Prepapration Of New Iron-based Function Composites And Remediation Of Soil Plumbum Pollution

In recent years,the rapid development of industry and agriculture in China has caused a series of serious environmental pollution problems,especially plumbum pollution in soil.Once plumbum enters the human body,it will seriously affect human health,causing great harm,and it is difficult to reverse and discharge.Therefore,soil plumbum pollution has attracted worldwide attention and various repair methods have also emerged.Among them,the curing stabilization technology has many advantages including low investment,high efficiency,short repair period and simple operation.It can solve the problems encountered by traditional methods and has a good application prospect.In this paper,FeCl3·6H2O was used as the starting material,ethylene glycol as solvent and two ethylene three amine as amino source by hydrothermal method.Under the reaction conditions of 160 ?and 8 h,NH2-FeOOH was synthesized in one step.After grafting,chitosan(CS)was loaded on the prepared NH2-FeOOH to obtain CS/NH2-FeOOH.At the same time,the influence of the time and temperature of the hydrothermal reaction on the phase characteristics of the material was investigated.Two new materials,NH2-Fe2O3 and NH2-Fe3O4,were obtained.The NH2-Fe3O4 prepared at 220 ? for 2 h was used as an adsorbent.The effect of curing the heavy metal Pb was investigated by the indoor batch balance method.The p H of the plumbum nitrate solution was adjusted with the 0.1 mol/L HCl and Na OH solution to explore the effect of p H on the cure effect.On the other hand,under the reaction conditions of 160 ? and 8 h,two materials,NH2-FeOOH and CS/NH2-FeOOH,were used as curing agents.The effect of heavy metals in solidified soil was analyzed by outdoor potted wheat experiment.A large number of studies have shown that the wet and dry alternation has a significant impact on the cure stabilization technology.Therefore,in this paper,activated carbon and diatomaceous earth were chosen as curing agents.Pot experiments were conducted to investigate the effect of alternating wet and dry on the effect of curing agent on soil heavy metals.The main contents and conclusions of the article are as follows:1)Preparation of materials.Using hydrothermal method,NH2-FeOOH was directly prepared in one step,then chitosan was loaded by grafting to obtain CS/NH2-FeOOH.The SEM,XRD,FTIR,specific surface and porosity characterization showed that both of them are flaky and belong to the nano-scale materials,and have a mesoporous structure and a large specific surface area.The aperture sizes of the two are 16.368 nm and 16.543 nm,respectively.The specific surface areas were 103.949 m2·g-1 and 84.973m2·g-1,respectively.2)Optimization of preparation of NH2-FeOOH material.The conditions were prepared at 160 ?,8,10,12,14,16,18 h and 180 ?,200 ?,and 220 ? for 2,4,6,and 8 h,respectively,at four different temperatures.The macroscopic performance is as follows: With the increase of temperature and time,the process of deepening the color of the sample is orange yellow-brown-gray black,and the magnetic properties are also enhanced.The particles become thinner and the adhesion is enhanced,the yield of the material is reduced.The micro-morphology analysis shows that the temperature and time increase,the sample growth process is: from the sheet into a granular,and gradually formed a uniform sphere,and finally the state of nano-sized small balls and micro-scale block coexist;After scanning Electron microscopy analysis showed that the morphology of the three samples at 180 ?,200 ?,and 220 ? was representative at 2 h,and further analysis by XRD and FTIR showed that the materials prepared under these conditions were amino ?-Fe2O3,FeOOH,Fe3O4.3)Indoor simulation experiments.After adding NH2-Fe3O4 to the soil,the amount of plumbum adsorbed increases with the amount of added material.When the amount of added material was 9 % of the soil,the adsorption of plumbum was balanced.At different p H,the amount of plumbum adsorption on the heavy metals was alkaline> neutral> acidic.4)Outdoor pot experiment.Pot experiments were conducted to investigate the effect of NH2-FeOOH and CS/NH2-FeOOH on the recovery of heavy metals Cu,Zn,Pb,and As in the soil.The results of p H,organic matter,soil digestion and available state extraction results showed that NH2-FeOOH and CS/NH2-FeOOH had the best remediation effect on Pb.The removal rate of Pb in the active state of heavy metals by NH2-FeOOH material was up to 19.2 %.5)Wet and dry alternation effects.After adding 0.6 % activated charcoal and diatomaceous earth to the soil,potted wheat experiments were conducted to establish flooding,flooding-drought,and drought treatments.We investigated the effects of alternating wet and dry treatments on heavy metals in soils.After two months of cultivation,the results of p H,organic matter,soil digestion and available state extractions showed that flooding treatment can improve the solidification effect of the material.Through the above experiments and conclusions,it can be seen that a variety of new amino functionalized composite materials have been successfully prepared in this study,and they have certain effects in the repair of plumbum.