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ZIF-94 is a zeolitic imidazolate framework with the same SOD type topology than ZIF-8 but with an aldehyde group functionalized organic ligand. This turns ZIF-94 less thermally stable than ZIF-8 but with interesting properties of water and carbon dioxide adsorption, making the former a material highly suitable for carbon capture technologies. In this work, an alternative procedure for the synthesis of ZIF-94 was developed based on the use of NaOH as deprotonator. Besides, the crystallization was carried out in a very short time (1–20 min) at room temperature while centrifuging at 10,000 rpm. This made possible the simultaneous crystallization and separation of the product material giving rise, together with the use of the inorganic deprotonator, to a very efficient process with crystallization yields higher than 65%. For the best conditions tested (crystallization-centrifugation time of 5 min), 66 ± 24 nm in particle size, highly crystalline ZIF-94 with 485 m2 g−1 of specific surface area was obtained at a crystallization yield of 66.9%. Similar properties were obtained for ZIF-94 when prepared from recycled reagents (solvent, ligand and Zn salt).

[Background] The commercialization of thin film composite (TFC) hollow fiber (HF) membranes remains challenging owing to issues associated with membrane manufacturing., [Methods] TFC membranes were synthesized by microfluidic interfacial polymerization of polyamide (PA) on polysulfone hollow fiber (HF) membrane modules. A total of 33 HF membrane modules were prepared with different number of HFs (from 1 to 25) and different lengths (from 10 to 50 cm). They were evaluated in a nanofiltration operation in terms of water permeance and rose Bengal (RB) and MgSO4 rejections., [Significant findings] Among the 33 modules, 73% showed RB rejections higher than 95%, while 36% of the modules reached rejections above 99%. During the membrane synthesis, different parameters, such as PA monomer concentration, residence time and reaction time, were studied. As a result, the amount of monomer was reduced by ca. 80%. The versatility of microfluidics allowed incorporating hydrophilic metal-organic framework (MOF) ZIF-93 to produce HF modules with PA/MOF bilayered membranes (a continuous layer of MOF between the support and the PA film) which led to an important enhancement of the water permeance from 1.3 (bare PA membrane) to 5.3 L·m−2·h−1·bar−1 (PA/ZIF-93 HF membrane), maintaining RB rejection above 95%.

Global energy demand is met in large part, by burning of fossil fuels, which is causing global warming. Mixed matrix membranes (MMMs) with metal organic frameworks (MOFs) as fillers are an interesting alternative for capturing post combustion CO2 which would make the energy sector sustainable. This research is focused on the synthesis of MOF ZIF-94 from the recycling of its mother liquors and the incorporation of synthesized MOF into a Pebax MH 1657 for MMM fabrication. The pH and the temperature of ZIF-94 synthesis are modified and monitored and this results in various nanoparticle diameters (average particle size in the range of 41 ± 8–180 ± 73 nm). Incorporation of ZIF-94 significantly improves the performance of the bare Pebax MH 1657 membrane. The maximum CO2/N2 selectivity and CO2 permeability are obtained for 10 wt% ZIF-94 loading in 9 wt% (polymer concentration in 70/30 (v/v) ethanol/water solution) Pebax MH 1657 matrix being 36 ± 7 (71% increment compared to bare membrane) and 137 ± 31 Barrer (80% improvement), respectively.

