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

The sol–gel combustion method was employed to synthesize the nanocrystalline wollastonite by taking the raw eggshell powder as a calcium source and TEOS as a source of silicate. Glycine was used as a reductant or fuel and nitrate ions present in metal nitrate acts as an oxidizer. The phase purity of the wollastonite was analysed by powder XRD and the product is found to contain single-phasic wollastonite. FT–IR spectrum shows the characteristic peaks of the functional groups present in the wollastonite. SEM images show that particles are agglomerated and the particle size is found to be in the nanoregime. The calcination temperature was optimized based on the thermal analysis of the precursor. The bioactivity of wollastonite was investigated by immersing the scaffold in a simulated body fluid for 15 days at 37 °C and intermediate analysis of the surface by XRD shows the deposition of hydroxyapatite layer after 5 days.

The current investigation deals with the simple and ecological synthesis of CaO, MgO, CaTiO_3, and MgTiO₃ for the photocatalytic dilapidation of rhodamine B dye. CaO was procured from chicken eggshell waste by calcination process, while MgO was produced by solution combustion method using urea as a fuel source. Furthermore, CaTiO₃ and MgTiO₃ were synthesized through an easy and simple solid-state method by mixing thoroughly the synthesized CaO or MgO with TiO₂ before calcination at 900 °C. XRD and EDX investigations confirmed the phase formation of the materials. Moreover, FTIR spectra revealed the existence of Ca–Ti–O, Mg–Ti–O, and Ti–O which resembles the chemical composition of the proposed materials. SEM micrographs revealed that the surface of CaTiO₃ is rougher with relatively dispersed particles compared to MgTiO₃, reflecting a higher surface area of CaTiO₃. Diffuse reflectance spectroscopy investigations indicated that the synthesized materials can act as photocatalysts under UV illumination. Accordingly, CaO and CaTiO₃ effectively degraded rhodamine B dye within 120 min with a photodegradation activity of 63% and 72%, respectively. In contrast, the photocatalytic degradation activity of MgO and MgTiO₃ was much lower, since only 21.39 and 29.44% of the dye were degraded, respectively after 120 min of irradiation. Furtheremore, the photocatalytic activity of the mixture from both Ca and Mg titanates was 64.63%. These findings might be valuable for designing potential and affordable photocatalysts for wastewater purification.