A series of UiO-66/polyaniline (UiO-66/PANI) nanohybrids
with various
UiO-66 to aniline weight ratios ranging from 0.01 to 0.1 was synthesized
using an in situ polymerization technique. The adsorption behavior
of the neat PANI nanofiber network and the synthesized nanohybrids
was examined toward anionic methyl orange (MO) dye from aqueous media.
It was realized that the maximum adsorption capacity of PANI (229
mg/g) increases steadily by increasing the UiO-66 content in the nanohybrid
up to 7 wt % at 426 mg/g, and then, it approximately levels off at
432 mg/g for the nanohybrid sample containing 10 wt % UiO-66, that
is, UP10. Based on a thorough characterization, it was shown that
UiO-66 is completely encapsulated by PANI nanofibers. Further adsorption
examinations on the nanohybrids exhibited that the Langmuir isotherm
model and pseudo-second-order kinetics model best describe the adsorption
performance of all the prepared adsorbents during the adsorption of
MO. Meanwhile, thermodynamic investigations demonstrated that the
adsorption of MO onto UP10 is endothermic and spontaneous, and entropy
controls the adsorption process. UP10 exhibited high selectivity indices
of 100, 20, and 34 for the adsorption of MO as an anionic dye over
crystal violet (CV), malachite green (MG), and methylene blue (MB),
respectively, as cationic dyes.