Adsorption Characteristics And Migration Behavior Of Heavy Metal Manganese In Mining Area Soil

Heavy metal manganese is a global environmental pollutant,which has chronic toxicity and cancerous degeneration to human beings and organisms.The solid waste?ore,waste ore,tailings sand,waste residue?and production sewage produced in the process of long-term continuous mining and metallurgy of manganese ore area are entered into the soil of mining area in different ways.In the longitudinal dimension,the pollutants are often accumulated in the soil layer due to the characteristics of the stability and difficult reactivity of the heavy metals,and they are migrated under the effect of water infiltration and biological migration.Regional soil pollution.Taking Hongqi mining area of Xiangtan manganese mine as the research object,the basic properties of vertical soil at different levels were obtained through field sampling and laboratory measurement.By controlling the adsorption time,pH value and initial concentration of heavy metal manganese in three kinds of soil,the adsorption model of heavy metal manganese in different soil types was obtained by controlling the adsorption time of heavy metal manganese in soil,and the adsorption characteristics of manganese in the upper and lower three layers under different control conditions were analyzed.X and XRD analysis of soil samples before and after adsorption further explained the adsorption process and reaction mechanism.A one-dimensional soil column experiment was used to simulate the migration of heavy metal manganese in the vertical direction of soil.The important hydrodynamic parameters such as hydrodynamic dispersion coefficient,adsorption distribution coefficient and so on were obtained.The simulation analysis was carried out by Hydrus software.The model was good for describing the migration process of heavy metal manganese in soil soil.The important conclusions of the study are as follows:?1?the basic physical and chemical properties of three different types of soil samples were measured,including pH value,particle size classification,organic matter content,bulk density,cation content,water content,soil composition and so on,and the method was also introduced.?2?the adsorption process of heavy metal manganese by three kinds of soil can be described by Freundlich model and Langmuir model adsorption isothermal model.In order to compare the square difference,the Freundlich equation has better fitting.?3?the changes of the pH value of the reaction environment during the adsorption process were measured and analyzed.The results showed that the pH values of the soil samples all appeared to decrease rapidly at the beginning stage,and then gradually reached the lowest point and finally reached the stable value.In the80mg/L concentration group,the desorption rates of the upper,middle and lower layers were 39%,40%and 56%in the 20mg/L concentration group,and the desorption rates of the upper,middle and lower layers were 43%,28%and 45%respectively in the concentration group of 80mg/L.?4?under the three set of temperature conditions set by the experiment,the adsorption amount of manganese in the three soil increases with the increase of temperature.It is proved that the adsorption reaction of heavy metal manganese in soil is endothermic reaction.In the range of pH value,the adsorption amount of heavy metal manganese is obviously increased when the pH value is from 3 to 4,and the adsorption change of the upper soil is greater than that of the other two soil samples,and the solution pH is more than that of the other two soil samples.When the value changed from 4 to 7,the adsorption capacity of three soils remained relatively stable.The change of pH had little effect on the adsorption capacity of manganese.?5?X ray diffraction analysis and infrared spectrum analysis of the three kinds of soil samples before and after adsorption,and compared with the soil samples before adsorption,the location of the characteristic absorption peak of-COOH group appears at the position of-COOH group at the location of the wave number of 1633cm^-11 and1379cm-1 at the 1733cm^-1,and the MnCO₃ characteristic peak appears at the diffraction angle 2 theta=37.53 degrees,and the Mn?OH?₂ peak appears at 2 theta=55.36 degrees,and at 2 theta=35.03 degrees.The Mn₂SiO₄ characteristic peak appears at 37.62,50.23,and 50.66 degrees.?6?the hydrodynamic dispersion coefficient?D?of heavy metal manganese in the upper soil,middle soil and lower soil in the mining area is 0.6763,1.5675,1.2396,and the adsorption distribution coefficient K_d is 0.88070,53460 and 7370,respectively.Using HYDRUS-1D Rosetta module inversion,we get the intake value reciprocal a,empirical parameter n,saturated hydraulic conductivity Ks and soil void connectivity L.?7?input the basic value of HYDRUS software,obtain the prediction model of heavy metal manganese in the soil,and compare with the measured value,the correlation degree reaches 0.963,which indicates that the manganese migration process can be simulated well.