Emerging Membrane Technology Research Articles

The physical basis for solvent flow in organic solvent nanofiltration.

Organic solvent nanofiltration (OSN) is an emerging membrane technology that could revolutionize chemical separations in numerous vital industries. Despite its significance, there remains a lack of fundamental understanding of solvent transport mechanisms in OSN membranes. Here, we use an extended Flory-Rehner theory, nonequilibrium molecular dynamic simulations, and organic solvent transport experiments to demonstrate that solvent flow in OSN membranes is driven by a pressure gradient. We show that solvent molecules migrate as clusters through interconnected pathways within the membrane pore structure, challenging the widely accepted diffusion-based view of solvent transport in OSN. We further reveal that solvent permeance is dependent on solvent affinity to the OSN membrane, which, in turn, controls the membrane pore structure. Our fundamental insights lay the scientific groundwork for the development of next-generation OSN membranes.

Ultrafiltration of anaerobically digested sludge centrate as key process for a further nitrogen recovery process

In a wastewater treatment plant, the centrate generated in the dehydration process of the anaerobically digested sludge has a high potential for nutrients recovery because of its high nutrients concentration (specifically nitrogen and phosphorous). However, the high organic matter and solids content may make difficult its management. Membrane fouling is the most significant challenge limiting the application of membrane techniques for wastewater treatment. Results in this article highlight the potential of conventional filtration followed by ultrafiltration as pretreatment for further nutrients recovery using emerging membrane technologies (as membrane contactor, membrane distillation or forward osmosis). Thus, a conventional filtration (with 1, 5 and 60 μm filters) followed by an ultrafiltration process were tested. The UF membranes studied were two PES membranes (5 kDa and 0.01 μm) and one PVDF membranes (100 kDa). Results demonstrated that a conventional filtration with a cartridge filter of 60 μm and a subsequent UF process with a 0.01 μm RAY100 membrane (Orelis, France) achieved the best results in terms of the maximum organic matter (66% COD removal) and solids (over 97% suspended solids removal) separation, hardly varying nutrients concentration (13% NH4+ removal). Concerning membrane fouling, FESEM-EDX confirmed salt precipitation on the membrane surface, which has to be controlled to avoid loss of performance.

Advanced 3D multiscale modeling of forward osmosis-membrane distillation integrated designs

The development of eco-friendly desalination and water reuse is key to secure water for future generations. The hybridization of emerging membrane technologies such as forward osmosis (FO) and membrane distillation (MD) stand among alternatives that proved sustainable in treating various feeds. As such, in-series integration of MD and FO enabled the simultaneous treatment of challenging streams, with MD producing fresh water while increasing the draw solution concentration before FO treatment. It is within this context that numerical modeling plays a key role by accelerating hybrids process design and scale-up, shedding light on viable directions and shortening development time. This work presents an advanced 3D multiscale modeling approach that integrates FO and MD heat and mass transfer membrane scale calculations to equipment scale computational fluid dynamics, executed on high performance computers. A methodology based on laboratory scale FO-MD integrated module experiments and runtime optimization is proposed for model calibration and process scale-up. The parallelization of the numerical model is shown to be key to efficient integrated modules development, enabling full 3D analysis on fine meshes and the solution of intricately coupled physical phenomena, which leads to a straightforward process scale-up evaluation.

Zinc sulfate as a draw solute in forward osmosis and its regeneration by reagent precipitation

Forward osmosis (FO) is an emerging membrane technology that has gained huge interest for water treatment and reclamation, owing to its low energy consumption. Nevertheless, the lack of ideal draw solutions and efficient membranes hinder its large-scale applications. In this study, the potential of zinc sulfate draw solute to recover water from different brackish waters by FO was evaluated in terms of permeate water flux, reverse solute flux, and rate of water recovery. Product water having 9.8 and 360 ppm of total dissolved solids (TDS) was recovered from the diluted draw solution by employing a reagent precipitation (RP) and nanofiltration (NF) process, respectively. The draw solution was regenerated by adding a stoichiometric amount of sulfuric acid to the precipitates obtained in RP. In addition, the specific energy consumption (SEC) and water production cost for the water desalination using an FO-RP process were calculated and compared to the FO-NF and a stand-alone RO process. The SEC and water production cost for the FO-RP process were found to be about 0.5 kWh·m−3 and 0.09 $·m−3, respectively. Finally, it is suggested that zinc sulfate could be an excellent choice as a draw solute for water desalination by FO when coupled with reagent precipitation.

