Preparation, Application And Removal Mechanisms Of Mineral-Supported Iron-based Environmental Nanocomposites

Heavy metals and organics are two important class of pollutants in water.The pollution,the harm to ecological environment and human health and the the remediation of contaminated water have caused widespread concern around the world.Nano zero-valent iron and iron oxide are considered to be suitable for the removal of a variety of environmental contaminants with excellent performance and stability.However,they are easily aggregated,oxidized and lack mechanical strength,leading to the failure in the removal of contaminants.Clay minerals may be suitable materials to resolve this problem as a stabilizing agent.nZVI-montmorillonite,nZVI-kaolinite,Fe2O3-Fe3O4-Montmorillonite and Fe2O3-Fe3O4-Montmorillonite-Graphene were prepared.Synthesized nZVI-montmorillonite and nZVI-kaolinite were used to adsorb heavy metal ions from aqueous solution.The photocatalysis performance of Fe2O3-Fe3O4-clay and Fe2O3-Fe3O4-Clay-Graphene to degrade organics were evaluated.The main results are obtained in the following aspects through the study:(1)A simulation study helps us assess the migration characteristics of elements in fly ash and the horizontal distribution of elements and the effects of fly ash on the quality of the underlying groundwater.Sensitive elements were seclected and classified,in order to simplify the environment monitoring activity near coal mines and metallurgy sites.The work was done to analyze the causes of pollution and lay the foundation for the adsorption of heavy metals using iron-based nanocomposites later.(2)Montmorillonite(Kaolinite)-supported zero-valent iron nanoparticles were prepared by a liquid-phase reduction under ambient atmosphere.The presence of clay decreased the aggregation and the oxidation of iron nanoparticles.The physical and chemical characteristics of materials were investigated through different characterization methods.The relationship between material quality and preparation conditions,the adsorption effect and mechanism of materials were illustrated.(3)Inexpensive and non-toxic novel Fe2O3-Fe3O4 nano-composites supported by montmorillonite and modified by graphene were successfully synthesized using the liquid phase reduction hydrothermal method.The results from current study shed new light on synergetic effects of visible-light responsible compositions,magnetic active ingredient,reduced size of nanoparticles by montmorillonite and enhanced electron separation by graphene on photocatalysis under the variation of mechanical structure by inexpensive and non-toxic iron oxide particles.(4)The removal mechanisms for Cu(Ⅱ),Ni(Ⅱ),Zn(Ⅱ),Pb(Ⅱ)by clay-zero-valent iron nano composite and the photocatalytic mechanism for organics by clay-iron-oxides nano composite were investigated.In addition,the correlation of conversion and environmental application between nano zero-valent iron and iron oxide in water was explored.As a matter of fact,the conceptual model of environmental application for iron-based nano material under complex water quality condition was established.