Lampshade coating designed to purify indoor air
Most people already know that house plants such as pothos help neutralize indoor air pollutants. In the near future, however, a special coating applied to lampshades could serve much the same purpose.
Volatile organic compounds (VOCs) are given off by a variety of household materials, such as carpeting, paint and particleboard. And while they're typically only present in small amounts in most people's homes, over time they can eventually cause eye, nose and throat irritation, headaches, and even damage to the liver, kidneys and central nervous system.
There are air filters that capture VOCs, but they utilize filtration media that periodically has to be replaced. Homeowners can also use devices that incorporate thermocatalysts or photocatalysts, which are compounds that break down VOCs when heated or exposed to light, respectively. Most of these gadgets, however, require a separate heater or source of ultraviolet light.
Led by Dr. Hyoung-il Kim, scientists at South Korea's Yonsei University have now developed a thermocatalyst that can be applied to the inside surface of a lampshade. Composed of titanium dioxide and "a small amount" of platinum, this material is triggered to break down VOCs when warmed by the lamp's existing incandescent or halogen bulb.
In lab tests, the coating was applied to the inside of an aluminum lampshade, then heated to about 250 ºF (121 ºC) by a 100-watt halogen bulb located inside that shade. This setup was placed in a sealed chamber containing air and acetaldehyde gas, the latter of which is a common VOC.
It was found that the coating quickly converted the acetaldehyde gas into acetic acid, then into formic acid, and finally into carbon dioxide and water. Similar results were obtained using an incandescent bulb, and when trying to neutralize formaldehyde. The acids are claimed to be quite mild, and the small amount of carbon dioxide produced is reportedly harmless.
Of course, many household lamps now utilize LED bulbs, which produce very little heat. With that fact in mind, the scientists are looking into compounds that would convert some of an LED's visible light output into heat, along with photocatalysts that would be triggered by near-infrared light emitted by LEDs.
The researchers are also working on a less expensive alternative to platinum, and have already had good results using iron and copper – the latter metal may have the added benefit of killing airborne microorganisms, as copper is known for its antimicrobial properties.
"Our ultimate goal is to develop a hybrid catalyst that can utilize the full spectrum produced by light sources, including UV and visible light, as well as waste heat," said Kim.