High temperature CO2 capture of hydroxyapatite extracted from tilapia scales

Abstract

Hydroxyapatite (HAp) was obtained from tilapia scales by two extraction methods: direct calcination and acid-base treatment. The physicochemical characteristics of the obtained HAps were evaluated by thermogravimetric analysis, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, surface area, infrared spectroscopy, and basicity measurement at 298 K by CO 2 -pulse titration. Furthermore, the CO 2 capture capacity of the solids at high temperature was also determined. Both methods showed the presence of a HAp phase although significant differences in the properties of the solids were found. The HAp obtained by direct calcination, exhibited a lower crystallinity and a greater surface area and basicity than the HAp obtained by the acid-base treatment. These features were correlated with the solid's CO 2 capture capacity. In this work, CO 2 capture capacity values for HAp yielded by calcination ranged from 2.5 to 3.2 mg CO 2 /g captured at 973 K, and for the acid-base treatment-derived HAp, CO 2 capture capacity values between 1.2 to 2.5 mg CO 2 /g were recorded. These results reveal the potential of HAps extracted from tilapia scales as solids with high CO 2 capture capacity, thermal stability, and capture/release cycles reversibility.Keywords: fish scales; tilapia; hydroxyapatite; calcium; CO 2 capture IntroductionMillions of tons of fish scales are discarded and wasted around the world. In Colombia, fish scales are considered worthless, unusable, and are often eliminated as waste. Consequently, the local fish industry generates large amounts of fish waste per year, of which tilapia scales have a considerable share. Ideas have been proposed on how to create value for fish scales and how to use this resource [1 -4]. The surface of fish scales is constituted by numerous high-value organic and inorganic components, such as hydroxyapatite

Comparative analysis and antibacterial properties of thermally sintered apatites with varied processing conditions

“…The organic matter which is mainly collagen is present in the centre of the fishbone and in the outer vicinity of the fish scale. The lower crystallinity of the apatite obtained from fish scales by sintering suggests that heat treatment hindered the formation of apatite crystals because of the rapid decomposition of organic matter 39 . Rapid decomposition of the organic matter does not take place in fish bones as the collagen is present in the interior, hence, sintering fish bones result in more crystalline particles than sintering fish scales.…”

“…Previous study showed that acid/base treatment of the fish scales removes the organic matter due to solubilization of proteins and carbohydrates. This resulted in the nucleation and growth of HA during sintering and produced a more crystalline structure than the untreated fish scales 39 . The crystallite size is 13 nm for FS‐0900‐06 and 40 nm for FB‐0900‐06.…”

“…This resulted in the nucleation and growth of HA during sintering and produced a more crystalline structure than the untreated fish scales. 39 The crystallite size is 13 nm for FS-0900-06 and 40 nm for FB-0900-06. At the lower part of the fish scales which is attached to the flesh, collagen is most pronounced whereas, at the upper part, HA is more distinct.…”

“…The lower crystallinity of the apatite obtained from fish scales by sintering suggests that heat treatment hindered the formation of apatite crystals because of the rapid decomposition of organic matter. 39 Rapid decomposition of the organic matter does not take place in fish bones as the collagen is present in the interior, hence, sintering fish bones result in more crystalline particles than sintering fish scales. Previous study showed that acid/base treatment of the fish scales removes the organic matter due to solubilization of proteins and carbohydrates.…”

Potassium–carbonate co-substituted hydroxyapatite compositions: maximising the level of carbonate uptake for potential CO2 utilisation options

“…Whilst not yet explored in great detail as a potential CO 2 utilisation option, hydroxyapatite has already proven to have application in several fields including aqueous solution remediation, gas detection, agriculture as a fertiliser, ionic conduction and catalysis, [14][15][16][17][18][19][20][21][22] and has been studied as a solid sorbent for carbon capture, with a previous study showing stoichiometric hydroxyapatite can adsorb approximately 0.06-0.07 mmol of CO 2 per gram of material when operating at 650-800 1C. 23,24 Hydroxyapatite, HA, (Ca 10 (PO 4 ) 6 (OH) 2 ) is a widely studied and adaptable calcium phosphate material. Its potential for CO 2 utilisation arises from the fact that the HA crystal structure can accommodate a significant quantity of CO 2 owing to its ability to substitute both hydroxyl (OH À ) and phosphate (PO 4 3À ) groups for carbonate (CO 3 2À ) ions without compromising the crystal structure of the material.…”