The majority of the current energy is produced from burning fossil fuels, being it electricity, fuel or gas. Without a doubt these processes result in the emission of carbon dioxide to the atmosphere. CO2 holds a major share in causing dramatic climate changes and its impact can now be seen on the world panorama. Gas streams focused on the separation of CO2 from CH4 is one of the possible remediation technologies, especially important for the gas industry. Membranes can provide an eco-friendly and low energy consumption alternative to traditional separation techniques. Various membranes with different structures have been studied for this purpose and thin film composite (TFC) membranes being especially attractive due to their high performance thanks to their small thicknesses (ca. 50 nm) and possibility of modification with porous nanoparticles (e.g. metal-organic frameworks (MOF)). In general, the structure of these membranes, usually prepared by interfacial polymerization, enables that the chemistry and porosity of both layers are changed separately. In this work, we focused on synthesizing a continues MOF layer on the lumen side of the hollow fibre instead of MOF being dispersed in the polymeric matrix. Gas separation with MOF based thin-film nanocomposite membranes represent a unique opportunity to produce a technology breakthrough able to address the environmental tasks just mentioned. Until now the fabrication of these membranes has been mainly demonstrated with a single hollow fiber (HF) [1,2]. Thus, another goal of this work is the implementation of the microfluidic synthesis methodology at larger scale and to increase the number of HF membranes that can be modified simultaneously of up to 10. Briefly, the synthesis procedure involves using three syringe pumps and pumping of first: metal salt, second: ligand, and third: methanol to the inner side of the polysulfone hollow fiber. The fabricated containing a thin selective MOF layer mini-modules are tested in

Thin film composite membranes (TFC) of polyamide (PA) prepared by interfacial polymerization (IP) between a diamine and an acyl chloride are applied to industrial nanofiltration and reverse osmosis. Water, to dissolve the diamine, and n-hexane, to dissolve the acyl chloride, solvents are involved in the IP process. Eliminating the use of n-hexane would be crucial to produce a greener TFC membrane synthesis method. This is achieved here by carrying out an interfacial polymerization from the vapor phase. First, the membrane support was impregnated with the aqueous diamine solution. Second, the support with the diamine was contacted with vapors of the acyl chloride to unchain the IP reaction. Besides the absence of n-hexane, acyl chloride was applied more efficiently avoiding its loss during the cleaning operations carried out in the typical IP process. These membranes were applied in the nanofiltration of simulated micropollutants in water (rose Bengal, sunset yellow and acridine orange dyes), with higher water permeance (up to 3.3 L·m−2·h−1·bar−1) than that of conventional TFC membranes and dye rejections higher than 94% in all cases.

This work deals with the use of octadecylamine (ODA)-functionalized reduced graphene oxide (rGO) for thin film nanocomposite (TFN) membranes. The functionalization of rGO with ODA leads to graphene-based nanofillers, more hydrophobic than GO, and thus to the easier dispersion in the organic phase of the interfacial polymerization (IP) reaction carried out to produce polyamide (PA) TFN membranes. The performance of the new TFN membranes is evaluated by organic solvent nanofiltration (OSN) of alcoholic solutions containing dyes Acridine Orange (AO, MW 265 g·mol−1), Sunset Yellow (SY, MW 452 g·mol−1) and Rose Bengal (RB, MW 974 g·mol−1). The functionalized nature of the nanoparticles introduced into the hydrophilic PA layer allows an increase of the ethanol permeance from 2.8, 3.4 and 3.7 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, corresponding to the bare thin film composite membrane (without rGO-ODA particles), to 4.3, 4.6 and 6.0 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, for the rGO-ODA based TFN membrane. In fact, we hypothesize that the increase of the ethanol flux achieved with the use of rGO-ODA as a filler in TFN membranes is owing to a combination of the simultaneous presence of polar and non-polar groups from rGO-ODA nanosheets and the creation of still selective narrow gaps between these particles and the polyamide (PA).

The effect of different deprotonators as well as washing steps and drying procedure on the synthesis of ZIF-8 from the mother liquor was investigated. The morphology, thermal stability, crystallinity, and surface area of the synthesized MOF were investigated. In addition, life-cycle assessment (LCA) or, in other words, eco-balance, was implemented as well. LCA compares the full range of environmental effects associated with the product by evaluating all inputs and outputs of material flows and predicting how such flow will affect the environment. ZIF-8 nanocrystals were synthesized from the recycled mother liquors using NaOH or NH4OH thus preserving the main characteristics of the ZIF-8 nanoparticles derived from the initial synthesis. The rest of the characterization methods confirmed the suitability of the synthesis methodology considering the phase purity of the obtained ZIF-8 and nanometer size particles. This procedure enabled us not only to obtain phase pure ZIF-8 but also to substantially decrease the amount of solvent used for washing making it a sustainable process.

