Synthesis Of Ni/Fe Bimetal Nanoparticles For Dechlorination Of PCB77

Ni/Fe nanoparticles were prepared by modifying the aqueous-phase reduction process with a SDS/PVPK30 composite stabilizer, preventing the agglomeration of nanoparticles. The variation of preparation conditions was studied and the results showed that they had great effects on PCB77 degradation efficiency. L9(3)3 orthogonal experiments were carried out in order to explore the optimum preparation condition. The results showed that Ni/Fe nanoparticles had the highest PCB77 degradation efficiency 93.43% when the concentration of SDS, the time of reductive reaction and the loaded amount of Ni were 0.028mol/L, 30 min, and 5%, respectively.0.3g Ni/Fe nanoparticles were added in 40 m L PCB77 solution at a concentration of 5mg/L. The final degradation efficiency was 93.43% and followed a first order kinetic model. Meanwhile, Ni/Fe nanoparticles synthesized under optimal preparation condition were characterized by TEM, XRD, surface area measurement and EDS. TEM image showed that most particles were independent with the spherical shape and small particle size about 10-20 nm. It can also be observed that the particles were covered by a layer which may be comprised of the stabilizer and limited the further aggregation. The existence of SDS and PVPK30 retarded oxidation of Ni/Fe nanoparticles from the XRD spectrum. The BET curves showed that the specific area of Ni/Fe nanoparticles was 34.703m2?g-1. EDS characterization showed that Fe and Ni were main components of Ni/Fe nanoparticles and Ni content was 5% of Fe content.The variation in water environment could exert influence on the degradation performance of Ni/Fe nanoparticles in actual application. The investigation of PCB77 degradation efficiency was conducted under different water environment. Degradation efficiency of PCB77 was decreased with the increase of p H. Dechlorination was promoted in acid environment and inhibited under alkaline condition. The existence of Cl- in water environment could prompt the degradation efficiency, but it played limited role when the concentration was too high. The existence of SO42- showed a slight inhibition of dechlorination. The degradation efficiency showed less change with the increase of the concentration of Ca2+ and Mg2+.The circulating type reactor was designed in order to widen the application of Ni/Fe nanoparticles in engineering, which could prevent the diffusion of bimetal nanoparticles to the effluent and secondary contamination. Quartz sand had little effect on PCB77 degradation and the adsorption was likely physical adsorption, which was reversible and caused by molecular force. Degradation efficiency was 80.72% in 48 hours and the degradation followed the first-order kinetics when a mixture of Ni/Fe nanoparticles and quartz sand was packed into the column of the circulating type reactor.