Preparation and characterization of calcium oxide nanoparticles from marine molluscan shell waste as nutrient source for plant growth

Abstract: Calcium (Ca) is one among the major essential nutrients for plant growth and development. It activates enzymes, nitrate uptake, plant biomass ratio, the rate of photosynthesis and increase metabolisms. In the present study, calcium carbonate (CaCO₃) and calcium oxide (CaO) nanoparticles were prepared using three marine molluscan shells. The elemental composition of three molluscan shells (Lima lima, Lottioidea and Oliva reticularis) was analyzed using XRF. The physico-chemical characterization of raw shell powder (CaCO₃) and CaO nanoparticles was carried out using TGA–DSC, XRD, FT-IR, HR-SEM and TEM. TGA–DSC, a major weight loss peak, has been identified for all the three shells at a temperature range of 650–850 °C indicated the formation of CaCO₃ into CaO. The average size of the CaO nanoparticles of Lima lima, Lottioidea and Oliva reticularis were determined to be 29, 32 and 25 nm, respectively. The effects on the plant growth as a nutrient source revealed that the CaO synthesized at nanoscale from all the marine molluscan shells (Lima lima, Lottioidea and Oliva reticularis) at a concentration of 250 ppm have given higher radicle growth (9.52, 7.92 and 8.12 cm), germination (100, 100 and 100%), shoot length (12.48, 12.12 and 12.40 cm), root length (13.02, 12.80 and 12.24 cm) and vigor index (2550, 2492 and 2464) then CaCO₃ and normal control. Among the marine molluscan shells, the CaCO₃ and CaO synthesized from Lima lima have effected high level of radicle growth and seed quality parameters then Lottioidea and Oliva reticularis. Graphic Abstract: [Figure not available: see fulltext.].