Synthesis of nanostructured mixed matrix membranes for facilitated gas separation

The separation of gas mixture is a major operation in the petrol-chemical industry. The\ud separation of oxygen/nitrogen is one of the main applications. The most common\ud applied commercial gas separation processes are cryogenic distillation, adsorption and\ud classical membrane permeation. Depending on the specific requirements for the\ud process, i.e., process scale and product purity, one or more of the available gas\ud separation techniques will be economically preferable. Under economic considerations\ud membrane systems have been proven to be loss energy intensive and thus more cost\ud effective to operate than the traditional techniques mentioned. Classical polymeric\ud membrane materials used so far possessing high selectivities for specific gas pairs show\ud generally low permeabilities, which is referred to as an “upper bound” relationship.\ud Facilitated transport of a specific gas molecule can therefore be suggested as one of the\ud promising methods to improve single bulk material (polymer) properties.\ud The main goal of this project was to synthesise a new class of gas separation\ud membranes based on carrier facilitated transport for oxygen/nitrogen separation

Modified PEEK mixed-matrix membranes for pervaporation applications

La deshidratación del ácido acético a través de la destilación es difícil porque requiere un alto número de etapas y relaciones de reflujo. La pervaporación (PV) es una técnica de separación de membranas donde un componente de una mezcla líquida penetra selectivamente a través de una membrana densa, esta tecnica se utiliza para separaciones donde la destilación es imposible de emplear o no es económica. El problema a los que se enfrentan las membranas es el balance entre la permeabilidad y la selectividad, particularmente, en condiciones ácidas, asi como tambien la resistencia química frente al ácido. Por lo tanto, el desarrollo de las membranas está orientado a mejorar este balance a través de la investigación del rendimiento de varios materiales en mezclas ácidas, como ácido acético y agua.Se investigaron varias membranas compósitas (MMM) densas con PEEK-WC como matriz para la deshidratación de ácido acético mediante pervaporación. Se utilizaron tres MOFs: ZIF-8, HKUST-1 y MIL-101(Cr) en dos concentraciones: 2.5 wt% and 5 wt% respecto al polímero. Las caracterizaciones de las nanoparticulas sintetizadas están de acuerdo con los resultados reportados en la literatura. Además, las caracterizaciones de las MMM mostraron que no tienen defectos, son de naturaleza ligeramente hidrofílica y tienen buenas propiedades térmicas y mecánicas. Los tests de hinchamiento mostraron que las membranas MZ y MH tienen grados más bajos de hinchamiento que la membrana PEEK-WC.De las cinco muestras de membranas, sólo dos (PEEK-WC y MH-2.5) dieron valores estables de permeación. A concentraciones altas de ácido (5%), la membrana PEEK-WC tiene una permeación de agua de 1142 GPU con una selectividad de 7.3 y la membrana MH-2.5 mejoró su permeación (3176 GPU) manteniendo su selectividad (7.7) igual a la de la membrana PEEK-WC. Si el contenido de nanopartículas en la membrana aumenta a 5 wt% (MH-5), la selectividad cae. Esto demostró que con elegir el tipo y el contenido de las nanopartículas apropiadas, las MMM basadas en PEEK-WC pueden mejorar su rendimiento a la permeación del agua.<br /

A more sustainable membrane preparation using triethyl phosphate as solvent

Abstract In this work, hydrophobic poly(vinylidene fluoride) membranes for potential membrane distillation applications, with pore sizes ranging from ~ 0.05 to ~ 0.30 μm, were prepared by employing triethyl phosphate (TEP) as a substitute to the hazardous, commonly used, toxic solvents. Membrane morphologies and properties were tailored based on the main parameters, such as the casting solution composition and the operational conditions, which affect the phase inversion process. Experimental results showed that exposure time to controlled humid air and temperature, as well as additive content in the dope solution, strongly influence the membrane formation. The use of TEP as an alternative solvent may contribute to the development of sustainable separation operations

Tungsten promoted ammonium and potassium ferrierite: deactivation during the skeletal isomerization of linear butenes

