Study On The Adsorption Performance Of Tl(Ⅰ) By Manganese Dioxide And Diatomite Composites

Thallium（Tl）is a highly toxic element with two valence states Tl（Ⅰ）and Tl（Ⅲ）,and the+1 valence compound is more stable than+3 valence.In order to remove Tl（Ⅰ）in water,manganese dioxide and diatomite,adsorption materials commonly used in the process of heavy metal adsorption and removal,were selected and modified in this study to prepare manganese dioxide and diatomite composite materials,namely diatomite loaded manganese dioxide and magnetic diatomite loaded manganese dioxide.In this paper,manganese dioxide（δ-MnO₂）,diatomite,diatomite loaded manganese dioxide（SiO₂-MnO₂）and magnetic diatomite loaded manganese dioxide（γ-Fe₂O₃/SiO₂-MnO₂）were used as adsorbents for the study of Tl（Ⅰ）adsorption in solution.In this paper,we study in different p H,ionic strength,temperature,time,organic matter,adsorbent additive quantity,oxides,and other factors on the four kinds of Tl（Ⅰ）the effects of adsorbent to remove water,determine the best adsorption conditions,and through the adsorption isothermal adsorption kinetics experiment,experiment and adsorption thermodynamics experiment,adsorption mechanism,adsorption performance evaluation.The characteristics and advantages of the new material magnetic diatomite loaded manganese dioxide（δ-MnO₂）,diatomite loaded manganese dioxide and diatomite composite materials,diatomite loaded manganese dioxide and magnetic diatomite loaded manganese dioxide adsorption Tl（Ⅰ）were analyzed.With the increasing pH,the removal rate of Tl（Ⅰ）by magnetic diatomite loaded with manganese dioxide gradually increased.At p H 9.0,the adsorption capacity reached the maximum value of 191.78 mg/g.When the solution contains different sodium nitrate and calcium nitrate concentrations,the magnetic diatomite loaded manganese dioxide adsorption process of Tl（Ⅰ）belongs to the inner layer complexation adsorption.Magnetic diatomite loaded with manganese dioxide has a very good removal effect on Tl（Ⅰ）.When the dosage is 1.0 mg/g,the removal rate is up to 98.54%.With the increasing Na Cl O concentration,the adsorption amount decreased slightly.Potassium persulfate has little effect on the adsorption capacity,while potassium persulfate has a greater effect.Organic extracellular polymer and humic acid have little effect on adsorption.The kinetic adsorption process conforms to the quasi-second-order kinetic model,and the correlation coefficient R² is 0.999.The isothermal adsorption processes were more consistent with the Langmuir model at different temperatures,and the correlation coefficient R² was above 0.9.Thermodynamic experiments showed that the adsorption process was endothermic and can react spontaneously at high temperature.Compared with other three adsorption materials,δ-MnO₂,diatomite and diatomite loaded manganese dioxide adsorbed Tl（Ⅰ）under different conditions,the magnetic diatomite loaded manganese dioxide adsorbed Tl（Ⅰ）has a higher removal rate,and magnetic field can be used to quickly separate the adsorbent from the solution,and the ability of regeneration is strong,reusable environmental protection and no pollution.