Study On Measurement Technology And Sensor Of Residual Chlorine

Residual chlorine is one of the most important indicators in the detection of drinking water quality.It refers to the remaining active chlorine in the water after the disinfectant was added.The residual chlorine is usually divided into two categories:one is hypochlorous acid and hypochlorite-based free residual chlorine;another is the combined residual chlorine,mainly refers to the chloramine in water;free residual chlorine and the combined residual chlorine is called total residual chlorine(TRC).The free residual chlorine with a strong oxidizing capacity is usually used as a disinfectant in life drinking water,and the subject of this study is focused on the measurement of the content of free residual chlorine.This paper first introduced the backgrcund of residual chlorine measurement,residual chlorine-related national standards and research status of residual chlorine measurement,and then analyzed the most commonly used residual chlorine measurement method-electrochemical method deeply.Through the contrast test implemented on two well-known foreign residual chlorine analyzer,we figured out the disadvantages of these two electrochemical methods with different mechanisms.Finally,a new residual chlorine measurement method is proposed to measure the residual chlorine--photolysis method,the principle of this method is through the photolysis of hypochlorous acid in disinfectant,producing a strong electrolyte(sodium chloride),leading to increased conductivity of the solution.Thus,the content of the residual chlorine in solution was figured out indirectly by the amount of change in conductivity.In this paper,a set of sensor devices for photolysis and detection of residual chlorine content is devised and fabricated,and the design and fabrication of the whole sensor device are described in detail.Firstly,the development of residual chlorine photolysis reaction device and its water system was introduced;Secondly,a set of waterway control system is designed to control the operation of the sensor device and is programmed with LabVIEW.It is convenient for us to carry out the programming of the sensor device by means of the host computer.And the PCB board and the finished product of the device control system were displayed.Finally,we studied the residual chlorine measurement by the photolysis method in the residual chlorine photolysis experiments.Experiments show that the new idea of measuring the residual chlorine content by the photolysis method has feasibility.