Preparation And Adsorption Performance Of N-doping Fe-based Transitional Bimetallic Materials

Given the unique advantages of transitional metallic elements,represented by Fe,in heavy metal adsorption,two kinds of adsorbents with different structures,N-doped Fe/Co layered double hydroxides（Fe Co-LDH@G）and N-doped bimetallic organic nanosheets（Fe/M@TPA）,were prepared,selecting different transitional metallic elements M.（1）N-doped Fe/Co layered double hydroxides（Fe Co-LDH@G）Given the affinity of amino and Fe element for As（V）,Fe/Co layered double hydroxide was prepared.Fe Co-LDH@G was further prepared by the intercalation of glycine,improving the adsorption performance of materials for anions.With the Fe/Co ratio of 1:1,the intercalation of glycine in LDH materials was achieved in Fe_0.02Co_0.02-LDH@G.The N atoms of amino of glycine in Fe_0.02Co_0.02-LDH@G are the main active adsorption sites.After modified by glycine,the removal rates and equilibrium adsorption capacities of Fe Co-LDH@G for each anion were improved in certain degree.The selectivity of Fe_0.02Co_0.02-LDH@G for As（V）was enhanced.The regeneration of Fe_0.02Co_0.02-LDH@G saturated with As（V）can be achieved by an electrochemical method.After 4 times of regeneration,the decline in the equilibrium capacity for As（V）was only 13.31%.After regeneration,there was no significant change in the chemical structure or elemental composition of Fe_0.02Co_0.02-LDH@G.The adsorption of Fe_0.0Co_0.02-LDH@G for As（V）followed BET isotherms model and pseudo-second-order kinetics model.The saturated adsorption capacity was 819.76 mg·g^-1.（2）N-doped bimetallic organic nanosheets（Fe/M@TPA）N-doped metal-organic nanosheets Fe/M@TPA（Fe/Co@TPA and Fe/Ni@TPA）were prepared using terephthalic acid as the organic component and triethylamine as the N source.Fe/M@TPA owns ultrathin sheet structure with nanoscale thickness.The N atoms of triethylamine in Fe/M@TPA are the main active adsorption sites.Fe/M@TPA exhibited excellent adsorption performances for trace Pb（II）.The regeneration of Fe/M@TPA saturated with Pb（II）can be achieved by vibrated in HCl solutions.After 4 times of regeneration,the decline in the equilibrium capacity for Pb（II）was not higher than 18%.After regeneration,there was no significant change in the chemical structure or elemental composition of Fe/M@BDC.The adsorption of Fe/M@BDC for Pb（II）followed BET isotherms model and pseudo-second-order kinetics model.The adsorption rates were fast.The adsorption for 10mg·L^-1 Pb（II）reached equilibrium within 15 min.