Ameliorating the existing purification methods with more affordable, efficient, and industrially adoptable methods that remove heavy metal ions from contaminated drinking water constitutes a persistent technological challenge. Metal–organic framework (MOF)-based materials with their excellent adsorption performance are recently explored as an alternative method to the traditional methods. Here, we report a MOF/biopolymer composite-based aerogel that is a cost-effective, highly efficient, and environmentally sustainable material for the removal of large concentrations of heavy metal ions (1277 mg of Pb2+, 466 mg of Cd2+, and 706 mg of Cr6+ per gram of the aerogel) and the selective removal of the cationic dye crystal violet (310 mg/g) from its mixture with (anionic) methyl orange from contaminated water samples. The MOF used herein is 2-methylimidazole zinc complex (ZIF-8), whereas the biopolymer is the nontoxic and biodegradable Iota-Carrageenan (iCG), a sulfated polysaccharide extracted from red seaweeds. We have transformed the ZIF-8 powder into a moldable, load-bearable, flexible, and eco-friendly ZIF-8@iCG aerogel. SEM images confirmed that ZIF-8 is physically embedded in Iota-Carrageenan, forming a honeycomb structure. The ZIF-8 is located onto the fibers of iCG, forming a thermally stable, flame-retardant ZIF-8@iCG hydrogel, with high mechanical strength and intrinsic porosity. The aerogel removes 92.03% of Pb2+ ions from an intentionally spiked Pb2+ solution (1 ppm), making this water sample drinkable upon three successive filtrations. The thermodynamics of metal ion adsorption suggest that the adsorption kinetics follow the Langmuir adsorption isotherm model and the adsorption process is endothermic. Ion leaching experiments suggest that leaching of zinc ions from the aerogel is negligible. Thus, the newly designed ZIF-8@iCG aerogel is a potentially effective adsorbent for the removal of heavy metal ions and organic dyes from drinking water and is intended for industrial use.

Hierarchical self-assembly of new age surfactants, surface-active ionic liquids (SAILs) has attracted increasing interests because of its close resemblance to membrane mimetic structure and its application in drug delivery. Among these self-assembled structures, thermodynamically stable vesicular nanoaggregates are of great importance due to its structure that can carry both, hydrophilic and hydrophobic molecules within its core and bilayers, respectively. Here, we report the ester functionalized SAILs to synergistically interact with cholesterol, the natural sterol to transform the micellar nano-aggregates to the vesicular nano-aggregates with outstanding stability with dilution, pH, and temperature. The molecular self-assembly formed was studied through state of the art analytical techniques including small-angle neutron scattering (SANS) and fluorescence resonance energy transfer (FRET) upon varying the cholesterol/SAIL ratio. The thermodynamically stable vesicular nano-aggregates were further used as the nano-vehicles for the encapsulation and sustained release of the anticancer drugs, curcumin and 5-flurouracil. Results of the present study could pave way for the realistic drug delivery applications of these thermodynamically stable nano-aggregates and replace the traditional lipid based vesicle systems.