Application Of Membrane Processes Research Articles

Biogas Upgrading Using a Single-Membrane System: A Review.

In recent years, the use of biogas as a natural gas substitute has gained great attention. Typically, in addition to methane (CH4), biogas contains carbon dioxide (CO2), as well as small amounts of impurities, e.g., hydrogen sulfide (H2S), nitrogen (N2), oxygen (O2) and volatile organic compounds (VOCs). One of the latest trends in biogas purification is the application of membrane processes. However, literature reports are ambiguous regarding the specific requirement for biogas pretreatment prior to its upgrading using membranes. Therefore, the main aim of the present study was to comprehensively examine and discuss the most recent achievements in the use of single-membrane separation units for biogas upgrading. Performing a literature review allowed to indicate that, in recent years, considerable progress has been made on the use of polymeric membranes for this purpose. For instance, it has been documented that the application of thin-film composite (TFC) membranes with a swollen polyamide (PA) layer ensures the successful upgrading of raw biogas and eliminates the need for its pretreatment. The importance of the performed literature review is the inference drawn that biogas enrichment performed in a single step allows to obtain upgraded biogas that could be employed for household uses. Nevertheless, this solution may not be sufficient for obtaining high-purity gas at high recovery efficiency. Hence, in order to obtain biogas that could be used for applications designed for natural gas, a membrane cascade may be required. Moreover, it has been documented that a significant number of experimental studies have been focused on the upgrading of synthetic biogas; meanwhile, the data on the raw biogas are very limited. In addition, it has been noted that, although ceramic membranes demonstrate several advantages, experimental studies on their applications in single-membrane systems have been neglected. Summarizing the literature data, it can be concluded that, in order to thoroughly evaluate the presented issue, the long-term experimental studies on the upgrading of raw biogas with the use of polymeric and ceramic membranes in pilot-scale systems are required. The presented literature review has practical implications as it would be beneficial in supporting the development of membrane processes used for biogas upgrading.

Application of Membrane Processes for Nitrate (NO3-) Removal

Background: The primary sources of nitrate contamination in groundwater resources are excessive fertilizer use and unregulated land discharges of treated wastewater. Due to its harmful nature to human health and its contribution to eutrophication, the removal of nitrate from water has been of great interest in the last decades. Various techniques, such as adsorption, ion exchange, catalytic and biological denitrification, and membrane processes, have been applied for NO3 - removal. Objective: In this review study, the removal of NO3 - by membrane processes, including electrodialysis (ED), electrodeionization (EDI), reverse osmosis (RO), and ultrafiltration, has been reviewed. Method: The pressure-driven membrane and electro-membrane processes applications to NO3 - removal have been reviewed. Results: The effects of process parameters, interferences, and limitations of membrane processes have been summarized. Conclusion: Membrane processes could be a promising alternative for NO3 - removal. After suitable membrane preparation/modification, the nitrate removal rate could reach >99%.

Novel Thin Film Nanocomposite Membranes Based on Chitosan Succinate Modified with Fe-BTC for Enhanced Pervaporation Dehydration of Isopropanol.

The application of environmentally friendly and energy-efficient membrane processes allows improvement the ecological safety and sustainability of industrial production. However, the effective application of membrane processes requires novel high-performance thin film composite (TFC) membranes based on biopolymers to solve environmental problems. In this work for the first time novel thin film nanocomposite (TFN) membranes based on biopolymer chitosan succinate (ChS) modified with the metal organic framework iron 1,3,5-benzenetricarboxylate (Fe-BTC) were developed for enhanced pervaporation dehydration. The formation of a selective layer of TFN membranes on the porous membrane-support was carried out by two methods—dynamic technique and physical adsorption. The effect of the membrane formation method and Fe-BTC content in ChS layer on the structure and physicochemical properties of TFN membranes was investigated. The developed TFN ChS-based membranes were evaluated in the pervaporation dehydration of isopropanol (12–30 wt.% water). It was found that TFN ChS-Fe-BTC membranes prepared by two methods demonstrated improved permeation flux compared to the reference TFC ChS membrane. The best transport properties in pervaporation dehydration of isopropanol (12–30 wt.% water) were possessed by TFN membranes with 40 wt.% Fe-BTC prepared by dynamic technique (permeation flux 99–499 g m−2 h−1 and 99.99% water in permeate) and TFN membranes with 5 wt.% Fe-BTC developed by physical adsorption (permeation flux 180–701 g m−2 h−1 and 99.99% water in permeate).

Fouling Prevention in Polymeric Membranes by Radiation Induced Graft Copolymerization.

