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

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, CaCO supported nZVI-Ni catalyst, namely nZVI-Ni@CaCO was prepared and used for the efficient removal of trichloroethylene (TCE) in PS oxidation process. The successful disbursement of nZVI-Ni on CaCO support material not only increased the surface area of nZVI-Ni@CaCO (69.45 m/g) with respect to CaCO (5.92 m/g) and bare nZVI (13.29 m/g) but also improved the catalytic activity. XRD, XPS and FTIR analysis confirmed the successful formation of nZVI-Ni@CaCO nanoparticles. The nZVI-Ni@CaCO 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 CaCO as support material for nZVI-Ni could have significant influence on contaminant removal process. Scavenging and EPR tests validated the existence of SO, OH and O radicals in PS/nZVI-Ni@CaCO system and highlighted the dominant role of SO radicals in TCE removal process. HCO 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@CaCO nanoparticles could be served as an alternative strategy for environmental remediation.