A review on fly ash high-value synthesis utilization and its prospect

As a common industrial solid waste, fly ash requires proper processing and utilization to alleviate environmental pressure. In contrast to earlier low-value treatment methods for fly ash, such as its use in construction materials, it is more practical to explore the high-value utilization of fly ash, considering its elemental ingredient and morphological characteristics. Herein, this work comprehensively reviews the methods and research progress of extracting and preparing silica, alumina, and zeolite respectively derived from silicon and aluminum elements in fly ash. Specifically, the mechanisms and processes of various methods are elucidated in detail, and the virtues and drawbacks of the production technologies are compared to identify a more economical and environmentally friendly method. Importantly, this work first reviews the utilization of fly ash in energy storage electrode materials. Different synthesis and treatment strategies are thoroughly examined, especially in fully utilizing fly ash as a primary resource, converting it into energy storage materials. Finally, this paper summarizes the opportunities and challenges associated with the high-value utilization of fly ash.