| dc.description.abstract | This study aimed to focus on two critical organic substances, which were 15 carbonyls and 54 photochemical ozone precursors (54 PAMS) in ambient air. This study consists of two parts; the first part is to develop the
analytical method to detect the ambient carbonyls and collect the field data from various emission sources. The second part is to utilize the novel metal-organic frameworks (MOFs) materials that apply to the adsorption
investigation of 54 PAMS. The first section is to develop the cartridge method for detecting ambient carbonyls, which provides a lower MDL (method detection limit) option than the current method (impinger method). The data collected from the three petrochemical designated industrial zones (DIZs) were often shown as ＂Non-Detected＂ (ND), which is unable to provide sufficient information for ozone reduction assessment. By referencing the USEPA TO-11A compendium method, an optimized method for detecting carbonyls as well as the self-made cartridges were developed for ambient monitoring. The MDL for cartridge method was sub ppbv level (0.09-0.15 ppbv), which was 1/60 fold compared with the current method. Field measurement sites were selected from Wan-hua PAMS (mobile sources), the sixth naphtha cracker DIZ, and Renda Industrial complex (stationary sources). The results show that the measurement for formaldehyde in Wanhua PAMS is below 0.6 ppbv, and acetaldehyde is mostly ND. The diurnal trend showed that the mixing ratio is the highest at noon, indicating that the carbonyls mainly came from the secondary photochemical reaction.
According to the data collected from the sixth naphtha cracker DIZ,formaldehyde and acetaldehyde are below 1 ppbv, and the impinger method show ND, which is roughly consistent. The lower MDL for the cartridge method provides lower mixing ratios which can be used to investigate the photochemical reaction of the ozone precursors. The results
from Renda Industrial complex showed the highest mixing ratio for formaldehyde was 11.23 ppbv, which indicated that the source was from a formaldehyde-process factory in the southeast. Acetaldehyde was below 1 ppbv through the whole monitoring period.
The second section of the thesis is the application of the novel MOFs used to investigate the 54 PAMS adsorption studies. The main MOF is used in UiO-66, a porous crystalline polymeric material with adjustable pore
size, high porosity, high specific surface area, and reusability, and is widely used in various fields. However, very little literature has been published on VOC studies′ adsorption. UiO-66 is a highly stable and hydrophobic
material. In this study, 54 PAMS of mixing ratio 100 ppbC, were used to investigate the adsorption capability of UiO-66, compared with the traditional multiple-bed carbon adsorbents. The research results show that a single material, UiO-66 could adsorb 54 PAMS covering C2-C11, similar to the multi-bed carbon adsorbents. The calibration curve has good linearity (R2 > 0.9950), and the thermal desorption ability could achieve 99% at 250°C. To test the per carbon response, the adsorption results of UiO-66 are highly consistent with the multiple carbon adsorbents. After
repeated cold trap and thermal desorption of the UiO-66 adsorbents, the Xray diffractometer (XRD) results show that the crystal of UiO-66 has collapsed unevenly, resulting in the formation of different size surface holes. The uneven size pore of the single UiO-66 provides the adsorption
capability for the wide range of 54 PAMS. As a result, UiO-66 is applied to the five-days continuous measurement calibration and blank test. The recovery is 78%-109%, and RSD (relative standard deviation) is below 7%, which meets the regulation of the standard method. The results showed that a single UiO-66 is a suitable adsorbent for ambient monitoring. | en_US |