Separation Efficiency Of Membrane Research Articles

One-pot in-situ deposition toward fabricating superhydrophobic fiberglass membranes with composite microstructure for fast water-in-oil emulsions separation

The separation of oily wastewater, especially surfactant-stabilized water-in-oil emulsions, has become a pressing global challenge. Herein, to achieve ultrafast and efficient separation of water-in-oil emulsions, this work took advantage of the Dodecyltrimethoxysilane (DTMS)-modified TiO2 sol to prepare a superhydrophobic fiberglass (FG) membrane via a facile one-pot in-situ deposition technique. The unique composite microstructure: stalactite-shaped TiO2-SiO2 composite nanoparticles and multi-layer rough fibers were constructed on the fibrous membranes, which significantly increased the roughness and led to a water contact angle of 162.7°. As-prepared composite microstructures combined the capture, coalescence, and interception effects to achieve ultrafast gravity-driven separation of surfactant-stabilized emulsions, with a flux up to 3130.4 L m−2h−1 for surfactant stabilized water-in-hexane and high separation efficiency above 99% for various emulsions. Additionally, the prepared membrane exhibited an excellent cyclic adsorption capacity of 4.25–19.07 gg−1 and high stability. Such an easy, cost-efficient one-pot in-situ deposition method provides a brand-new solution to fabricate superhydrophobic membranes for efficient separation of water-in-oil emulsions, thus exhibiting great potential in applications of domestic wastewater treatment, oil spill treatment, and oil industry development.

Photo-Fenton reaction derived self-cleaning nanofiltration membrane with MOFs coordinated biopolymers for efficient dye/salt separation

Membrane technology has been widely used in textile industry for the separation of dye/salt mixtures. However, membranes inevitably suffered from the fouling issue, which greatly abated the water permeability and reduced the separation efficiency of membranes. Herein, a novel thin film nanocomposite (TFN) nanofiltration (NF) membrane was prepared by introducing photocatalytic sensitive material into the selective layer to directly degrade the foulants on the membrane surface. This functional selective layer was achieved by a complexation of carboxymethyl cellulose (CMC) and MIL-53 (Fe), which greatly enhanced the self-cleaning ability of the TFN membrane while MIL-53 (Fe) was served as nanofiller and photocatalyst simultaneously. The optimized TFN NF membrane modified with 0.5 mg CMC and 0.075 mg MIL-53 (Fe) exhibited a high pure water permeability of 39.83 L m−2 h−1 bar−1, while maintaining high dye rejections above 99.00 % for CR, G250 and MB. Meanwhile, the obtained membrane exhibited impressive rejections of salts (61.49 % for Na2SO4 and 17.22 % for NaCl). This simple fabrication strategy provided new insights to augment the separation performance of TFN NF membrane with self-cleaning ability in organic separation systems.

Preparation and performance of UiO‐66‐(COOH)2‐based mixed matrix membranes for efficient separation of Sr2+ ions from aqueous solutions

AbstractBACKGROUNDDeveloping new materials for separating Sr2+ ions from aqueous solutions is significant. Metal–organic frameworks are regarded as excellent adsorption materials due to their high specific surface area and abundant adsorption sites. In this work, a novel UiO‐66‐(COOH)2‐based mixed matrix membrane (MMM) was prepared by combining UiO‐66‐(COOH)2 with polyethersulfone (PES) for separating Sr2+.RESULTSThe MMMs were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and water contact angle and water flux measurements. Various contents (0–2.5 wt%) of UiO‐66‐(COOH)2 were blended into PES membranes. The results showed that incorporating UiO‐66‐(COOH)2 significantly increased membrane porosity and water flux, and reduced contact angle. The membrane (M4) that contained 2.0 wt% UiO‐66‐(COOH)2 exhibited an excellent morphology and the highest Sr2+ uptake capacity (111.9 μg cm−2). Adsorption kinetics and isotherms showed that the nature of the adsorption of the membrane towards Sr2+ was chemisorption, homogeneous and monolayer. Compared with the adsorption capacity of UiO‐66‐(COOH)2 towards Sr2+ in adsorption packed column, these values of M4 decreased by about 75% during membrane filtration. The rejection performance of MMMs increased with increasing UiO‐66‐(COOH)2 content. Breakthrough curves of MMMs were not correlated with flow rate in the range of 10–180 mL h−1. The presence of Ca2+ and Mg2+ ions did not obviously affect the separation of Sr2+, but Pb2+ had a significant influence. Furthermore, after five adsorption–desorption experiments, the regeneration remained at about 95% of initial values.CONCLUSIONSThe MMMs showed good adsorption capacity for Sr2+ and exhibited favorable reusability and stability. © 2023 Society of Chemical Industry (SCI).

