Perchlorate removal using granular activated carbon supported iron compounds: Synthesis, characterization and reactivity

Synthesis and use of the iron compounds supported on granular activated carbon (ICs/GAC) have shown significant environmental implications for perchlorate (ClO4−) removal. ICs/GAC was synthesized via hydrolyzing FeSO4·7H2O on GAC, reduced by NaBH4 solution in polyethylene glycol 6000 and ethanol solution, dried in vacuum condition and exposed to air. Synthesized ICs/GAC was characterized using transmission electron micrograph (TEM), Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy (XPS). ICs/GAC was determined to be containing a large amount of FeOHSO4, Fe2O3 and a small amount of zero-valent iron (ZVI) nanoparticles according to TEM and XPS measurements. Batch static kinetic tests showed that 97% of ClO4− was removed within 10 hr at 90°C and 86% of ClO4− was removed within 12 hr at 25°C, at ICs/GAC dosage of 20 g/L. The experimental results also showed that FeOHSO4 and Fe2O3 nanoparticles have the function of perchlorate adsorption and play important roles in ClO4− removal. The activation energy (Ea) was determined to be 9.56 kJ/mol.