ABSTRACT
CuFe2O4 nanoparticles were synthesized and immobilized on sepiolite fibers and graphene oxide sheets, producing a CuFe2O4/sepiolite/GO (CFSG) nanocomposite via a facile single-pot method. The synthesized nanocomposite was characterized using TEM, FTIR, SEM-EDX, XRD, and TGA techniques to determine its composition, structure, and thermal stability. The adsorptive removal of Pb(II) and Cd(II) heavy metal ions from aqueous solutions was studied using the synthesized CFSG nanocomposite. Adsorption parameters such as CFSG loading, pH, contact time, and temperature were investigated. The CFGS nanocomposite showed a higher Pb(II) removal (qm = 238.1 mg/g) compared to Cd(II) (qm = 14.97 mg/g) in a Pb(II) and Cd(II) binary system. The Pb(II) and Cd(II) adsorption fitted well with the Langmuir model, followed by the pseudo-second-order model, and was found spontaneous. Adsorption thermodynamic analysis showed that the Pb(II) adsorption process was exothermic while Cd(II) adsorption was endothermic. The CuFe2O4 nanoparticles on the CFSG surface could facilitate the adsorption of heavy metal ions through electrostatic interaction and complexation processes.
ABSTRACT
The ordered open organic frameworks membranes are attractive candidates for flow-assisted molecular separations. The physicochemical properties of such membranes mostly depend on their selectively chosen functional building blocks. In this work, we have introduced a novel concept of functional switchability of three-dimensional covalent organic framework (3D-COF) membranes through a simple solvent-influenced fragmentation method. This room-temperature interfacial synthesis provides free-standing 3D-COF membranes with distinct physicochemical properties from the same building monomers. Notably, the change of solvent from chloroform to ethyl acetate switches the membrane property from hydrophilic (water contact angle 60°) to hydrophobic (water contact angle 142°) nature. The hydrophobic 3D-COF membrane selectively passes oil molecules from an oil-water emulsion with a gravitational flux of 1536â L m-2 h-1 .
ABSTRACT
Nanomodification of ultrafiltration (UF) membranes has been shown to be a simple and efficient technique for the preparation of high-performance membranes. In this work, an iron oxide functionalized halloysite nanoclay (Fe-HNC) nanocomposite was prepared and used as a nanofiller for polyethersulfone (PES) membranes. The effect of Fe-HNC concentration on the filtration performance of the membrane was investigated by varying the nanocomposite dosage (0-0.5 wt %) in the casting dope. Various characterization studies showed that the incorporation of Fe-HNC nanocomposites improved the membrane morphology and enhanced the surface properties, thermal stability, mechanical strength, hydrophilicity, and porosity. The permeability to pure water and filtration of humic acid (HA) were significantly improved by incorporating Fe-HNC into the PES membranes. The membrane with Fe-HNC loading of 0.1 wt % exhibited the highest pure water permeability (174.3 L/(m2 h bar)) and removal of HA (90.1 %), which were 1.8 times and 29 % higher, respectively than the pristine PES membrane. Moreover, fouling studies showed the enhanced antifouling ability of the Fe-HNC nanocomposites modified PES membranes, especially against irreversible fouling. Continuous membrane regeneration-based fouling removal studies from HA showed that the PES/0.1 wt % Fe-HNC membrane exhibited a high fouling recovery of 70.4 % with very low reversible and irreversible fouling resistance of 9.61 % and 14.78 %, respectively, compared to the pristine PES membrane (fouling recovery: 40.4 %; reversible fouling: 21.7 %; irreversible fouling: 20.1 %). Overall, the Fe-HNC nanocomposite proved to be an effective nanomodifier for improving the permeability of PES membranes and the antifouling ability to treat HA polluted aqueous streams.
