Sustainable lithium extraction enabled by responsive metal-organic frameworks with ion-sieving adsorption effects.

Metal-organic frameworks (MOFs) are superior ion adsorbents for selectively capturing toxic ions from water. Nevertheless, they have rarely been reported to have lithium selectivity over divalent cations due to the well-known flexibility of MOF framework and the similar physiochemical properties of Li and Mg. Herein, we report an ion-sieving adsorption approach to design sunlight-regenerable lithium adsorbents by subnanoporous MOFs for efficient lithium extraction.

Emerging contaminants in the water environment: Disinfection-induced viable but non-culturable waterborne pathogens.

Disinfection is essential for the control of waterborne pathogens (WPs), especially during the COVID-19 pandemic. WP can enter the viable but non-culturable (VBNC) state to evade disinfection, seriously threatening water safety. VBNC WPs should be considered as an emerging contaminant to ensure a higher level of safety of the water environment.

Stimuli-Responsive Ion Adsorbents for Sustainable Separation Applications.

Stimuli-responsive ion absorbents (SRIAs) with reversible ion adsorption and desorption properties have recently attracted immense attention due to their outstanding functionalities for sustainable separation applications. Over the past decade, a series of SRIAs that respond to single or multiple external stimuli ( pH, gas, temperature, light, magnetic, and voltage) have been reported to achieve excellent ion adsorption capacity and selectivity while simultaneously allowing for their reusability. In contrast to traditional adsorbents that are mainly regenerated through chemical additives, SRIAs allow for reduced chemical and even chemical-free regeneration capacities, thereby enabling environmentally friendly and energy-efficient separation technologies.

A review of struvite crystallization for nutrient source recovery from wastewater.

Nutrient recovery from wastewater not only reduces the nutrient load on water resources but also alleviates the environmental problems in aquatic ecosystems, which is a solution to achieve a sustainable society. Besides, struvite crystallization technology is considered a potential nutrient recovery technology because the precipitate obtained can be reused as a slow-release fertilizer. This review presents the basic properties of struvite and the theory of the basic crystallization process.

Partial quaternization promoted metal-organic frameworks for efficient photocatalytic removal of chromium(VI).

A one-step strategy is applied to partially quaternize the ligand of UiO-66-NH, and the resultant UiO-66-N(CH) showed greatly improved photocatalytic performance for Cr(VI) reduction, with the apparent reaction rate constant increasing by 8.3 times. This strategy could be used to effectively promote the performance of other MOFs-NH, demonstrating general applicability.

Effect of Anion Species on Ion Current Rectification Properties of Positively Charged Nanochannels.

Biological ion channels can realize delicate mass transport under complicated physiological conditions. Artificial nanochannels can achieve biomimetic ion current rectification (ICR), gating, and selectivity that are mostly performed in pure salt solutions. Synthetic nanochannels that can function under mixed ion systems are highly desirable, yet their performances are hard to be compared to those under pure systems.

Unidirectional and Selective Proton Transport in Artificial Heterostructured Nanochannels with Nano-to-Subnano Confined Water Clusters.

The construction of biological proton channel analogues has attracted substantial interest owing to their wide potential in separation of ions, sensing, and energy conversion. Here, metal-organic framework (MOF)/polymer heterogeneous nanochannels are presented, in which water molecules are confined to disordered clusters in the nanometer-sized polymer regions and to ordered chains with unique molecular configurations in the 1D sub-1-nm porous MOF regions, to realize unidirectional, fast, and selective proton transport properties, analogous to natural proton channels. Given the nano-to-subnano confined water junctions, experimental proton conductivities in the polymer-to-MOF direction of the channels are much higher than those in the opposite direction, showing a high rectification up to 500 and one to two orders of magnitude enhancement compared to the conductivity of proton transport in bulk water.

Sulfonated Sub-1-nm Metal-Organic Framework Channels with Ultrahigh Proton Selectivity.

Biological proton channels are sub-1-nm protein pores with ultrahigh proton (H) selectivity over other ions. Inspired by biological proton channels, developing artificial proton channels with biological-level selectivity is of fundamental significance for separation science. Herein we report synthetic proton channels fabrication based on sulfonated metal-organic frameworks (MOFs), UiO-66-X, X = SAG, NH-SAG, (NH-SAG) (SAG: sulfonic acid groups), which have sub-1-nm windows and a high density of sulfonic acid groups mimicking natural proton channels.