Emerging membrane technology and hybrid treatment systems for the removal of micropollutants from wastewater

Currently, substances have been detected that have always been present but have long been unnoticed; among these substances called emerging pollutants are pharmaceuticals, pesticides, cosmetics, cleaning, and personal care products, among others. Membrane Bioreactor (MBR) technology has gained extensive popularity in enhancing the treatment and reutilization of wastewater. It exhibits efficiencies ranging from 40 to 79 % for treating high organic loads such as dairy wastewater while achieving impressive rates of up to 90 % for effectively removing emerging contaminants. However, traditional MBRs with ultrafiltration or porous microfiltration membranes are not intended to remove hazardous micropollutants from water, which are constantly present in trace concentrations and can adversely affect terrestrial and aquatic ecosystems. Several effective techniques have been used to remove hazardous micropollutants from water, especially for hydrophilic and resistant chemicals. These tactics consist mainly of improving the operating environment, using high-retention membranes instead of porous membranes, adding functional materials to the bioreactor, and including additional procedures for effluent treatment. To ensure almost complete removal of micropollutants, the MBR can be complemented with effluent treatment, recently the use of high retention membranes, hybrid MBR-nanofiltration systems, or other processes such as electrocoagulation or advanced oxidation (AOP) have been reported. Nevertheless, additional investigation is required to assess these strategies' technical and economic viability, particularly regarding real-time effectiveness. This evaluation is crucial for identifying the most appropriate techniques for industrial applications.

Emerging membrane technologies for low-cost desalination

Reverse osmosis (RO) has become an attractive option to produce potable water to cater the global needs. Despite the potential advantages of the RO process, it has limitations too. To address such limitations membrane distillation (MD), forward osmosis (FO) and pressure-retarded osmosis (PRO) are now becoming emerging areas of research for seawater desalination. With significant advances in FO and MD for desalination, the entire operation to be conducted at low hydraulic pressure, which reduces fouling and improves membrane life. PRO is an osmotically driven process that produces green energy from the brine stream. However, hybrid desalination processes in combination with RO, are found to be efficient compared to stand-alone technology, with a reduced desalination cost. Although a few studies are available, practical integration of the current state of the art and its gradual progress is rarely addressed. In this context, emerging FO, MD, PRO processes, and the development of membranes for energy minimisation with improved performance are presented herein. Hybrid processes in combination with renewable energy resources are evaluated. Significant technological development and emergence of new materials is anticipated to play a pivotal role so that membrane-based desalination technologies become more efficient and economical in near future.

Emerging membrane technologies and disinfection methods for efficient removal of waterborne pathogens during the COVID-19 pandemic and post-pandemic

We summarize the use of diverse materials like metals/metal oxides in the preparation of filtration systems for water treatment.

Toward anti-fouling properties and enhanced performance in separation process - carbon nanotubes - PVDF hybrids

The development of membranes with anti-fouling properties is one of the leading research paths for emerging membrane technology. In work, anti-fouling PVDF-based membranes were produced. The material engineering focused on the silanization, via molecules equipped either with one or three reactive groups, of the PVDF surface rich in hydroxyl (OH) moieties. Subsequently, carboxylic functionalized multi-walled carbon nanotubes (MWCNTs) were covalently attached to the silanized surfaces. For the first time, the chemically-covalently attached MWCNTs were used to tune the surface features of PVDF for fouling mitigation. All produced materials were characterized and utilized in osmotic membrane distillation for the juice dehydration process of raw apple juice. The tests covered morphology, changes in materials chemistry, wettability, surface charge, thermal stability, and fouling studies in the separation process with natural products. It was revealed that modification mitigates fouling significantly and improves the transport properties of the membranes. The membranes prepared during the modification with a one-reactive group modifier possessed better transport and materials features than hybrid materials grafted with silanes with three reactive groups. It was related to better self-organization of the grafted layers with a one-reactive group molecules.

