Preparation of hybrid CaCO3–pepsin hemisphere with ordered hierarchical structure and the application for removal of heavy metal ions

In this paper, a simple way for preparation of hybrid CaCO3–pepsin material with ordered hierarchical structure was reported. It could be observed that the nanoparticles self-assembled into a lot of tetrahedral calcite crystals, which assembled into highly ordered surfaces of hemisphere-shaped CaCO3 with hierarchical structures. These products were characterized by X-ray powder diffraction (XRD), Scanning electron microscope (SEM), High resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry-differential thermal analyses (TG-DTA) and photoluminescence (PL). A rational mechanism was proposed for the formation of hybrid CaCO3–pepsin material ordered hierarchical structure. Functional study using the hybrid CaCO3–pepsin material as an adsorbent for removal of heavy metal ions demonstrates that its distinguishing features in water treatment involve not only high removal capacities, but also decontamination of trace ions. The acquired experimental data show that both the functional and hierarchical structural features of hybrid CaCO3–pepsin material provide a promising adsorbent for removal of heavy metal ions.

► A hybrid CaCO3–pepsin material with highly ordered superstructures is obtained facilely.
► Self-assembly of a large number of nanoparticles has been observed.
► Pepsin could play a role on the formation of the material with ordered superstructures.
► This material could be promising in life sciences for removal of heavy metals.