Highly Efficient Chalcogel-Based Molecular Filters

Abstract

Chalcogels are three-dimensional porous networks with unique applications in catalysis, gas adsorption, energy storage, and environmental remediation. Here, we demonstrate the efficacy of antimony sulfide chalcogels for the selective sequestration of organic dyes from aqueous solutions. The chalcogels exhibit high adsorption capacities for the dyes rhodamine B (RhB), methylene blue (MB), and methyl violet (MV), however, display poor adsorption capacity for the orange G (OG) dye. Lewis-basicity of chalcogel's network is responsible for selective affinity toward RhB, MB, and MV, thus favoring the capture of electron accepting dyes through Lewis acid−base interactions. The adsorption kinetics obeys the pseudo second-order model rather than the pseudo first-order model, and the equilibrium adsorption data fits well to the Langmuir isotherm equation. Dye removal efficiencies up to 99% are achieved in 30 min for an initial concentration of 25 mg/100 mL of the aqueous dye solutions. Langmuir adsorption capacities are found to be 442, 303, and 210 mg/g for RhB, MB, and MV, respectively. Using the selective adsorption behavior of antimony sulfide chalcogels, separation of mixed dyes MB/OG (RhB/OG) is realized through molecular filtration. These results suggest that chalcogels are potential candidates for the treatment of industrial effluents, thus providing a new platform for molecular filtration of organic dyes and other organic molecules.

Multiscale structural control of thiostannate chalcogels with two-dimensional crystalline constituents

“…Conventionally, the sol–gel metathesis reaction between the chalcogenide cluster anions and linker counterions develops a three-dimensional random porous network with a highly polarizable and Lewis-basic porous surface. Consequently, these form the centers for selective soft-Lewis-acid cation attraction, enabling the application of chalcogels in water treatment 21 , 22 , catalysis 23 , 24 , gas adsorption 25 , and radionuclide control 26 . However, uncontrolled and spontaneous metathesis reaction generally yields disordered domains without adequate control over the macroscopic alignment of the molecular integrity.…”

Recent developments in porous metal chalcogenides for environmental remediation and sustainable energy

“…Additionally, the covalent interaction with a smaller electronegativity difference and the facile polarization of chalcogen elements in metal‐chalcogen bonding, combined with a poor affinity for hard acidic alkali metal ions, result in an internal chalcogel surface with higher polarizability compared to metal‐oxide compounds. These traits are critical in enhancing the efficiency of ion exchange, gas adsorption, and gas separation processes with porous metal chalcogenide materials 82,83 . With a highly polarizable surface, porous metal chalcogenides can also be used to remove toxic and hazardous waste in water‐management systems 84,85 .…”