Simultaneous Removal Of Mixed Contaminants-Cu(Ⅱ)and Nitrate From Solution Using Kaolin-Fe/Ni Bimetallic Nanoparticles

Over the last 30 years, the environmental pollution in China is receiving public concerns since China economy has become increasingly prominent. The contaminants, including heavy metal, inorganic and organic contamination, have been the issue to be solved. This is due to the fact that wastewater often contains the mixed contaminants, and hence it is a challenge to sire remediation. In this study, we proposed that iron-based nanoparticles (Fe NPs) were used to remove these mixed contaminants simultaneously. However, many fundamental issues are still unclear. As an original work, kaolin-supported bimetallic Fe/Ni nanoparticles (Kaolin-Fe/Ni) were synthesized and used to remove the mixed contaminants such as Cu2+ and NO3-, which was selected as the target contaminant. The objective of this study is to understand the degradation mechanism of mixed contaminants, which could provide a new insight of nanoremediation of mixed contaminants using iron-based nanoparticles.Kaolin-Fe/Ni was synthesized using sodium borohydride (NaBH4) in liquid phase, both fresh and used Kaolin-Fe/Ni were characterized by various techniques, including field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction spectroscopy (XRD), BET-N2 surface area analyzer (BET-N2), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). New findings include (ⅰ) the specific surface area of Kaolin-Fe/Ni was 18.25 m2/g, (ii) SEM images show that aggregation of Fe/Ni on surface of used Kaolin-Fe/Ni nanoparticles increased than that of the fresh ones, and (ⅲ) the results from EDS, XRD and XPS confirm that Fe0 was loaded on the surface of fresh and used Kaolin-Fe/N, where elements of Fe, Cu and O were detected by EDS, while Fe and Cu species were observed by XPS. These results reveal that simultaneous removal of Cu2+ and NO3- by Kaolin-Fe/Ni was based on the reductive degradation. In addition,96.5%of Cu2+ and 40.4%of NO3- was simultaneously removed by Kaolin-Fe/Ni with a mixed concentration of Cu2+(200 mg/L) and NO3- (40 mg/L). Furthermore, the removal of Cu2+and NO3- was well-fitted with pseudo first-order model, and suggest that formation of Fe/Ni/Cu trimetallic nanoparticles enhanced the degradation of NO3- when Cu2+was degraded to Cu0.To explore the possibility of potential application, simultaneous removal of Cu2+and NCV using Kaolin-Fe/Ni in presence of various cations and anions to understand the impact of ion on the degradation of mixed contaminants since these ions often presented in wastewater. These anions included Cr2O72-, NO2-, SO42-and Cl-, and those cations involved Cd2+, Cr3+, Pb2+ and Zn2+ were used in this study. Based on the results of this study, the reducible ions (e.g. Cr2O72-, NO2- and Pb2+) could compete with Cu2+ and NO3-for reacting with Kaolin-Fe/Ni, and the irreducible ions (e.g. SO42-, Cl", Cd2+, Cr3+ and Zn2+) can promote reductive removal of Cu2+and NO3- mixture due to corrosion of the Fe0 surface.In summary, Kaolin-Fe/Ni is a potential nanomaterial for the remediation of mixed Cu2+ and NO3- based on the reductive degradation, and it is possible to treat wastewater in the presence of ions.