Preparation of iron-containing exfoliated graphite from graphite intercalation compounds with iron chloride treated by liquid ammonia and alkylamines

Abstract

Composites of exfoliated graphite (EG) with metals are promising magnetic sorbents for oil sorption and recovery. This work presents a method for preparation of iron-containing EG from graphite intercalation compound (GIC) with iron chloride and ammonia/amines complexes. GICs with FeCl₃ were treated by liquid ammonia, methylamine and ethylamine, followed by rapid heat treatment in a nitrogen atmosphere. Thermal decomposition of ammonia-treated adduct resulted in the formation of metallic α-Fe on the EG surface, while methylamine-treated adduct produced a mixture of α-Fe and iron carbide Fe₃C. The structure of both GIC and EG were investigated by XRD analysis and Mössbauer spectroscopy. Ammonia and methylamine react with iron chloride and form the complex compounds within the graphite matrix, whereas ethylamine shows weak reaction with GIC. The presence of alkyl groups in the amines influences both the composition of the iron-containing phase and the EG surface morphology. Iron interacts with carbon to form a γ-(Fe,C) alloy and iron carbide Fe₃C and amorphous carbon coats the EG surface leading to increasing hydrophilicity. The resulting EG/Fe composites exhibited high saturation magnetization (up to 50 emu/g) and exceptional hydrocarbon sorption capacity (up to 30 g/g), demonstrating their potential as efficient magnetic sorbents for oil remediation.