Isolation and characterization of hydroxyapatite powder from the scale of freshwater fish Labeo rohita using green technology

Abstract

The objective of the present work was to isolate and characterize hydroxyapatite (HAP) from Labeo rohita scale using green technology. The method used only 0.6% KOH solution for isolation, which did not generate any spent liquid for disposal to the environment. Investigation through thermogravimetric analysis, X-ray diffraction study, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and particle size distribution measurement was carried out for characterization of HAP. The powder after isolation from scale contained < 7% organic matter and could be converted to thermally stable perfectly crystalline pure HAP without any organic impurity by exposition to 1000 °C for only 1 h. The heated HAP powder had a Ca:P ratio of 1.52 and indicated the grains to be in submicron size but remaining in soft agglomerated condition with 50% of the mass passing through ≈ 167 µm.