Applications Of Magnetic Nanoparticles@carbon-based Composites For The Adsorptive And Catalytic Removal Of Water Contaminant

Magnetic carbon-based composites are a kind of hybrid materials that combine magnetic nanoparticles with porous carbon materials.Recently,they have been widely studied in the field of wastewater treatment application owing to the unique physical and chemical properties,easy magnetic separation and functional modification.Combined with the encapsulation of nanomaterials,the design and construction of magnetic nanoparticles@carbon-based composites can effectively control the structural stability of magnetic nanoparticles,which has a vital significance and practicality for improving the recycle ability and the reactivity of magnetic carbon composites.Herein,four different magnetic nanoparticles@carbon-based composites were controllably prepared,and their application for the adsorptive/catalytic removal of different environmental pollutants were also investigated,respectively.By establishing the relationship between the structure,composition and performance,it provides a theoretical support for the development of efficient and practical magnetic nanoparticles@carbon-based composites.The main researches are summarized as follows:(1)Highly dispersed Fe-based nanoparticles embedded in nitrogen-doped magnetic carbon nanospheres are rationally designed and fabricated via in situ carbonization of Fe3+-mediated polymerization of dopamine,which allows the full encapsulation of Fe-based nanoparticles in the interior.Fe/N-C-700 displayed the spherical morphology,high content of metallic Fe,ultrahigh surface area,and magnetic performance,affording superb U(VI)removal capability,surpassing the hybrids pyrolyzed at other temperatures.During the adsorption process,different environmental factors and the adsorption mechanism were analyzed in detail.(2)Decorating the discrete and active Ag nanoparticles on the surface of magnetic carbonized polydopamine nanospheres were fabricated by an in-situ solidstate decomposition process.The geometric configuration and phase composition of the M/C-PDA/0.1Ag catalyst were characterized.The results revealed that C-PDA nanospheres were decorated with the high dispersion of Ag nanoparticles(less than 50 nm),and embedded with ultrafine Fe3C nanoparticles(3-5 nm).M/C-PDA/0.1Ag exhibited an outstanding catalytic performance for FA-mediated Cr(VI)reduction,due to the synergism of Ag nanoparticles and functional nitrogen doping.Besides,M/C-PDA/0.1Ag held a good recycle stability after several successful cycles.(3)An interconnected hierarchical nickel-carbon hybrid material(Ni@IHC)was synthesized by a solvothermal method and one-step pyrolysis.Due to threedimensional flower-like morphology,porous Ni@C nanosheets,large specific surface area and abundant Ni nanoparticles,the Ni@IHC hybrid can completely remove Cr(VI)(50 mg/L)in 25 mins.Furthermore,the experimental parameters were investigated systematically.Highly dispersed Ni nanoparticles not only contributed significantly to the Cr(VI)reduction,but also facilitated the rapid magnetic separation and recycle use.(4)Ultrafine Co nanoparticles strongly confined in interconnected nitrogendoped carbon networks was synthesized by one-step pyrolysis of PPy/ZIF-67 composites.Both pyrolyzed Co2+-coordinated PPy and ZIF-67 contributed to generate a mass of Co nanoparticles,which ensure structural integrity and high content of N doping.Benefiting from the 3D interconnected carbon networks for large mass transfer and considerably exposed active sites,the Co@INC possessed remarkedly enhanced catalytic performance with almost 100%of 4-NP conversion within 120 s with NaBH4.Meanwhile,it also held the outstanding reusability and practicability.