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an energy-efficient and environmentalfriendly approach, CDI depends on electrical double layers (EDLs) formed at the carbon-based electrode surface to absorb ions from feed solutions. [8] Membrane capacitive deionization (MCDI) is an improved method from CDI by simply integrating ion-exchange membranes (IEMs), in which an anion-exchange membrane is tightly fixed in front of the anode, and a cation-exchange membrane is for the cathode. In MCDI process, the counter-ions can migrate to the electrode more effectively. And the coions on the electrode surface are preserved which further increases the salt adsorption capacity and charge efficiency. [9] Another advanced improvement for CDI and MCDI is the innovation of electrode materials. It has been proven that porous carbon materials with a high specific surface area and good electrical conductivity are generally favorable for electrosorption performance where the EDLs are easier to form. [8] Since 1990s, various kinds of carbon materials have been studied as electrode materials for CDI and MCDI, including carbon aerogels, [10] carbon nanotubes, [11,12] activated carbons, [13] carbon nanofibers, [14] carbon composites, [12,15] etc. Recently, porous carbons derived from metal-organic framework (MOF) have shown greatly enhanced performance in desalination due to their large surface area and uniform morphology. [16,17] Moreover, the synthesis process for certain MOFs are facile and applicable in industrial manufacturing. For example, a zeolitic imidazolate framework (ZIF), ZIF-8, is able to produce porous carbon polyhedral with a large surface area of 1187.8 m 2 g −1 and exhibits a high salt adsorption capacity of 13.86 mg g −1 in a CDI system. [16] However, the carbon derived from ZIF-8 has a low electrical conductivity that reduces the charge efficiency for the adsorption process. In our prior work, we improved the electrical conductivity of carbon derived from ZIF-8 by fusing another MOF called ZIF-67. ZIF-67 is a cobalt-based MOF that can catalyse graphitic carbon during pyrolysis. [18] With the improved conductivity, the porous carbons derived from Znand Co-based bimetallic MOF achieve a high salt adsorption capacity of 45.62 mg g −1 for MCDI. [19] Besides suffering from a low electrical conductivity, porous carbon derived from ZIF-8 has a severe aggregation during the pyrolysis process, which decreases the specific surface area and impedes the diffusion path for salt ion into the microporous structure. Hence there Membrane capacitive deionization is considered as a promising technology for water treatment with their high efficiency, low capital cost, and environmental friendliness. However, the complex fabrication process of membrane capacitive deionization electrodes mainly hinders its viability in large-scale applications. In this study, a facile and general method to prepare free-standing electrodes for membrane capacitive deionization with an excellent electrosorption performance is presented. Electrospun nanofibers enclosing zinc-based nanoparticles are fabr...

The scarcity of drinking water and the contamination of water sources in underdeveloped countries are serious problems that require immediate low-tech and low-cost solutions. In this study, we fabricated polyacrylonitrile (PAN) porous membranes coated with silver nanoparticles (AgNP) and demonstrated their use for water filtration and water treatment applications. The membranes were prepared by electrospinning a PAN solution and treating in a hydroxylamine (NH2OH) aqueous solution to form –C(NH2)N–OH groups that were used for functionalization (Ag+ ions) of the membrane. The coordinated silver ions were then converted to silver nanoparticles. The microstructure of the membrane, water permeability, antimicrobial effect (using Escherichia coli), and particulate filtration capabilities were studied. This study verified that the membrane demonstrated a 100% reduction for Gram-negative bacteria with an effective filtration rate of 8.0 mL/cm2 min. Furthermore, the membrane was able to eliminate 60% of latex beads as small as 50 nm and over 80% of the 2 µm beads via gravity filtration. This study demonstrated that PAN–AgNP membranes can be employed as antimicrobial membranes for the filtration of water in underdeveloped countries.

The reaction of 1,3‐dicarbonyl compounds (I) or (V) with 2 molecules of an aromatic or aliphatic amine and two molecules of a benzaldehyde affords the piperidines.

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