The application of membrane processes in various fields has now undergone accelerated developments, despite the presence of some hurdles impacting the process efficiency. Fouling is arguably the main hindrance for a wider implementation of polymeric membranes, particularly in pressure-driven membrane processes, causing higher costs of energy, operation, and maintenance. Radiation induced graft copolymerization (RIGC) is a powerful versatile technique for covalently imparting selected chemical functionalities to membranes’ surfaces, providing a potential solution to fouling problems. This article aims to systematically review the progress in modifications of polymeric membranes by RIGC of polar monomers onto membranes using various low- and high-energy radiation sources (UV, plasma, γ-rays, and electron beam) for fouling prevention. The feasibility of the modification method with respect to physico-chemical and antifouling properties of the membrane is discussed. Furthermore, the major challenges to the modified membranes in terms of sustainability are outlined and the future research directions are also highlighted. It is expected that this review would attract the attention of membrane developers, users, researchers, and scientists to appreciate the merits of using RIGC for modifying polymeric membranes to mitigate the fouling issue, increase membrane lifespan, and enhance the membrane system efficiency.

Nanodiamond-decorated thin film composite membranes with antifouling and antibacterial properties

Membrane fouling is the main bottleneck that restricts the practical applications of membrane processes. In this work, we report an effective and scalable method to reduce the fouling of polyamide thin film composite (TFC) membranes by grafting amine-functionalized nanodiamond (ND) particles. The surface chemistry of ND was modified to improve the compatibility of nanoparticles with the polyamide membranes. Fouling experiments with sodium alginate (SA) and bovine serum albumin (BSA) showed that the ND layer substantially reduced fouling of the membranes. The flux of the ND-modified membrane made with a solution containing 1000 ppm ND particles declined only by 15% (SA) and 9% (BSA) after 180 min of filtration, while the flux of the pristine TFC membrane declined by 42% (SA) and 21% (BSA). The ND particles increased the antibacterial activity of the membranes, increasing the inactivation and mortality rate of Escherichia coli (E. coli) bacteria cells. Because they are easy to make and have antifouling and antibacterial properties, these membranes can be applied in a broad range of forward osmosis water reclamation applications.

Application of membrane processes in mining and mineral processing

Sustainable mining and mineral processing is of paramount importance for producing metals needed for our society development. Membrane processes are able to contribute to the comprehensive extraction of metals from mined ores, while at the same time decrease the amounts of used water and reagents and ensure discharge to the environment of wastewater meeting the legislation requirements. Membranebased technologies are still underused in metals obtaining although their development and price have made their application affordable. The paper presents in brief membrane processes and displays examples of their application in various areas of mining and mineral processing, such as coping with acid mine drainage and mine influenced water, recovery of metals, reagents and water in hydrometallurgy, recovery of lithium from brines, and treatment of wastewater. Emphasis is placed on pressure driven membrane processes, as well as on the very recent studies in the area. Advantages of membrane processes application in mining and mineral processing are pointed out as well as constrains to be overcome.

Realtime and in-situ monitoring of membrane fouling with fiber-optic reflectance UV-vis spectrophotometry (FORUS)

Organic fouling is a major obstacle to the sustainable application of membrane processes in water treatment. While organic fouling has been extensively studied due to its importance, there exists no current method for in-situ and real-time quantification of the amount of accumulated foulant on the membrane surface. The surface concentration of foulants is the most directly relevant information for quantifying the extent of fouling and is critical for elucidating the mechanism of fouling in membrane processes. Using two most commonly studied foulants, bovine serum albumin (BSA) and humic acid (HA), we demonstrate in this study the feasibility of using fiber-optic reflectance UV–vis spectrophotometry (FORUS) to enable real-time and in-situ measurement of the surface foulant concentrations in ultrafiltration. We first show the existence of a linear correlation between the surface concentration and the UV–vis absorbance measured by FORUS for each type of foulants. We then apply FORUS in ultrafiltration to quantitatively reveal the dynamic behavior of organic fouling.

Classical and Recent Applications of Membrane Processes in the Food Industry

Membrane processes are extensively used in the food industry, especially in the dairy, wine and beer, fruit juice, and sugar industries. In the dairy industry, removal of bacteria and spores from skim milk (cold pasteurization), separation of casein micelles, separation and fractionation of fat globules from whole milk, concentration and demineralization of whey and milk ultrafiltration permeate, fractionation of whey proteins, and desalination of whey membrane processes are realized by membrane processes. In the wine and beer industry, cross-flow of wines and beer clarification and stabilization of wines by electrodialysis are of common use. Fruit juice processing involves clarification, concentration, and deacidification. In the sugar industry, purification and demineralization are realized by membrane processes. This review presents these membrane processes by focusing on the main parameters and phenomena like permeation flux, selectivity, and fouling of membranes. Innovative pilot designs and cleaning methods are presented. The potentials of more unusual techniques like membrane emulsification and electrodialysis of organic acids from fermentation broth are also underlined. A specific attention is paid to the recent development of membrane processes in the food industries.

