The Synthesis Of Nanoscale Zero-Valent Modified By Bentonite Iron Ant Its Research On Removal Of Heavy Metals

Lead ion and copper ion pollution are prominent parts of heavy metal pollution.In this study,lead ion and copper ion were taken as research target to study the removal efficiencies of lead ion and copper ion by modified nanoscale zero-valent iron?nZVI?under various environments.In this study,nZVI was synthesized by liquid-phase reduction method,and the defects such as easy agglomeration in synthetic process could be solved by modifing the nZVI on bentonite.The synthesized nZVI were adsorbed between and on the surface of bentonite,and was in a dispersed state.With the increase of iron content,agglomeration of nZVI will occur gradually.Some of nZVI was oxidized when the iron content was 50%.The experiment indicates that the iron content is within the range of30%-40%according to the optimal proportion by mass as nZVI modified by bentonite?B-nZVI?shows the best removal efficiecy on the heavy metal lead ion.Based on hydrophilicity,adsorption and large specific surface area of graphene oxide?GO?,adding appropriate proportion of GO can made the synthesis nZVI in a more scattered state,and further improve the removal efficiencies of heavy metal lead and copper ion by nZVI.The synthesis nZVI is of typical shell-core structure.When 1 g of nZVI modified by bentonite and GO?GO-B-nZVI?was synthesized,the GO incorporation of0.15 g showed the best removal efficiecy on lead ions.After about 24,GO-B-nZVI and B-nZVI reach a saturation state in the adsorption of heavy metal lead and copper ions.The removal efficiencies of lead and copper ions by GO-B-nZVI and B-nZVI increased with the increase of pH value of the solution.The removal efficiencies of heavy metal lead and copper ions was not affected too much by the increase of solution temperature.The removal efficiencies of lead and copper ions by GO-B-nZVI and B-nZVI conforms to the quasi-second-order kinetic model.The adsorption isotherm can be described by Langmuir model.From the fitting curve,it can be calculated that the saturation adsorption capacity of GO-B-nZVI on copper ions is 184.5mg·g^-1,which is higher than that of B-nZVI whose saturation adsorption capacity on copper ions is 130.7 mg·g^-1.In the co-contaminants heavy metal lead and copper ions,the removal efficiency of B-nZVI on lead ions was affected by the concentration of copper ions in the solution,while the removal efficiency of B-nZVI on copper ions is less affected by the concentration of lead ions in the solution.B-nZVI removed lead ions in the co-contaminants solution by adsorption.Through adsorption and reduction,B-nZVI removed copper ions from the co-contaminants.