Study On The Remediation Of As Contaminated Groundwater With Magnetic Graphene Oxide Based Surface As(?)-imprinted Polymers

Groundwater arsenic pollution is one of the most serious environmental problems facing the international community.The remediation of As???pollution in groundwater is a current popular research.Iron-based adsorption materials are widely studied because of their high reactivity and high adsorption efficiency,but the limited adsorption capacity for As???and the agglomeration phenomenon in aquifers due to the high surface energy are making these materials problematic in applications of practical contaminated sites.With the development of surface imprinting technology,efficient removal of As??? becomes possible.Based on these theories,this research developed a magnetic graphene oxide based surface As???-imprinted polymer?Fe3O4/GO-As???-IIP?as an adsorption material,using the huge specific surface area of GO to provide positions for imprinted cavities,and the layered structure is beneficial to the coating of Fe₃O₄for enhancing its dispersibility.Fe3O4 acts as the core of the adsorbent to achieve rapid separation and directional migration under external magnetic field.The imprinted caivties on the surface can specifically adsorb As???in the presence of various of ions for improving the adsorption efficiency.The Fe₃O₄/GO-As???-IIP has been studied through one-dimensional simulation column and two-dimensional simulation trough experiment for revealing the mobility in aquifers and the removal efficiency of As???contaminated groundwater.The results of this study are as follows:?1?A magnetic graphene oxide based arsenic imprinted polymer?Fe₃O₄/GO-As???-IIP?was successfully prepared by in-situ precipitation method and cross-link polymerization method.The optimal dosage of GO in Fe3O4/GO was determined within 12%¹5%by VSM,XRD and FTIR proved that Fe₃O₄ was distributed on GO.The cavities on the surface of the imprinted material were observed by SEM for comparing the difference between Fe₃O₄/GO-As???-IIP and NIP.?2?The adsorption process of Fe₃O₄/GO-As???-IIP conformed to the Langmuir isotherm adsorption model,which indicated that the adsorption process is monolayer adsorption.The maximum adsorption quantity could achieve 49.42mg/g.The adsorption kinetics results were well described by the quasi-second-order kinetic model,confirming that chemical adsorption dominated the adsorption process.Thermodynamic studies showed that the adsorption process is a spontaneous endothermic reaction,and the value of?S indicated that Fe₃O₄/GO-As???-IIP has a good affinity for As???.The comparison of specific studies discovered that the selective adsorption capacity of Fe3O4/GO-As???-IIP for As???is significantly higher than that of NIP.There was a certain degree of influence of SO₄^2-and PO₄^3-and other ions with similar structure to As???,and the organic components had no significant effect on the adsorption of As???.The adsorption efficiency of Fe₃O₄/GO-As???-IIP was about 89%of its original efficiency after five times reuse.It was determined that the adsorption mechanism of Fe3O4/GO-As???-IIP for As???is the specific adsorption of imprinted cavities.There were two different types of binding sites on the surface of Fe₃O₄/GO-As???-IIP,which play a major role at different As???concentrations,respectively.?3?The experiments of one-dimensional simulation column showed that there is a critical value for the hydrodynamic shear force.When the injection speed was lower than 0.069 cm/s,increasing the injection speed significantly increases the migration of Fe₃O₄/GO-As???-IIP.Without affecting the migration effect of Fe₃O₄/GO-As???-IIP in the simulated columns,the maximum injection concentration could reach 3g/L.The width of the reaction zone formed in the coarse sand medium was about 2.5 times of that in the medium sand.The addition of external magnetic field could help improve the migration and recovery of Fe₃O₄/GO-As???-IIP.In the coarse sand medium,when the injection concentration of Fe₃O₄/GO-As???-IIP was 4g/L,the recovery efficiency reached 44.8%by the external magnetic field,and the recovered material still had good magnetic response.?4?In the experiments of two-dimensional simulation trough,the formation of the Fe₃O₄/GO-As???-IIP reaction band could be observed,and showed good removal efficiency for As???within 96 hours.Fe₃O₄/GO-As???-IIP,which could stably distribute around the magnetic field,showed excellent mobility under the external magnetic field,and the removal efficiency of As???was obviously improved?from71.9%to 83.3%within 96 hours?.