Optical Sensing of Copper and Its Removal by Different Environmental Technologies

AbstractHeavy metal detection by sensing technology is an important field of research as the heavy metals are toxic and are found in the environmental matrix. The detailed structure and sensing property studies of the probes enhance the knowledge for the future design and development of a probe for same metal. In this review, we have discussed about different chemo and fluorosensors for copper detection and their sensing parameters in different media with detailed structural studies. The removal of copper from the water medium is also addressed in this review. Application of membrane process, adsorption, and electrocoagulation along with their implementation challenges are discussed.

Fabrication of porous polyketone forward osmosis membranes modified with aromatic compounds: Improved pressure resistance and low structural parameter

In this study, we fabricated porous polyketone (PK) support membranes with high pressure resistance and low structural parameter (S) by surface modification with aromatic compounds for osmotically driven membrane process applications. The effects of surface modification of PK using aromatic compounds on the membrane structure, mechanical properties, and membrane performance were investigated. Based on an estimation of the affinity between PK and aromatic compounds using Hansen solubility parameters and mechanical properties, m-phenylenediamine (MPD) was selected as an appropriate chemical modifier for PK membranes. The PK support membranes modified with MPD (PK-MPD) had a dense structure on the bottom side. The thickness and porosity of the PK membranes were changed by the treatment temperature. As a result, polyamide (PA)/PK-MPD thin film composite membranes showed superior pressure resistance in reverse osmosis. PA/PK-MPD modified at 110 °C possessed the highest pressure resistance of 21 bar, which was 3.5 times higher than that of the PA/untreated PK membrane, while maintaining a high water flux of 19.4 L m−2 h−1 in FO. This performance overcame the trade-off relationships between pressure resistance and FO flux and between pressure resistance and S value.

Bleaching of Olive Oil by Membrane Filtration

AbstractIn this study the application of membrane processes for olive oil bleaching is investigated. Olive oil is treated by adding 0.7 wt% of bleaching earth, 0.3 wt% of activated charcoal, and 5% wt% of sodium dodecyl sulfate solution (0.05 m) and then charged into the membrane cell. Operating conditions including pressure ((2−4) × 105 Pa), temperature (25–45 °C), and stirring rate (100–300 rpm) are optimized. Physico‐chemical properties of membrane bleached oil are evaluated and compared with crude and industrially bleached olive oil. Results show that the filtration conditions for the optimized point are as follows: pressure = 3.7 bar (3.7×105 Pa), temperature = 36.5 °C, and stirring rate = 300 rpm. Under optimum conditions, the amounts of carotenoid and chlorophyll contents are decreased (71.3% and 40.42%, respectively). Acidic and thiobarbituric acid values reduction in membrane‐processed oil (12.42% and 14.46%, respectively) are more than the industrial one. Also, some bioactive compounds such as sterols and phenolic compounds are increased in the membrane‐filtered sample (23.13% and 57.12%, respectively).Practical Applications: Olive oil bleaching is an important step along the refining process. Pigments and minor impurities that reduce olive oil stability are removed in this step. Given the disadvantages of conventional bleaching, alternative methods are introduced. In this study, the effect of membrane filtration on olive oil color is studied. Because of the mild operating conditions, the reduction of clay percentage, as well as the increase of bioactive compounds in optimum conditions, this method has the potential to be a good alternative to conventional bleaching processes.

Mitigation of Membrane Fouling Using an Electroactive Polyether Sulfone Membrane.

Membrane fouling is the bottleneck limiting the wide application of membrane processes. Herein, we adopted an electroactive polyether sulfone (PES) membrane capable of mitigating fouling by various negatively charged foulants. To evaluate anti-fouling performance and the underlying mechanism of this electroactive PES membrane, three types of model foulants were selected rationally (e.g., bovine serum albumin (BSA) and sodium alginate (SA) as non-migratory foulants, yeast as a proliferative foulant and emulsified oil as a spreadable foulant). Water flux and total organic carbon (TOC) removal efficiency in the filtering process of various foulants were tested under an electric field. Results suggest that under electrochemical assistance, the electroactive PES membrane has an enhanced anti-fouling efficacy. Furthermore, a low electrical field was also effective in mitigating the membrane fouling caused by a mixture of various foulants (containing BSA, SA, yeast and emulsified oil). This result can be attributed to the presence of electrostatic repulsion, which keeps foulants away from the membrane surface. Thereby it hinders the formation of a cake layer and mitigates membrane pore blocking. This work implies that an electrochemical control might provide a promising way to mitigate membrane fouling.

