Detection of nitrate ions in water by optical fiber

摘要

This paper work reports the early stage development of optical fiber to detect the presence of nitrate ions in water. The outer cladding of multi-mode optic fiber had been removed and follows by a chemical etch-erosion process to etch out the unclear cladding. The fiber optic sensor has been utilized as a device for measuring the spectral absorption of a liquid containing of nitrate ions. All the experiments were performed using the ASD FieldSpec 3 Hi-Res Portable Spectroradiometer and halogen lamp as a light source. To measure the presence of nitrate ions in water, the reflectance spectra obtained were observed in the range of wavelength between 350 nm to 2500 nm. In this paper, reflectance spectra were investigated with different concentration of nitrate ions in water. In each experiment, the data were recorded and the result was observed on different concentration of nitrate ions range from 0.00 to 2.50 mg/l. The obtained results indicate that a linear relationship between the reflectance with the concentration of nitrate ions in water.