Investigating the crystallization pathways of struvite using in-situ liquid-phase and cryogenic transmission electron microscopy

世界范围内的自然磷供应正在枯竭，而矿石磷被认为是一种关键资源。这种情况导致了从替代来源提取磷的新方法的探索。一种如此丰富的磷酸盐资源是在城市和工业废水中，那里有大量的磷，可以通过矿物鸟粪石(磷酸铵镁)的结晶来提取。然后鸟粪石可以直接用于化肥，从而有助于节约有限的磷资源。然而，这一回收过程的效率取决于对鸟粪石结晶机理和途径的更好理解。只有有了这些知识，才能有效地从废水中回收磷，减少磷对水环境的影响和对磷资源的需求。以前对水介质中鸟粪石的形成进行了研究，但大多是通过非直接方法，已被证明存在各种人工制品。因此，仍然缺乏对这一进程的有效和简单的机械性理解。在这里，我建议使用原位液相和低温电子显微镜相结合的方法，实时跟踪鸟粪石从初始离子到最终固体的所有结晶阶段。这两种技术的最新进展提高了我们对成核和生长的认识，但它们以前从未被应用于同一系统。通过对展开过程的成像和显微光谱分析，可以使用液态和低温电子显微镜来获得高度动态的(高时间和空间分辨率)信息。通过这个科学网络，我的目标是将世界一流的液体电池和低温技术和工艺专家聚集在一起，并应用他们来更好地了解鸟粪石的结晶途径。

Natural supplies of phosphorus are depleting worldwide and rock phosphorous is considered a critical resource. This situation has led to the exploration of new methods to extract phosphorus from alternative sources. One such abundant resource of phosphate is in municipal and industrial wastewaters where phosphorous is abundant and can be extracted via crystallization of the mineral struvite (magnesium ammonium phosphate). Struvite can then directly be used in fertilizers, thus helping to conserve finite phosphorus resources. However, the efficiency of this recovery process depends on an improved understanding of struvite crystallisation mechanisms and pathways. Only with such knowledge will the recovery of phosphate from wastewater be efficient and the environmental impact of phosphorous on the aquatic environment and the demand on phosphorus resources be reduced.The formation of struvite from aqueous media has been studied before, but mostly via non-direct methods which have been proven to suffer from various artefacts. Thus an efficient and simple mechanistic understanding of the process is still lacking. I propose here to use a combination of in-situ liquid-phase and cryogenic transmission electron microscopy to follow in real time all the crystallisation stages of struvite from initial ions to final solids. Recent advances in both techniques have improved our knowledge in nucleation and growth, but never before have they been applied to the same system. Together, liquid-phase and cryogenic transmission electron microscopy can be used to derive highly dynamic (both at high temporal and spatial resolution) information through imaging and micro-spectroscopic analyses of a process as it unfolds. With this science network I aim to bring together world class experts in liquid-cell and cryo technologies and processes and apply them to gain a better understanding of the crystallisation pathways of struvite.