EVALUATION OF DRAW SOLUTIONS FOR FORWARD OSMOSIS USING A SODIUM ALGINATE-BACTERIAL CELLULOSE MEMBRANE FOR WATER RECOVERY

Forward osmosis (FO) is an emerging membrane technology that is comparable with existing industrial membrane separation processes. Several studies have shown the potential of bacterial cellulose-alginate (BCA) as membrane material for FO system. An ideal draw solution (DS) compatible with this material was investigated. The three solutions used in the study include NaCl, MgCl2, and fructose. A simulated dirty water was used as the feed solution (FS) and a BCA as the membrane. An optimization study was conducted using central composite design (CCD) with the aid of Design Expert 7.0.0. The optimization was based on a fitted linear model analyzed through ANOVA with the normalized water flux maximized. The optimal solution was determined to be fructose with operating conditions at an osmotic pressure of 70 bar and a flow rate of 300 mL/min. The normalized water flux given these optimal conditions is predicted to be 1.437 LMH∙mm with a desirability of 0.768.

Simulation of forward osmosis and pressure retarded osmosis membrane performance: Effect of TiO2 nanoparticles loading on the semi-permeable membrane

Forward osmosis (FO) has made significant progress in recent years as an emerging membrane technology for the treatment of water and wastewater. Differential osmotic pressure is used to extract pure water across a semi-permeable membrane in this process. CFD simulations were used to investigate the performance of flux changes in membrane systems in this study. This paper simulates the performance of a thin film composite (TFC) membrane with a titanium dioxide (TiO2) modified substrate in terms of FO and pressure retarded osmosis (PRO). The results showed how the simulation results (CFD) can be used to detect flux changes with additive particles. It was discovered that even a small amount of TiO2 nanoparticles can alter water flux. In the FO and PRO systems, adding 1 wt% TiO2 to the membrane matrix increased water flux by about 15% and 14%, respectively. Nevertheless, the increased solute flux was insignificant in simulation, which indicates the positive effect of adding TiO2 nanoparticles. Finally, a comparison of the results for different membranes indicated the best correlation between the simulation and experimental results, when 0.75 wt% TiO2 was used, and a relative error of 0.3% has been recorded in PRO process. Also, the maximum pure water flux rate (8·974×10−4molm2·s)obtained in the simulation of thin film nanocomposite (TFN) 1 and PRO process.

Experimental and theoretical parametric study of forward osmosis system using NH4HCO3 and NaCl draw solutes

Forward osmosis (FO), is an emerging membrane technology for water desalination, wastewater treatment and diverse other applications. The technology has known growing attention mainly due to its potential for energy costs reduction. Although FO performances, expressed in terms of water flux and reverse solute flux, have been investigated for individual draw solute (DS) under a certain fixed conditions of concentration and temperature, sensitivity analysis of the impact of the DS concentration and both feed and draw solutions temperature and flowrate on the process performance have not yet been extensively addressed in the literature. In this work, a simulation approach combined with an experimental study has been conducted to evaluate the effect of operating conditions on the process performance and internal concentration polarization phenomena (ICP) using ammonium bicarbonate and sodium chloride as draw solutes. Osmotic performances of the two considered DSs were contrasted throughout the entire ranges of concentration, temperature, and cross-flow velocity. Differences between predicted and experimental results for concentration-dependent, temperature-dependent, and flowrate-dependent fluxes [Jw, Js], expressed in terms of mean absolute error have been consecutively estimated at [3.24%, 6.54%], [3.43%, 4.22%], and [6.04%, 3.08%] for NaCl, and [4.15%, 3.33%], [2.27%, 6.8%], and [5.58%, 2.87%] for NH4HCO3. Regarding ICP, the increase of concentration has shown to induce severe ICP effects causing up to 70.25% of water flux decline at 2 M NaCl. Meanwhile, increasing operating temperature have demonstrated a slight reduction of ICP; 11.63% for NaCl DS and 10.15% for ammonium bicarbonate for an increase of temperature from 10 to 35 °C.

