Extraction of Calcium Phosphate Nanoparticles from Cooked Bone Wastes by Supercritical Water

As a typical food waste, bone waste is always disposed of in landfills or incineration or used to make products with low added values. In contrast, extracting calcium phosphate micro/nanoparticles from bone wastes is a feasible method of valorization. However, the bones previously used for extracting Ca-P micro/nano particles are limited to fresh bones rather than cooked bone wastes, and tedious multi-step pretreatments are required, which greatly restricts the further application of this technology. Here, Ca-P nanoparticles were obtained from cooked pork bone during a one-step supercritical water treatment at 380 °C for 20 ~ 24 MPa with high yields. It was the first time to convert bone wastes after real cooking to value-added products without any pretreatments. The thermal treatment method was performed at high temperatures (815 °C) as a comparison. Ca-P nanoparticles obtained by both supercritical water and thermal treatments have the crystal phase of hydroxyapatite. Compared with the thermal treatment, Ca-P nanoparticles obtained in supercritical water showed rod-like morphology with high length–width ratios, narrower size distributions, and smaller sizes, most of which were below 100 nm. The successful extraction of Ca-P nanoparticles from cooked bone wastes provided a feasible method of valorizing the wastes with complicated compositions. Graphical Abstract: [Figure not available: see fulltext.].