Deactivation of tungsten promoted ferrierite during the skeletal isomerization of 1-butene at 400°C, atmospheric pressure and 0.15 atm 1-butene partial pressure was studied. Both potassium and ammonium ferrierites were impregnated with tungsten species using either tungstic acid or ammonium metatungstate as precursors, reaching loadings between 1.4 and 7.3%. After the tungsten addition on both ferrierite samples, neither the acid strength distribution nor the total acidity corresponding to the unpromoted materials change significantly. The strongest acid sites present on the ammonium ferrierite with and without tungsten and absent on the tungsten promoted potassium ferrierite, are responsible for the side-reactions. Deactivation of tungsten promoted ferrierites shows differences. Ammonium ferrierite with and without tungsten reach similar carbon contents, being larger than the ones obtained on potassium ferrierite with and without tungsten. In all cases, the carbonaceous deposit shows both olefinic and aromatic species, the proportion depending on the samples. Coke on tungsten promoted potassium ferrierite shows mainly an olefinic nature, while the deposit formed on tungsten promoted ammonium ferrierite has a more aromatic character. For the latter samples, the complete coke removal needs higher temperatures. The strength of acid sites determines not only the carbonaceous deposit amount but also its degree of condensation. The low isobutene selectivity at short time-on-stream (TOS) is avoided by starting the 1-butene feed with the catalytic bed at 200°C and then increasing temperature up to 400°C. It can be considered that a strong adsorption of reactant molecules takes place at low temperatures, thus deactivating the strongest acid sites.Fil: Finelli, Zunilda Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Querini, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Figoli, Nora Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Comelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Submerged Membrane Bioreactor (SMBR) for Treatment of Textile Dye Wastewatertowards Developing Novel MBR Process

Abstract This paper deals with the application of a submerged membrane bioreactor (SMBR) with commercial membrane module and novel MBR modulefor the treatment of model textile dye wastewater (MTDW). For this work, MTDW was developed based on different publications and a pilot-scale automated SMBR unit was applied to carry out the tests with this model wastewater. The system is on the way to be upgraded to attain novel MBR module replacing the applied commercial membrane by novel membrane materials which have been developed by the European Commission funded project "BioNexGen" [1] . The hydraulic volume of the employed SMBR reactor was 57 L. One flat sheet commercial MBR module was submerged in the reactor. The module consisted of 3 sheets, with 25 cm × 25 cm dimensions of each sheet covering total active membrane area of 0.33 m2. To reach the target, different MBR process parameters like COD, BOD, TOC, pH, conductivity, flux, TMP, MLSS, colour contents, air supply, O2 consumption, HRT, SRT, drying residue, nutrients etc. have been investigated. It is reported that under the operating conditions of permeate flux of 4 L/m2h, around 50 mbar of TMP, 12 g/L of MLSS, 40-80 h of HRT, 1.0 m3/h of air supply to MBR reactor, pH of 8.2 ± 0.2- 10.5 ± 0.2 and temperature of 18 ± 2 °C, the COD removal efficiency was around 90% for 2450 mg/L inlet COD fed to the membrane bioreactor and Red and Blue colour removal efficiencies were 25-70% and 20-50% respectively. In order to develop novel MBR process, a novel MBR module has already been applied replacing the commercial one and the preliminary results are reported

Monitoring of membrane processes with fluorescence molecular probes

This work discusses the use of molecular probes that change their fluorescence response in the presence of different local environmental conditions. In particular, probes able to respond to temperature and to oxygen concentration were identified and used to report the value of these parameters at a molecular scale. The development of a stable, reproducible and sensitive molecular probing system was then applied to monitor oxygen concentration at the surface of different membrane materials and also in order to obtain oxygen concentration profiles inside dense membranes. Ultimately, a temperature sensitive probe was used to measure temperature at membrane surfaces making possible its measurement locally. This technique was applied with success to experimentally measure temperature polarization in membrane distillation processes, on-line, in a non-invasive mode. Future developments of molecular probing will be also presented and discussed

A scale-up procedure to Dialkyl Carbonates: purification, chemical physical properties, biodegradability and cytotoxicity tests

Among the different dimethyl carbonate (DMC) derivatives, dialkyl carbonates DACs are extensively investigated as safe alternatives to chlorine reagents. In fact, they can replace alkyl halides and dimethyl sulfate in alkylation and carbonylation reactions as well as phosgene and its derivatives in the alkoxycarbonylation ones. In this work we explored the high yielding scale-up synthesis of non-commercially available or expensive dialkyl carbonates (DACs) via transcarbonylation reactions of an alcohol with dimethyl carbonate (DMC) promoted by a nitrogen-based organocatalyst. Compared to previously published works, the proposed procedure has been customized for DACs large scale production (up to 70 mL of product obtained). Purification of these compounds has been achieved by fractional distillation and the exceeding reagents have been recovered and recycled. The selected DACs for this study include both symmetrical and unsymmetrical compounds, incorporating several alkyl, alkoxyalkyl, alkylamino and alkylthio functional groups. The chemical-physical properties of the new DACs have been also evaluated, as well as their water solubility. Furthermore, both biodegradability and cytotoxicity tests have been carried out to investigate the effects of the different substituents on the greenness of these potential solvents and reagents

