Analysis of the effect Hydroxyapatite formation from Precipitate Calcium Carbonate of thorn shell waste (Murex trapa) with carbonation method

• 1 Thorn Shells The utilization of shell waste is still considered ineffective. Thorn clams are considered detrimental to fishermen because the thorns contained in the shells can damage fishermen's nets. Clam shells have a very high calcium carbonate (CaCO3) content, reaching around 95 - 99%. The high content of CaCO3 contained in the shell makes it can be utilized as a raw material for the formation of hydroxyapatite. • 2. Hydroxyapatite Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is a ceramic material that has mineral content similar to human bones and teeth that is biocompatible, bioactive, and bioresorbable. These properties make hydroxyapatite usable in biomedicine as an implant and repair for fractured or broken bones. • 3. Precipitate Calcium Carbonate (PCC) Precipitate Calcium Carbonate (PCC) is a product of calcium processing through a series of chemical reactions. Technically, PCC is characterized by its small and homogeneous particle size. With its special characteristics, the use of PCC in industry or chemical processes is becoming increasingly widespread. • 4. Carbonation The diffusion of carbon dioxide gas aims to decompose ammonium carbonate and the amount of CaCO3 yield. Hydroxyapatite is a biomaterial that exhibits similarities to the inorganic mineral constituents present in bones and teeth. Consequently, its significance in the field of orthopedic medicine is substantial. The bioactive nature of hydroxyapatite is very possible as a place for the growth of new bone tissue. This research utilizes the CaO content contained in the shells of thorn clams where the CaO content is 91.08%. This shell waste can often be found on the Kenjeran coast, Surabaya, East Java, thus the use of thorny clam (Murex trapa) shells is very easy to obtain as a raw material for the formation of hydroxyapatite. The PCC process uses CO 2 gas flow with a flow rate of 1 ml/s up to pH 8. Assessment of the research to be carried out on the formation of hydroxyapatite uses a range of pH 5, 9 and 13 and the molar ratio of Ca/P is 1.27; 1.67 and 2.07. From the process, hydroxyapatite was obtained with the highest yield of 96% under pH 9 conditions with a Ca/P molar ratio of 1.67. FTIR analysis conducted on hydroxyapatite with a Ca/P molar ratio of 1.67 detected the presence of functional groups PO 4 3- , OH-, and CO 3 2- . SEM-EDX analysis performed on hydroxyapatite at pH 9 with a Ca/P molar ratio of 1.67 showed that the crystal structure of hydroxyapatite tends to be spherical and agglomerated.