Experimental Study On The Adsorption Of Cadmium Contaminated Soil By Magnetic Mesoporous Nanomaterial Adsorption And Magnetodynamic Separation

Magnetic mesoporous nanomaterials not only have the special properties of magnetic nanomaterials,but also have the large specific surface area and suitable pore size of mesoporous nanomaterials,and are widely used in the removal of environmental pollutants.In this paper,the synthesis and characterization of magnetic mesoporous nanomaterials and their adsorption properties in water and soil media are studied.The specific research results are as follows:?1?The Fe₃O₄ magnetic core was prepared by co-precipitation method,and its average particle size was about 12 nm,which was superparamagnetic.The surface of the magnetic core was coated with TEOS and CTAB,and the particle size of Fe₃O₄@SiO₂ was about 150 nm.The dispersibility is good,the specific surface area is286.1340 m²/g,the pore diameter is 2.5 nm;the specific surface area after ethanol-ammonium nitrate extraction is 809.1130 m²/g,the pore diameter is 2.6 nm and 4 nm.FTIR characterization indicated that the amino group and EDTA had been grafted onto Fe₃O₄@SiO₂.?2?ThefouradsorbentsFe₃O₄,Fe₃O₄@SiO₂,Fe₃O₄@SiO₂-NH₂,Fe₃O₄@SiO₂-EDTA have good hydrophilicity and magnetic responsiveness.In the aqueous medium,heavy metal Cd?II?ions The adsorption is affected by the pH of the system,and the adsorption capacity of the material for Cd?II?can be greatly improved by modification.At 25°C,the adsorption capacities of the four adsorbents were 17.69mg/g,22.98 mg/g,27.62 mg/g,and 40.93 mg/g,respectively.The adsorption isotherm model can be described by the Redlich-Peterson equation,which is biased toward Langmuir.The equation is a non-ideal monolayer adsorption.According to the data fitting results,it can be inferred that the adsorption of heavy metal Cd?II?ions by four adsorbents is mainly chemical adsorption mainly by chemical reactions such as ion exchange;the adsorption capacity of four adsorbents for heavy metal Cd?II?ions The strength is:Fe₃O₄@SiO₂-EDTA>Fe₃O₄@SiO₂-NH₂>Fe₃O₄@SiO₂>Fe₃O₄.?3?The adsorption of heavy metal Cd?II?ions by soil sample particles is also affected by the pH of the system.At 25°C,the adsorption amount of soil samples is9.2 mg/g;the adsorption isothermal model of soil samples can be performed by Langmui equation.Description,the adsorption and release process of cadmium particles by soil samples are well described by the quasi-second-order kinetic equation.The adsorption process is dominated by chemisorption,and the release process is controlled by heterogeneous diffusion.?4?Morphological analysis of contaminated soil samples and soil after repair,it can be seen that the morphology distribution of soil samples is carbonate-bound state>organicboundstate>iron-manganeseoxideboundstate>exchange state>residual state;adsorption time increases The adsorption capacity of soil particles to heavy metal cadmium is gradually reduced,and the adsorption capacity of the two adsorbents is Fe₃O₄@SiO₂-EDTA>Fe₃O₄@SiO₂-NH₂;the physical and chemical properties of the soil before and after the restoration are basically unchanged,which indicates the added adsorbent.It is not harmful to the environment and is safer.