Nonlinear Adsorption-desorption Characteristics Of Suspended Matters And Saturated Quartz Sands

Studying the adsorption-desorption characteristics of suspended materials in soil is of great significance for the deep understanding of the migration mechanism of various suspended particles and heavy metal ions in geotechnical engineering,and also helps to recover or dispose of these materials.The thesis mainly explores the influence of the particle size,concentration,temperature and material type of silicon powder on the adsorption-desorption process of suspended particles,graphene oxide and heavy metal ions in porous media through a static adsorption-desorption experiment in the laboratory.The limitations of the classical adsorption-desorption control equation for pollutant transport are studied,and a new nonlinear adsorption-desorption model is proposed.The COMSOL numerical calculation software was used to perform fitting analysis on the model,and the calculation results were compared with the test data to evaluate the applicability of the model.The main research contents are as follows:(1)The limitations of the classical isotherm adsorption-desorption model were studied.Considering the factors of maximum deposition amount and the decrease of deposition rate after the increase of deposition amount,a nonlinear adsorption-desorption model was established.(2)A static adsorption-desorption test was conducted.In the test,silicon powder with four particle sizes of 869.2nm,5.1?m,17.1?m and 24.7?m was used to prepare a suspension of silicon powder according to a certain concentration gradient with a concentration of 0 mg/m L to 2.5 mg/m L.Prepare a graphene oxide solution with a concentration of 0 ng/m L to 200ng/m L.Prepare a copper ion solution with a concentration of 0 ng/m L to 10 ng/m L.Put the silicon powder suspension,graphene oxide solution,and copper ion solution into the quartz sand saturated porous medium respectively,and perform the static adsorption-desorption test under the conditions of 20 °C,40 °C,and 60 °C.Study the mechanism of adsorption-desorption characteristics of different substances.(3)The test results were analyzed,and the linear adsorption-desorption model and the nonlinear adsorption-desorption model were fitted to evaluate the applicability of the two adsorption-desorption models.(4)Using numerical calculation software,for the one-dimensional seepage soil column model,the proposed nonlinear adsorption-desorption model is used to calculate the infiltration migration process of various suspended materials.The calculated results are compared with the data obtained from previous experiments to verify the applicability of the nonlinear adsorption-desorption model.