Flower and Leaf Extracts of Sambucus nigra L.: Application of Membrane Processes to Obtain Fractions with Antioxidant and Antityrosinase Properties.

This study aimed at evaluating and comparing the chemical profile as well as the antityrosinase and antioxidant activities of ethanol (EtOH) and methanol (MeOH) extracts of Sambucus nigra L. (Adoxaceae) flowers and leaves in order to discover new candidates for food additives and cosmetic and pharmaceutical products. For this purpose, a novel lower-melting-point ethylene-chlorotrifluoroethylene (LMP ECTFE) nanofiltration (NF) membrane was employed in order to produce the concentrated fractions of S. nigra. Floral extracts were richer in phytochemicals in comparison to the leaf extracts. The High-performance liquid chromatography (HPLC) profile revealed rutin, quercetin, protocateuchic acid, 3,5-dicaffeoylquinic acid, and neochlorogenic acid as the most abundant compounds. Ferric reducing antioxidant power (FRAP), 2,2’-diphenil-1-picrylhydrazil (DPPH) radical scavenging, and 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) tests were used to investigate the antioxidant properties. NF retentate fractions of floral ethanol extracts exerted the highest tyrosinase inhibitory activity with an IC50 of 53.9 µg/mL and the highest ABTS radical scavenging activity (IC50 of 46.4 µg/mL). In conclusion, the present investigation revealed the potential benefits of NF application in S. nigra extracts processing, suggesting the use of retentate fractions as a promising source for antioxidant and tyrosinase inhibitory compounds which could pave the way for future applications.

Membrane Processes for the Regeneration of Liquid Desiccant Solution for Air Conditioning

Regeneration of liquid desiccant solutions is critical for the liquid desiccant air conditioning (LDAC) process. In most LDAC systems, the weak desiccant solution is regenerated using the energy-intensive thermal evaporation method which suffers from desiccant carry-over. Recently, membrane processes have gained increasing interest as a promising method for liquid desiccant solution regeneration. This paper provides a comprehensive review on the applications of membrane processes for regeneration of liquid desiccant solutions. Fundamental knowledge, working principles, and the applications of four key membrane processes (e.g., reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), and membrane distillation (MD)) are discussed to shed light on their feasibility for liquid desiccant solution regeneration and the associated challenges. RO is effective at preventing desiccant carry-over; however, current RO membranes are not compatible with hypersaline liquid desiccant solutions. FO deploys a concentrated draw solution to overcome the high osmotic pressure of liquid desiccant solutions; hence, it is feasible for their regeneration despite the issues with internal/external concentration polarization and reverse salt flux. ED has proven its technical feasibility for liquid desiccant solution regeneration; nevertheless, more research into the process energy efficiency and the recycling of spent solution are recommended. Finally, as a thermally driven process, MD is capable of regenerating liquid desiccant solutions, but it is adversely affected by the polarization effects associated with the hypersalinity of the solutions. Extensive studies are required to realize the applications of membrane processes for the regeneration of liquid desiccant solutions used for LDAC systems.

Experimental investigation of oil-in-water microfiltration assisted by Dielectrophoresis: Operational condition optimization

Membrane filtration is an efficient method in treating oily waste water containing fine oil droplets. However rapid fouling of membrane and decay in process performance has resulted in limited industrial application of membrane processes for oily waste water treatment. In this paper, electric field is used as an assisting force to improve oil in water microfiltration performance. An electrically safe membrane module is fabricated and used for microfiltration studies in the presence of electric field. A statistical study is developed for conducting necessary experiments to identify optimum processing conditions in the presence of an AC electric field. Two response functions of stable flux and oil rejection are defined and optimized with response surface methodology and central composite design. The effects of trans membrane pressure, cross flow velocity, feed concentration and applied voltage on stable permeate flux and oil rejection are studied for an emulsion of 1.93μm oil droplets in water in a microfiltration system with cellulose acetate membrane of 0.45μm pore size. Results reveal that induction of electric field can considerably improve process performance. Variation in studied factors results in the flux ranging from 64 to 140L/m2hr while rejection varies between 85% and 97%. Quadratic models are suggested for flux and rejection with 0.93 and 0.83 R2 values respectively. Optimum conditions are predicted at 136.2L/m2hr for flux and 94.1% for rejection, observed at 360V, 1.1m/s, 900ppm and 2.5bar. The real values for flux and rejection are 131.8L/m2hr and 88.7% respectively representing −3.4% and −6.0% relative errors for the correlations.