Design and testing of a pilot-scale submerged membrane bioreactor (MBR) for textile wastewater treatment

Abstract The objective of this paper is to deal with the design of a pilot-scale submerged membrane bioreactor (MBR) and a short-term functionality test to be performed with textile wastewater. The design calculations were done based on the design parameters analysed from local textile wastewater and typical values of activated sludge kinetic coefficients. Other process parameters like bioreactor volume (tank size), hydraulic residence time (HRT), biomass loading (F/M ratio), oxygen demand, etc., were calculated depending on the real textile wastewater characteristics. Taking the design basis into consideration, a pilot-scale MBR was constructed equipped with LabVIEW programme- and sensors-controlled computer system. Based on the theoretical calculations, the hydraulic volume of the MBR reactor was around 56.6 L with flat sheet membranes (3 sheets, with 25 cm × 25 cm dimensions of each sheet) with HRT of 16.9 h. Finally, performance tests for 6 weeks were carried out in a local (Darmstadt, Germany) laundry textile wastewater to test the functionality of MBR pilot plant. Under the operating conditions of 250 mbar suction pressure and 12 g/L of MLSS, the COD removal efficiency was around 90% for 800–3500 mg/L inlet COD fed to the membrane bioreactor

Polyvinylidene Fluoride-Graphene Oxide Membranes for Dye Removal under Visible Light Irradiation

[EN] In this study, polyvinylidene fluoride (PVDF)-graphene oxide (GO) membranes were obtained by employing triethyl phosphate (TEP) as a solvent. GO nanosheets were prepared and characterized in terms of scanning and transmission electron microscopy (SEM and TEM, respectively), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), chemical analysis and inductively coupled plasma mass spectroscopy (ICP). Two different phase inversion techniques, Non-Solvent Induced Phase Separation (NIPS) and Vapour-Induced Phase Separation (VIPS)/NIPS, were applied to study the effect of fabrication procedure on the membrane structure and properties. Membranes were characterized by SEM, AFM, pore size, porosity, contact angle and mechanical tests, and finally tested for photocatalytic methylene blue (MB+) degradation under visible light irradiation. The effect of different pH values of dye aqueous solutions on the photocatalytic efficiency was investigated. Finally, the influence of NaCl salt on the MB+ photodegradation process was also evaluated.The authors acknowledge the financial support from Iran Science Ministry. The authors also sincerely thank the Institute on Membrane Technology, National Research Council of Italy (ITM-CNR) for kindly collaborate.Alyarnezhad, S.; Marino, T.; Parsa, JB.; Galiano, F.; Ursino, C.; García Gómez, H.; Puche, M.... (2020). Polyvinylidene Fluoride-Graphene Oxide Membranes for Dye Removal under Visible Light Irradiation. E-Polymers. 12(7):1-19. https://doi.org/10.3390/polym12071509S119127Figoli, A., Ursino, C., Galiano, F., Di Nicolò, E., Campanelli, P., Carnevale, M. C., & Criscuoli, A. (2017). Innovative hydrophobic coating of perfluoropolyether (PFPE) on commercial hydrophilic membranes for DCMD application. Journal of Membrane Science, 522, 192-201. doi:10.1016/j.memsci.2016.08.066Dao, V.-D., Vu, N. H., & Choi, H.-S. (2020). 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Smart Embedded Passive Acoustic Devices for Real-Time Hydroacoustic Surveys

This paper describes cost-efficient, innovative and interoperable ocean passive acoustics sensors systems, developed within the European FP7 project NeXOS (Next generation Low-Cost Multifunctional Web Enabled Ocean Sensor Systems Empowering Marine, Maritime and Fisheries Management) These passive acoustic sensors consist of two low power, innovative digital hydrophone systems with embedded processing of acoustic data, A1 and A2, enabling real-time measurement of the underwater soundscape. An important part of the effort is focused on achieving greater dynamic range and effortless integration on autonomous platforms, such as gliders and profilers. A1 is a small standalone, compact, low power, low consumption digital hydrophone with embedded pre-processing of acoustic data, suitable for mobile platforms with limited autonomy and communication capability. A2 consists of four A1 digital hydrophones with Ethernet interface and one master unit for data processing, enabling real-time measurement of underwater noise and soundscape sources. In this work the real-time acoustic processing algorithms implemented for A1 and A2 are described, including computational load evaluations of the algorithms. The results obtained from the real time test done with the A2 assembly at OBSEA observatory collected during the verification phase of the project are presented.Postprint (author's final draft