Hyperfast Water Transport through Biomimetic Nanochannels from Peptide-Attached (pR)-pillar[5]arene

Synthetic water channels offer great promise to replace natural aquaporins (AQPs) for making new-generation biomimetic membranes for water treatment. However, the water permeability of the current synthetic water channels is still far below that of AQPs. Here, peptide-attached (pR)-pillar[5]arene (pR-PH) channels are reported to mimic the high permeability of AQPs. It is demonstrated that the pR-PH channels with an open pore can transport water smoothly and efficiently. The pR-PH channels are competitive with AQPs in terms of water permeability and are much superior to diastereomer peptide-attached (pS)-pillar[5]arene (pS-PH) and other reported synthetic water channels. The exceptional water-transport properties of the pR-PH channels are further demonstrated in a composite polymeric membrane that incorporates the nanochannels into the top selective layer. This membrane gives a significantly improved water flux while retaining high salt rejection. The results establish a tangible foundation for developing highly efficient artificial water channel-based biomimetic membrane for water purification applications.

Osmosis, from molecular insights to large-scale applications

Osmosis is a universal phenomenon occurring in a broad variety of processes and fields. It is the archetype of entropic forces, both trivial in its fundamental expression - the van 't Hoff perfect gas law - and highly subtle in its physical roots. While osmosis is intimately linked with transport across membranes, it also manifests itself as an interfacial transport phenomenon: the so-called diffusio-osmosis and -phoresis, whose consequences are presently actively explored for example for the manipulation of colloidal suspensions or the development of active colloidal swimmers. Here we give a global and unifying view of the phenomenon of osmosis and its consequences with a multi-disciplinary perspective. Pushing the fundamental understanding of osmosis allows one to propose new perspectives for different fields and we highlight a number of examples along these lines, for example introducing the concepts of osmotic diodes, active separation and far from equilibrium osmosis, raising in turn fundamental questions in the thermodynamics of separation. The applications of osmosis are also obviously considerable and span very diverse fields. Here we discuss a selection of phenomena and applications where osmosis shows great promises: osmotic phenomena in membrane science (with recent developments in separation, desalination, reverse osmosis for water purification thanks in particular to the emergence of new nanomaterials); applications in biology and health (in particular discussing the kidney filtration process); osmosis and energy harvesting (in particular, osmotic power and blue energy as well as capacitive mixing); applications in detergency and cleaning, as well as for oil recovery in porous media.

Artificial water channels: inspiration, progress, and challenges

Developing bioinspired artificial water channels may lead to the next-generation filtration membranes with ultra-high pore density and exclusive water permeability.