Optimization-based modeling and economic comparison of membrane distillation configurations for application in shale gas produced water treatment

Membrane distillation (MD) is an emerging membrane technology with great potential for treatment of hypersaline wastewater generated by unconventional (shale) oil and gas reservoirs. However, the low energy efficiency of this technology makes the operating cost of MD systems relatively high, especially in the absence of waste heat. There are several MD configurations with inherent advantages and disadvantages and varying performance. As such, there is a need for thermo-economic optimization of MD systems in a systematic manner to assess their economic performance. We present an optimization framework to model and compare the performance of six MD configurations (DCMD, AGMD, PGMD, CGMD, SGMD, and VMD) in continuous recirculation mode for treatment of hypersaline wastewater. The optimization results show that AGMD with small gap size operated at low stream Reynolds number outperforms all other configurations with treatment cost of 4.57 US $/m3 of feed. However, restricting the system design to more practically relevant operating conditions, such as higher Reynolds number and larger gap size, diminishes the cost superiority of AGMD over other configurations. We also observed that treatment cost using PGMD configuration approaches those of CGMD and DCMD, particularly when modules with small gaps are used.

Ultra-strong polymeric hollow fiber membranes for saline dewatering and desalination

Osmotically assisted reverse osmosis (OARO) has become an emerging membrane technology to tackle the limitations of a reverse osmosis (RO) process for water desalination. A strong membrane that can withstand a high hydraulic pressure is crucial for the OARO process. Here, we develop ultra-strong polymeric thin film composite (TFC) hollow fiber membranes with exceptionally high hydraulic burst pressures of up to 110 bar, while maintaining high pure water permeance of around 3 litre/(m2 h bar) and a NaCl rejection of about 98%. The ultra-strong TFC hollow fiber membranes are achieved mainly by tuning the concentration of the host polymer in spinning dopes and engineering the fiber dimension and morphology. The optimal TFC membranes display promising water permeance under the OR and OARO operation modes. This work may shed new light on the fabrication of ultra-strong TFC hollow fiber membranes for water treatments and desalination.

Emerging forward osmosis and membrane distillation for liquid food concentration: A review.

As emerging membrane technologies, forward osmosis (FO) and membrane distillation (MD), which work with novel driving forces, show great potential for liquid food concentration, owing to their low fouling propensity and great driving force. In the last decades, they have attracted the attention of food industry scientists in global scope. However, discussions of the FO and MD in liquid food concentration advancement, membrane fouling, and economic assessment have been scant. This review aims to provide an up-to-date knowledge about liquid food concentration by FO and MD. First, we introduce the principle and applications of FO and MD in liquid food concentration, and highlight the effect of process on liquid food composition, membrane fouling mechanism, and strategies for fouling mitigation. Besides, economic assessment of FO and MD processes is reviewed. Moreover, the challenges as well as future prospects of FO and MD applied in liquid food concentration are proposed and discussed. Comparing with conventional membrane-based or thermal-based technologies, FO and MD show outstanding advantages in high concentration rate, good concentrate quality, low fouling propensity, and low cost. Future efforts for liquid food concentration by FO and MD include (1) development of novel FO draw solution (DS); (2) understanding the effects of liquid food complex compositions on membrane fouling in FO and MD concentration process; and (3) fabrication of novel membranes and innovation of membrane module and process configuration for liquid food processing.

