Application of Raman spectroscopy to industrial membranes. Part 1—polyacrylic membranes

Boukari, Mohammed El; Bribes, J.‐L.; Maillols, Jacques

doi:10.1002/jrs.1250211109

Cited by 26 publications

(18 citation statements)

References 18 publications

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“…1360 cm –1 corresponding to disordered sp 2 carbon (defect, D band), while the peak at ca. 1580 cm –1 was due to the resonant phonon vibrations of the crystalline graphitic carbon (graphitic, G band). , The additional peaks at 667, 725, and 798 cm –1 are due to CF 2 wagging, CF 2 symmetric stretching, and C–S stretching of the Nafion binder used for coating MOFs on the GDE, respectively . These peaks were absent before the reaction due to their overlap with catalyst material peaks, showing a broad shoulder between 550 and 1200 cm –1 .…”

Section: Resultsmentioning

confidence: 99%

“…12,39 The additional peaks at 667, 725, and 798 cm −1 are due to CF 2 wagging, CF 2 symmetric stretching, and C−S stretching of the Nafion binder used for coating MOFs on the GDE, respectively. 40 These peaks were absent before the reaction due to their overlap with catalyst material peaks, showing a broad shoulder between 550 and 1200 cm −1 . However, the MOF is depleting during the prolonged experiment using the flow cell due to the high alkalinity of the electrolyte used, which leaves the Nafion binder behind.…”

Section: Resultsmentioning

confidence: 99%

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Ligand-Engineered Metal–Organic Frameworks for Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

et al. 2021

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The economic feasibility of electrocatalytic carbon dioxide reduction reaction (CO2RR) relies on developing highly selective and efficient catalysts operating at a high current density. Herein, we explore a ligand-engineering strategy involving the use of metal–organic frameworks (MOFs) and combining the desirable features of homogeneous and heterogeneous catalysts for boosting the activity of CO2RR. Zn-based MOFs involving two different azolate functional ligands, i.e., 1,2,4-triazole (Calgary Framework 20, CALF20) and 2-methylimidazole (zeolitic imidazolate framework-8, ZIF-8), were investigated for CO2RR in an alkaline flow cell electrolyzer. The highest CO partial current density of −53.2 mA/cm2 was observed for a Zn-based MOF (CALF20). CALF20 showed the highest reported Faradaic efficiency of Zn-based MOFs for CO production (∼94% at −0.97 V versus reversible hydrogen electrode, RHE), with a turnover frequency (TOF) of 1360.8 h–1 and a partial current density of −32.8 mA/cm2. Experimental and density functional theory (DFT) results indicate that the sp2 carbon atoms in azole ligands coordinated with the metal center in MOFs are the active sites for CO2RR due to the fully occupied 3d orbital of Zn(II) centers. Ab initio investigation shows that both azolate frameworks in CALF20 and ZIF-8 have the most favorable adsorption sites at the N–sp2 C. Adopting the triazole ligand in CALF20 enhances the charge transfer (as compared with the diazole group in ZIF-8), which induces more electrons in the adjacent active sites at the azole ligand and facilitates *COOH formation, boosting current density and Faradaic efficiency toward CO production. This study suggests that ligand engineering in MOFs could be a viable approach to design a highly efficient CO2RR catalyst.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Ligand-Engineered Metal–Organic Frameworks for Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

et al. 2021

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“…Such interactions might include those between the PAA–alginate or PAA–PAA. , Furthermore, the Raman spectrum revealed a high-intensity band centered at 2936 cm –1 , which was assigned to the v (C–H) stretching vibrations of the PAA chain, which correspond to the polyethylene chain with grafted carboxylate groups (Figure S4b). , On the basis of the FT-IR and Raman characterization, it was concluded that the ACP bead is a cross-linked network consisting of alginate, Ca 2+ ions, and PAA. Previous reports suggest that acryloyl-6-aminocaproic acid-based hydrogels have reversible hydrogen-bonded carboxyl groups, which are sensitive to high pH >9 .…”

Section: Resultsmentioning

confidence: 99%

Preparation of Highly Porous Metal–Organic Framework Beads for Metal Extraction from Liquid Streams

et al. 2020

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Metal–organic frameworks (MOFs) offer great promise in a variety of gas- and liquid-phase separations. However, the excellent performance on the lab scale hardly translates into pilot- or industrial-scale applications due to the microcrystalline nature of MOFs. Therefore, the structuring of MOFs into pellets or beads is a highly solicited and timely requirement. In this work, a general structuring method is developed for preparing MOF–polymer composite beads based on an easy polymerization strategy. This method adopts biocompatible, biodegradable poly(acrylic acid) (PAA) and sodium alginate monomers, which are cross-linked using Ca2+ ions. Also, the preparation procedure employs water and hence is nontoxic. Moreover, the universal method has been applied to 12 different structurally diverse MOFs and three MOF-based composites. To validate the applicability of the structuring method, beads consisting of a MOF composite, namely Fe–BTC/PDA, were subsequently employed for the extraction of Pb and Pd ions from real-world water samples. For example, we find that just 1 g of Fe–BTC/PDA beads is able to decontaminate >10 L of freshwater containing highly toxic lead (Pb) concentrations of 600 ppb while under continuous flow. Moreover, the beads offer one of the highest Pd capacities to date, 498 mg of Pd per gram of composite bead. Furthermore, large quantities of Pd, 7.8 wt %, can be readily concentrated inside the bead while under continuous flow, and this value can be readily increased with regenerative cycling.

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“…Laser‐enhanced Raman spectroscopy. This technique, also still in the R&D stage, provides nondestructive chemical analysis of membranes and surfaces as well as information on membrane deterioration and fouling 12 . It can be used under natural conditions and in real applications.…”

Section: Membrane Materials and Analysismentioning

confidence: 99%

Committee Report: Membrane processes

1998

Journal AWWA

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Researchers are tackling issues related to larger modules and plants, pretreatment, permitting, and disposal of residuals. This review focuses on membrane technology research needs in the context of drinking water treatment. It considers practical issues like membrane piloting, scale‐up, residuals discharge, and costs, as well as more fundamental issues like membrane polymers, surface characterization, biofouling, and modeling of the transport of dissolved and particulate species in membrane systems. It is concluded that because the period since this committee's last report has been a fertile one for research, many new questions have arisen on both applied and fundamental issues in the development, use, and understanding of membrane processes in drinking water treatment.

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Application of Raman spectroscopy to industrial membranes. Part 1—polyacrylic membranes

Cited by 26 publications

References 18 publications

Ligand-Engineered Metal–Organic Frameworks for Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

Ligand-Engineered Metal–Organic Frameworks for Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

Preparation of Highly Porous Metal–Organic Framework Beads for Metal Extraction from Liquid Streams

Committee Report: Membrane processes

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