Toxic Metal Sequestration Exploiting a Unprecedented Low-Molecular-Weight Hydrogel-to-Metallogel Transformation

We
report herein the development of a unique low-molecular-weight
gelator-induced technique for environmental remediation. The motive
of this work is wastewater purification using a gel-based toxic heavy
metal sequestration. The essence of this technique was to bring two
different functionalities, one capable of multiple coordination and
another with gel-forming ability, arranged in tandem within a single
ligand molecule. Naturally, the success of the approach depends on
whether the two tandem-arrayed functionalities are indeed working
in tandem. Our results show that the ligand molecule is an excellent
example of concomitant hydrogelator and metallogelator. The most interesting
aspects of this study involve the toxic metal sequestration of Pb,
Cd, and Hg which was further studied in detail with spectroscopic,
microscopic, and diffraction techniques. We also report here a rare
property of pure organic hydrogel-to-metallogel transformation which
could open up a new avenue on wastewater purification. In essence,
the hydrogels can be envisaged as a unique class of metal-free zeolite
analogue for environmental remediation not by just absorbance but
through absorbance cum coordination, which are further corroborated
by the inductively coupled plasma-optical emission spectroscopy results.