Cigarette filter

While laboratory tests show a reduction of "tar" and nicotine in cigarette smoke, filters are ineffective at removing gases of low molecular weight, such as carbon monoxide.

[2] In 1925, Hungarian inventor Boris Aivaz patented the process of making a cigarette filter from crepe paper.

It was considered a specialty item until 1954, when manufacturers introduced the machine more broadly, following a spate of speculative announcements from doctors and researchers concerning a possible link between lung diseases and smoking.

Of the three cellulose hydroxy groups available for esterification, between two and three are esterified by controlling the amount of acid (degree of substitution (DS) 2.35-2.55).

[12][13] The five largest manufactures of filter tow are Celanese and Eastman Chemicals in the United States, Cerdia in Germany, Daicel and Mitsubishi Rayon in Japan.

The pH of the cellulose acetate used is modified, so that its colour becomes darker when exposed to smoke (this was invented in 1953 by Claude Teague,[1] working for R. J. Reynolds Tobacco Company).

[19] Various add-on cigarette filters ("Water Pik", "Venturi", "David Ross") are sold as stop-smoking or tar-reduction devices.

The idea is that filters reduce tar and nicotine levels, permitting the smoker to be weaned away from cigarettes.

Cellulose acetate is hydrophilic and retains the water-soluble smoke constituents (many of which are irritating, including acids, alkali, aldehydes, and phenols), while letting through the lipophilic aromatic compounds.

After cigarette butts are discarded, they can leach toxins including nicotine, arsenic, polycyclic aromatic hydrocarbons and heavy metals into the environment.

Humans cannot digest cellulose and excrete the fibers in feces, because, unlike ruminant animals, rabbits, rodents, termites, and some bacteria and fungi, they lack cellulolytic enzymes such as cellulase.

Others have suggested banning the sale of filtered cigarettes altogether on the basis of their adverse environmental impact.

[24] Recent research has been put into finding ways to use the filter waste in order to develop other products.

One research group in South Korea have developed a one-step process that converts the cellulose acetate in discarded cigarette filters into a high-performing supercapacitor electrode material.

[33] Another group of researchers has proposed adding tablets of food grade acid inside the filters.

Instead of acetate or cardboard filters, it consists of two ceramic caps on either sides containing activated charcoal, which reduces tar and other toxins in the smoke.