锰掺杂纳米纤铁矿/整体多孔碳去除地下水中砷的效能与机制研究

Geogenic high arsenic groundwater is one of the global environmental geological disasters. At present, iron-based nanosorbents are being widely used as remediation materials for groundwater. However, several application bottlenecks exist, such as relatively low removal rate of As(III), strong tendency to agglomerate, and difficulty in reuse, which seriously restrict its application scope. In this project, a novel class of material (MFO/MPC), composed of Mn-doped nano FeOOH (MFO) supported on monolithic porous carbon(MPC), is developed for efficient removal of arsenic. Unlike conventional nanosized remediation materials, MFO/MPC not only has the bifunctionality of oxidation and adsorption, but also possesses the property of anti-agglomeration, which makes it possible to achieve a high removal efficiency toward As(III) even being reused repeatedly. After controllable synthesis of MFO/MPC and systematical analysis on its physicochemical properties, the adsorption and oxidation behaviors of MFO/MPC will be investigated under the simulated conditions. Then the mechanism on interaction between MFO/MPC and As species will be clarified through theoretical calculations and experimental characterization. Moreover, given the impact of competitive components, the arsenic removal efficiency of MFO/MPC on geogenic high arsenic groundwater in typical area will be evaluated. It is aimed to optimize the bifunctionality of oxidation and adsorption in MFO/MPC, achieving their cooperative coupling. Further, in order to obtain a stable and excellent performance in reuse, activation and regeneration process of MFO/MPC will be investigated. All the above research is expected to offer a feasible technical proposal and theoretical basis when remediating geogenic high arsenic groundwater in a high-efficency, environmentally-friendly and low-cost way.

原生高砷地下水是全球性环境地质灾害问题，铁基纳米吸附剂是当前广泛采用的改良材料，但普遍存在对高毒性As(III)去除能力较弱且易团聚、难回收等瓶颈，严重制约了其推广应用。本项目拟发展一类具有“氧化(Mn(IV))-吸附(Fe(III))”双活性及抗团聚/脱落特性的锰掺杂纳米纤铁矿(MFO)/整体多孔碳(MPC)除砷材料，实现As(III)的高效去除与材料的回收再利用。项目首先考察MFO/MPC在含砷模拟溶液中的氧化、吸附规律，并结合理论计算与表征测试手段揭示其与砷的相互作用机制；继而评估MFO/MPC用于典型原生高砷地下水的除砷效果，探究竞争组分的影响，优化实现“氧化-吸附”双功能的协同耦合；进一步研究MFO/MPC的活化再生工艺，以获得稳定优异的重复使用性能。研究结果以期为高效、绿色、低成本改良原生高砷地下水提供可行的技术方案和理论依据。

原生高砷地下水是全球性水环境问题，常用的除砷材料铁基纳米吸附剂因对高毒性As(III)去除能力较弱、易团聚、难回收等瓶颈难以推广应用。基于此，本项目制备了一类具有“氧化(Mn(IV))-吸附(Fe(III))”双活性及抗团聚/脱落特性的锰掺杂纳米纤铁矿（Mn-FeOOH）/整体多孔碳（CF）除砷材料CF@Mn-FeOOH，研究了其除砷效能与影响因素，通过考察锰和砷在除砷过程中的形态转化规律，阐明了材料与砷的相互作用机制，重点探究了材料在高砷地下水实际除砷应用中的双功能调控方法，进一步优化材料的活化再生工艺与重复使用性能，为实现原生高砷地下水中As(III)和As(V)的高效去除与吸附材料的回收再利用提供支撑。研究取得的主要进展如下：（1）成功制备了具有“氧化-吸附”双功能的整体支撑型除砷材料，其对As(III)和As(V)的最大吸附容量分别高达107.3 mg/g和152.5 mg/g；（2）Mn(IV)与FeOOH的协同作用是CF@Mn-FeOOH能同时高效去除As(III)和As(V)的关键，通过调变材料合成过程中的铁锰比（Fe/Mn）可针对性的调控材料的除砷性能，而针对大同盆地典型高砷地下水区域CF@Mn-FeOOH的最优铁锰比为Fe/Mn=30；（3）使用NaOH溶液、H2SO4溶液和0.1%的H2O2溶液解吸、活化使用过的CF@Mn-FeOOH，可达到优异的再生效果，经五次循环使用后，材料对As(III)和As(V)的吸附量仍能保持在初始值的82%和85%。研究内容以山西大同盆地典型原生高砷地下水为改良目标，将具有“氧化-吸附”双功能的Mn-FeOOH和宏观稳定结构的CF有机结合，针对性地研发了一类整体支撑型CF@Mn-FeOOH材料，室内静态与动态吸附实验验证了材料实际应用的可行性，为后续有针对性的开展原生高砷地下水的高效、绿色、低成本改良工作提供了理论依据和数据支撑。