Sponge-like Porous Photocatalytic Filter for Visible Light Purification
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Solution Overview
Problem
Conventional three-dimensional ceramic filters are not designed to transmit light, leading to poor photocatalytic action under visible light, and existing photocatalytic filters face challenges in efficiently purifying polluted air and water without electricity, especially under visible light sources.
Innovation Solution
A visible-light-responsive three-dimensional fine cell-structured photocatalytic filter with a sponge-like porous structure coated with anatase-type titanium oxide, manufactured by immersing a porous structural body in a titanium oxide solution and firing it in an oxidizing atmosphere, allowing for efficient photocatalytic action under visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional three-dimensional ceramic filters are used, then structural strength is maintained, but light transmission is poor and photocatalytic action under visible light is insufficient
Solution Approach 1:
The patent employs a sponge-like porous structural body with high porosity (85 vol% or more) as the base material. This porous structure allows light to penetrate deeply into the filter while maintaining mechanical integrity through the three-dimensional network of interconnected pores and struts. The porous architecture increases the surface area for photocatalyst deposition and improves light transmission compared to conventional dense ceramic filters.
Solution Approach 2:
The filter is constructed as a composite material system combining the sponge-like porous structural body (providing mechanical strength and light transmission) with coated titanium oxide photocatalyst particles (providing photocatalytic activity). This composite structure integrates the beneficial properties of both components: the porous substrate provides structural support and optical properties, while the photocatalyst coating provides pollution degradation functionality.
2Reliability
If titanium oxide powder is used directly, then photocatalytic activity is high, but the powder scatters in gas or fluid and cannot be conveniently used
Solution Approach 1:
The titanium oxide photocatalyst is not uniformly distributed throughout the filter but is locally concentrated on the surface of the sponge-like porous structural body. This localized deposition ensures that the photocatalyst remains in fixed position for convenient operation while maintaining high photocatalytic activity at the surface where it contacts the polluted air or water flowing through the filter.
Solution Approach 2:
The photocatalyst is applied as a thin coating layer on the porous structural body surface. This thin film approach allows the photocatalyst to remain attached to the substrate (preventing scattering) while still providing adequate catalytic surface area for effective pollution degradation. The coating is thin enough to allow light penetration to activated photocatalyst sites.
3Ease of manufacture
If fine hollow glass spheres coated with titanium oxide are used, then ease of manufacture is improved, but sufficient ultraviolet light cannot reach the titanium oxide for effective photocatalysis
Solution Approach 1:
The sponge-like porous structural body provides an open three-dimensional network with 85 vol% or more porosity, allowing light to penetrate deeply into the interior of the filter. This contrasts with fine hollow glass spheres which can block light paths. The porous architecture ensures that ultraviolet and visible light can reach photocatalyst coating sites throughout the filter volume, not just at the exterior surface.
4Reliability
If conventional filters are designed for mechanical filtration, then filtration function is achieved, but photocatalytic action under visible light is not optimized
Solution Approach 1:
The filter is designed to perform multiple functions simultaneously: mechanical filtration of particles, photocatalytic degradation of organic pollutants and toxic substances, and operation under both ultraviolet and visible light. The sponge-like porous structure provides mechanical filtration capability while the titanium oxide coating enables photocatalytic action. The high porosity and light transmission properties enable visibility light responsiveness, making the filter adaptable to various lighting conditions including natural sunlight.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The filter enables high-efficiency photocatalytic purification of pollutants in air and water under visible light, expanding the use of photocatalysts beyond electricity-dependent systems and improving mechanical strength and light transmission.
Implementation Method 1
titanium oxide shows strong oxidation on its surface due to photocatalytic action
Implementation Method 2
titanium oxide is placed in sunlight or under a fluorescent lamp, especially at ultraviolet wavelengths
Implementation Method 3
immersing a porous structural body in a titanium oxide solution and firing it in an oxidizing atmosphere
Implementation Method 4
firing it in an oxidizing atmosphere
Data Source
AI summary
A visible-light-responsive three-dimensional fine cell-structured photocatalytic filter in accordance with the present invention includes a sponge-like porous structure (B) containing an anatase-type titanium oxide coating formed on a surface of a sponge-like porous structural body (A) which has a porosity of 85 vol % or more. The sponge-like porous structural body (A) is composed of one material selected from the group consisting of one metal selected from the group consisting of (a) to (e): (a) carbon and either or both of silicon and a silicon alloy; (b) silicon carbide and at least one material selected from the group consisting of silicon, a silicon alloy, and carbon; (c) silicon nitride and at least one material selected from the group consisting of silicon, a silicon alloy, carbon, and silicon carbide; (d) carbon; and (e) carbon and one metal selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, silver, platinum, and gold.