This week, news came out of China that nanomaterials made from titanium dioxide, (TiO2), can be used in cigarette filters to reduce the amount of harmful chemicals inhaled by smokers. The researchers suggest that this may be a cheaper alternative than carbon-based nanomaterials. This development could make smoking safer than what it is now but it doesn’t make smoking a safe activity. However, if it does become safer, that’s not something to be seen as encouraging people to take up smoking. I see it as a development due to the recognition that smoking is unsafe and perhaps it might mean that people like my grandfather horribly addicted to cigarettes won’t develop cancer before my PhD graduation, (the fact that I have to yet enroll in a PhD program is irrelevant but I am heading in that direction).
Currently cigarette filters are made from cellulose acetate. These filters absorb some of the toxic compounds like tar and nicotine. There has been research done to improve the filters by adding carbon nanotubes and mesoporous silica to increase the absorption of these chemicals but they are costly and pose unknown health risks.
A research team at Fuzhou University in the Fujian province together with the Fujian Tobaccon Industrial Corporation, Xiamen, developed titanate nanosheets and nanotubes with the ability to filter tobacco smoke. It was found that a range of compounds including, tar, nicotine, ammonia, hydrogen cyanide, and some carbonyls and phenolic compounds were absorbed efficiently. The materials were synthesised using TiO2 as a precursor which is widely and readily available. It is used already in a wide variety of products like sunscreen, cosmetics, and food, which boosts the confidence of the team’s beliefs that these filters do not pose a risk to smokers by inhalation.
The team tested the nanosheets and nanotubes by adding them to the filter tips of cigarettes and machine smoking them. The smoke particles and chemicals were then captured on filter pads which were then tested by using ion chromatography and high performance liquid chromatography to measure the amount of captured chemicals. The results indicated that the nanotubes were twice as efficient as the sheets as filters.
It was concluded that the difference in results was related to the properties of the two materials as the tubes were made of crystalline multilayer walls resembling a chromatography column on the nanoscale whereas the sheets were sheep shaped. This implies that there would be a larger amount of reactive areas to capture the toxic chemicals in tubes than the sheets. However the explanation may be much simpler than that and that it could be due to the difference in surface area of the structures as suggested by Dmitry Bavykin who investigates titanate nanomaterials at the University of Southampton, in an interview with Chemistry World Blog.
Whatever the reason may be, this development does not make smoking safe, just safer.
- Titanate cigarette filter could be safer (physorg.com)