Desalination of saline water via forward osmosis using magnetic nanoparticles covalently functionalized with citrate ions as osmotic agent

ABSTRACT Forward osmosis is an emerging membrane technology in water desalination. In this study, desalination of saline water via forward osmosis was investigated using a new magnetic osmotic agent. For this purpose, Fe3O4 nanoparticles covalently functionalised with tri-sodium citrate was synthesised and characterised. The structural examinations revealed that the sodium citrate had been immobilised onto the magnetic nanoparticles. The highest water flux was obtained 17.1 L M−2 h (LMH) per 80 g L−1 osmotic agent solution against deionised water, while the ratio of salt flux to water flux was very low (0.088 g L−1). The osmotic solution was evaluated for saline water desalination using different concentrations of sodium chloride (NaCl) as feed solutions. The average water fluxes of 6.2, 4.5, and 2.7 LMH was obtained for 0.1, 0.2, and 0.5 M salt solutions, respectively. The magnetic osmotic agent was separated by a magnet and re-used for several times without considerable decrease in the water flux.

Bio-route synthesis of carbon quantum dots from tulsi leaves and its application as a draw solution in forward osmosis

Abstract Forward osmosis (FO) is one of the emerging membrane technologies which has gained interest for being a low energy process. The important factors controlling the FO process are membrane, draw solution (DS) and its recovery. In this research paper, a novel draw solution based on carbon quantum dots (CQDs) was synthesized using Tulsi (Ocimumtenuiflorum). 5 % concentration CQDs were prepared via two different hydrothermal methods i.e. autoclave (A-1) and reflux (R-1). Prepared CQDs were physically characterized by fluorescence spectra, DLS, TEM, XRD, FT-IR and biologically analysed by minimum inhibitory concentration. To prevent microbial growth and to obtain higher water flux, 25 % and 50 % glycerol is added in prepare CQDs. Among both, 50 % glycerol is effective in inhibit microbial growth. Hence, prepared 5 % CQDs of R-1 method with 50 % glycerol is termed as “TCQD-G” and this used for all experimental work as a novel draw solution. TCQD-G performance was investigated and compared with 1 M NaCL in FO with DI water. The prepared draw solute TCQD-G was also used in FO with synthetic wastewater as feed. Maximum water flux achieved by draw solution i.e., TCQD-G and 1 M NaCl was 10.72 L/m2h (LMH) and 8.002 LMH, respectively for DI water as a feed solution. The highest water flux achieved using synthetic waste water as a feed solution was 5.34 LMH with TCQD-G as DS. Reverse solute flux (RSF) was observed 0.03 g/m2h (gMH) and 0.13 gMH for TCQD-G and 1 M NaCl draw solutions, respectively for DI water as feed.

Athermal forward osmosis process for the concentration of liquid egg white: Process performance and improved physicochemical property of protein

The concentrated liquid egg white (LEW) by dewatering process displays the remarkable advantages. However, the concentration process was hindered by the high viscosity and heat sensitivity of LEW. Forward osmosis (FO) as an emerging membrane technology to concentrate LEW was evaluated for the first time in this study. The effects of process conditions on FO flux, fouling control, and product quality were investigated. The LEW can be concentrated up to about 2.1 folds by a single FO process. Flux decline (up to 80%) occurred during the process which was attributed to membrane fouling and dilution of draw solution. However, the membrane fouling could be mitigated by higher cross-flow velocity and the flux could be recovered up to 100% by osmotic backwash. There was no significant leakage of draw solutes and loss of protein in LEW during FO process. The concentration of LEW resulted in a promoted products quality.

CDs@ZIF-8 Modified Thin Film Polyamide Nanocomposite Membrane for Simultaneous Enhancement of Chlorine-Resistance and Disinfection Byproducts Removal in Drinking Water.

