| The concentration of hydrogen peroxide solution is a significant parameter in the bleaching process.The concentration of the hydrogen peroxide solution determines the bleaching effect and affects the processing efficiency of the pre-printing process.Therefore,if the concentration of hydrogen peroxide in the bleaching liquid can be accurately detected,the bleaching effect can be improved while ensuring process reproducibility.Moreover,it can also improve the yield rate and reduce the repair rate,thereby achieve the purpose about saving energy,reducing costs,and improving the economic efficiency of printing and dyeing industry.However,due to the high concentration of hydrogen peroxide in the bleaching liquid accompanied by the influence of alkaline substances and temperature,the current on-line hydrogen peroxide detection products cannot detect it very well.Therefore,factories often use manual titration to detect it.The manual titration method takes a long time and has a high error rate,which makes the bleaching effect difficult to control.Therefore,how to develp an on-line detection of the alkaline hydrogen peroxide concentration in the bleaching liquid has become one of the urgent problems in the printing and dyeing automation.In this thesis,an alkaline hydrogen peroxide solution was used as the research object.Combined with the research status at home and abroad,an on-line detection method for high concentration alkaline hydrogen peroxide solution was proposed,and a multi-sensor detection based on electrochemistry was designed.The main research contents of the system are as follows:(1)Explain the advantages,disadvantages and adaptation environment of the main methods of detecting hydrogen peroxide concentration such as redox titration,electrochemical analysis and spectrophotometry.On this basis,the reasons for using the amperometric method are explained in combination with the objectives of the project.(2)The electrochemical mechanism of alkaline hydrogen peroxide was analyzed in detail,and the mechanism mathematical model was derived by combining the Butler Volmer equation with electrochemical kinetics.(3)The experiment of concentration detection of amperometric alkaline hydrogen peroxide solution was designed.The relationship between rotational speed,H2O2 concentration,NaOH concentration,temperature and detection current was studied.The increase of the rotational speed can increase the current,but the current level gradually becomes gentle with the increase of the rotational speed.The H2O2 concentration and the NaOH concentration affect the current by changing the chemical reaction intensity and the solution resistance.Low concentrations of H2O2 can accelerate the chemical reaction and increase the current,but high concentrations of H2O2 can cause a large solution resistance,resulting in a significant reduction in current.On the one hand,NaOH and temperature can accelerate the chemical reaction,on the other hand,the solution resistance can be reduced,so the current is positively correlated with NaOH concentrations.Temperature promotes current,and the natural logarithm of current is approximately linear with temperature.On this basis,the mechanism model is improved by fitting,and the mathematical model for detecting H2O2 is obtained.However,the model is affected by the solution resistance and its detection range is limited.(4)The relationship between conductivity and H2O2 concentration,NaOH concentration and temperature was studied experimentally.Experiments show that the conductivity decreases with the increase of H2O2 concentration,but increases with the increase of NaOH concentration and temperature.On this basis,the BP neural network classification algorithm based on conductivity is used to solve the ambiguity problem caused by the solution resistance,and the detection range of the detection model is improved by this way.(5)Completed the software and hardware platform construction of the detection system and verified its detection effect.It is verified that the root mean square error of the detection system is 0.76,the correlation coefficient is 0.996,the deviation is 0.1.The H2O2 concentration can be accurately detected in the temperature range of 30-70℃ with the NaOH concentration in the range of 10-30 g/L.The H2O2 detection range is 1-30 g/L. |
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