New journal: Applied Water Science

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membrane engineering for green process engineering

Abstract Green process engineering, which is based on the principles of the process intensification strategy, can provide an important contribution toward achieving industrial sustainable development. Green process engineering refers to innovative equipment and process methods that are expected to bring about substantial improvements in chemical and any other manufacturing and processing aspects. It includes decreasing production costs, equipment size, energy consumption, and waste generation, and improving remote control, information fluxes, and process flexibility. Membrane-based technology assists in the pursuit of these principles, and the potential of membrane operations has been widely recognized in the last few years. This work starts by presenting an overview of the membrane operations that are utilized in water treatment and in the production of energy and raw materials. Next, it describes the potential advantages of innovative membrane-based integrated systems. A case study on an integrated membrane system (IMS) for seawater desalination coupled with raw materials production is presented. The aim of this work is to show how membrane systems can contribute to the realization of the goals of zero liquid discharge (ZLD), total raw materials utilization, and low energy consumption

Membrane Condenser: Direct and Indirect Support to CO2 capture

Today membrane technology for gas separation (GS) is a well-consolidated technique, in various cases competing with traditional operations. The separation of air components, H2 from refinery industrial gases, natural gas dehumidification, separation and recovery of CO2 from biogas and natural gas are some examples in which membrane technology is successfully used in industry. Recent constraints and regulations on CO2 emissions from power plants have forced researchers to focus on the separation of CO2 from flue gas streams and to develop specific CO2 capture technologies that can be retrofitted to existing power plants as well designed into new plants with the goal to achieve 90% of CO2 capture limiting the increase in cost of electricity to no more than 35%. Currently, the main strategies for the carbon dioxide capture in a fossil fuel combustion process are: Oxy-fuel combustion, pre-combustion capture and post-combustion capture. The main technical problems are related to the fact that polymeric membranes cannot withstand, however, high temperatures and/or chemically harsh conditions. Refinery gas streams contain impurities such as water vapor, acid gases, olefins, aromatics and other organics. Heavy hydrocarbons can be present in the feed also in petrochemical plants and natural gas treatment, representing a problem, mainly in hollow fiber modules. At relatively low concentrations, these impurities cause membrane plasticization and loss of selectivity, while at higher concentrations they can condense on the membrane surface which could be damaged. Many polymers are swollen or plasticized in presence of hydrocarbons or CO2 at high partial pressure: the result is a significant reduction in their separation performance, or, their damage. Another issue is physical aging which negatively affect the properties of interesting polymers (PTMSP, PIMs, etc.) and limit their applicability. The solution for a successful operation of polymeric modules is a careful selection of feed pre-treatment. In this field, membrane condensers can be considered as a proper solution for pre-treating the flue gas streams that have to be fed to another membrane unit for CO2 separation and whose performances are strongly affected by the presence of such contaminants as SOx, NH3, etc. In a membrane condenser, the waste gaseous stream (e.g. flue gas) from an industrial plant at a certain temperature and, in most cases, water saturated, is fed to the membrane condenser kept at a lower temperature for cooling the gas up to a super-saturation state. The water condenses onto the membrane surface and the hydrophobic nature of the latter prevents the penetration of the liquid into the pores, letting the dehydrated gases pass through the membrane and retaining the liquid water at the retentate side. In comparison with other technologies, the membrane condensers offer higher water recovery and are not affected by desiccant losses, corrosion phenomena typical of traditional condensers or desiccant units. Compared with the dense membrane technology, the latter requires a high pressure difference between the two membrane sides to promote the permeation of water vapor but allows the recovery of a very pure stream. On the contrary, the purity of the water recovered in membrane condensers can be affected by the possible condensation of contaminants – if present in the gaseous stream – but it is sufficient for cooling tower or boiler make up. However, further purifications would be needed to make it drinkable. Moreover, the possibility of controlling, by opportunely tuning the operating conditions, the condensation of contaminants in the liquid water recovered in the retentate side of the membrane condenser could lead to two different options for its use: as a unit for water recovery, minimizing the contaminants content, or, as the pre-treatment stage in post-combustion capture, forcing most of the contaminants to be retained. References Macedonio F., Brunetti A., Barbieri G., Drioli E. Membrane Condenser as a new technology for water recovery from humidified “waste” gaseous streams. Industrial & Engineering Chemistry Research, 2012; 52(3): 1160-1167. Macedonio F., Cersosimo M., Brunetti A., Barbieri G., Drioli E. Water recovery from humidified waste gas streams: Quality control using membrane condenser technology. Chemical Engineering and Processing: Process Intensification, 2014; 86: 196-203

integrated membrane desalination systems with membrane crystallization units for resource recovery a new approach for mining from the sea

