Fabrication of Hierarchical Layered Double Hydroxide Framework on Aluminum Foam as a Structured Adsorbent for Water Treatment

A hierarchical Mg-Al layered double hydroxide (LDH) framework has been fabricated via the in situ crystallization technique on aluminum foam, which can be used to remove heavy metal ion Cr(VI) and anionic dye (Remazol Brilliant Blue R, denoted as RBBR) from aqueous solutions. The as-prepared LDH/Al-foam displays flowerlike LDH microspheres composed of numerous LDH nanoplatelets, which was confirmed by XRD and SEM. The sorption kinetics of hierarchical LDH framework for Cr(VI) was appropriately described by a pseudo-second-order model. Sorption isotherms of both Cr(VI) and RBBR were also studied, which can be fitted by the Langmuir model more satisfactorily than the Freundlich one. It was found that the sorption capacities (q(MAX)) of the LDH framework reached 27.8 mg g(-1) for Cr(VI) and 212.8 mg g(-1) for RBBR, respectively, much larger than those of the corresponding LDH powder sample (21 mg g(-1) for Cr(VI) and 166.7 mg g(-1) for RBBR). Furthermore, the hierarchical LDH framework exhibits excellent sorption-regeneration performances compared with the powder sample, which facilitates its repeatable and cyclic usage over a long period. Owing to the high sorption capacity, low-cost preparation, convenient manipulation, and easy regeneration of the hierarchical LDH framework, it can be potentially used as a structured adsorbent in the field of water treatment.