Dissolution Performance of Carbon/Hydroxyapatite Nanocomposite Prepared from Fish Scales

The utilization of waste as raw materials in the production of functional materials is a growing area of interest to promote global sustainable growth. This work studied the microstructure, chemical properties, and phosphorus (P) dissolution efficiency of carbon/hydroxyapatite (HAP) nanocomposites derived from fish scale wastes, namely FSBCs. Tilapia scales were pyrolyzed at different temperatures (450–600 °C) and the dissolution performance of the biochars in acidic media was evaluated. The pyrolysis of fish scales yielded biochars which are carbon/HAP nanocomposites of which the characteristics, including the specific surface area, carbon content, degree of crystallinity of HAP, and the degree of CO32− substitution in HAP crystals, were dependent on the pyrolysis temperature and had an influence on the dissolution efficiency. P dissolution experiments suggested that the specific surface area and the presence of carbon in the composite played an important role during the dissolution process. The presence of the organic residues on the carbon could potentially block the calcium sites on HAP from citric acid and lower the dissolution efficiency. The ratio of CO32−/PO43− substitution in HAP also affected the dissolubility of FSBCs. The manipulation of their surface area and the CO32−/PO43− ratio of these materials would allow us to increase its solubility, which could benefit a prospective application such as P fertilizer production.