Green Synthesis of Bentonite-Hydroxyapatite from Eggshell Waste for Methylene Blue Dye Adsorption

Eggshells, as a by-product of egg consumption, represent a highly potential waste material. Their high calcium content makes them a suitable precursor for hydroxyapatite (HAp) synthesis. This study aimed to determine the characteristics of HAp derived from chicken eggshells and to evaluate the ability of bentonite–HAp composites to reduce methylene blue (MB) through adsorption. The precipitation method was used for HAp synthesis because it can produce HAp with a high level of purity and low levels of contaminants. The X-ray diffraction (XRD) diffractogram of the synthesized HAp exhibited a characteristic peak at ۲θ = ۳۱.۹۴°. FTIR (Fourier transform infrared) characterization of HAp indicated the presence of functional groups, including –OH at ۳۴۳۴ CO₃²⁻ at ۱۴۲۱, PO₄³⁻ bending at ۵۶۶, and PO₄³⁻ stretching at ۱۰۳۵ cm⁻¹. The FTIR spectrum of the bentonite–HAp composite showed the presence of Si–O–Si groups at ۱۰۳۷ cm⁻¹. The bentonite–HAp composite was effective in removing MB dye, achieving an adsorption efficiency of ۹.۶۴۹ mg g-۱ (۹۶.۴۹%) at a bentonite:HAp ratio of ۲:۴ within ۲۴۰ min. Based on this adsorption efficiency, the bentonite–HAp composite demonstrates strong potential as an adsorbent for MB.

کلیدواژه ها:

Adsorption ، Bentonite ، Hydroxyapatite ، Methylene blue ، Eggshell