Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

• Eggshell biowaste was used as a calcium source to prepare calcium magnesium silicate.
• Sol–gel combustion method is used for the first time to synthesize calcium magnesium silicate.
• Detailed study of in-vitro hydroxyapatite formation in SBF solution by calcium magnesium silicate.

The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7) using eggshell biowaste (as calcium source), magnesium nitrate and tetraethyl orthosilicate (TEOS) as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent) and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesium silicate was carried out by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) techniques. Calcium magnesium silicate crystallite size was observed in nano regime which can effectively mimic natural bone apatite composition. In-vitro bioactivity was investigated by immersing calcium magnesium silicate pellet in simulated body fluid (SBF) for three weeks. Results show effective deposition of crystallized hydroxyapatite (HAP) layer on its surface and predicting its possibilities for applications in hard tissue regeneration.