Homochiral MOF-Polymer Mixed Matrix Membranes for Efficient Separation of Chiral Molecules.

Homochiral metal-organic framework (MOF) membranes have been recently reported for chiral separations. However, only a few high-quality homochiral polycrystalline MOF membranes have been fabricated due to the difficulty in crystallization of a chiral MOF layer without defects on porous substrates. Alternatively, mixed matrix membranes (MMMs), which combine potential advantages of MOFs and polymers, have been widely demonstrated for gas separation and water purification.

Monovalent Cation-Phenolic Crystals with pH-Driven Reversible Crystal Transformation.

The conversion of renewable plant polyphenol to advanced materials with tailorable properties and various functions is desirable and challenging. In this work, monovalent cation-phenolic crystals contained K or Na ions were synthesized by using plant polyphenol as an organic source in alkaline solution. The crystal structure was resolved, showing a laminar crystal structure with M as connecting nodes.

Thermoresponsive Amphoteric Metal-Organic Frameworks for Efficient and Reversible Adsorption of Multiple Salts from Water.

Regenerable, high-efficiency salt sorption materials are highly desirable for water treatment. Here, a thermoresponsive, amphoteric metal-organic framework (MOF) material is reported that can adsorb multiple salts from saline water at room temperature and effectively release the adsorbed salts into water at elevated temperature (e.g.

Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer pores.

Porous membranes with ultrafast ion permeation and high ion selectivity are highly desirable for efficient mineral separation, water purification, and energy conversion, but it is still a huge challenge to efficiently separate monatomic ions of the same valence and similar sizes using synthetic membranes. We report metal organic framework (MOF) membranes, including ZIF-8 and UiO-66 membranes with uniform subnanometer pores consisting of angstrom-sized windows and nanometer-sized cavities for ultrafast selective transport of alkali metal ions. The angstrom-sized windows acted as ion selectivity filters for selection of alkali metal ions, whereas the nanometer-sized cavities functioned as ion conductive pores for ultrafast ion transport.

Periodic oscillation of ion conduction of nanofluidic diodes using a chemical oscillator.

Periodic ion-conduction oscillation of biological ion channels in a living system is essential for numerous life processes. Here we report an oscillatory nanofluidic system that can self-regulate its ion-conduction states under constant conditions. The oscillatory nanofluidic system is constructed by integrating a chemical oscillator into an artificial single nanochannel system.

Hydrogel-polyurethane interpenetrating network material as an advanced draw agent for forward osmosis process.

Water desalination and purification are critical to address the global issue of the shortage of clean water. Forward osmosis (FO) desalination is an emerging low-cost technology for clean water production from saline water. The lack of a suitable draw agent is one of hurdle for the commercialization of FO desalination technology.

Robust Thermoresponsive Polymer Composite Membrane with Switchable Superhydrophilicity and Superhydrophobicity for Efficient Oil-Water Separation.

Herein, we report for the first time on the fabrication of a robust, thermoresponsive polymer membrane produced by the combination of an elastic polyurethane (TPU) microfiber web and poly(N-isopropylacrylamide) (PNIPAM). PNIPAM hydrogel is evenly coated on the surface of TPU microfibers, and thus, the wettability of TPU-PNIPAM membrane is amplified by taking advantage of the hierarchical structure and increased surface roughness. The TPU-PNIPAM membrane possesses switchable superhydrophilicity and superhydrophobicity as the temperature of membrane changes from 25 to 45 °C.

Bioinspired Smart Gate-Location-Controllable Single Nanochannels: Experiment and Theoretical Simulation.

pH-activated gates intelligently govern the ion transport behaviors of a wide range of bioinspired ion channels, but the mechanisms between the gate locations and the functionalities of the ion channels remain poorly understood. Here, we construct an artificial gate-location-tunable single-nanochannel system to systematically investigate the impact of the gate location on the ion transport property of the biomimetic ion channel. The gate-location-controllable single nanochannels are prepared by asymmetrically grafting pH-responsive polymer gates on one side of single nanochannels with gradual shape transformation.