Reverse osmosis (RO) is an emerging membrane technology for disinfection byproducts (DBPs) removal. However, the chlorine-resistance and DBPs removal performance of thin film composite (TFC) polyamide membranes should be simultaneously improved when used in chlorinated drinking water. This study was dedicated to synthesize a novel nanoparticle of ZIF-8 with carbon dots (CDs@ZIF-8) and then modify thin film nanocomposite (TFN) membranes to enhance their performance in removing four trihalomethanes (THMs), four haloacetonitriles (HANs), and two haloketones (HKs) in chlorinated drinking water. The fabricated CDs@ZIF-8 nanoparticles and TFN membranes were characterized by FESEM, AFM, XPS, water contact angle, membrane surface potential, and a three-dimensional excitation-emission matrix (EEM) to investigate the influences of CDs@ZIF-8 on TFN membranes. After chlorination, percentage reduction in salt rejection of the CDs@ZIF-8 TFN membranes was lower than that of the TFC membranes due to hydrogen bonding between CDs and polyamide, replacing amidic hydrogen with chlorine, rendering the membrane less susceptible to chlorine attack and enhancing chlorine-resistance. Results also showed that the rejection of DBPs in chlorinated drinking water by CDs@ZIF-8 TFN membranes was more than 95%. The large surface area and abundant oxygen-containing groups of CDs@ZIF-8 made the nanoparticle act as a nanocarbon filler with high adsorption capacity of DBPs. The enhanced performances of chlorine-resistance and DBPs removal by CDs@ZIF-8 TFN membranes determined in this study provided valuable insights on the DBPs control in chlorinated drinking water by RO membranes.

Recent advances in membrane technologies for hydrogen purification

Planet Earth is facing accelerated global warming due to greenhouse gas emissions from human activities. The United Nations agreement at the Paris Climate Conference in 2015 highlighted the importance of reducing CO2 emissions from fossil fuel combustion. Hydrogen is a clean and efficient energy carrier and a hydrogen-based economy is now widely regarded as a potential solution for the future of energy security and sustainability. Although hydrogen can be produced from water electrolysis, economic reasons dictate that most of the H2 produced worldwide, currently comes from the steam reforming of natural gas and this situation is set to continue in the foreseeable future. This production process delivers a H2-rich mixture of gases from which H2 needs to be purified up to the ultra-high purity levels required by fuel cells (99.97%). This driving force pushes for the development of newer H2 purification technologies that can be highly selective and more energy efficient than the traditional energy intensive processes of pressure swing adsorption and cryogenic distillation. Membrane technology appears as an obvious energy efficient alternative for producing the ultra-pure H2 required for fuel cells. However, membrane technology for H2 purification has still not reached the maturity level required for its ubiquitous industrial application. This review article covers the major aspects of the current research in membrane separation technology for H2 purification, focusing on four major types of emerging membrane technologies (carbon molecular sieve membranes; ionic-liquid based membranes; palladium-based membranes and electrochemical hydrogen pumping membranes) and establishes a comparison between them in terms of advantages and limitations.

Adsorptive mixed matrix membrane incorporating graphene oxide-manganese ferrite (GMF) hybrid nanomaterial for efficient As(V) ions removal

Millions of people in the world are exposed to arsenic-contaminated drinking water, causing them to have serious health problems. Compared to the conventional treatment method that uses nanoparticles to eliminate arsenic from water, emerging membrane technology, i.e., adsorptive mixed matrix membrane (MMM) offers unique features including one-step treatment, high reusability and effective even for extremely low concentration of contaminant. In the present study, hybrid nanomaterial namely graphene oxide-manganese ferrite (GMF) was self-synthesized followed by incorporation into polymeric membrane matrix to produce MMM for arsenate (As(V)) ion removal via adsorption-filtration method. The synthesized nanomaterial was characterized using Brunauer, Emmett and Teller (BET) analyzer, Fourier transform Infrared (FTIR) spectroscope, X-ray diffraction (XRD) analyser and transmission electron microscope (TEM), while the developed MMMs were characterized using scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) spectroscope and contact angle goniometer before being used in adsorption-filtration process. The maximum adsorption capacity (qmax), adsorption isotherm and kinetic properties of the MMMs were determined by batch adsorption studies, while the adsorption-filtration experiment was conducted to evaluate the MMMs ability with respect to As(V) removal in cross-flow system and regeneration capability. The best performing MMM could achieve maximum adsorption capacity of 75.5 mg/g at pH 4 and uphold permeates level below the drinking water standard for up to 4 h in a cross-flow filtration process. These findings indicated that the newly developed MMMs are potential to be used as single-treatment method for As(V) ion removal.