Microporous polymer adsorptive membranes with high processing capacity for molecular separation

Abstract

Trade-off between permeability and nanometer-level selectivity is an inherent shortcoming of membrane-based separation of molecules, while most highly porous materials with high adsorption capacity lack solution processability and stability for achieving adsorption-based molecule separation. We hereby report a hydrophilic amidoxime modified polymer of intrinsic microporosity (AOPIM-1) as a membrane adsorption material to selectively adsorb and separate small organic molecules from water with ultrahigh processing capacity. The membrane adsorption capacity for Rhodamine B reaches 26.114 g m−2, 10–1000 times higher than previously reported adsorptive membranes. Meanwhile, the membrane achieves >99.9% removal of various nano-sized organic molecules with water flux 2 orders of magnitude higher than typical pressure-driven membranes of similar rejections. This work confirms the feasibility of microporous polymers for membrane adsorption with high capacity, and provides the possibility of adsorptive membranes for molecular separation.

Adsorption- and Displacement-Based Approaches for the Removal of Protein-Bound Uremic Toxins

“…Adsorptive membranes are generally prepared by mixing adsorptive filler particles with traditional polymer materials and exhibit the dual function of adsorption and membrane separation [ 35 , 36 ]. Figure 1 schematically shows the concept behind adsorptive membranes where nanoparticles of different nature (activated carbon, zeolites, metal-organic frameworks, etc.)…”

Removal of Transition-Metal Ions by Metal-Complexing Polythiosemicarbazone Membranes

“…A pretreatment step is therefore sometimes needed to reduce fouling and scaling on the membrane surface, resulting in higher-energy demand and increased costs. Therefore, combining the membrane filtration with an adsorption approach can be advantageous because an adsorptive membrane separates the metal ions via specific interactions like complexation/chelation, e.g., by hydrogen-bonding and π–π interactions that exist between the functional groups of the membranes and the heavy metal ions . Consequently, adsorptive membranes have the advantage of maintaining higher water fluxes while essentially retaining heavy metal ion selectivity .…”

“…As a result, the overall adsorption capacity of the membranes is low, meaning that they can only process low concentrations of heavy metal ions. Although this limitation has somewhat been addressed by incorporating nanomaterials like metal–organic frameworks (MOFs) or graphene oxide, which has led to the significantly improved adsorption capacity of the mixed matrix membranes, the limited stability of MOFs in alkaline or acidic conditions hinders their regeneration and operation in the long term …”

“…Therefore, combining the membrane filtration with an adsorption approach can be advantageous because an adsorptive membrane separates the metal ions via specific interactions like complexation/chelation, e.g., by hydrogenbonding and π−π interactions that exist between the functional groups of the membranes and the heavy metal ions. 16 Consequently, adsorptive membranes have the advantage of maintaining higher water fluxes while essentially retaining heavy metal ion selectivity. 17 Vo et al summarized many different types of adsorptive membranes in their review and highlighted their versatility in terms of regeneration and reusability.…”

Fabrication and Characterization of Self-Healable Polydisulfide Network-Based Composites

“…Recently, researches have been actively conducted on the synthesis of dynamic polymer structures that form polymer networks by using various reversible chemical covalent bonds as cross-linking between chains. − There are several types of reversible covalent bonds designed to date, such as CN, C–C, CC, C–O, S–S, Se–Se, B–O, and Si–O, and more bonds are currently being found. − The various proposed reversible covalent bonds break existing bonds with external stimuli (e.g., changes in physical contact or heat, ultraviolet, or pH), and bonds are created. − The characteristics allow for the structural dynamics of polymer networks generated by cross-linking with reversible covalent bonds. − Thus, reversible covalent-based polymer structures are used in applications requiring dynamics, such as cell adhesives, cell regeneration, drug delivery, pressure sensor devices, and coating materials. − In addition, a combination of a cross-linking agent and a dynamic covalent bond can be applied as a shape memory material that under specific conditions is capable of returning to its original shape. − However, until now, research on the material has focused on the development of a polymer chain structure capable of reversible covalent bonding in a form. In addition, research on forming composite materials with other materials and applying them to application fields is still insufficient.…”