Fe(Ⅱ) Removal from Aqueous Solution by Layered Double Hydroxide/Graphene Composites: Adsorption Coupled with Surface Oxidation

摘要

Layered double hydroxide (LDH) and LDH-graphene (LDH-G) composites were successfully fabricated using a facile one-step coprecipitation route. Scanning electron microscopy and energy dispersive spectroscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and X-ray powder diffraction patterns were used to characterize the composites before and after reacting with Fe(II). The LDH-G composites exhibited a noticeable enhancement in Fe(II) removal compared to the LDH. The maximum adsorption capacity was 654.66 mg/g for LDH-G. The better performance for Fe(II) removal was due to the unique structural characteristics of the LDH-G. The coexistence of oxidation and adsorption was the key factor for the improvement of Fe(II) removal in the presence of oxygen. The characterizations of the samples after the reaction reveal that the removal of Fe(II) was a complex process, including multiple surface adsorption and oxidation steps. The effective and stable Fe(II) removal capability of the LDH-G particles indicated great potential as an effective and environmentally friendly agent, which can replace existing technology for Fe(II) removal from groundwater.