

Abstract: A method of recovering rare earth elements from a rare earth-containing material comprises contacting the rare earth-containing material with a solution formulated and configured to dissolve rare earth elements from the rare earth-containing material and form a solution including a plurality of rare earth elements dissolved therein. The method further includes exposing the solution including the plurality of rare earth elements dissolved therein to one of a liquefied gas or a supercritical fluid to isolate the rare earth elements from each other. Related methods of removing and purifying rare earth elements from materials and phosphor lamps are also disclosed.

Abstract: A method of recovering rare earth elements from a rare earth-containing material comprises contacting the rare earth-containing material with a solution formulated and configured to dissolve rare earth elements from the rare earth-containing material and form a solution including a plurality of rare earth elements dissolved therein. The method further includes exposing the solution including the plurality of rare earth elements dissolved therein to one of a liquefied gas or a supercritical fluid to isolate the rare earth elements from each other. Related methods of removing and purifying rare earth elements from materials and phosphor lamps are also disclosed.

Abstract: A fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. The fiber may be used for removing uranium from seawater and toxic metals from drinking water.

Abstract: Methods of increasing the solubility of a base in supercritical carbon dioxide include forming a complex of a Lewis acid and the base, and dissolving the complex in supercritical carbon dioxide. The Lewis acid is soluble in supercritical carbon dioxide, and the base is substantially insoluble in supercritical carbon dioxide. Methods for increasing the solubility of water in supercritical carbon dioxide include dissolving an acid or a base in supercritical carbon dioxide to form a solution and dissolving water in the solution. The acid or the base is formulated to interact with water to solubilize the water in the supercritical carbon dioxide. Some compositions include supercritical carbon dioxide, a hydrolysable metallic compound, and at least one of an acid and a base. Some compositions include an alkoxide and at least one of an acid and a base.

Abstract: Methods of increasing the solubility of a base in supercritical carbon dioxide include forming a complex of a Lewis acid and the base, and dissolving the complex in supercritical carbon dioxide. The Lewis acid is soluble in supercritical carbon dioxide, and the base is substantially insoluble in supercritical carbon dioxide. Methods for increasing the solubility of water in supercritical carbon dioxide include dissolving an acid or a base in supercritical carbon dioxide to form a solution and dissolving water in the solution. The acid or the base is formulated to interact with water to solubilize the water in the supercritical carbon dioxide. Some compositions include supercritical carbon dioxide, a hydrolysable metallic compound, and at least one of an acid and a base. Some compositions include an alkoxide and at least one of an acid and a base.

Abstract: Methods of increasing the solubility of a base in supercritical carbon dioxide include forming a complex of a Lewis acid and the base, and dissolving the complex in supercritical carbon dioxide. The Lewis acid is soluble in supercritical carbon dioxide, and the base is substantially insoluble in supercritical carbon dioxide. Methods for increasing the solubility of water in supercritical carbon dioxide include dissolving an acid or a base in supercritical carbon dioxide to form a solution and dissolving water in the solution. The acid or the base is formulated to interact with water to solubilize the water in the supercritical carbon dioxide. Some compositions include supercritical carbon dioxide, a hydrolysable metallic compound, and at least one of an acid and a base. Some compositions include an alkoxide and at least one of an acid and a base.

Abstract: Methods of increasing the solubility of a base in supercritical carbon dioxide include forming a complex of a Lewis acid and the base, and dissolving the complex in supercritical carbon dioxide. The Lewis acid is soluble in supercritical carbon dioxide, and the base is substantially insoluble in supercritical carbon dioxide. Methods for increasing the solubility of water in supercritical carbon dioxide include dissolving an acid or a base in supercritical carbon dioxide to form a solution and dissolving water in the solution. The acid or the base is formulated to interact with water to solubilize the water in the supercritical carbon dioxide. Some compositions include supercritical carbon dioxide, a hydrolysable metallic compound, and at least one of an acid and a base. Some compositions include an alkoxide and at least one of an acid and a base.

Abstract: Metal and/or silicon oxides are produced by hydrolysis of alkoxide precursors in the presence of either an acid catalyst or a base catalyst in a supercritical fluid solution. The solubility of the acid catalysts in the supercritical fluid can be increased by complexing the catalyst with a Lewis base that is soluble in the supercritical fluid. The solubility of the base catalysts in the supercritical fluid can be increased by complexing the catalyst with a Lewis acid that is soluble in the supercritical fluid. The solubility of water in the solution is increased by the interaction with the acid or base catalyst.

