Preparation and characterization of MWCNTs/LDHs nanohybrids for removal of Congo red from aqueous solution

The assembly of layered double hydroxides (LDHs) and multi-walled carbon nanotubes (MWCNTs) nanohybrids was prepared as MWCNTs/LDHs by co-precipitation. The synthesized nanoparticles were characterized by using XRD, FT-IR, SEM/EDX, TGA and BET. XRD and SEM studies proved that MWCNTs phases did not enter into the interlayers of LDHs, they dispersed over the LDHs surface homogeneously. BET results showed that MWCNTs/LDHs possessed hierarchically porous nanostructure with large surface area (124.974 m2/g) and great pore volume (0.604 cm3/g). Batch experiments were conducted to study the adsorption efficiency of Congo red (CR). It was worthy to note that MWCNTs/LDHs exhibited excellent adsorption performance with the maximum CR adsorption capacity of 595.8 mg/g in weak acidic environment. The adsorption kinetics and isotherm parameters can be well described by the pseudo-second-order and the Langmuir isotherm models, respectively. The thermodynamic studies indicated that the adsorption process was spontaneous and endothermic.