The mining industry is facing problems of clean production in terms of mineral processing, pollution, water consumption, and renewable energy. An interesting outlook can be to combine the mining industry with membrane-based desalination in the logic of mining from the sea. In fact, several of the drawbacks found in both mining and desalination can be minimized or overcome, which includes hindering mineral depletion, water production instead of water consumption, smart usage of brine instead of disposal, and low energy consumption, etc. Recently, membrane crystallization (MCr) has been developed to recover minerals from highly concentrated solutions. This study suggests MCr for the treatment of nanofiltration (NF) retentate and reverse osmosis (RO) brine leaving membrane-based desalination system. Thermodynamic modeling has been carried out to predict at which water recovery factor and which amount of minerals can be recovered. Theoretical results deviate only 2.09% from experimental results. Multivalent components such as barium, strontium, and magnesium are easier to recover from NF retentate with respect to RO brine. KCl and NiCl2 might be recovered from both NF retentate and RO brine, whereas lithium can only be recovered from RO brine. Moreover, copper and manganese compounds might also be recovered from desalination brine in perspectives

Membrane condenser as emerging technology for water recovery and gas pre-treatment: current status and perspectives

Abstract The recent roadmap of SPIRE initiative includes the development of "new separation, extraction and pre-treatment technologies" as one of the "key actions" for boosting sustainability, enhancing the availability and quality of existing resources. Membrane condenser is an innovative technology that was recently investigated for the recovery of water vapor for waste gaseous streams, such as flue gas, biogas, cooling tower plumes, etc. Recently, it has been also proposed as pre-treatment unit for the reduction and control of contaminants in waste gaseous streams (SOx and NOx, VOCs, H2S, NH3, siloxanes, halides, particulates, organic pollutants). This perspective article reports recent progresses in the applications of the membrane condenser in the treatment of various gaseous streams for water recovery and contaminant control. After an overview of the operating principle, the membranes used, and the main results achieved, the work also proposes the role of this technology as pre-treatment stage to other separation technologies. The potentialities of the technology are also discussed aspiring to pave the way towards the development of an innovative technology where membrane condenser can cover a key role in redesigning the whole upgrading process

membrane engineering for environmental protection and sustainable industrial growth options for water and gas treatment

The increasing demand for materials, energy and products drives chemical engineers to propose new solutions everyday able to promote development while supporting sustainable industrial growth. Membrane engineering can offer significant assets to this development. Here, they are identified the most interesting aspects of membrane engineering in strategic industrial sectors such as water treatment, energy production and depletion and reuse of raw materials. The opportunity to integrate membrane units with innovative systems to exploit the potential advantages derived from their synergic uses is also emphasized. The analysis of the potentialities of these new technologies is supported by the introduction of process intensification metrics which provide an alternative and innovative point of view regarding the unit performance, highlighting important aspects characterizing the technology and not identified by the conventional analysis of the unit performance

Preparation and characterization of mixed matrix membranes for gas separation and pervaporation

