碳包覆磁性镍纳米粒子对亚甲基蓝的吸附性能

Nanoparticles of carbon encapsulated nickel (Ni@C NPs) were in-situ synthesized by direct current arc-discharge plasma method through evaporating pure Ni in methane atmosphere. Transmission electron microscopy observation revealed that the nanoparticles (Ni@C NPs) exhibited an encapsulation structure with Ni metal as core and carbon 3-5 nm in thickness as shell. The BET surface area of the prepared Ni@C NPs is 38.82 m2-1 according to N2 adsorption-desorption isotherm. Surface modification with hydrogen peroxide was carried to graft oxygen-containing groups on carbon, which can improve the wettability and hydrophilicity of the Ni@C NPs. Then the effect of contact time, adsorption time and pH values on the adsorption of methylene blue was systematically investigated with the surface modified Ni@C NPs as adsorbent. The adsorption kinetics was analyzed with pseudo-first-order and pseudo-second-order models and the adsorption isotherm of methylene blue onto Ni@C NPs was fitted by Langmuir and Freundlich models. In addition, the result of recycling experiments for 5 cycles showed that a recovery rate 69.4% for the adsorbent could be reached. Furthermore, results of trial separation of Ni@C NPs by applied magnetic fields show that the magnetic field assisted separation technology is efficient means for the recycling and reuse of this adsorbent.