Study On Nanoscale Zero-Valent Iron Loaded On The High Silica Zeolite Molecular Sieve(ZSM-5) For The Removal Of Heavy Metal In Waster Water

With the development of industry,a large amount of lead and its compounds are widely used in mining,electroplating industry,battery manufacturing,dyes,printing industry and so on.Lead waste discharged into water,has caused serious pollution of water and great threat on human health.In recent years,nano zero-valent iron has been widely used in the removal of lead water.However,nano scale zero-valent iron was easily oxidized and easy to agglomerate in air.So we prepared nano zero-valent iron loaded on ZSM-5 by chemical impregnation and mall milling methods in order to solve the poor dispersion of nano zero valent iron and low reactivity problems.Under different conditions,we discuss about the reaction kinetics and mechanism by using two materials to removal of lead.At last we compare the performance with the removal of lead.This research maily to the following contents:We prepare the ZSM-5/ZVI by chemical impregnation and the ball milling methods,the characterization of loaded material showed that nano zero-valent iron particle size in 50nm-100 nm,spherical structure,uniform size and no agglomeration by impregnation method.Iron is homogeneously distributed on ZSM-5 by ball milling.?-Fe is present in the material prepared by two methods.Its reaction kinetics analysis show that they are in line with the pseudo-first-order reaction kinetics when we investigate effects of different conditions in the solution of Pb²⁺,and then we find that it is not conducive to the removal of Pb²⁺ in the high pH and low pH values.But the removal rate of Pb²⁺ reached at 41.1% at the pH=4.The removal rates of Pb²⁺ is increased with the increasing of additive quantity.The reaction rate constant is consistent with it,the removal rates of Pb²⁺ is decreased with the increasing of Pb²⁺ in the case of material dosing quantity.But absolute removing Pb²⁺ volume is increased.To test the total iron released in the process of reaction,we find that total iron released is first increased and then decreased,however,the trend of Fe²⁺ is increased and gradually stable.Total iron and Fe²⁺ are increased because of Fe0 oxidized by Pb²⁺ and water system.We survey the pH value changes and find that pH value difference is increased with the increasing of concentration of reaction.To analyze the mechanism of ZSM-5/NZVI for removing Pb²⁺,X-ray photoelectron spectroscopy?XPS?analysis shows that Pb²⁺and FeOOH exist on the surface of the nano zero-valent iron when ZSM-5/NZVI is reacting with Pb²⁺,It indicates that Pb²⁺ is adsorbed to the surface of ZSM-5/NZVI by the physical way.We study the two different methods of prepared materials for the removal effect of Pb²⁺ and find that the reaction rate constant and removal rate of ZSM-5/NZVI are higher than ZSM-5/Fe⁰ because of different particle size.