Nanoporous metal foam gas and fluid filters

A filtration system comprising:

• a housing;
• a first filter element and a second filter element disposed within an interior of the housing, wherein:
• the second filter element is downstream from the first filter element,
• the first filter element comprises a freeze-cast, polycrystalline metal foam comprising of an interconnected three-dimensional gel ultrafine metallic wire mesh comprising interconnected ultrafine metallic wires that consist of a non-metal-oxide metal, wherein the mesh was formed through a process comprising:
• a formation step consisting of forming a dispersion of the metallic nanowires in a liquid,
• a placement step that consists of placing the dispersion in a form and freezing the dispersion,
• a sublimation step consisting of leaving a structure of interlocked nanowires,
• a bonding step consisting of bonding points of contact between the nanowires,
• the interconnected three-dimensional ultrafine metallic wire mesh comprises a plurality of nanometer to micron scale pores defined by gaps between the interconnected ultrafine metallic wires, and
• the interconnected three-dimensional ultrafine metallic wire mesh is capable of capturing at least some of a plurality of particulates in the flow after the flow passes through the first filter element, and
• the interconnected ultrafine metallic wires have dimensions in the nanometer to micron scale;
• a voltage source electrically coupled to the first filter element that is operable to apply a voltage to the first filter element so that the first filter element functions as an ionization grid capable of charging at least some of the plurality of particulates that are neutral particulates in the flow as the flow passes through the first filter element, resulting in the plurality of neutral particulates becoming a plurality of charged particulates;
• and
• a second filter element disposed within the interior of the housing that is downstream from the first filter element through which the flow passes, wherein:
• the flow comprises the plurality of charged particulates,
• the second filter element comprises a coated metal foam that is operable to trap at least some of the plurality of charged particulates within the pores of the coated metal foam, and
• the coated metal foam comprises an interconnected ultrafine metallic wire network coated with a catalytic metal oxide or carbon.

A method of removing particulates and contaminants from a flow, the method comprising:

• intaking the flow via an intake port of a filter housing;
• filtering the particulates and contaminants from the flow through a first filter element comprising a freeze-cast, polycrystalline metal foam that comprises of an interconnected three-dimensional ultrafine metallic wire mesh comprising interconnected ultrafine metallic wires that consist of a non-metal-oxide metal, wherein:
• interconnections of interconnected ultrafine metallic wires of said interconnected ultrafine metallic wire mesh are bonded, and
• the interconnected ultrafine metallic wire mesh comprises a plurality of nanometer to micron scale pores defined by gaps between the interconnected ultrafine metallic wires,
• the interconnected ultrafine metallic wires have dimensions in the nanometer to micron scale, and
• the interconnected ultrafine metallic wire mesh captures at least some of the particulates and the contaminants from the flow and
• wherein the mesh was formed through a process comprising:
• a formation step consisting of forming a dispersion of the metallic nanowires in a liquid,
• a placement step that consists of placing the dispersion in a form and freezing the dispersion,
• a sublimation step consisting of leaving a structure of interlocked nanowires,
• a bonding step consisting of bonding points of contact between the nanowires,
• applying a voltage using a voltage source coupled to the first filter element so that the first filter element functions as an ionization grid capable of charging at least some of the particulates and the contaminants that are neutral particulates in the flow as the flow passes through the first filter element, resulting in the neutral particulates becoming a plurality of charged particulates;
• and
• filtering at least some of the plurality of charged particulates in the flow using a second filter element disposed within the interior of the filter housing that is downstream from the first filter element through which the flow passes, wherein:
• the second filter element comprises a coated metal foam that is operable to trap at least some of the plurality of charged particulates within the pores of the coated metal foam, and
• the coated metal foam comprises an interconnected ultrafine metallic wire network coated with a catalytic metal oxide or carbon.