Cu²⁺ And Fe₃O₄ Co-migration And Transformation Of Nanoparticles In The Vadose Zone

The aerated zone is an unsaturated zone above the surface below the surface of the subsurface.It is an important communication path between surface water and groundwater exchange.All the pollutants on the surface have to pass through the aeration zone for groundwater pollution.Therefore,the aeration zone has a great impact on groundwater quality.The essential.In today's environment,due to the arbitrary discharge of copper-containing wastewater in the industrial“three wastes”,the problem of copper pollution in the aerated zone is very serious.The copper content of the aerated zone exceeds the standard,which has a serious impact on the growth and development of plants,and may even cause ecological disorders.In addition,due to the characteristics of copper enrichment,copper will accumulate through the layers of the food chain,causing serious toxicity to plants and even humans.The traditional method of treating copper pollution:such as the common soil replacement method and soil phytoremediation method,due to its high economic cost and specificity of soil restoration,there is no way to widely apply it.Nanomaterials have been widely used in the field of pollution remediation in recent years due to their large specific surface area and strong adsorption.It is found that Fe₃O₄ magnetic nanoparticles?MNPs?have strong adsorption capacity for copper ions,and the polymers formed by the combination of MNPs and copper ions are more easily adsorbed by soil,which reduces the migration of copper ions in soil.Distance reduces the risk of copper pollution.In recent years,there have been few reports on the law of co-migration of nanomaterials and copper ions in the aeration zone.Therefore,the co-migration of nanomaterials with copper ions in the saturated zone is used as a control,and the soil column experiment is used to simulate the saturated zone and the aerated zone.Band,respectively,explore the migration of copper ions in the vadose zone with or without MNPs,and set different influencing factors?flow rate,pH,ionic strength,humic acid?,and analyze the effect of environmental changes on copper migration.Happening.Experimental results show:?1?The three kinds of aerated zone/saturated zone of coarse,medium and fine sand have the adsorption capacity for Cu²⁺:coarse sand<medium sand<fine sand.As Cu²⁺decreases with the particle size of porous media,the transport velocity of Cu²⁺in the aerated zone/saturated zone porous media slows down.The reason is that the porosity coarse sand>medium sand>fine sand,the contact time of the porous medium with large porosity and Cu²⁺is reduced,and the adsorption capacity is weakened.Cu²⁺migrates longer in the aerated zone than the saturated zone.Due to the poor molecular diffusion ability of Cu²⁺in the vadose zone,the adsorption capacity of porous media for Cu²⁺is reduced.?2?In the aeration zone,as the particle size of the porous medium decreases,the adsorption capacity of the porous medium for co-migrating Cu²⁺with MNPs is enhanced,and the migration distance is reduced.Because Cu²⁺and MNPs co-migrate in porous media,Cu²⁺and MNPs can chelate on the surface,and the chelating substances formed are more likely to form physical adsorption with porous media,thus reducing the migration distance of Cu²⁺.In the saturated zone,the three porous media of coarse,medium and fine sand have the adsorption capacity for co-migrating Cu²⁺with MNPs:coarse sand<medium sand fine sand.This is due to the obvious solute diffusion phenomenon in the solution.Therefore,when the particle size of the porous medium is reduced to a certain extent,the difference in hydraulic retention caused by the particle size can be neglected,which leads to the adsorption of Cu²⁺during the co-migration between the medium sand and the fine sand.The difference in capabilities is small.?3?Through the correlation analysis of Spearman's environmental impact,the migration of Cu²⁺and Cu²⁺/MNPs in the aeration zone is greatly affected by the environment,and the change of seepage velocity in the aeration zone has the greatest influence on the migration of Cu²⁺.Because the percolation velocity is slowed down,the adsorption time of the porous medium and Cu²⁺is increased,and the adsorption efficiency of the porous medium for Cu²⁺is increased.In the aeration zone,as the pH decreases and the ionic strength increases,Cu²⁺competes with the cation to adsorb,which reduces the adsorption of Cu²⁺by the porous medium and increases the migration of Cu²⁺.Humic acid chelate with Cu²⁺,and the resulting chelate is more easily adsorbed by porous media.Therefore,when the concentration of humic acid in the infusion increases,the adsorption capacity of porous media for Cu²⁺increases,and the migration distance of Cu²⁺in porous media.Reduced.The research results will provide a research method and data support for quantitative evaluation of the behavioral fate of engineering nanoparticles and heavy metal ions in the aeration zone,and provide a scientific basis for the nano-remediation technology of gas-bearing heavy metal pollution and the environmental safety conversion of engineering nano-materials..The research results in the detailed study of MNPs and Cu²⁺co-migration,providing a new idea for groundwater pollution prevention and control.