A mesoporous silicate has been developed for the removal of volatile organic compounds (VOCs). The indoor air pollutants of interest were formaldehyde, toluene, ethylbenzene, o-xylene, cumene and dichlorobenzene. The indoor air pollutants were actively sampled onto (i) Tenax filled sampling tubes and subsequently analysed by thermal desorption gas chromatography mass spectrometry or (ii) chemically modified Cāā silica cartridges analysed by high performance liquid chromatography ultraviolet spectroscopy. A pollutant atmosphere suitable for testing the sorbents chambers were created in-house. Mesoporous silicates were synthesised to control the surface area, pore size and pore volume of the material. Several preparation methods were used to produce the final mesoporous silicate sorbent. The mesoporous silicates were mainly synthesised using tetraethyl orthosilicate as a precursor with either a quaternary ammonia silicate or triblock copolymer as the organic template synthesising MCM-41 and SBA-I5, respectively. A selection of the successfully synthesised mesoporous silicates were modified with propyl amine to investigate the possibility of formaldehyde chemisorption. Material characterisation was performed using powder x-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption and elemental analysis. Sorbents were selected for adsorption efficiency testing based on the characterisation results. The synthesised mesoporous sorbent VOC and formaldehyde adsorption efficiencies were then compared with commercially available sorbents. It was observed that the commercial sorbents were inefficient at adsorbing both the formaldehyde and the selected VOCs. The modified sorbents adsorbed formaldehyde strongly compared to the unmodified parent sorbent. However when using the modified mesoporous silicate an unwanted release of toluene was also recorded. Simulated closed environments were generated with the selected VOCs. SBA-15 was efficient in reducing the VOC chamber concentration over a period of 2 hours. SBA -15 adsorbed ethylbenzene, cumene and dichlorobenzene with efficiency rates of 89.4, 99.9 and 97.7 %, respectively. The adsorption efficiency for toluene was reduced at 35.4 %.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:487873 |
| Date | January 2008 |
| Creators | Robertson, Claire J. |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21847 |
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