Novel in situ Synthesized Fe@C Magnetic Nanocapsules Used as Adsorbent for Removal of Organic Dyes and its Recycling

Abstract

Core/shell type carbon-coated Fe nanocapsules (Fe@C NCs) were in situ synthesized by DC arc-discharge plasma method in methane atmosphere. Such Fe nanocapsules have saturation magnetization of 29.32[Formula: see text]emu/g and specific surface area of 85.86[Formula: see text]m2/g. The carbon shell of Fe@C NCs was functionalized with oxygen-containing groups (such as –OH or –COOH) by using H2O2. The adsorption of organic dye, e.g., methylene blue (MB) was systematically investigated in different conditions, such as contact time, pH values and temperature. The maximum adsorption capacity (46.5[Formula: see text]mg/g) was calculated by fitting the adsorption isotherms with Langmuir model, coincident with the experimental result of 44.5[Formula: see text]mg/g. Kinetics data supported pseudo-second order model, and the thermodynamic process of adsorption was revealed as endothermic and spontaneous physisorption. The MB-absorbed Fe@C NCs can be entirely separated from the contaminative solution by a magnetic field and then successfully cycled for regeneration. After repetitive cycles of the adsorption/desorption experiments for five times, the removal efficiency can be maintained over 90%.