Preparation Of Ni/Fe Nanoparticles And Composite Materials With Soybean Lecithin To Remove Polychlorinated Biphenyls

Polychlorinated biphenyls(PCBs) are a type of persistent organic pollutant with high toxicity, chemical stability, long distance transfer, and biological accumulation. Both the damage of PCBs and inability of natural degradation at a significant rate make a major environmental concern regarding the effective removal of PCBs. Recently, the iron-based bimetallic nanoparticles have been widely used in removing the persistent organic pollutants because of the superior intrinsic reactivity. In this study, Ni/Fe nanoparticles with high activity and correlative composite materials have been designed and prepared. And 3, 3′, 4, 4′-tetrachlorobiphenyl(PCB77) was selected as the target contaminant to examine the efficacy of the synthetic removal materials.The addition of a template material is a convenient and feasible method to assist the synthesis of nanomaterials. The dual soft clusters, which are composed of polyvinylpyrrolidone(PVP) and sodium dodecyl sulfate(SDS), have the effectiveness to direct the synthesis of Ni/Fe nanoparticles with superior properties. The sustained functionality of PVP-SDS soft clusters afforded specialized structures with two gradations of Ni/Fe nanoparticles, correlating to more active sites and higher reactivity. The improved activity of the Ni/Fe nanoparticles was exhibited by the higher ratio(99.3% in 72 h) and efficiency(kobs of 0.0674 h-1) of PCB77 removal.Solid carriers have been frequently used to promote the efficacy of bimetallic nanoparticles. In this research, a kind of combined material(presented lecithin-nano Ni/Fe) that composed of soybean lecithin and nanoscale Ni/Fe bimetal was synthesized via in-site loading process with the deposition of lecithin carrier in a microemulsion system. Lecithin acted as both the component of the microemulsion and the functional material to accumulate organic contaminants. Although such a combined material required further improvement, the preliminary synergistic effect of lecithin and bimetal was exhibited through the more rapid removal of PCB77 by lecithin-nano Ni/Fe than that by blank carrier.To further improve the design, a novel composite material of lecithin coating Ni/Fe nanoparticles has been prepared using an innovative synthetic method. It was confirmed that the thorough hydration of traditional technology will severely damage the reductive potential. Therefore, an emulsion-solvent diffusion technology followed by short-time ultrasonic dispersion in acetone or water was attempted to thoroughly or partially replace the hydration process. Although usage of acetone favored the avoidance of oxidation, dispersion in water led to the better functionality of the composite material, which revealed the relationship between controllable hydration and the good dispersibility. Subsequently, the optimization for the initial mass ratio of lecithin to bimetal was also conducted to acquire the proper value of 5: 1.