Effect of Ca(OH)2 and Heat Treatment on The Physico-Chemical Properties of Bovine Bone Powder; a Material Useful for Medical, Catalytic, and Environmental Applications

Abstract

In this study the authors investigated the effect of alkali (Ca(OH)₂) and heat treatment on the physico-chemical properties of bovine bone powder. For this purpose, raw and alkali treated samples were heated separately at temperatures of 400 °C, 600 °C, 800 °C, and 1000 °C. A combination of characterization techniques, such as TGA, XRD, N₂-adsorbtion isotherms, and EDX were used. It was found that the boiling of cleaned solid pieces of bones in 2 molar Ca(OH)₂ solution results in a mass loss of about 10 % (mainly discards oily liquid). TGA analysis affirms that the hydrocarbons of bone matrix are partially extractable (~ 10 %) in the boiling alkaline solution. The color of raw and treated bone samples remained similar, that is changing from yellowish white to grayish black before turning into white over temperatures ranging from 30 °C (room temperature), 400 – 600 °C, and 800 – 1000 °C, respectively. Moreover, XRD signatures were also comparable at unified temperature ranges, however, it was noted that carbonization due to heating engenders a significant change in the intensities of the x-ray reflections. Despite of having similarities, surface area of raw and treated bones at 400 °C, 600 °C and 800 °C were found to be different, indicative of a chemical interactions of calcium ions with bone. Quite interestingly, TGA, XRD, and N₂-adsorbtion isotherms support the argument that a limited amount of calcium ions diffuses into the vacancies or interstitial sites of bone lattice. Furthermore, EDX analysis of the samples calcined at 1000 °C confirms that the Ca(OH)₂ treatment increases the total calcium content of hydroxylapatite (inorganic part of bone matrix).