Experimental data on the characterization of hydroxyapatite synthesized from biowastes

The purpose of the dataset is to present the morphological features, elemental composition and functional groups of hydroxyapatite (HAp) synthesized from non-separated biowastes (animal bones) by a modified facile heat treatment method up to a maximum temperature of 1100 °C. The synthesized powders were characterized using scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). These evaluations were to reveal the surface features, elemental composition and identify the functional groups of the synthesized powders. After heat treatment of the raw biowastes to 900 °C, 1000 °C, and 1100 °C (regime of heat treatment), the morphological features of the samples exhibited a more densely packed microstructure at the highest sintering temperature (1100 °C). The elemental composition as evaluated by EDX on a weight and atomic basis for all samples provided information on the calcium to phosphate transforms into apatite with a Ca/P ratio of 3.60, 2.04, 2.50 and 2.32 wt % and 2.79, 1.58, 1.94 and 1.78 at. % respectively for raw biowastes (RB) to sintered samples (HA-900, HA-1000 and, HA-1100 °C). The FTIR data showed phosphate and hydroxyl peaks in the thermally treated samples and all the samples produced characteristic stretching modes of O–H bands at about 3417 cm−1 which are noticed in all FTIR spectra of HAp.

The purpose of the dataset is to present the morphological features, elemental composition and functional groups of hydroxyapatite (HAp) synthesized from non-separated biowastes (animal bones) by a modified facile heat treatment method up to a maximum temperature of 1100 C. The synthesized powders were characterized using scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). These evaluations were to reveal the surface features, elemental composition and identify the functional groups of the synthesized powders. After heat treatment of the raw biowastes to 900 C, 1000 C, and 1100 C (regime of heat treatment), the morphological features of the samples exhibited a more densely packed microstructure at the highest sintering temperature (1100 C). The elemental composition as evaluated by EDX on a weight and atomic basis for all samples provided information on the calcium to phosphate transforms into apatite with a Ca/P ratio of 3.60, 2.04, 2.50 and 2.32 wt % and 2.79, 1.58, 1.94 and 1.78 at. % respectively for raw biowastes (RB) to sintered samples (HA-900, HA-1000 and, HA-1100 C). The FTIR data showed phosphate and hydroxyl peaks in the thermally treated samples and all the samples produced characteristic stretching modes of OeH bands at about 3417 cm À1 which are noticed in all FTIR spectra of HAp.
© 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Data
The dataset presented in this article for SEM and FTIR analyses as shown in Figs. 1 and 2 are for synthesized hydroxyapatite subjected to various sintering temperatures (900 C, 1000 C, 1100 C). The morphology of samples in Fig. 2 is at a magnification of 10.0 and 15.0 kx. The elemental composition and FTIR summary tables (Tables 1a and 1b and Table 2) show Ca/P ratios and obtained functional groups which provides useful information about the composition of samples and the location of peaks, their intensities, width and shape in the required wave number range. Raw data for FTIR spectrogram is presented as supplementary files.
The surface morphology of the samples after sintering at 900 C, 1000 C and 1100 C at different magnifications (10.0 and 15.0 kx) is shown in Fig. 1 and the corresponding EDS spectra is shown in Specifications Table   Subject Engineering Specific subject area Biomedical Materials: synthesis and characterization Type of data Table  Image Chart Graph Figure  How  Data obtained in this study would be useful for future investigation on the industrial applicability of biowastes derived hydroxyapatite Fig. 2. Close observation of the SEM images reveal increasingly dense microstructure as a function of increased sintering temperature. The densification of hydroxyapatite particles as revealed by SEM increases as sintering temperature increase. Samples sintered at 900 C reveal fine grains which are not closely packed. Samples sintered at 1000 C show some grain growth tendencies which can be attributed to re-crystallization phase with porosities embedded between the large grains. The sample sintered at 1100 C show grain growth, closely packed particles as well as decreasing pore sizes and density. In addition, the micrographs in Fig. 1 show morphologies for all samples with fine particles and  , it is observed that the particles are clustered with more pore size details reavealed. From the EDX spectra as depicted in Fig. 2, the characteristic peaks of Ca, P and O are present with the atomic and weight percentages which provides the mean relative calcium to phosphate ratios as shown in Tables 1a and 1b.  Tables 1a and 1b represents the elemental composition of the raw biowastes and synthesized hydroxyapatite with their corresponding calcium to phosphate (Ca/P) ratios obtained by energy dispersive X-ray analysis (EDX). Weight percentage (wt%) and atomic percentage (at%) were considered to give Ca/P approximations. From the data (Tables 1a and 1b), calculated Ca/P ratios for sample HA-900 were 2.04 and 1.58 for weight and atomic percentages respectively. Comparatively, the atomic Ca/P ratio (1.58) of HA-900 was the closest to stoichiometric Ca/P ratio of hydroxyapatite (1.67) amongst all the hydroxyapatite samples investigated in this study. Fig. 3 shows the Fourier Transform Infrared (FT-IR) spectrogram of synthesized HAp before and after sintering at different temperatures with further description in Table 2. Typical characteristic bands corresponding to the carbonate groups of the CaCO 3 component of hydroxyapatite are located around 1411 cm À1 and 1465 cm À1 . The sintered samples showed small frequency bands around 2345 cm À1 and 2353 cm À1 ascribed to the release of CO 2 during heat treatment [10]. The initial formative indicator of hydroxyapatite at all point of sintering (900 C, 1000 C, 1100 C) was in the form of a pronounced broad band around 1000 cm À1 e1100 cm À1 which can be ascribed to asymmetric stretching mode of vibration of PO 4 group. However, as noticed for the raw biowastes bone, a small band noticed at 1033 cm À1 indicates a deficient asymmetric stretching mode of vibration of PO 4 group that was made pronounced by heat treatment. Also, the band between 570 cm À1 e 565 cm À1 for all the samples  Under influence of thermal treatment, absorption band becomes narrower [2,8,9,12 e14] corresponds to symmetric PeO stretching vibration of PO 4 group [11]. The prominent bands at 3417 cm À1 for all samples is due to the vibratory stretching of OH group of HAp while the bands at 1643 cm À1 for all samples were attributed to adsorbed water molecules [1]. All the samples produced typical stretching modes of OeH bands at about 3417 cm À1 characteristic of FT-IR spectrogram of HAp. From the FT-IR spectrogram, differences between the spectrum of the raw and heat treated hydroxyapatite samples can be noticed for the bands at 1411 and 1465 cm À1 for HA-1000 and HA-1100 samples as compared to the bands ascribed to RB and HA-900 samples. These differences are indicative of the degree of carbonate ion substitution. The bands at 1643 and 3417 cm À1 for all samples with broader bands for RB and HA-900 samples correspond to the disappearance of absorbed water after sintering [15,16].

