Preparation of Oriented Layered Double Hydroxide Film Using Electrophoretic Deposition and Its Application in Water Treatment

Abstract

Oriented Mg/Al−NO3-layered double hydroxide (LDH) films have been fabricated by the electrophoretic deposition method (EPD) on aluminum substrate, which can be used to remove heavy metal ion and anionic dye from aqueous solutions. The LDH films with thickness of ∼4 μm by EPD method show a high degree of c-orientation of the LDH platelets (the ab-plane parallel to the substrate) and strong adhesion to the substrate confirmed by XRD and SEM. The sorption kinetics of the LDH film for Cr(VI) and Remazol Brilliant Blue R dye (RBBR) was appropriately described by the pseudo-second-order model. Sorption isotherms for Cr(VI) and RBBR by the LDH film were studied, which can be fitted by the Langmuir model more satisfactorily than by the Freundlich model. It was found that the sorption capacity (qMAX) reached ∼79.4 mg g−1 for Cr(VI) and ∼222 mg g−1 for RBBR respectively, much larger than that of the corresponding LDH powder sample (∼67.6 mg g−1 for Cr(VI) and ∼192.3 mg g−1 for RBBR, respectively). Furthermore, the LDH film exhibits excellent sorption−regeneration performances as compared to the powder sample, which facilitates its repeatable and cyclic usage over a long period. Because of the low-cost preparation, high sorption capacity, convenient manipulation, as well as easy regeneration of the LDH film, it is expected that this film can be potentially used as a structured adsorbent in the field of water treatment.