Synthesis and applications of CaCO₃/HPC core-shell composite subject to heavy metals adsorption processes

Core-shell particles are a class of materials from nanostructures that have received increased attention recently due to their interesting properties and wide range of applications in catalysis, biology, chemistry of materials and sensors. Simple and cost-effective one-pot synthesis route to directly prepare CaCO₃@highly porous carbon microsphere in a core-shell structure (denoted as CaCO₃/HPC) had been developed as a high-performance heavy metals sorbent. XRD (X-Ray Diffraction), SEM (scanning electron microscopy), Raman, FTIR (Fourier Transform Infrared Spectroscopy) and BET tools were used in structure characterization of the products. The adsorption properties of the products obtained were studied. From this study the adsorption performances of CaCO₃/HPCwere found to be optimal by comparing the maximum adsorption capacity of heavy metal ions (Pb (II) and Co(III)) with CaCO₃/HPC.The adsorption of CaCO₃/HPCtest to Pb(II) and Co(III), in particular Pb(II) had a good effect over a wide pH range (pH 2-7). The maximum adsorption capacitiesof CaCO₃/HPC for Pb (II) and Co(III) were 677.6 mg/g, and 308.5 mg/g, respectively, at pH = 6 (lead ion was 5.5) and 25 °C, and the adsorption rate was fast. The lead ions can be adsorbed almost entirely in 5 minutes and only 0.2 g/L was the best effective doseof adsorbent. The prepared and carefully testednanocomposites had been found to be of excellent performances in adsorption and in analytical regeneration. The adsorption processof Pb(II) and Co(III) through core shell of the preparednanocomposite adsorbent was found to be a second-order chemical adsorption and fit for Langmuir and Freundlich isotherms, in the form of amonomolecular and multi-layer heavy metal adsorptionprocesses. The (CaCO₃/HPC)-based sorbents (with and without) pelletization shows superior heavy metals adsorption performances compared to a CaCO₃-based sorbent.