Efficient Iron Oxide/Expanded Graphite Nanocomposites Prepared By Underwater Plasma Discharge For Removing Heavy Metals

Y Recent studies have shown that expanded graphite (EG) is a suitable substrate for combining iron oxide nanoparticles (IONPs). However, the low density and insignificant hydrophobicity of pristine EG hinder its applicability in wastewater treatment systems. Herein, iron oxide (IO)-combined EG nanocomposites (IO/EGs) were prepared using an underwater plasma discharge process, which is a fast and simple method for synthesizing composites. The IO/EGs produced by this method are complex combinations of the FeOOH and gamma-Fe2O3 phases, whose compositions vary as the IO precursor content changes between 20 and 60 wt.%. Compared with pristine EG, the IO/EGs with varying IO precursor contents (IOx/EGs) exhibited approximately six times higher surface areas (>100 m(2)/g), nearly double zeta potential values (>39 mV), and excellent heavy-metal removal efficiencies. The excellent heavy-metal removal efficiencies (>80% within 10 min, [k] 1/4 2.30 h(-1), qe;>= 125 mg/g) of IO20/EGs are attributed to their high specific surface areas (117.5 m(2)/g), relatively positive surface potentials (41.76 mV), and abundant reactive active sites (hydroxyl group). Overall, this study demonstrates that the simple and fast combined IOx/EGs are suitable adsorbents for removing heavy metals from polluted solutions. (C) 2021 The Authors. Published by Elsevier B.V.