The Study Of Real-time And Pollution-free Multiparameter Water Environment Monitoring Technology And Instrument

Water is the source of human life and a valuable natural resource.Industrial production,agricultural irrigation and daily life could not continue without water.Under the reality of the increasingly serious water pollution,water environment monitoring become more and more important.In the future,water environment monitoring tends to be generalized,extensive and integrated.The equipment demand of water environment monitoring will increase exponentially.The equipment of real-time and pollution-free water environment monitoring will receive more and more attention.The target of this study is real-time and pollution-free water environment monitoring.Two instruments of water environment monitoring are developed based on electrochemical technology and ultraviolet-visible absorption spectrum separately.They could measure water environment including temperature,pH,ammonia nitrogen,flow velocity,chemical oxygen demand,turbidity and color in real-time and pollution-free.The main research contents and achievements include:(1)The pH measuring method using double platinums and chronopotentiometry is proposed.We study the internal mechanism of this new method according to a large number of experiments.The experimental results indicate that the new pH measuring method has good linear pH response,excellent selectivity,and it possess long life span and long-term measuring stability relative to traditional pH glass electrode.Relevant paper is published in“Sensors and Actuators B-Chemical".(2)The measuring method of liquid flow velocity based on tungsten oxide electrode is proposed for the first time.We study the internal mechanism of this new method,and verify the existence of streaming potential.The experimental results indicate that the open circuit potential of tungsten oxide electrode could achive the measurement 0.4mm/s ultralow flow velocity with pH and temperature compensation.Relevant papers are published in "Sensors and Actuators B-Chemical" and "Journal of Electroanalytical Chemistry".(3)The measuring method of ammonia nitrogen is proposed using open circuit potential of ammonia-ion selective electrode,pH and temperature.We study the relationship between ratio of ammonium ion in ammonia nitrogen and pH and temperature.The experimental results indicate that the new ammonia nitrogen measuring method has good linear response.In the meantime,multi-parameter water environment monitoring instrument based on electrochemical techonology is developed including the design of hardware circuit,slave computer software and PC software.The instrument could achieve the calibration and measurement of temperature,pH and ammonia nitrogen.(4)We study the measurement of COD,turbidity and water color based on UV-Vis absorption spectrum.The water color is measured using abosorbance in visible light range.Due to the different gradients of absorbance curves for various turbidity solutions,the difference of gradients is quantified as the difference of color coordinates which could be used for turbidity measurement.The COD is measured using abosorbance in ultraviolet light range.Turbidity compensation method is studied,and absorbance in ultraviolet light range is used for COD measurement after turbidity compensation.Relevant paper is published in "Sensors and Actuators B-Chemical".Moreover,multi-parameter water environment monitoring instrument based on UV-Vis abosoption spectrum is developed including the design of overall system,control and acquisition circuit and PC software.The instrument could achieve the calibration and measurement of COD,turbidity and water color in real-time and pollution-free.Because the novel method of turbidity measurement is proposed,the instrument adopts single channel system design,which avoids the removable aperture of double light path measurement system and improve the measurement stability of the system.