دانلود رایگان مقاله انگلیسی حذف موثر یون های فلز سنگین سمی از محلول آبی با استفاده از ذرات ریز CaCO3 - اشپرینگر 2018

Abstract

Heavy metals are a common contaminant in water supplies and pose a variety of serious health risks to nearby human populations. A promising approach to heavy metal decontamination is the sequestration of heavy metal ions in porous materials; however, current technologiesinvolve materials which can be difficultto synthesize, are high-cost, or are themselves potentially toxic. Herein, we demonstrate that rapidly synthesized calcium carbonate (CaCO3) microparticles can effectively remove high quantities of Pb2+, Cd2+, and Cu2+ ions (1869, 1320, and 1293 mg per gram of CaCO3 microparticles, respectively) from aqueous media. The CaCO3microparticles were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer–Emmett–Teller (BET) N2 sorption–desorption. It was found that the Ca2+ ions of the microparticles were replaced by the heavy metal ions, leading to partially recrystallized nanoparticles of new compositional phases such as cerussite (PbCO3). The adsorption, surface dissolution/re-precipitation, and nucleation/crystal growth mechanisms were determined by investigating the Ca2+ released, along with the changes to particle morphology and crystal structure. Importantly, this study demonstrates that the porous CaCO3 microparticles performed well in a system with multiple heavy metal ion species: 100% of Cu2+, 97.5% of Pb2+, and 37.0% Cd2+ were removed from an aqueous solution of all cations with initial individual metal concentrations of 50 mg/L and 1.5 g/L of CaCO3 microparticles. At this concentration, the CaCO3 microparticles significantly outperformed activated carbon. These results help to establish CaCO3 microparticles as a promising lowcost and scalable technology for removing heavy metal ions from contaminated water.

4 Conclusion

Porous CaCO3 microparticles were prepared successfully by a rapid precipitation reaction and were applied to heavy metal ion removal from aqueous media. There particles were found to be these particles were found to be highly effective in removing large quantities of toxic heavy metal ions from both single-metal and multiple metal systems due to the high surface area and negative charge of the particles and higher solubility of CaCO3 compared with the heavy metal carbonates that form during adsorption. Importantly, compared with other possible adsorbents, these CaCO3 microparticles are low cost, easy to scale up, and potentially can be applied for the large-scale sequestration and facile recovery of industrial heavy metal ions contaminating wastewater.