The Manufacture Of Nano-iron Modified By Starch And Remediation Of Soil And Water Solution Polluted By Chromium

With the advent of nanomaterials,the method that to repair heavy metal water and soil contaminated by heavy metals nano-iron(nZVI)was proposed,and has become a hot topic of research.Nanoparticles have surface effect and interfacial effect.The ratio of surface atomic number and total atomic number increases,which leads the surface atom becomes unstable because lack of adjacent coordination atoms,additionally the electrostatic force and van der Waals force between nanoparticles can be easily reunite and oxidize.In this paper,ultrasonic oscillation dispersion technology was adopted ton the basis of the liquid phase reduction method,to produce one kind of nano-iron modified by starch,then the the removal effect,removal mechanism and migration mechanism of S-nZVI on chromiun in water and soil under different experimental conditions,and evaluate the feasibility of remediation of water and soil contaminated by chromium.The characteristics and mechanism of S-nZVI were studied by XRD,SEM and XPS.The results of SEM show that the nano-iron successfully binds to the starch chain and effectively prevents the reunion of nano-iron,the particle size distribution is between 40 and 80 nm,and the mean particle size is 62.56nm.Results of XRD and XPS indicated that the nanometer iron is a kind of nucleocapsid structure wrapped with FeO and FeOOH.In water the appropriate amount of H+ will promote the corrosion and electron transfer of S-nZVI,which is benefit for the removal of total chromiun and Cr(VI).The removal process of chromium conforms to the quasi-secondary dynamics model.When the concentration of Cr(VI)was 160mg·L-1,the adsorption of S-nZVI on chromium was more than twice that of the commodity nano-iron(B-nZVI).The application results of plating wastewater contaminated by chromiun shows that:S-nZVI has a higher reaction activity,there was a positive correlation between pH and S-nZVI in soil(P<0.05).With the increase of S-nZVI,the Chromium of exchangeable(EX),Bound to Carbones(CB)and Bound to Organic Matters(OM)decreased,Bound to Iron and Manganese Oxides(OX)increases after 48h.As the number of days increased,the Chromium of EX decreased,CB and the residueal(RES)increase in soil of Si,meanwhile,the EX,CB and OX decreased,the RES increased In soil of S2.The content of the EX in both soils decreased and the content of the RES increased,which indicated that S-nZVI can effectively solidify chromium in soil and reduce the bioavailability of chromium.