Preparation of agar-nano-SiO₂ aerogels and their application to cigarette filter

In order to develop new materials for reducing harmful components in cigarette smoke, a series of agar-nano-SiO₂ aerogels was prepared by agar matrix and nano-SiO₂ powder through a sol-gel process. The morphology and microstructure of the aerogels were characterized, the adsorption property of the aerogels to crotonaldehyde in the simulated smoke was studied, and the application effect of the agar-SiO₂-60% (the mass fraction of nano-SiO₂ in aerogel was 60%) in the cigarette filter was investigated. The results showed that:1) The agar-nano-SiO₂ aerogels presented three-dimensional network porous structure with a specific surface area of 73.62-424.75 m²/g and the average pore size of 23.46-10.38 nm. 2) The amount of adsorbed crotonaldehyde increased from 1.65 mg/g to 3.13, 4.35, 8.91 and 13.80 mg/g when the mass fraction of nano-SiO₂ in aerogels increased from 0 to 20%, 40%, 60% and 80%, respectively. 3) When agar-SiO₂-60% was added to the dual-segment filtered cigarette at a rate of 30 mg/cig, the effects on the release of tar, nicotine and CO were negligible, and the release of NNK, NH₃ and crotonaldehyde was reduced by 12.8%, 11.3% and 9.5%, respectively. The overall hazard index of the test cigarette was decreased by 0.6, and the sensory quality of cigarette was unchanged.