El objetivo principal de esta investigación fue desarrollar membranas de matriz mixta(MMMs) que pueda proveer un rendimiento superior que los polímeros puros para dos diferentes tipos de tecnologías de membranas (por ejemplo separación de gas y pervaporación). En la primera parte de esta tesis, el mejoramiento de la permeación de CO2 de un polímero commercial, como la polimida Matrimid®5218, fue abordada. En este punto, fue propuesta por primera vez la preparación de MMMs ternarias rellenando nanopartículas ZIF-8 (33.83 ± 6.2 nm) en la mezcla Matrimid®-PEG 200. Las MMMs fueron probadas a diferentes composiciones (50:50) y presiones de alimentación (de 2 a 8 bar). Las MMMs fueron también caracterizadas usando SEM, EDX, DSC, and TGA.Los resultados indicaron que la incorporación del 30 %p/p de nanopartículas condujo a incrementar la permeabilidad al CO2 en las MMM binarias (hasta 31.47 Barrer ) y ternarias (hasta 33.12 Barrer); destacando que la adición del PEG y el ZIF-8 mejoró la permeabilidad al CO2 (mas de tres veces) en comparación con las membranas Matrimid® puras (7.16 Barrer).El uso de esta poliimida comercial Matrimid®5218, como un polímero hidrofílico, ha sido también extendido a otra tecnología de membrane (por ejemplo la pervaporación).La potencialidad de esta polimida se relaciona con la separación de mezclas azeotrópicas orgánicas-orgánicas. En este punto, membranas de Matrimid®5218 fueron preparadas y probadas por primera vez en separación por pervaporación (PV) de la mezcla azeotrópica methanol (MeOH)- metil terc-butil éter (MTBE) (14.3 y 85.7%p/p,respectivamente). Los experimentos PV fueron llevados acabo a diferentes temperaturas(25-45ºC) y presiones de vacío (0.0538, 0.2400, 2.1000 mbar) en el permeado. Los resultados destacan que la temperatura (en el rango de 25-45 ºC) afectó principalmente la permeación del MeOH, produciendo un incremento en su flujo de permeado y el factor de separación también. Los mejores rendimientos de Matrimid® fueron a 45 ºC y 0.054 mbar, donde un flujo de permeado y un factor de separación de alrededor de 0.073 kg m-2 h-1 y 21.16, respectivamente, fueron alcanzados.En la última parte de esta tesis, el mejoramiento de otro polímero comercial, como elalcohol de polivinilo (PVA), fue propuesto para aplicaciones de PV. De este modo, unmaterial altamente hidrofílico, como el óxido de grafeno (GO), fue existosamentepreparado e incorporado en una matriz de PVA reticulado. Las MMM fueron probadaspara la deshidratación de etanol (10:90 %p/p agua-etanol) monitoreando su rendimientoen terminus de flujo total de permeado, flujo por componentes, así como su factor deseparación. El efecto del relleno fue analizado duplicando el contenido del GO (a 0.5,1.0, and 2.0 %p/p) en las MMMs. Además, las membranas fueron caracterizadas porFESEM, DSC, TGA, XRD, grado de hinchamiento, ángulo de contacto con agua, ypropiedades mecánicas. El mejor rendimiento de dichas MMMs (conteniendo 1 %p/p deGO) fue encontrado a 40 ºC, mostrando un factor de separación de 263 y un flujo depermeado de alrededor de 0.137 kg·m-2·h-1 (en el cual 0.133 kg·m-2·h-1 corresponde aagua). Este resultado representa una mejora del 75 % de la tasa de permeación originalde las membranas reticuladas de PVA pura.Finalmente, este trabajo reporta el mejoramiento de dos polímeros comerciales (talescomo poliimida Matrimid®5218 y alcohol de polivinilo). Es importante mencionar quetales polímeros fueron selecionados acorde a su consolidación en producción a grandeescala y su aplicación cercana a escala industrial. En general los capítulos tambiénabordan revisiones de literatura para seleccionar cada caso de estudio y así ser atendidosdurante esta investigación (por ejemplo separaciones CO2/CH4 y MeOH-MTBE, asícomo deshidratación de etanol). Además, esta tesis provee puntos relevantes enprocedimientos de preparación adecuados para obtener MMMs con buen rendimientThe main aim of this research work was to develop mixed matrix membranes (MMMs), which may provide superior performance compared to the base pristine polymers, for two different types of membrane-based technologies (e.g. gas separation and pervaporation). In the first part of the thesis, the enhancement of CO2 permeation of a commercial polymer, like Matrimid®5218 polyimide, was aimed. At this point, it is proposed, for the first time, the preparation of ternary MMMs based on the filling ZIF-8 nanoparticles (33.83 ± 6.2 nm) into Matrimid®-PEG 200 blend. The MMMs membranes were tested at fixed feed composition (50:50) and different feed pressures (from 2 to 8 bar). The MMMs were also characterized using SEM, EDX, DSC, and TGA. The results indicate that the incorporation of 30 wt.