The detection of volatile organic compounds BTX by quratz crystal resonator

• Main Authors: Jiun-feng Ju, 朱君峰
• Other Authors: Hsisheng Teng
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/32936410215364419257

碩士 === 國立成功大學 === 化學工程學系 === 89 === Abstract An effective model from the first-order step response of a system was proposed for analyzing the signal of a crosslinked poly-β-cyclodextrin coated quartz crystal microbalance (QCM) detecting system. Different modes of detection signals, such as multi-step and pulse modes, were used in this continuous-flow QCM system. The fundamental guest-sorption properties of the host supramolecular layer in gaseous phase was also observed by using a quartz crystal chip as a film substrate of a piezoelectric mass transducer. The tested volatile organic pollutants, such as benzene, toluene, and p-xylene, were detected at concentrations of ppm level. Using cyclodextrin derivatives like β-cyclodextrin polymer crosslinked with maleic anhydride, host-guest chemistry can be applied to chemical sensor technology. To understand the property of the polymer, the qualitative analyses such as BET, TGA, DSC, IR, and NMR, were employed in this study. The parameters of first-order step function are significant. By observing the relationship between time constant (τ) and the various flow rates, the existence of the external mass transfer resistance can be identified and the optimal flow rate from 200 to 300 mL/min was determined in this system. The internal mass transfer effect was reflected in the relationship between time constant (τ) and the film thickness. Thus, the thickness of coating film was better to be less than 600 nm. Besides, the steady-state gain (KΔx) can be used to calibrate the concentration versus the signal response of QCM. Thus, molecular recognition methods further combined with principles of system response lead to a new improvement of sensor characteristics. The simulation results from the first-order step equation provided a good basis for analyzing the efficiency of this system.