Lamellar Graphene Oxide-Based Composite Membranes for Efficient Separation of Heavy Metal Ions and Desalination of Water.

Sufficient efforts have been carried out to fabricate highly efficient graphene oxide (GO) lamellar membranes for heavy metal ion separation and desalination of water. However, selectivity for small ions remains a major problem. Herein, GO was modified by using onion extractive (OE) and a bioactive phenolic compound, i.e., quercetin. The as-prepared modified materials were fabricated into membranes and used for separation of heavy metal ions and water desalination. The GO/onion extract (GO/OE) composite membrane with a thickness of 350 nm shows an excellent rejection efficiency for several heavy metal ions such as Cr6+ (∼87.5%), As3+ (∼89.5%), Cd2+ (∼93.0%), and Pb2+ (∼99.5%) and a good water permeance of ∼460 ± 20 L m-2 h-1 bar-1. In addition, a GO/quercetin (GO/Q) composite membrane is also fabricated from quercetin for comparative studies. Quercetin is an active ingredient of onion extractives (2.1% w/w). The GO/Q composite membranes show good rejection up to ∼78.0, ∼80.5, ∼88.0, and 95.2% for Cr6+, As3+, Cd2+, and Pb2+, respectively, with a DI water permeance of ∼150 ± 10 L m-2 h-1 bar-1. Further, both membranes are used for water desalination by measuring rejection of small ions such as NaCl, Na2SO4, MgCl2, and MgSO4. The resulting membranes show >70% rejection for small ions. In addition, both membranes are used for filtration of Indus River water and the GO/Q membrane shows remarkably high separation efficiency and makes river water suitable for drinking purpose. Furthermore, the GO/QE composite membrane is highly stable up to ∼25 days under acidic, basic, and neutral environments as compared to GO/Q composite and pristine GO-based membranes.

Membrane process for the extraction of casein and whey proteins from skim milk

In deep processing of milk, microfiltration is used to isolate native micellar casein. The need to reduce its cost by increasing the efficiency of this process determines the relevance of research work in this area. The purpose of our research is to analyze the a priori information. This will determine the practical value and prospects of subsequent experimental determination of optimal parameters of the skim milk microfiltration process. The main steps of information search by keywords: selection of databases (Scopus, WOS, ScienceDirect, Googlescolar, etc.) and the most authoritative editions (J. of Dairy Science, J. Membrane Science, J. Membranes), where appearance of publications with practical application in the research subject is noted since 2007, bibliography analysis of scientific articles. Non-academic materials are excluded from the search because they lack full descriptions of research methods, which complicates the reproducibility of the presented results. Analysis of publications devoted to methods of increasing the efficiency of membrane separation of dairy raw materials showed that most of them are partial solutions to this problem. With the limitations - the properties of separation objects, membrane materials, types of apparatuses, etc. cause difficulties in the practical use of the results under changing physical and chemical characteristics of natural milk. But always the main operating parameters of the skim milk microfiltration process are the transmembrane pressure, the circulation rate of the separated system in the apparatus and its temperature. Optimal conditions of milk microfiltration for separation of native micellar casein should be sought experimentally on the basis of creating mathematical models of the process followed by their analysis by numerical methods, as the data given by the authors should be considered as indicative, depending on raw materials, membranes and separation technology.

Layered double hydroxide/boron nitride nanocomposite membranes for efficient separation and photodegradation of water-soluble dyes

New CuAl–CO3 LDH/BNOx nanocomposite membranes demonstrate excellent dye retention characteristics and superior flow rates, as well as efficient photocatalysis for applications in membrane anti-fouling.

Preparation of lignosulfonate-based polycatecholamine composite membrane for efficient separation

Preparation of lignosulfonate-based polycatecholamine composite membrane for efficient separation

Graphene oxide-fullerene nanocomposite laminates for efficient hydrogen purification.

Graphene oxide (GO) with its unique two-dimensional structure offers an emerging platform for designing advanced gas separation membranes that allow for highly selective transport of hydrogen molecules. Nevertheless, further tuning of the interlayer spacing of GO laminates and its effect on membrane separation efficiency remains to be explored. Here, positively charged fullerene C60 derivatives are electrostatically bonded to the surface of GO sheets in order to manipulate the interlayer spacing between GO nanolaminates. The as-prepared GO-C60 membranes have a high H2 permeance of 3370 GPU (gas permeance units) and an H2/CO2 selectivity of 59. The gas separation selectivity is almost twice that of flat GO membranes because of the role of fullerene.

