Chlorapatite Derived From Fish Scales

Area of Science:

• Materials Science
• Biomaterials Engineering
• Inorganic Chemistry

Background:

• Fish scales, a byproduct of the fishing industry, represent a potential source of biomaterials.
• Apatite structures are known for their diverse applications, including in electronics and medicine.
• Sustainable synthesis routes for advanced materials are of significant interest.

Purpose of the Study:

• To demonstrate the production of chlorapatite (ClAp) from chemically treated fish scales of *Arapaima gigas*.
• To investigate the effect of thermal decomposition temperatures on the properties of the synthesized ClAp.
• To explore the potential applications of the synthesized ClAp and NaCaPO4 in electronics and biomedical fields.

Main Methods:

• Fish scales were deproteinized using hydrochloric acid (HCl) and neutralized with sodium hydroxide (NaOH).
• The apatite-rich slurry underwent thermal decomposition at 600 °C, 800 °C, and 1000 °C.
• Characterization involved X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM).

Main Results:

• XRD and FTIR confirmed the successful incorporation of chlorine into the apatite structure, identifying chlorapatite (Ca5(PO4)3Cl), NaCl, and NaCaPO4 phases.
• The highest ClAp content achieved was 87.4 wt%.
• SEM analysis revealed increasing grain size and crystallinity with temperature, with grains ranging from 1 to 5 μm and 84.27% crystallinity at 1000 °C.

Conclusions:

• Chemically treated fish scales are a viable precursor for producing chlorapatite via thermal decomposition.
• The synthesized chlorapatite and sodium calcium phosphate exhibit properties suitable for phosphor materials in electronics and for biomedical applications.
• This method offers a sustainable approach to valorize fish waste into functional materials.