Synthesis of CaCO3 supported nano zero-valent iron-nickel nanocomposite (nZVI-Ni@CaCO3) and its application for trichloroethylene removal in persulfate activated system

Abstract

Nano zero-valent (nZVI) based composite have been widely utilized in environmental remediation. However, the rapid agglomeration and quick deactivation of nZVI limited its application on large scale. In this work, CaCO3 supported nZVI-Ni catalyst, namely nZVI-Ni@CaCO3 was prepared and used for the efficient removal of trichloroethylene (TCE) in PS oxidation process. The successful disbursement of nZVI-Ni on CaCO3 support material not only increased the surface area of nZVI-Ni@CaCO3 (69.45 m2/g) with respect to CaCO3 (5.92 m2/g) and bare nZVI (13.29 m2/g) but also improved the catalytic activity. XRD, XPS and FTIR analysis confirmed the successful formation of nZVI-Ni@CaCO3 nanoparticles. The nZVI-Ni@CaCO3 nanoparticles combined with PS had achieved complete removal of TCE (99.8%) with dosage of 36 mg/L and 1.34 mM respectively. These results showed that the use of CaCO3 as support material for nZVI-Ni could have significant influence on contaminant removal process. Scavenging and EPR tests validated the existence of SO4•–, OH• and O2•– radicals in PS/nZVI-Ni@CaCO3 system and highlighted the dominant role of SO4•– radicals in TCE removal process. HCO3ˉ ions and humic acid have shown adverse effect on TCE removal due to radical scavenging and buffering effect. Owing to improved catalytic activity and easy preparation, the nZVI-Ni@CaCO3 nanoparticles could be served as an alternative strategy for environmental remediation.