Background: The increasing generation of biological waste and the associated environmental concerns have highlighted the necessity of reutilising these materials and converting them into value-added products. In this context, the use of
mineral-rich biowaste through simple and low-cost methods can lead to the production of knowledge-based materials within the framework of green chemistry. Aim: The objective of this study was to utilise waste bones of Hoover fish collected from the Persian Gulf coastline as a sustainable, low-cost, and environmentally friendly source for the extraction of nano-hydroxyapatite, to determine the simplest and most efficient extraction conditions, to prepare its nanocomposites and hydrogels, and to evaluate their applications in photocatalytic, electrochemical, and water treatment systems for the removal of heavy metals and organic dyes.
Methodology: This research was conducted as a laboratory-based experimental study. After appropriate pre-treatment, Hoover fish bones were calcined at different temperatures and durations, and the optimal extraction conditions were determined. Structural and physicochemical characterisation of the extracted hydroxyapatite was performed using XRD, FTIR, SEM, BET, and EDX analyses. The photocatalytic performance of the samples was evaluated through the degradation
of methylene blue under solar irradiation, and the degradation mechanism was investigated using LC–MS. Furthermore, hydroxyapatite/gelatin nanocomposites were prepared and employed as electrode modifiers in cyclic voltammetry and
differential pulse voltammetry (DPV). Subsequently, various hydroxyapatite-based hydrogels were synthesised using glutaraldehyde and poly(vinyl alcohol), and their lead ion adsorption performance was investigated.
Conclusions: The results indicated that a calcination temperature of 850 °C and a duration of 2.5 h were optimal for obtaining single-phase hydroxyapatite with high yield and low carbon content. The extracted hy