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Nanoscale dispersing of zero-valent iron on CaCO3 and their significant synergistic effect in high performance removal of lead

Zhang, Xiaodi, Shi, Dongyang, Li, Xiang, Zhang, Yajing, Wang, Jianji, Fan, Jing
Chemosphere 2019 v.224 pp. 390-397
absorption, calcium carbonate, dispersibility, iron, lead, remediation, synergism, water pollution
Rapid aggregation and deactivation of nanoscale zero-valent iron (nZVI) hinder its application in environmental remediation. In this work, micro-scale CaCO3 is used as a dispersive carrier of nZVI to create a novel composite, CaCO3-supported nZVI (nZVI@CaCO3), through simplified liquid-phase reduction strategy. The morphology analysis shows that CaCO3 exhibits a fagot-like structure, and Fe0 particles are well dispersed on CaCO3 with an average diameter of around 15 nm. The removal of Pb(II) from water by nZVI@CaCO3 is studied, and it is found that the removal capacity of lead is as high as 3828 mg/g, which is much greater than that by neat CaCO3 (2209 mg/g) and bare nZVI (1308 mg/g). Owing to the loading of Fe (50%) in nZVI@CaCO3, a significant synergistic effect is observed between CaCO3 and nZVI in high performance removal of lead. Furthermore, a possible removal mechanism is proposed from a comparative investigation on the surface valence state and nZVI@CaCO3 phase before and after absorption of Pb(II). Considering the advantages of improved dispersibility, easy preparation and remarkable performance, the as-prepared nZVI@CaCO3 has the potential to become a promising remediation material for Pb(II) polluted water.