Preparation Of Fe-TAML-MgO-CDP Composite Material For The Removal Of Aromatic Pollutants In Groundwater

The development of heavy industry in Northeast China and the exploitation of oil and gas fields have led to the concentrations of petroleum pollutants,ammonia nitrogen,and sulfide are much higher than the groundwater standard.These problems bring challenges to groundwater pollution remediation.Fe-TAML（TAML=tetraamidomacrocyclic ligand）is an oxidant catalyst,which is easily soluble in water and has high activity under alkaline conditions.Fe-TAML can adapt to the complex environment where various anions,cations and NOM exist in groundwater.In order to solve the pH limit of water body and the shortcomings of easy loss in the homogeneous system.the cyclodextrin material is selected as the carrier,and the hydrophobic cavity with the supramolecular recognition function of the cyclodextrin unit is used to selectively include and adsorb the pollutants in the water.Doped with Fe-TAML with high catalytic reaction activity and MgO to maintain the alkaline environment of the system,a cyclodextrin material loaded Fe-TAML,MgO composite material is prepared,and hydrogen peroxide is activated to degrade and remove pollutants.The Fe-TAML-MgO-CDP composite was prepared by the reverse emulsion method,and the Fe-TAML-MgO-CDP composite with a ratio of 0.1:5:50（Fe-TAML:MgO:CD）was selected.FTIR and XRD results confirmed that Fe-TAML and MgO were successfully loaded on CDP.The composite material has a 100-300μm block structure under the electron microscope,which can swell into a regular spherical structure in water.The content of Fe-TAML in the composite material is 0.68‰.In the first four washing processes,the total amount of Fe TAML released accounted for 57%of the total content of Fe TAML in the material.From the fifth cycle,the release of Fe TAML was stable,and the release of Fe TAML in each cycle accounted for 2-3%of the total content of Fe TAML in the material.The composite material showed good acid resistance,and the removal rate of chlorophenol reached 100%under the condition of pH=2 for 4 cycles.The effects of pH,NH4⁺,S^2-,DOM on the removal of chlorophenols by cyclic adsorption and oxidation of composite materials are discussed.The results showed that the degradation of chlorophenol was not affected at different pH values（pH=3,5,7,9）.When the concentration of NH4⁺is less than 100 mg/L,the degradation effect of the material has no effect.When the NH4⁺concentration is 100 mg/L and 200 mg/L,the removal rate of the material in the 5th,6th,and 7th cycle increases from 59%-88%to 63%-96%.When the sulfide concentration is less than 1 mg/L,it has no effect on the degradation effect of the material.When the sulfide concentration is more than 50 mg/L,the material can not degrade chlorophenol,because hydrogen peroxide is consumed by sulfide.Different DOM concentration（0-20 mg C/L）has no effect on the degradation effect of the material.The composite material is packed into the column.The removal efficiency of simulated groundwater containing chlorophenol,toluene,ethylbenzene and p-xylene was tested.After the treatment of 19 column volumes,the effluent concentrations of toluene,ethylbenzene and p-xylene all reached the class IV water body standard specified in the groundwater quality standard（GB 14848-2017）,and chlorophenol reached the class IV water body standard after the treatment of the first 18 column volumes.