System and method for photoelectrochemical air purification

Abstract

An air purification system including a filter assembly including a substrate including a fibrous media, and a photocatalytic material disposed on the substrate, wherein the photocatalytic material includes a first quantity of crushed nanostructures; and a photon source arranged to illuminate the photocatalytic material with optical radiation.

We claim: 
     
         1 . A filter system, comprising:
 a filter medium;   an active composition, attached to the filter medium, that oxidizes organic material when the active composition is illuminated with nonionizing radiation, wherein the active composition comprises a mixture of:
 a plurality of nanospheroids, wherein a characteristic size for each nanospheroid of the plurality of nanospheroids is distributed according to a first size distribution; and 
 a plurality of postprocessed nanorods, wherein a characteristic size for each postprocessed nanorod of the plurality of postprocessed nanorods is distributed according to a second size distribution; 
 wherein the second size distribution is broader than the first size distribution; and 
   a light source configured to illuminate the active composition with nonionizing radiation, wherein the nonionizing radiation comprises photons, each photon having a wavelength greater than 280 nm.   
     
     
         2 . The system of  claim 1 , further comprising a support structure attached to the filter medium, wherein the support structure is electrically conductive, wherein the active composition is electrically coupled to the support structure. 
     
     
         3 . The system of  claim 1 , wherein a mass ratio of the plurality of nanospheroids to the plurality of crushed nanorods is at least one. 
     
     
         4 . The system of  claim 1 , wherein the filter system is incorporated into an air filtration system, the air filtration system comprising:
 a housing defining an air flow path between an inlet and an outlet of the housing, wherein the housing comprises a filter attachment region, wherein the filter medium is connected to the housing via the filter attachment region such that the filter medium intersects the air flow path; and   an impeller module connected to the housing, wherein the impeller module is configured to drive air flow along the air flow path.   
     
     
         5 . A filter system comprising:
 a support structure that is electrically conductive;   a filter medium connected to the support structure; and   an active material attached to the filter medium, wherein the active material is electrically coupled to the support structure, wherein the active material is configured to oxidize organic materials adjacent to the active material when the active material is illuminated with nonionizing radiation output by a light source, wherein the active material comprises a plurality of crushed nanocrystals.   
     
     
         6 . The system of  claim 5 , wherein the active material further comprises a second plurality of nanocrystals. 
     
     
         7 . The system of  claim 6 , wherein a ratio of the plurality of crushed nanocrystals to the second plurality of nanocrystals is at most one. 
     
     
         8 . The system of  claim 7 , wherein the ratio is one to nine. 
     
     
         9 . The system of  claim 6 , wherein the second plurality of nanocrystals comprises nanospheroids. 
     
     
         10 . The system of  claim 6 , wherein a characteristic size for each nanocrystal of the second plurality of nanocrystals is distributed according to a Gaussian distribution. 
     
     
         11 . The system of  claim 10 , wherein an expected value of the Gaussian distribution is 25 nanometers (nm). 
     
     
         12 . The system of  claim 5 , wherein the active material consists essentially of a metal oxide. 
     
     
         13 . The system of  claim 5 , wherein the plurality of crushed nanocrystals comprises at least one of crushed nanotubes, crushed nanorods, and crushed nanowires. 
     
     
         14 . The system of  claim 5 , wherein each crushed nanocrystal of the plurality of crushed nanocrystals corresponds to a characteristic size, wherein the characteristic size corresponds to at least one of a crystal grain size, a length, a diameter, and a distance between cracks. 
     
     
         15 . The system of  claim 14 , wherein the plurality of crushed nanocrystals defines a mollified uniform distribution of characteristic sizes of crushed nanocrystals. 
     
     
         16 . The system of  claim 14 , wherein the characteristic size for each crushed nanocrystal from the plurality of crushed nanocrystals is between about 50 and about 250 nanometers (nm). 
     
     
         17 . The system of  claim 5 , wherein each crushed nanocrystal absorbs light according to a light absorption spectrum, wherein the light absorption spectrum is based on the characteristic size of the crushed nanocrystal, and wherein the light absorption spectrum for a crushed nanocrystal having a characteristic size equal to a peak of a distribution of characteristic sizes of the plurality of crushed nanocrystals corresponds to a wavelength of the nonionizing radiation. 
     
     
         18 . The system of  claim 5 , wherein the nonionizing radiation consists of wavelengths equal to or longer than 280 nm. 
     
     
         19 . The system of  claim 5 , wherein the filter system is incorporated into an air filtration system, the air filtration system comprising:
 a housing defining an air flow path between an inlet and an outlet of the housing, wherein the housing comprises a filter attachment region, wherein the filter medium is connected to the housing via the filter attachment region such that the filter medium intersects the air flow path; and   an impeller module connected to the housing, wherein the impeller module is configured to drive air flow along the air flow path.   
     
     
         20 . The system of  claim 19 , wherein the light source is coupled to the housing, and wherein the filter medium is arranged concentrically around the light source.