End use applications for Mesoporous Silica

Application area 4: Removal of Volatile Organic Carbons (VOCs) from Indoor air using Porous Silica Particles

In recent years indoor air pollution has become a major concern due to its well demonstrated effect on human health. The adverse health effects of indoor air pollution are expected to become more significant as lifestyles are predicted to become even more sedentary. In 2001, this was demonstrated in the national human activity pattern survey (NHAPS), where it was shown that US citizens typically spent 90% of their time indoors. Aldehydes in particular have adverse health effects (eye and lung irritation), and formaldehyde and acrolein are suspected carcinogens. Changes in building design and improved energy efficiency, along with maximising insulation and minimising air exchange, have led to increasingly airtight buildings. Modern synthetic building materials, such as sealants, plastics and solvent-based coatings, have further added to the problem of indoor air pollutants. Volatile organic compounds (VOCs), non-volatile organic compounds (NVOCs) and semi-volatile organic compounds (SVOCs) are of particular concern as indoor pollutants.

Recent work has shown that Porous Silica Spheres (PSS) can be used to efficiently trap various indoor air pollutants, both in a simulated environment and in an indoor environment. The adsorbent was tested at relatively high concentrations (500 ppbV) and flow rates (10 L min_1). It was shown that PSS was found to be more efficient than the commercially available Amberlite XAD-4 resin at trapping non-polar VOCs and significantly more efficient at trapping polar VOCs present in ambient air. PSS adsorbent was shown to trap 100% of the gas phase carbonyl compounds present in a simulation chamber experiment in the first 10 min of sampling, while the XAD-4 resin was shown to have various levels of efficiency ranging from 100 to 8% over the sampling period for the same group of carbonyl compounds. The indoor at trapping polar carbonyls than XAD-4 resin in an indoor environment. Specifically, SSPH was shown to be significantly more efficient than the XAD-4 resin at trapping glyoxal, C5 and C6 unsaturated carbonyls.