基于单分子基磁体的团聚开关型双磁性纳米吸附剂及其吸附重金属过程研究

The wastewater discharge in mining and metallurgy industry is challenged by its huge volume, complex composition and dilute content of target metal ions. The development of new methods capable of removing heavy metals from dilute and complex solution is essential to reduce the overall discharge of heavy metal ions in our county. While a higher selectivity to the target metal ion is obtained, the imprinting treatment leads to an unexpected loss of magnetic responsibility and thus a low recovery of the imprinted magnetic nanoparticles (MNPs). This thus prevents its industrial practice. Targeting at this problem, this proposal presents a de novo design of imprinted MNPs, in which an agglomeration magnetic switch on MNPs surface is attached through conjugating a temperature-responsive molecular magnet with the imprinted MNPs adsorbent. An expected magnetism conversion below the blocking temperature enhances the formation of MNPs aggregates, and thus enable a rapid and complete recovery of the imprinted MNPs adsorbent. Included into this study is, firstly, the design and fabrication of the proposed temperature-responsive molecular magnet with the imprinted MNPs adsorbent. Then the adsorption performance and magnetic responsiveness of the proposed magnet adsorbent will be characterized. Finally, a molecular insight of the adsorption and agglomeration will be generated by a complementary input from both multi-scale molecular simulation and experimental analysis. With these efforts, we wish to identify the major factors, elucidate how they affect the adsorption and agglomeration of the imprinted MNPs, and provide molecular and process fundamentals for the design and application of the proposed magnetic adsorbents with tunable magnetic responsiveness for the adsorption of heavy metal ions from dilute solution.

矿业废水具有排放量大、成分复杂的特点，研究高效去除其低浓度重金属的新型分离方法，对降低我国重金属排放总量具有重要意义。常规的磁性纳米铁氧化物颗粒（以下简称MNPs）通过印迹改性处理后能够特异性吸附目标重金属污染物，但改性处理会导致其磁响应性急剧下降，给回收复用带来困难。本项目提出将具有磁转变性的单分子基磁体与印迹MNPs结合形成“团聚开关型”双磁性纳米吸附剂的设想，利用改性MNPs来“识别性”吸附重金属污染物，吸附结束后通过降温使单分子基磁体转变为弱铁磁性以强化纳米吸附剂颗粒的团聚，实现印迹MNPs的快速磁性回收。研究内容包括：1）常温下团聚可“开关”型双磁性MNPs的分子设计与可控制备；2）双磁性纳米印迹吸附剂的构筑及其吸附与磁回收特性；3）双磁性纳米吸附剂吸附与回收过程影响因素的作用机制。通过上述工作为重金属的深度处理技术的创新和工程实施提供理论和技术支持。

矿业废水具有排放量大、成分复杂的特点，虽然经过处理后大都能够达到综合污水排放标准，但其含重金属总量巨大，并且国家对污染物排放总量控制提出了要求，在这样的背景下，研究高效去除其低浓度重金属的新型分离方法，对矿业废水重金属排放总量的降低具有重要意义。本项目首次将螺旋管式微通道反应器应用到了磁性纳米铁氧化物吸附剂的水相共沉淀法制备，得到的磁性纳米颗粒在保持良好的磁回收特性的同时具有更好的结晶性、粒径均匀性、分散性，实现了低成本、高均匀度的连续化批量制备；系统性建立了磁性纳米吸附剂表面胺基化、巯基化、羧基化以及印迹化等改性方法，研究了各种改性方法对纳米吸附剂的团聚状态与磁回收性能的影响，同时结合理化性质变化，分析了对不同类型重金属的吸附特性与吸附机理，建立了关联性模型，为在实际体系中应用提供了精细化指导；将量化计算与具体实验相结合，分析了pH、离子强度等外源性条件对磁性纳米吸附剂的磁回收性与重金属吸附能力的影响以及微观作用机制，实现了磁性纳米吸附剂回收性能与吸附性能的可控调节，为后续应用工艺操作参数设计提供具体依据。