Water scarcity is a pressing global challenge. Filtration with actual polymeric membranes shows good capability for pollutant separation, but broad applications of polymeric membranes are limited. Filtration can be improved using nanocomposite membranes, which are formed by incorporating nanofillers into polymeric membrane matrixes. The most extensively investigated nanofillers are carbon-based nanoparticles and metal/metal oxide nanoparticles. Here, we review the performance of nanocomposite membranes in antifouling and permeability, their physical and chemical properties and we compare nanocomposite membranes with bare membranes. Nanocomposite membranes generally display better antifouling properties due to the antimicrobial properties of nanoparticles and the reduced roughness of membrane. They also demonstrate higher permeability because of the higher porosity and narrower pore size distribution created by nanofillers. The concentration of nanofillers changes membrane performance, and the optimal concentration depends on both the properties of nanoparticles and the membrane composition. Higher concentrations of nanofillers above the optimal value result in poor performance due to nanoparticle aggregation. Despite intensive research in the synthesis of nanocomposite membranes, most previous efforts are limited to laboratory scale, and the long-term membrane stability following nanofiller leakage has not been extensively investigated.

The high porosity and tunability of metal–organic frameworks (MOFs) have made them an appealing group of materials for environmental applications. However, their potential in the photocatalytic degradation of per- and polyfluoroalkyl substances (PFAS) has been rarely investigated. Hereby, we demonstrate that over 98.9% of perfluorooctanoic acid (PFOA) was degraded by MIL-125-NH2, a titanium-based MOF, in 24 h under Hg-lamp irradiation. The MOF maintained its structural integrity and porosity after three cycles, as indicated by its crystal structure, surface area, and pore size distribution. Based on the experimental results and density functional theory (DFT) calculations, a detailed reaction mechanism of the chain-shortening and H/F exchange pathways in hydrated electron (eaq – )-induced PFOA degradation were revealed. Significantly, we proposed that the coordinated contribution of eaq – and hydroxyl radical (•OH) is vital for chain-shortening, highlighting the importance of an integrated system capable of both reduction and oxidation for efficient PFAS degradation in water. Our results shed light on the development of effective and sustainable technologies for PFAS breakdown in the environment.

Increasing demand for food due to rapid population growth has exerted unprecedented pressure on the global agricultural industry. Agrochemicals are widely used to ensure productivity, leading to the prevalence of legacy and emerging agricultural chemicals in the environment, most of which are toxic and persistent. Metal−organic frameworks (MOFs) as a group of novel photocatalytic materials with ultrahigh porosity and tunability have demonstrated high potential for efficient removal of these recalcitrant pollutants. This critical review aims to present the potential of MOF-catalyzed photodegradation of pesticides and antibiotics. Initially, the capabilities of different MOF-based composites to harvest visible light are compared. Examples include MOFs combined with bismuth oxyhalides (BiOX) and graphite oxide (GO). Mechanisms involved in MOF-induced photocatalytic processes such as electron−hole (e − /h + ) separation, generation of reactive species, and degradation pathways of representative pollutants as well as impacts of water chemistry are illustrated in detailed. Research on applying MOF-catalyzed processes is largely in progress, and many more studies with greater mechanistic evaluation are needed to fully assess the potential of such processes to depollute water.

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Activation of peroxydisulfate (PDS, S2O8 2–) via various catalysts to degrade pollutants in water has been extensively investigated. However, catalyst-free activation of PDS by visible light has been largely ignored. This paper reports effective visible light activation of PDS without any additional catalyst, leading to the degradation of a wide range of organic compounds of high environmental and human health concerns. Importantly, the formation of reactive species is distinctively different in the PDS visible light system with and without pollutants [e.g., atrazine (ATZ)]. In addition to SO4 •– generated via S2O8 2– dissociation under visible light irradiation, O2 •– and 1O2 are also produced in both systems. However, in the absence of ATZ, H2O2 and O2 •– are key intermediates and precursors for 1O2, whereas in the presence of ATZ, a different pathway was followed to produce O2 •– and 1O2. Both radical and nonradical processes contribute to the degradation of ATZ in the PDS visible light system. The active role of 1O2 in the degradation of ATZ besides SO4 •– is manifested by the enhanced degradation of contaminants and electron paramagnetic resonance spectroscopy measurements in D2O.