Optimization Of Optical Fiber BOD Sensing Film And Investigation Of BOD Apparatus

Biochemical oxygen demand (BOD) is the amount of oxygen required for the bio-oxidation of organic pollutants in a solution. BOD is one of the most widely used and important parameter for the estimation of water quality. The authorized method for BOD is the BOD5 method, which requires 5 days of tedious procedures and the experience and skill to obtain reproducible results. As a result, it is not satisfactory with the rapid evaluation for water quality. The development of on-line approaches for BOD determination has been becoming attractive. In the past decade, although fiber optical chemical sensors for the determination of oxygen have been developed owing to their rapid response, without oxygen consuming and difficult to be poisoned, few BOD sensors have been applied to detect the BOD of seawater. In this dissertation, an optical BOD sensor for the application in seawater was introduced. Based on the BOD device set in our laboratory, a portable BOD apparatus was assembled and its characteristics were studied.This dissertation includes four chapters:In chapter I, the principles, developmental routes and the research status of BOD sensors were reviewed.In chapter II, the experimental conditions for the preparation of the BOD sensing film was optimized. A BOD sensing film immobilizing microorganisms from seawater was found to be rapid response, excellent stability and good linearity to BOD in seawater samples.In chapter III, the measurement theory, the structure of a BOD apparatus and its manipulation methods were introduced. The assembled BOD apparatus presented a good linearity, excellent stability and suitable for BOD determination of the seawater.In chapter IV, a new fluorescence indicator, 5,10,15,20-tetrakis (pentafluorophenyl) porphyrin, was synthesized and selected for dissolved oxygen determination. In the oxygen sensing film, dimethyldimethoxysilane.(DiMe-DMOS) and tetramethoxysilane (TMOS) was selected as precursor. Furthermore, the characteristics for oxygen sensing film, including spectrum properties and response performance, were investigated.