Abstract: A method for depositing one or more materials on a substrate, such as for example, a semiconductor substrate that includes providing the substrate; applying a polymer film to at least a portion of a surface of the substrate; and exposing the semiconductor substrate to a supercritical fluid containing at least one reactant for a time sufficient for the supercritical fluid to swell the polymer and for the at least one reactant to penetrate the polymer film. The reactant is reacted to cause the deposition of the material on at least a portion of the substrate. The substrate is removed from the supercritical fluid, and the polymer film is removed. The process permits the precise deposition of materials without the need for removal of excess material using chemical, physical, or a combination of chemical and physical removal techniques.

Abstract: Embodiments of a method and a system for recovering a metal, such as uranium, from a metal-containing material are disclosed. The metal-containing material is exposed to an extractant containing a liquid or supercritical-fluid solvent and an acid-base complex including an oxidizing agent and a complexing agent. Batches of the metal-containing material are moved through a series of stations while the extractant is moved through the stations in the opposite direction. After the extraction step, the metal is separated from the solvent, the complexing agent and/or other metals by exposing the extract to a stripping agent in a countercurrent stripping column. The complexing agent and the solvent exit the column and are separated from each other by reducing the pressure. The recovered complexing agent is recharged with fresh oxidizing agent and recombined with fresh or recovered solvent to form a recovered extractant, which is distributed through the extraction stations.

Abstract: A method for depositing one or more materials on a substrate, such as for example, a semiconductor substrate that includes providing the substrate; applying a polymer film to at least a portion of a surface of the substrate; and exposing the semiconductor substrate to a supercritical fluid containing at least one reactant for a time sufficient for the supercritical fluid to swell the polymer and for the at least one reactant to penetrate the polymer film. The reactant is reacted to cause the deposition of the material on at least a portion of the substrate. The substrate is removed from the supercritical fluid, and the polymer film is removed. The process permits the precise deposition of materials without the need for removal of excess material using chemical, physical, or a combination of chemical and physical removal techniques.

Abstract: A method for depositing one or more materials on a substrate, such as for example, a semiconductor substrate that includes providing the substrate; applying a polymer film to at least a portion of a surface of the substrate; and exposing the semiconductor substrate to a supercritical fluid containing at least one reactant for a time sufficient for the supercritical fluid to swell the polymer and for the at least one reactant to penetrate the polymer film. The reactant is reacted to cause the deposition of the material on at least a portion of the substrate. The substrate is removed from the supercritical fluid, and the polymer film is removed. The process permits the precise deposition of materials without the need for removal of excess material using chemical, physical, or a combination of chemical and physical removal techniques.

Abstract: Embodiments of nanostructures and nanocomposites and embodiments of methods for forming and modifying these nanostructures and nanocomposites are disclosed. The methods can include transporting a metal, metallic compound or precursor to a surface of a nanostructure substrate in a carrier while the carrier is in supercritical fluid form. Embodiments of the disclosed methods can be used to form catalytic structures, such as catalytic structures including nanostructure supports and catalytic metallic nanoparticles attached to the nanostructure supports. These catalytic structures are useful for catalyzing reactions in fuel cell applications, such as oxygen reduction and methanol oxidation reactions. Some of the disclosed nanostructures and nanocomposites include carbon nanotubes.

Abstract: The invention includes a method of forming a metal-containing film over a surface of a semiconductor substrate. The surface is exposed to a supercritical fluid. The supercritical fluid has H2, at least one H2-activating catalyst, and at least one metal-containing precursor dispersed therein. A metal-containing film is formed across the surface of the semiconductor substrate from metal of the at least one metal-containing precursor. The invention also includes semiconductor constructions having metal-containing layers which include one or more of copper, cobalt, gold and nickel in combination with one or more of palladium, platinum, iridium, rhodium and ruthenium.

Abstract: The invention includes a method of forming a metal-containing film over a surface of a semiconductor substrate. The surface is exposed to a supercritical fluid. The supercritical fluid has H2, at least one H2-activating catalyst, and at least one metal-containing precursor dispersed therein. A metal-containing film is formed across the surface of the semiconductor substrate from metal of the at least one metal-containing precursor. The invention also includes semiconductor constructions having metal-containing layers which include one or more of copper, cobalt, gold and nickel in combination with one or more of palladium, platinum, iridium, rhodium and ruthenium.