Hydroxyapatite extracted by animal bone image analysis in ionic liquid choline chloride-glycerol

In this paper, the dissolving process of animal bone (chicken bone) in ionic liquid (IL) choline chloride-glycerol (ChCl-GL) was researched, and the product hydroxyapatite (HAp) was extracted. The optimum conditions of extracted HAp were determined by single factor, orthogonal, and verification tests. Based on dissolving situation of observing bone power in the IL by means of thermal stage polarized optical microscope (HSPOM), it could be preliminarily concluded that this dissolving process was a direct physical dissolution. IR analyses, which was for undissolved bone, under different solution temperature and time, showed that bone collagen was dissolved mainly in the IL. This was consistent with HSPOM observations. The change of internal hydrogen bond was an important factor of IL dissolving bone. IR characterization indicated that the macroscopic composition and microstructure of the extracted HAp had characteristics of natural bone. XRD and SEM displayed that the product HAp was much similar to a standard sample, and its crystal structure was relatively complete; moreover, its purity is higher than the sample's. The BET tests exposed that specific surface area and aperture of the extracted HAp were similar to the values of the sample, which belonged to the mesoporous. Analysis of N-2 adsorption-desorption revealed that the extracted HAp had a significant specific surface area, so as to be used for different adsorption processes. TG characterization exposited that pyrolysis temperature of the product HAp was higher, so it had better stability.