Metal–organic frameworks (MOFs) are increasingly utilized for the design of molecular sieve membranes with unprecedented separation performance, mainly attributed to their nanopore structure and superior polymer affinity. Herein, UiO-66-NH₂ crystals were synthesized as functional nanofillers to prepare polyamide (PA) composite membranes. The aqueous solution containing piperazine and evenly dispersed UiO-66-NH₂ was transferred onto a membrane surface via vacuum filtration, followed by interfacial polymerization (IP) with trimesoyl chloride (TMC). Covalent bonding between the terminal amine groups of Zr-MOFs and TMC enables the stable immobilization of MOF crystals in the formed PA layer. The positioned MOF nanoaggregates that serve as robust nodes connected by the formed continuous striped film after IP reaction facilitate a rough, fishnet-like surface, which has a larger surface area in comparison to the nodular structure. This unique structure is beneficial for the creation of increased water transport channels, while not compromising the salt rejection. The best performing TFN membranes with a loading mass of 20.5 μg cm⁻² exhibited a favorable Na₂SO₄ rejection of 97.5%, and excellent water permeability (30.8 L m⁻² h⁻¹ bar⁻¹). This facile, controlled loading of hydrophilic MOFs via vacuum filtration allows fabrication of crumpled PA membranes with outstanding separation performance.

Brackish water is a potential fresh water resource with lower salt content than seawater. Desalination of brackish water is an important option to alleviate the prevalent water crisis around the world. As a membrane technology ranging between UF and RO, NF can achieve the partial desalination via size exclusion and charge exclusion. So, it has been widely concerned and applied in treatment of brackish water during the past several decades. Hereon, an overview of the progress in research on and application of NF technology for brackish water treatment is provided. On the basis of expounding the features of brackish water, the factors affecting NF efficiency, including the feed water characteristics, operating conditions and NF membrane properties, are analyzed. For the ubiquitous membrane fouling problem, three preventive fouling control strategies including feed water pretreatment, optimization of operating conditions and selection of anti-fouling membranes are summarized. In addition, membrane cleaning methods for restoring the fouled membrane are discussed. Furthermore, the combined utilization of NF with other membrane technologies is reviewed. Finally, future research prospects are proposed to deal with the current existing problems. Lessons gained from this review are expected to promote the sustainable development of brackish water treatment with NF technology.

Catalytic denitrification is an emerging technology that can remove nitrate and nitrite from water. However, the undesirable formation of ammonia requires further suppression. By preparing three types of Pd-based nanocatalysts with different electronic structures as model catalysts, we demonstrate the interfacial electronic effects induced by ethanol (EtOH) and 1-dodecanethiol (C12T) modifications on the selectivity of nitrite catalytic reduction. XPS and in situ DRIFTS spectral characterization studies illustrate that the electron density of the Pd surface atoms increased with the ethanol modification and decreased with the 1-dodecanethiol modification. The nitrite reduction results show that the Pd–EtOH@MIL-101 catalyst (Pd^δ−) exhibited an unexpectedly low ammonia selectivity of 0.31%, while a higher value of 10.18% was obtained for the Pd–C12T@MIL-101 catalyst (Pd^δ+), which indicated that the electronic structure of Pd can control the ammonia selectivity during the nitrite reduction. Thermodynamics studies revealed that increasing the electron density of the Pd surface atoms reduced the nitrite reaction activation energy and changed the reaction pathways, which resulted in a significant decrease in the ammonia selectivity. The results in this paper may provide new insight into designing and optimizing Pd-based catalysts with low ammonia selectivity for nitrate and nitrite catalytic reduction.