Purification of nanoparticles is an important step during preparation of nanoparticles in order to remove impurities and excess ligands. Such excess ligands in the solution may have unfavorable effects on downstream processing such as ligand exchange and shell growth. Most purification methods are batchwise and time-consuming. In this work, we developed an extraction system with a membrane separation to continuously purify nanoparticles. Here, silver nanoparticles (AgNPs) in an aqueous solution were used as a case study. AgNPs were synthesized with sodium dodecyl sulfate (SDS) as capping ligands, and ethyl acetate was used as an extraction solvent to remove the ligands. This novel method showed more 56.73% removal of the ligands while maintaining the morphology of the AgNPs. In addition, the AgNPs from this method was compared with those from conventional methods such as precipitation-redissolution in terms of purity well as catalytic activity. The integration of flow synthesis of AgNPs and continuous-flow purification was also demonstrated.

Graphical abstract

纳米颗粒的纯化是制备纳米颗粒期间的重要步骤，以去除杂质和过量的配体。溶液中此类过量的配体可能对下游加工（如配体交换和壳生长）产生不利影响。大多数纯化方法是分批且费时的。在这项工作中，我们开发了一种具有膜分离功能的提取系统，可连续纯化纳米颗粒。在此，以水溶液中的银纳米颗粒（AgNPs）为例。用十二烷基硫酸钠（SDS）作为封端配体合成AgNP，并使用乙酸乙酯作为提取溶剂以除去配体。这种新方法显示出更多的56.73％的配体去除，同时保持了AgNPs的形态。此外，将该方法的AgNP与常规方法的AgNP进行了比较，如纯度和催化活性方面的沉淀-再溶解。还证明了AgNPs的流式合成与连续流纯化的集成。

图形概要