Study On Mechanical Properties And Adsorption Behavior Of Sepiolite

Due to its unique pore structure and excellent physical properties,natural sepiolite has been widely used as adsorbents,deodorants,decolorants,filter materials,rubber fillers,fertilizer suspensions,detergents,soil improvement,etc.People generally pay attention to the physical characterization and application of sepiolite.There were few reports on its mechanical properties.Therefore,this paper selected Xiangtan sepiolite as the research object,and used molecular dynamics methods to carry out the theoretical analysis on the mechanical properties,ion and gas adsorption performance of sepiolite.The main research contents are as follows:（1）The calculation model of sepiolite is established.The elastic constant,bulk modulus,shear modulus and Poisson’s ratio of the sepiolite cell have been obtained through molecular dynamics simulation.With the increase in the number of zeolite water in the pore structure,the compression and shear resistance of sepiolite gradually increase.Adsorbed gases（NH₃,H₂S,SO₂）will affect the mechanical properties of sepiolite.The bulk modulus and shear modulus will increase after SO₂molecules are adsorbed.（2）Theoretical analysis of the molecular structure characteristics and dynamic behavior of the three gases NH₃,H₂S and SO₂in the sepiolite pores shows that sepiolite has a certain adsorption capacity for the three gases,but the adsorption mechanism is different.The adsorption capacity of the three gases SO₂>H₂S>NH₃.Among the sepiolite pores,NH₃has the strongest interaction with water molecules.H2S has a strong interaction with water molecules and bridged O on the channel wall,and SO₂has a strong interaction with the bridged oxygen and Si atoms on the channel wall.So the adsorption force is strong and relatively stable.In addition,H₂S and SO₂both present a similar ring structure distribution in the sepiolite pores.（3）Experiments show that sepiolite has a certain potential for energy storage and can be used as an electrode material for lithium-ion batteries.Molecular dynamics simulations show that the silanol groups（Si-OH）on the surface of sepiolite provide a large number of active sites and form stable ionic bonds with alkali metal ions（Li⁺,Na⁺,K⁺）.The adsorption capacity of sepiolite for the three kinds of alkali metal ions is different,the adsorption capacity of the inner ring on the surface of the sepiolite is Na⁺>Li⁺>K⁺,and the adsorption capacity of the outer ring is K⁺>Li⁺>Na⁺.Take Li⁺as an example.The acidic environment will inhibit the adsorption of Li⁺on the surface of sepiolite.When the concentration of the solution is large,the external electric field will promote ion adsorption;in organic solvents,the accumulated Cl^-ions will form a small-scale electric field.Competing for the adsorption of Li⁺reduces the ion adsorption capacity of sepiolite.