% of ZIF-8 nanoparticles leads to increase of CO2 permeability in binary (up to 31.47 Barrer) and ternary MMMs (up to 33.12 Barrer); pointing out that the addition of PEG and ZIF-8 enhanced the CO2 permeability (more than 3-folds) comparing to the neat Matrimid® membranes (7.16 Barrer). The use of this commercial Matrimid®5218 polyimide, as a hydrophilic polymer, has been also extended to other membrane technology (e.g. pervaporation). The potentiality of this polyimide deals with the separation of organic-organic azeotropic mixtures. Herein, Matrimid® membranes were prepared and tested, for the first time, in pervaporation (PV) separation of azeotropic methanol (MeOH)- methyl tert-butyl ether (MTBE) mixture (14.3 and 85.7%, respectively). The PV experiments were carried out at different feed temperatures (25-45ºC) and vacuum pressures (0.0538, 0.2400, 2.1000 mbar) at permeate side. The results pointed out that the feed temperature (in the range of 25-45 ºC) affected mainly the MeOH permeation producing an increasing on its partial permeate flux and separation factor as well. Importantly, the best performances of Matrimid® were found at 45 ºC and 0.054 mbar, where a permeate flux and a separation factor of about 0.073 kg m-2 h-1 and 21.16, respectively, were reached. In the last part of this thesis, the enhancement of another commercial polymer, like poly(vinyl alcohol) (PVA), was proposed for PV applications. In this way, a highly hydrophilic inorganic material, like graphene oxide (GO), was successfully prepared and incorporated into a cross-linked PVA matrix. The MMMs were tested for the dehydration of ethanol (10:90 wt. % water-ethanol), monitoring their performance in terms of total permeate flux, components fluxes, as well as their separation factor. The effect of filler was analyzed by doubling the GO content (at 0.5, 1.0, and 2.0 wt.%) in the MMMs. Furthermore, the membranes were characterized by FESEM, DSC, TGA, XRD, and measurements of degree of swelling, water contact angle, and mechanical properties. The best performance of such MMMs (containing 1 wt.% of GO) was found at 40 ºC, displaying a separation factor of 263 and a permeate flux of about 0.137 kg·m-2·h-1 (in which 0.133 kg·m-2·h-1 corresponds to water). This result represents a 75 % enhancement of the original permeation rate of pristine cross-linked PVA membranes. Finally, this work reports the enhancement of two commercial polymers (such as Matrimid®5218 polyimide and poly(vinyl alcohol) (PVA)). It is important to mention that such polymers were chosen according to their consolidation in large-scale production and their near application at industrial scale. In general, the chapters also address the literature reviews to select each case of study, and thus to be attended during this research (e.g. CO2/CH4 and MeOH-MTBE separations as well as ethanol dehydration). Moreover, this thesis provides relevant insights into the suitable preparation procedures to reach high performing MMMs<br /

CO2/CH4 separation by means of Matrimid hollow fibre membranes

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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

A Novel Approach to Synthesize Helix Wave Hollow Fiber Membranes for Separation Applications

Helix wave hollow fiber membranes are promising candidate to mitigate fouling and polarization effects in membrane operations. Current study describes a novel but simple approach to synthesize hollow fiber membranes with helix wave configuration. Poly(ether sulfone) (PES) based helix-waved hollow fiber membranes have been fabricated by dry-wet phase inversion process by using asymmetric coagulation conditions. Frequencies of the wave cycle have been observed approximately 20 and the wave length 7.1-7.6mm under the specifically required operating conditions defined by dope solution extrudate rate of 1g/min through 4cm of air-gap heights with 8.6m/min of winding speeds. On the other hand, simple hollow fibers are formed when the elongation force exerted by the winder is much higher than the surface tension of the external coagulant. The process can be useful for making polymer fibers for other applications as well