As(III)印迹材料定向修复砷污染地下水机理与效能研究

“Adsorption－Immobilization” is the common approach to remediate As(III) polluted groundwater. Fe3O4 nanoparticle adsorbent was widely used. However, selectivity and stability of the absorbent for As(III) were low, and Fe3O4 nanoparticle would be aggregated when it was used in groundwater remediation, so the remediation efficiency would be reduced in low permeability zones; also, the changing of pH and Eh would lead to release of As(III) and cause secondary pollution. Based on the principle of “Selective Adsorption－Orientation Migration－Recycle”, the project develops As(III)-ion-imprinted polymer (Fe3O4/GO-As(III)-IIP) as a remediation agent, and to achieve orientation remediation and recycling of As(III) for arsenic contaminant groundwater under an applied magnetic field. The project is to study the selective adsorption mechanism of Fe3O4/GO-As(III)-IIP for As(III); investigate orientation migration characteristics of Fe3O4/GO-As(III)-IIP in aquifers; reveal mechanisms of Fe3O4/GO-As(III)-IIP reactive zone remediating As(III) contaminant; clarify recovery efficiency and the main control parameters of As(III) and Fe3O4/GO-As(III)-IIP; assess efficacy of As(III) orientation remediation with Fe3O4/GO-As(III)-IIP intensified by magnetic field. The findings of this project can serve as theoretical bases for efficient remediation of arsenic contaminant in aquifers.

“吸附－固定”是修复砷污染地下水的主要途径。以Fe3O4为代表的铁系纳米吸附剂被广泛关注，但其对As(III)的选择吸附性和吸附稳定性差，且易发生团聚，导致修复效率低；另外，随着pH或Eh的改变As(III)将再次释放造成二次污染。本项目基于“选择吸附－定向迁移－回收”原理，研发As(III)印迹材料—Fe3O4/GO-As(III)-IIP，结合外磁场的驱动力，定向修复砷污染地下水。在解析Fe3O4/GO-As(III)-IIP除砷行为特征的基础上，重点研究磁场作用下Fe3O4/GO-As(III)-IIP在含水层中定向迁移规律；阐明Fe3O4/GO-As(III)-IIP反应带定向修复机理；分析修复试剂及砷的定向回收效率及主要控制参数；明确反应带的发展演化过程；综合评估Fe3O4/GO-As(III)-IIP反应带定向修复砷污染地下水的效能。研究成果可为地下水砷污染去除提供理论依据。

“吸附－固定”是修复砷污染地下水的主要途径。铁系纳米吸附剂对As(III)的选择吸附性和吸附稳定性差，且易发生团聚，导致修复效率低；随着pH或Eh改变As(III)将再次释放造成二次污染。本项目研究砷印迹材料Fe3O4/GO-As(III)-IIP对As(III)的选择吸附特征，揭示磁场强化印迹材料的定向迁移行为，阐明砷污染地下水的反应带定向修复机理、材料及As(III)的定向回收效率及主要控制参数。结果表明：1）通过VSM、XRD、FTIR、SEM等表征证实了砷印迹材料的成功合成，材料具有较好的分散性和磁分离性，且吸附属于化学和单分子层吸附，最大吸附量达49.42mg/g。吸附过程是吸热反应且自发的。砷印迹材料具有较好的选择吸附性和重复利用性。2）当注入速度<0.069cm/s时，提高注入速度可增强材料的迁移性，当注入浓度高于3g/L时，材料截留量大、迁移性减弱；粗砂介质中形成的反应带宽度约为中砂的2.5倍；外加磁场有助于印迹材料的迁移和回收，外加磁场强度大于0.5T时，对材料的迁移影响明显。回收后的材料仍有较好的磁响应性，有利于材料的再利用。3）印迹材料在含水层中迁移受重力影响较大，外加磁场下有较好的定向迁移能力，并稳定形成反应带；连续注入1mg/L As(III)污染液，在96h内对As(III)具有显著的去除效果（83.2%），回收率到达42.7%，有利于材料的重复利用，避免污染物的二次释放。本研究为地下水砷污染去除提供理论依据和科技支撑。