Metal Oxide based Antibacterial Membrane

Biofouling is one of the major problems that hamper the application of membrane processes. Biofouling causes performance deterioration and higher energy consumption due to membrane pore blockage. In addition, it also results in a higher cleaning frequency and a shorter membrane lifetime which increases membrane operating and maintenance cost. Preparation or modification of membrane with antibacterial properties has been considered as one of the attractive strategies to control biofouling. Recently, the combination of polymeric with biocidal materials has attracted a great attention in the preparation of antibacterial membrane. A lot of metal oxide nanoparticles which have biocidal characteristics have been used to prepare nanocomposite membrane with remarkable antibacterial properties and significant biofouling reduction. According to studies that have been reported, the enhancement of anti-biofouling of the membrane was due to an interaction between the metal oxides and microorganism on the membrane surface which prevents biofilm formation. The enhancement of metal oxide nanoparticles antibacterial effect has been studied, including the elaboration of nanostructured oxide consisting of two or metallic components. In this paper, the metal oxide-based antibacterial membrane is comprehensively reviewed. In addition, mechanism of metal oxide particles in preventing biofilm formation will be discussed.

Tackling membrane fouling in microalgae filtration using nylon 6,6 nanofiber membrane

Microalgae technology, if managed properly, has promising roles in solving food-water-energy nexus. The Achilles' heel is, however, to lower the costs associated with cultivation and harvesting. As a favorable technique, application of membrane process is strongly limited by membrane fouling. This study evaluates performance of nylon 6,6 nanofiber membrane (NFM) to a conventional polyvinylidene fluoride phase inverted membrane (PVDF PIM) for filtration of Chlorella vulgaris. Results show that nylon 6,6 NFM is superhydrophilic, has higher size of pore opening (0.22 vs 0.18 μm) and higher surface pore density (23 vs 18 pores/μm2) leading to higher permeance (1018 vs 493 L/m2hbar) and better fouling resistant. Such advantages help to outperform the filterability of PVDF PIM by showing much higher steady-state permeance (286 vs 120 L/m2hbar), with comparable biomass retention. In addition, unlike for PVDF PIM, imposing longer relaxation cycles further enhances the performance of the NFM (i.e., 178 L/m2hbar for 0.5 min and 236 L/m2hbar for 5 min). Overall findings confirm the advantages of nylon 6,6 NFM over the PVDF PIM. Such advantages can help to reduce required membrane area and specific aeration demand by enabling higher flux and lowering aeration rate. Nevertheless, developments of nylon 6,6 NFM material with respect to its intrinsic properties, mechanical strength and operational conditions of the panel can still be explored to enhance its competitiveness as a promising fouling resistant membrane material for microalgae filtration.

Membrane separation for non-aqueous solution

Membrane technology has been widely used in a number of applications competing with conventional technologies in various ways. Despite the enormous applications, they are mainly used for the aqueous system. The use of membrane-based processes in a non-aqueous system is an emerging area. This is because developed membranes are still limited in separations involving aqueous solution which show several drawbacks when implemented in a non-aqueous system. The purpose of this paper is to provide a review of the current application of membrane processes in non-aqueous solutions, such as mineral oil treatment, vegetable oil processing, and organic solvent recovery. Developments of advanced membrane materials for the non-aqueous solutions such as super-hydrophobic and organic solvent resistant membranes are reviewed. In addition, challenges and future outlook of membrane separation for the non-aqueous solution are discussed.

Ag modified g-C3N4 composite entrapped PES UF membrane with visible-light-driven photocatalytic antifouling performance

Membrane fouling is still the main obstacle for the wider application of membrane processes.

Application of membrane processes in fractionation of elements in river water.

The influence of wastewater treatment plant (WWTP) effluents from one microelectronic industrial zone on element concentrations and partitioning in river water was investigated. The stepwise membrane filtration is used to distinguish different size fractions including large particulate (>18 μm), particulate (0.2-18 μm), colloidal/nanoparticle (10 kDa-0.2 μm) and truly dissolved fractions (<10 kDa) in river water samples and WWTP effluents. Results demonstrated that anthropogenic inputs (WWTP effluents and industrial area) had an important influence on concentrations and partitioning of some elements in river water. Mass balance results showed that membrane filtration processes could realize a good fractionation for many elements (good recoveries) in water samples. Flux decline during 0.2 μm and 10 kDa filtrations were analyzed, and corresponding fouling mechanisms are discussed.