Study On Electrochemical Sensor For Trace Water In Transformer Sealed Oil

Determination methods and technologies of trace water in organic solvents are a hot spot in current research. In this thesis, the developed rapid and accurate determination method and technology for trace water in the transformer sealed oil have very important application value, providing a possible option for the in-situ quick determination of trace water content in the transformer sealed oil.In this thesis, we studied the process conditions for the synthesis of chloromethylated polystyrene through the appropriate emulsion polymerization, the synthesis of the polystyrene derivative containing quaternary ammonium group by a quaternization reaction between the tertiary amine and the chloromethylated polystyrene, and the preparation of electroactive polymeric membrane materials by adding potassium ferricyanide/ferrocyanide into the water solution of polystyrene derivative containing quaternary ammonium group.The electroactive ion pairs between poly(diallyl dimethyl ammonium chloride)(PDMDAAC), polyallyl ammonium chloride(PAH), polystyrene derivative containing quaternary ammonium functional group and Fe(CN)63-/Fe(CN)64- were used as the water sensitive materials of the electrochemical sensors. The water solutions containing a certain amount of the electroactive ion pairs were prepared and then dip coated onto the surface of interdigitated gold electrodes on glass substrates to form the membranes. In this way, the electrochemical sensors which are sensitive to the trace water in the transformer sealed oil were achieved. The effects of the electroactive material concentrations, Fe(CN)63-/Fe(CN)64- concentrations and ratios in the membranes on the properties of sensors were studied to optimize the process conditions of the sensors. The measurements of the sensor’s properties include linear response range, response time, and stability under high temperature to the trace water in the transformer sealed oil. The results showed that the sensor has a good linear response between 0 and 0.10% to the trace water in the transformer sealed oil under both room and high temperatures. In addition, the response mechanism of trace water in organic solvents was preliminarily analyzed through the comparison test of the sealed oil and acetone. It was found that the response behaviors of trace water in the sealed oil and acetone are totally different. The reason remains to be further explored.