Nanosized hydroxyapatite powder synthesized from eggshell and phosphoric acid

Prior research has shown that hydroxyapatite is widely used in biomedical applications due to its biocompatibility. However, traditional synthesis methods often require expensive calcium sources. This gap motivated researchers to explore alternative, sustainable calcium sources. Eggshells, a common waste product, contain high calcium content. No prior work had resolved the feasibility of using eggshells in hydroxyapatite synthesis. Existing methods typically use calcium carbonate or calcium hydroxide as starting materials. This paper introduces a novel approach using calcined eggshells as a calcium source. The study addresses the need for cost-effective and eco-friendly synthesis routes. The approach combines wet chemical processing with ball milling to produce nano-sized powders.

The aim of this study was to develop a wet chemical method for synthesizing nano-sized hydroxyapatite powders. The specific problem addressed is the need for affordable and sustainable calcium sources in HAp production. Researchers sought to determine if calcined eggshells could replace conventional calcium sources. The motivation stems from the abundance and low cost of eggshells as a waste material. The study also aimed to control the Ca/P ratio through mixing parameters. Ball milling was selected to achieve nano-sized particles. The goal was to fully densify the powder at a specific sintering temperature. The research focused on optimizing the synthesis process for biomedical applications.

The study employed a wet chemical synthesis route using calcined eggshells and phosphoric acid. The raw eggshells were first converted to calcium oxide through calcination. Phosphoric acid was then mixed with the calcined eggshell powder in varying weight ratios. A ball-milling process was used to homogenize the mixture and reduce particle size. X-ray diffractometry was applied to analyze the crystalline phases of the synthesized powders. Scanning electron microscopy was used to examine the microstructural features of the samples. The sintering process was conducted at different temperatures to assess densification. The particle size distribution of the final product was measured using appropriate analytical techniques.

The synthesized hydroxyapatite powders exhibited an average particle size of 70 nm. The Ca/P ratio was successfully adjusted to achieve the stoichiometric composition of HAp. The ball-milled powders demonstrated high sinterability when heated to 1300 degrees Celsius for one hour. X-ray diffractometry confirmed the formation of hydroxyapatite phases in the samples. The crystallinity of the powders was found to be dependent on the mixing ratio of eggshell to phosphoric acid. Scanning electron microscopy revealed uniform microstructures in the sintered samples. The study showed that the calcined eggshell can effectively replace traditional calcium sources. The process yielded fully densified HAp powders suitable for biomedical applications.

The authors propose that calcined eggshells can serve as a viable calcium source for hydroxyapatite synthesis. The study confirms that the wet chemical route with ball milling produces nano-sized HAp powders. The Ca/P ratio was successfully controlled through adjustment of the mixing ratio. The sintering temperature of 1300 degrees Celsius achieved full densification of the powders. The results suggest that the method is both cost-effective and environmentally friendly. The use of eggshells as a waste material aligns with sustainable processing goals. The findings indicate that the synthesized HAp has potential for biomedical applications. The study provides a feasible alternative to traditional synthesis methods.