Effect of Acid, Alkali and Alkali–Acid Treatment on Physicochemical and Bioactive Properties of Hydroxyapatite Derived from Catla catla Fish Scales

In the present study, scales of Catla catla fish are treated using acid, alkali and alkali–acid followed by calcination at 1000∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1000\,^{\circ }\hbox {C}$$\end{document} to produce hydroxyapatite (HAp). The aim of the work is to investigate the effect of the three pretreatment processes on the physicochemical and bioactive properties of the synthesized HAp. The confirmation tests for the formation of HAp in the calcined powders are conducted using FTIR and XRD analysis. TGA is carried out on the synthesized HAp to investigate the thermal stability and phase changes which indicates that the HAp is thermally stable at 800∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$800\,^{\circ }\hbox {C}$$\end{document} with a maximum weight loss of 5.5%. Surface morphology of the synthesized powder is investigated by SEM analysis equipped with EDX to study its chemical composition. SEM-EDX analysis indicates highly porous morphology of HAp with fairly accurate Ca/P ratio to that of natural bone HAp. TEM analysis is performed to observe the morphology of the crystal and to determine the particle sizes of the synthesized HAp. The micrographs reveal formation of polycrystalline HAp particles having particle size in the range of 320–385 nm. Bioactivity test is performed on the extracted HAp which confirms the bioactive nature of all the pretreated HAp. The study reveals that acid-treated fish scale-derived HAp shows improved physicochemical and bioactive properties compared to the other two processes. The developed HAp may be a potential material in the field of biomedical engineering.