Fabrication of hierarchical bristle-grass-like NH4Al(OH)2CO3@Ni(OH)2 core-shell structure and its enhanced Congo red adsorption performance

Abstract

Hierarchical bristle-grass-like NH4Al(OH)2CO3@Ni(OH)2 core-shell structure is fabricated through a simple hydrothermal approach combined with subsequent chemical bath deposition. Electron microscopy characterization reveals that the ammonium aluminum carbonate hydroxide (NH4Al(OH)2CO3) microfibers were uniformly covered with interconnected and vertically aligned nickel(II) hydroxide (Ni(OH)2) nanosheets, forming hierarchical pore structure. The NH4Al(OH)2CO3 microfibers not only serve as substrate for the growth of the Ni(OH)2 nanosheets but also prevent the nanosheets from aggregating. The synthesized hierarchical bristle-grass-like NH4Al(OH)2CO3@Ni(OH)2 composite showed excellent adsorption performance toward Congo red (CR), which was superior to the aggregated Ni(OH)2 microspheres and the bare NH4Al(OH)2CO3 microfibers. The adsorption isotherm can be well described by the Langmuir model, with an estimated maximum adsorption capacity of 426 mg g−1 for the NH4Al(OH)2CO3@Ni(OH)2 composite. The major adsorption mechanism is electrostatic interaction between the CR molecules with negative charge and the positively charged sample surface of the Ni(OH)2 nanosheets at neutral pH. The as-prepared NH4Al(OH)2CO3@Ni(OH)2 core-shell microfibers can be expected to act as potential materials for CR removal in purification of wastewater.