Application Of Nano Zero Valent Iron Intercalated Organic Montmorillonite In The Treatment Of Groundwater Pollution

Fossil fuels are causing Greenhouse Effect and climate change is becoming increasingly apparent,nuclear energy as a clean energy as a first choice to meet the demand for energy.However,the waste water containing uranium discharged during the exploitation of uranium resources makes the environment polluted to varying degrees.At present,the adsorption method has attracted much attention in the removal of the neighboring area of uranium contamination.The composite adsorbent is widely used in uranium pollution treatment because of its advantages such as the wide distribution of demand-selective groups and matrix materials.In this paper,montmorillonite?MT?was used as the matrix,cetyltrimethylammonium bromide?CTAB?was used to modify the montmorillonite,and the composite adsorption material CTAB-nZVI-MT was prepared by NaBH4 reduction method.By comparing the adsorption effect of the composites with different CTAB and nZVI ratios,the optimum ratio of CTAB-nZVI-MT synthesis was determined.CTAB-nZVI-MT was characterized by EDS,SEM,ICP,Zeta-potential and XRD.The results of SEM and EDS show that the interlaminar structure of the composites is obviously interlaminar.The results of EA and Zeta potential analysis showed that the CTAB successfully introduced the composite material,and the potential value of the materials was improved.The results of ICP and XRD show that the nZVI in the composite is still in the form of 0 valence,and the quality of nZVI in the composite is high.The effects of solution pH,temperature,contact time,initial uranium concentration,total carbonic acid concentration,calcium ion concentration and humic acid content on CTAB-nZVI-MT and nZVI adsorption were studied by static adsorption experiments under aerobic and anaerobic conditions.The optimum pH value for CTAB-nZVI-MT adsorption of uranium is 6.0,and the adsorption equilibrium is achieved within 180 min,which accords with the quasi-second-order adsorption kinetic model.The saturated adsorption capacity increased from 357.61mg·g^-1 to 371.24 mg·g^-1 under anaerobic condition,and the adsorption was less affected by carbonate than nZVI.The adsorption of uranium by CTAB-nZVI-MT accords with the isothermal adsorption model of Langmuir and Freundlich.The thermodynamic parameters?H>0,?G<0 and?S>0 indicate that the adsorption of uranium by CTAB-nZVI-MT is a spontaneous endothermic chemical process.The total carbonate and calcium ions in the solution inhibit the adsorption of uranium;dynamic column experimental results show that the permeable reaction wall?PRB?with CTAB-nZVI-MT as active material has obvious removal effect on uranium.The penetration point and saturation point of the PRB column filled with CTAB-nZVI-MT decreased with the increase of the total carbonate concentration,calcium ion concentration and humic acid concentration of the solution.The penetration point of the PRB column filled with CTAB-nZVI-MT was 2.7-4.7 times of that of the PRB column filled with nZVI,and 5.9-8.3 times that of the pure soil column.It has a good application prospect in the field of in-situ treatment of uranium contamination.