Enhancing Strength Properties of Hydroxyapatite Composites with Bentonite Clay

Abstract

The main inorganic component of human hard tissues is hydroxyapatite (HA, Ca<inf>10</inf>(PO<inf>4</inf>)<inf>6</inf>(OH)<inf>2</inf>) and the mechanical and biological performance of HA can be improved by incorporating clay minerals to create HA-clay composite scaffolds. This study demonstrates a high-strength biocomposite of HA and bentonite with a significant reduction of open porosity, considering bentonite clay for its biocompatibility. Prawn shells (Fenneropenaeus indicus - marine resource) were utilized as a sustainable source of calcium to synthesize high-purity HA through a wet-chemical process, offering an innovative approach to valorize bio-waste. HA-bentonite clay composites were made by compacting 10-40 wt% of bentonite clay with HA using uniaxial pressing, followed by sintering at 1100°C for 2 h. Characterization techniques like X-ray diffraction, Raman, Fourier transform infrared spectroscopy and field emission scanning electron microscopy verified the phases, structures, vibrational bonds and morphology of the synthesized materials. Energy dispersive X-ray spectroscopy and inductively coupled plasma mass spectrometry analysis were performed for elemental composition and heavy metal detection, respectively. The HA-bentonite (30 wt%) composite achieved an exceptional compressive strength of 155 MPa and an open porosity of 7%, surpassing bare HA. Adding 30% bentonite increased compressive strength six fold and decreased open porosity by 51% compared to bare HA. This novel approach to HA-bentonite scaffolds promises enhanced wear resistance and cellular proliferation in bone tissue engineering. © 2025 Indian Ceramic Society.