Fiber-Optic Evanescent-Wave Absorption Cu(II) Sensor prepared by a Novel Sol-Gel-Derived Material

• Main Authors: Ta-Chuan Yeh, 葉大川
• Other Authors: Lai-Kwan Chau
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/58159913191307759099

碩士 === 國立中正大學 === 化學研究所 === 88 === Environmental monitoring is a research topic that has attracted a lot of interest. In which, the detection of heavy metals is an important issue. This research attempted to fabricate a Cu(II) sensor by using a novel sol-gel-derived material --[Propylethylenediamine Triacetate Functionalized Silica (PEDTAFS)]. The material has an EDTA-like functional group which can complex with a Cu(II) ion to form a colored complex. When PEDTAFS replaced the cladding of an optical fiber to form a Cu(II) sensor, the sensor work by an optical phenomenon called evanescent field. When absorption of light by Cu(II)-PEDTAFS takes place within the evanescent field, the intensity of the light propagated through the optical fiber will be reduced. This intensity decrease was used to quantitate the Cu(II) in the solution. Initially, quantitation of Cu(II) ion by the equilibrium approach was attempted. However, because of the large formation constant of the reaction, the equilibrium approach failed. Meanwhile, the kinetic approach worked. We found that with different concentrations of Cu(II) ion, the rate of intensity decrease varied according to concentration. As such, this phenomenon was used to quantify Cu(II) ion. To improve the performance of the sensor, various factors such as sol-gel process parameters, optical design, and sample preparation methods, have been optimized. The Cu(II) sensor had been evaluated. The linear dynamic range was 0.1~100 ppm (1.57 x 10-6 ~ 1.57 x 10-3 M ) and the detection limit of the sensor was 1.23 x 10-6 M。