A Comprehensive Review of Porous Materials Derived from Animal Bone Waste

As the global population grows and living standards rise, the demand for meat is increasing rapidly, inevitably generating about 100 million metric tonnes of animal bone waste (ABW). This biomass residue is mainly composed of organic collagen and inorganic hydroxyapatite. Therefore, ABW may cause environmental pollution if it is not properly treated, but it can also serve as a valuable resource for the circular economy if appropriately valorized. This comprehensive review aims to focus on thermochemical processes for converting ABW into porous hydroxyapatite-based materials and further summarize their value-added applications (e.g., environmental adsorbents, catalysts or their supports, biomedical materials for bone grafting and tissue engineering, and electrode materials for energy storage). Therefore, the four topics will be covered to echo the targets of this review paper, including the sources and characteristics of ABW, processes for transforming ABW into porous materials, pore property determinations for porous materials derived from ABW, and value-added applications of porous materials derived from ABW. Based on the information gathered in this review, the valorization of ABW and its derived pore materials may facilitate a practical circular economy case in which animal bones are reused as an available resource to produce newly porous materials for a variety of novel and high-value applications like medicine and energy fields.