Study On The Detection Method Of Tyndall Phenomenon Colloidal Solution Concentration Based On Digital Image

The measurement of solution concentration change is a research topic of great concern in the field of environmental pollution.Although there are many existing concentration detection technologies and corresponding detection equipment,they are mainly used in the laboratory and the equipment is large in size.However,the area of water sample measurement is wide,the collection site is scattered,it is difficult to carry it to the field for use due to the limitation of service conditions and power consumption.The source project of the subject in this thesis involves some unstable solutions that cannot be taken back to the laboratory for measurement,so a concentration detection method needs to be developed to enable real-time detection of sample concentration.This thesis mainly studies the solution whose solute is colloid,based on the optical properties of colloidal solution,image processing technology is applied to the measurement of colloidal solution concentration.The colloidal solution has the phenomenon of Tyndall.The results show that the light intensity of the colloidal solution satisfies the Rayleigh scattering law,and the light intensity of the colloidal solution decays with the increase of the optical path distance under certain incident light conditions.The attenuation of light in a uniform,non-scattered solution satisfies lambert-beer's law.Due to the particularity of the size of colloidal solution particles,there are both light scattering and light absorption in colloidal solution.According to the principle of linear superposition,the attenuation of light in colloidal solution is the sum of scattering and absorption.Based on the optical properties of colloidal solution,the transmission model:I_Ttyn=I₀e^-??_a+?_a?L of Tyndall light in colloidal solution is studied in this thesis.The correctness of the model is verified by simulation of photon transmission in colloidal solution through Monte Carlo method.This thesis completed the setup and manufacture of the image acquisition device.Seven known standard samples of different concentrations and one sample to be tested were put into a glass test tube and placed in a rotating disc.The red laser light source controlled by constant power was used to irradiate the sample rotating to the shooting station,and the ptc08 b image sensor was used to collect the optical path image in the vertical direction with the light source.According to the requirements of the experiment,the corresponding shading module design and light source selection were completed.By taking a large number of digital images of colloidal solution samples with different concentrations,the mathematical models:I_Tyn=a×c+? baTynof the intensity and concentration of Tyndall light and the mathematical models:c=a×?^b of the attenuation coefficient and concentration were established respectively.Aiming at the error problems in the experiment,in the actual measurement,seven standard samples were used to calibrate the model coefficient,and the established model was used to measure and verify.Finally,the feasibility and accuracy of the calculation model were verified by the colloid solution concentration measurement experiment.Choose the colloidal solution of ferric hydroxide prepared in the laboratory,measure several groups of colloidal solutions with different concentrations,use the least square method to carry out regression analysis on the data,and establish the mathematical model of Tyndall intensity,optical attenuation coefficient and concentration obtained from the optical path image data.In addition,several groups of solutions were prepared for the experiment.The experimental results show that the error of the established colloidal solution concentration measurement model for the sample to be tested(4.120 × 10^-5 2.230 × 10^-2g / ml)could be stable within the expected range.