In
this paper, we report a simple, novel, and highly selective
plasmonic nanoparticles (NPs)-based colorimetric nanoprobe for the
detection of Al(III) ions in aqueous solution. 5-Hydroxy indole-2-carboxylic
acid (5H-I2CA) was utilized as a reducing as well as capping agent
for the preparation of silver nanoparticles (5H-I2CA@AgNPs). The interaction
between Al(III) and AgNPs was determined by UV–vis absorption
spectroscopy, high-resolution transmission electron microscopy, Fourier
transform infrared, X-ray photoelectron spectroscopy, and dynamic
light scattering techniques. The absorption values (
A
452–410
) of the 5H-I2CA@AgNPs solution exhibited
a linear correlation with Al(III) ion concentrations within the linear
range of 0.1–50 nM. An outstanding selectivity toward Al(III)
was demonstrated by the proposed nanoprobe in the presence of interfering
cations. Kinetics was used to study the selectivity of nanoprobe,
which indicated second-order kinetics, and the rate constant was very
high. The activation energies of Al(III) were found to be the lowest
compared to those of other interfering ions. The results of kinetics
and thermodynamic study of Al(III) were compared to those of four
other competing ions. The thermodynamic data reveal that the interaction
best suited for Al(III) ion compared to other metal ions (Al(III)
> Co(II) > Hg(II) > Cr(III) ≅ Cr(VI)). The lower detection
limit of the proposed nanoprobe for Al(III) is 1 nM. The present method
also holds practical applicability for real water samples.