Comparison of in-situ and ex-situ methods for synthesis of iron magnetic nanoparticles-doped graphene oxide: Characterization, adsorption capacity, and Fenton catalytic efficiency

In this research, iron magnetic nanoparticles-doped graphene oxide (Fe3O4/GO or FG) materials were synthesized via the in-situ (FGI) and ex-situ (FGE) methods, with several mass ratios of precursors. The FG2I and FG2E samples with the mass ratio of Fe3O4:GO = 3:7 exhibit effective removal of methylene blue (MB) in water by utilizing the adsorption and Fenton catalyst methods. Characterizations of the materials were investigated by modern analysis methods. The results showed that FGI material possesses a larger specific surface area and Fe3O4 nanoparticles are more evenly dispersed on the GO surface than that of FG2E. The examination of MB removal also demonstrated the predominance of FGI over FGE material in both adsorption and Fenton catalyst evaluations. The MB adsorption process of FGI is consistent with the apparent second-order kinetics equation and the Langmuir isotherm model. The highest removal by Fenton reaction of MB (over 99 %) using FG2I was achieved with 1 mL of H2O2 and 50 mg/L of MB at a temperature of 50 degrees C for 180 min. Thus, the efficiency of the material via adsorption and Fenton catalytic experiments reached 69.21 and 91.23 %, respectively, after five consecutive runs. Therefore, the use of FGI is cost-saving and relatively effective for eliminating organic contaminants in water, which shows its high potential in future applications.