Preparation of borate anions intercalated MgAl-LDHs microsphere and its calcinated product with superior adsorption performance for Congo red

In the present study, the borate anions intercalated MgAl-layered double hydroxides (B-LDHs) microsphere and its calcinated product (B-LDOs) have been prepared by precursor method and characterized by the XRD, FT-IR, XPS, TG-DSC, SEM and TEM. This microsphere with hierarchical porous nanostructure was assembled by nanosheets. The B-LDHs and B-LDOs samples have high specific surface area of 138.6 m2 g −1 and 123.0 m2 g−1 measured by N2 adsorption−desorption, respectively. They were used as adsorbents to remove Congo red (CR) dye in an aqueous solution, exhibiting excellent adsorption performance with maximum adsorption capacities of 166 and 273 mg g −1 for CR respectively, which outperform most of the reported adsorbents in literatures. The adsorption processes nicely fitted with the kinetic pseudo-second-order rate equation and Langmuir adsorption model. The effects of B-LDOs sample dosage, pH and temperature of CR solution on adsorption were investigated. The possible adsorption mechanisms were also proposed. It can be expected that both samples, especially B-LDOs sample with higher adsorption efficiency and good reusability, could be considered as promising candidates for wastewater treatment.