A novel method for the synthesis of calcium carbonate (aragonite) nanoparticles from cockle shells

We report a simple, novel and low-cost method for the synthesis of aragonite nanoparticles from cockle shells. Aragonite is one of the least abundant biogenic polymorphs of calcium carbonate and is widely used as a biomaterial for the repair of fractured bone, development of advanced drug delivery systems, and tissue scaffolds. The method involves a simple mechanical grinding of the micron-sized cockle shell powders in the presence of a non-toxic and non-hazardous biomineralization catalyst, dodecyl dimethyl betaine (BS-12). The method produces rod-shaped aragonite particles with a diameter of 20 ± 5 nm with good reproducibility and without any additional impurities. This was confirmed by a combined analysis of variable pressure scanning electron microscopy (VPSEM), transmission electron microscopy (TEM), Fourier transmission infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), X-ray diffraction spectroscopy (XRD) and energy dispersive X-ray analyser (EDX). The method should find potential applications in industry for the large scale synthesis of aragonite nanoparticles from a low cost but abundant natural resource such as cockle shells.

Micron sized cockle shell powders were mixed with dodecyl dimethyl betaine in distilled water and then stirred using a Systematic Multi-Hotplate Stirrer at the rate of 1000 rpm for 90 min at room temperature. The samples were separated by filter paper and dried in a vacuum oven. Finally the clear rod-shaped calcium carbonate nanoparticles in the aragonite phase were observed.Figure optionsDownload as PowerPoint slideHighlights
► Micron sized cockle shell powders were synthesized using a blender.
► Micron sized cockle shell powders were mixed with 1 ml BS-12 and stirred using a hotplate stirrer.
► Characterized using VPSEM, TEM, EDX, FT-IR , XRD and TGA.
► Finally rod-shaped calcium carbonate nanoparticles with a diameter of 20±5 nm in the aragonite phase were synthesized.