Periodic Reporting for period 1 - ASPAir (Accelerated Synthesis of Nanoporous Photocatalysts for Indoor Air Purification)
Période du rapport: 2016-09-01 au 2018-08-31
Perhaps surprisingly, indoor air contains a greater number of Volatile Organic Carbons (VOCs), and at concentrations higher than outdoor air. Although the concentrations of these compounds are in the parts per billion (ppb) range, and with people spending up to 80% of their time indoors, continued exposure to VOCs, many of which are mutagenic or carcinogenic, can lead to ill health. Commercial photocatalytic air purifiers utilise UV light and titanium dioxide to purify air, however the effectiveness of this can be questioned, due to the challenge in measuring such low concentrations of pollutants; it could be that instead of destroying the pollutant, the air purifier is simply transforming one pollutant to another. There is therefore an excellent opportunity to improve this technology by fabricating next generation air purification photocatalysts. The project directly addresses this challenge through the investigation of next-generation nanoporous materials, namely, metal-organic frameworks (MOFs). MOFs consist of metal ions or clusters coordinated to multidentate organic ligands to form one-, two-, or three-dimensional porous structures, depending on the strategic choice of building blocks, and the preferred coordination geometry of the metal centres. Following rapid progress in the field over the past decade, MOFs are now widely regarded as having exceptional promise across a range of technological areas. `
The project delivered a number of novel MOFs, and protocols were developed for activating (removing guest molecules from the pores of high surface area MOFs) and monitoring the degradation of organic pollutants under UV and visible light.
The project aimed to use MOFs for indoor air purification applications; the challenge being the ppb concentrations of typical indoor air pollutants. A protocol was developed to monitor ppb concentrations of indoor air pollutants using a gas analyser, and to activate (remove guest molecules from the pores of high surface area MOFs) sufficiently to allow the sensitive gas analyser to monitor the ppb level concentrations of pollutants such as 2-propanol. A protocol was also developed to calculate the loading of the pollutants into the MOF at these ppb concentrations. Finally, a protocol was developed to monitor the photocatalytic degradation of the pollutants under visible and UV light with the MOF as the photocatalyst. SION-13 was utilised for this application due to its stability and light-responsiveness but it was shown to be unsuitable for this application, due to low selectivity for 2-propanol at ppb level concentrations. Al-PMOF, a known porphyrin MOF was demonstrated to degrade 2-propanol under UV light, however acetone was also detected by the gas analyser, implying complete degradation was not achieved, however with the protocol now setup, further work is underway to screen additional MOFs.