Experimental design, materials, and methods
The biowastes (animal bones) were obtained from an Abattoir in Zaria, Nigeria. The as-received bones were cleaned thoroughly to remove the protein externally by soaking for 24 h, washing with tap water and boiling for 3 h. This was followed by rinsing in warm water before drying at 150 C in an electric oven for 8 h. The as-produced powders were calcined under atmospheric condition using an electric furnace at 900 C at a ramp rate of 5 C/min with 2 h of soaking time. The calcined powders were crushed with a metallic mortar and pestle and sieved through a 300 mm mesh sieve to obtain a fine powder prior to characterization. Fig. 4 shows a schematic of the experimental procedure for the synthesized hydroxyapatite. The produced hydroxyapatite powders were further sintered at 1000 C and 1100 C to investigate the effects of sintering temperature on the morphological features and retention of functional groups relating to produced hydroxyapatite. The nomenclature of samples synthesized and analysed are: RB (raw biowaste), HA-900 (samples sintered at 900 C), HA-1000 (samples sintered at 1000 C) and HA-1100 (samples sintered at 1100 C).
The morphology of the samples was carried out on an ultra-high vacuum and high resolution MAIA3 TESCAN scanning electron microscopicdenergy dispersive X-ray analysis (SEM-EDX) operated at 5 kV. The samples were prepared by gold sputtering the surface of the samples using a low deposition rate. The functional groups present in the samples have been identified by FT-IR equipped with UATR sampling accessory in the range of 500e4000 cm À1 . Samples were grinded and mixed with dried KBr using ceramic mortar and loaded into a sample holder mounted in the instrument.