Thin film composite (TFC) membranes consist of a polyamide (PA) thin film (35-100 nm thick) as a selective layer, grown via interfacial polymerization (IP) of monomeric acid chlorides and amines on top of an asymmetric polyimide support, cast over a polypropylene non-woven backing material by phase inversion. This type of membrane is very competitive for organic solvent nanofiltration, where chemical stable polymers are mandatory. In order to increase membrane flux without decreasing rejection, nanoparticles are incorporating during the IP process, giving rise to Thin film nanocomposite (TFN) membranes (Fig. 1a). Their performance is determined by the structural and physicochemical properties of the fillers and PA thin film. Metal organic frameworks (MOFs), built from organic linkers and metal-containing clusters, have been extensively included as fillers in TFN membranes, showing exceptional affinity with polymer chains and improved solvent permeation. The combination of nanoscale visualization via conventional Transmission electron microscopy (TEM) and Scanning transmission electron microscopy (STEM), and spectroscopic analysis via energy dispersive X-ray spectroscopy (EDX) and Electron energy loss spectroscopy (EELS), are some of the most potent techniques for shedding further light into the connection between the nanostructure of the MOF-PA film and their transport and rejection properties. Sample preparation is a key step to examine the presence, distribution and morphology of MOF nanoparticles within the PA film, but also to confirm their crystallinity after the IP process by electron microscopy, given the multilayer and heterogeneous character of these membranes and but also because of the beamsensitive nature of MOFs. Here, we report different sample preparation protocols for applying TEM, STEM-EDS/EELS and electron diffraction depending on the nature of the TFN sample and on the characterization aim: 1. When the aim was to confirm the presence, distribution

The toxic solvent dimethylformamide has been replaced by the greener dimethylsulfoxide in the casting and activation processes for the preparation of thin film composite (TFC) membranes. This methodology has been validated with the use of MOFs ZIF-8, ZIF-93 and UiO-66 as fillers for thin-film nanocomposite (TFN) membranes. These membranes were successfully applied in the organic solvent nanofiltration of sunset yellow (SY) in methanol obtaining the highest permeance when UiO-66 and ZIF-93 were used with a value of 11 L m−2 h-1 bar-1. The permeance improvements are related to the MOF porosity, polyamide-MOF layer thickness and the hydrophilic/hydrophobic character of the membrane.

Nanofiltration can be a useful tool to remove pharmaceuticals in water sources. The performance of the most used thin film composite (TFC) membranes, typically with a thin polyamide (PA) layer, can be improved using thin film nanocomposite (TFN) membranes obtained by the introduction of a filler within the PA layer. In this work, to control the positioning of the filler two kinds of PA/metal–organic framework (MOF) bilayered TFC (BTFC) membranes, PA/ZIF-93 and PA/HKUST-1, were synthesized onto polyimide supports. First, the interfacial synthesis was used for the preparation of a MOF layer, and second, a PA layer was synthesized by interfacial polymerization. These BTFC membranes were applied in the nanofiltration of diclofenac and naproxen aqueous solutions obtaining a maximum water permeance of 33.1 and 24.9 L·m–2·h–1·bar–1, respectively, with a rejection of ≥98% when HKUST-1 was used. These permeance improvements (using diclofenac, 4.9 and 3.4 times the value of the TFC and TFN membranes, respectively) are related to the PA layer thickness, MOF porosity, membrane hydrophilicity, and membrane roughness.

The solvent‐free encapsulation of caffeine and kojic acid was carried out in different carboxylate‐based MOFs [MIL‐53(Al), UiO‐66 and Mg‐MOF‐74] by high pressure (0.32 GPa) contact. This methodology enables fast and ecofriendly encapsulation and gives rise to additive@MOFs with physical and features equivalent to those of materials obtained by common liquid phase encapsulation processes. It could be applied to other host–guest systems, simplifying the procedures, reducing the use and waste of harmful chemicals, and approaching the conditions of interest in the industry. The characterization carried out by thermogravimetry, X‐ray diffraction, N2 adsorption, and 13C NMR provided information about the presence and conformation of the additives in the MOFs. The highest encapsulation values for caffeine (37 %) and kojic acid (32 %) were obtained with MIL‐53(Al).