Magnetic carbon nanotubes synthesis by Fenton's reagent method, their potential application for removal of azo dye from aqueous solution

摘要

We report a simple and easy method to fabricate magnetic carbon nanotubes (CNTs) by Fenton's reagent method without the addition of any cations. H _2O _2 was added slowly into the FeSO _4 solution mixed with purified CNTs, and the resulting reactants were placed into a quartz tube to undergo heat treatment under a nitrogen/hydrogen flow. Iron oxide (Fe _2O _3) nanoparticles were uniformly dispersed on CNTs without any pretreatment such as strong acid or covalent functionalization processes. The as-produced magnetic CNTs were usedas an adsorbent forremovalof methyl orange (MO) dye fromaqueous solutions. Adsorption experiments indicated that the magnetic CNTs have good adsorption capacity (q _e) of MO (28mg/g). The Freundlich isotherm model fitted the experiment databetter than the Langmuirisothermmode. The mean energy of adsorption was calculated as 3.72kJ/mol based on the Dubinin-Radushkevich model, which suggests that theremoval process was dominated by physical adsorption. Kinetic regression results showed that the adsorption kinetics was more accurately represented by a pseudo second-order model. Intra-particle diffusionwasinvolved in the adsorption process, but it was not the only rate-controlling step. More importantly, a new photocatalytic regeneration technology can be enabled by the high nanoscale iron oxide loading (50%). The magnetic CNT adsorbents could be effectively and quickly separated by applying an external magnetic field and regenerated by UV photocatalysis. Therefore, CNTs/λ-Fe _2O _3 hybrid is a promising magnetic nanomaterial for preconcentration and separation of organic pollutants for environmental remediation.