Development of high flux nanofiltration membranes through single bilayer polyethyleneimine/alginate deposition

Cation Exchange Membranes and Process Optimizations in Electrodialysis for Selective Metal Separation: A Review

The selective separation of metal species from various sources is highly desirable in applications such as hydrometallurgy, water treatment, and energy production but also challenging. Monovalent cation exchange membranes (CEMs) show a great potential to selectively separate one metal ion over others of the same or different valences from various effluents in electrodialysis. Selectivity among metal cations is influenced by both the inherent properties of membranes and the design and operating conditions of the electrodialysis process. The research progress and recent advances in membrane development and the implication of the electrodialysis systems on counter-ion selectivity are extensively reviewed in this work, focusing on both structure-property relationships of CEM materials and influences of process conditions and mass transport characteristics of target ions. Key membrane properties, such as charge density, water uptake, and polymer morphology, and strategies for enhancing ion selectivity are discussed. The implications of the boundary layer at the membrane surface are elucidated, where differences in the mass transport of ions at interfaces can be exploited to manipulate the transport ratio of competing counter-ions. Based on the progress, possible future R&D directions are also proposed.

Congo red filtration by polyacrylonitrile-based copolymer membranes

In this study, Congo red removal from wastewater by a filtration method was studied via membranes obtained from polyacrylonitrile-co-poly(2-ethylhexylacrylate) copolymers having various monomer ratios and polyacrylonitrile-co-poly(2-ethylhexylacrylate)/polyaniline blends with various polyaniline contents. It was found that the dye rejection value increased with acrylonitrile content in polyacrylonitrile-co-poly(2-ethylhexylacrylate) membranes. Also, blending copolymers with polyaniline enhanced the dye rejection rate. The performance of membranes showed incremental increase with increase in the polyaniline content. Both pH and concentration effects on the dye rejection rate of membranes were evaluated. The performance of polyacrylonitrile-co-poly(2-ethylhexylacrylate) membranes did not change significantly, whereas polyaniline-containing membranes had higher dye rejection rates at acidic pH levels. PAN(92)-co-P2EHA(8)-PANI(15%) demonstrated the highest dye rejection value of 99.7% at pH 3 when the feed concentration was 50 ppm. It also showed good resistance to increase in feed concentration. It had dye rejection values of 97.2% and 88.5% for 100 and 200 ppm feed concentrations, respectively.

Optimization of rGO-PEI/Naph-SH/AgNWs/Frt/GOx nanocomposite anode for biofuel cell applications

The present study reports a new nanocomposite design using surface modified silver nanowires decorated on the surface of polyethyleneimine (PEI), a cationic polymer acting as glue for anchoring nanowires and reduced graphene oxide (rGO). The synthesized nanocomposite was employed as a promising electrode material for immobilization of biomolecules and effective transportation of electron, in enzymatic biofuel cell (EBFCs) application. The synthesized nanocomposite was confirmed by analytical techniques, for instance, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The electrochemical behaviour of the nanobioelectrocatalysts rGO-PEI/Frt/GOx, rGO-PEI/AgNWs/Frt/GOx, and rGO-PEI/Naph-SH/AgNWs/Frt/GOx was determined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). The maximum current density obtained by the modified bioanode was found to be 19.9 mA cm⁻² at the limiting glucose concentration of 50 mM in PBS (pH 7.0) as supporting electrolyte at a scan rate of 100 mVs⁻¹.