Controllable hydrogen-bonded poly(dimethylsiloxane) (PDMS) membranes for ultrafast alcohol recovery.

The lack of efficient separation membranes limits the development of bio-alcohol purification via a pervaporation process. In this work, novel controllable hydrogen-bonded poly(dimethylsiloxane) (PDMS) membranes are prepared from self-synthesized supramolecular elastomers for alcohol recovery. Different from the conventional covalently-bonded PDMS membranes, the hydrogen-bonding content and therefore the crosslinking degree in the as-synthesized PDMS membranes can be exactly regulated, by the suitable molecular design of the supramolecular elastomers. The effects of hydrogen-bonding content on the flexibility of the polymer chains and the separation performance of the resultant supramolecular membranes are investigated in detail. In comparison with the state-of-the-art polymeric membranes, the novel controllable hydrogen-bonded supramolecular PDMS membrane exhibits ultrahigh fluxes for ethanol (4.1 kg m-2 h-1) and n-butanol (7.7 kg m-2 h-1) recovery from 5 wt% alcohol aqueous solutions at 80 °C, with comparable separation factors. The designed supramolecular elastomer is therefore believed to provide valuable insights into the design of next-generation separation membrane materials for molecular separations.

Removal of CO2 from Flue Gas by Membrane Separation Technology

As the main gas of the greenhouse effect, carbon dioxide (CO2) must be effectively captured and recycled, and the high separation efficiency and low cost of membrane separation make it stand out to remove CO2 among many gas separation methods. Considering the gas contained in the flue, a more efficient CO2 membrane separation method is proposed, that is, improving the separation coefficient by adopting a separation device coupled with multi-layer separation membrane and absorption membrane. If this method is used, the separation quality can be improved, the purity of CO2 will be close to 99%, and the cost for the developed separation technology can be greatly reduced. As a result, this research is devoted to describe a novel method of removing CO2 from the flue gas, which is by combining separation membrane and absorption membrane. The method can reduce the cost and external pollution, combined with various advantages, to improve the separation quality as far as possible.

Simultaneously enhanced separation and antifouling properties by synergistic effect of pore-formation and surface segregation through incorporating bowl-like amphiphiles

Herein, we propose a new strategy to improve the separation and antifouling properties of ethylene vinyl alcohol (EVAL) membranes by a dual pore formation mechanism modified with natural macrocyclic amphiphiles cyclodextrin (CDs). The amphiphilic bowl-like geometry of CDs, consisting of a hydrophobic cavity and hydrophilic rim, induces spontaneous surface segregation during the non-solvent induced phase separation to form a CD-enriched layer. Here, CDs play multiple roles, including pore-forming and antifouling enhancement agents, by modifying the morphological, physical, permeation, and separation properties of the membranes. The three-dimensional honeycomb sponge-like structure was determined by SEM analysis, and the elemental composition was examined by SEM-EDX analysis. The O element indicated a gradient decrease distribution from the top to the bottom layer of the cross-section, concomitant with the combination of pore-forming and surface segregation functions. The introduction of amphiphilic CDs increases the roughness, hydrophilicity, and porosity of the membranes. Furthermore, the CDs-modified EVAL (d-M) membranes have excellent mechanical properties, a high water flux (148 L/m2h) with superior rejection to BSA (98%), and can be used for dye separation (Congo Red: 99.7%, Coomassie brilliant blue: 97.5%, Trypan blue: 92.4%). Moreover, the modified EVAL with the best performance has excellent antifouling capacity and long-term stability. This work demonstrates the effect of the addition of CDs and octanol as dual pore formers on the fabrication of hydrophilic antifouling membranes for efficient separation.

Effect of Nanofillers on Properties and Pervaporation Performance of Nanocomposite Membranes: A Review.

In recent years, a well-known membrane-based process called pervaporation (PV), has attracted remarkable attention due to its advantages for selective separation of a wide variety of liquid mixtures. However, some restrictions of polymeric membranes have led to research studies on developing membranes for efficient separation in the PV process. Recent studies have focused on preparation of nanocomposite membranes as an effective method to improve both selectivity and permeability of polymeric membranes. The present study provides a review of PV nanocomposite membranes for various applications. In this review, recent developments in the field of nanocomposite membranes, including the fabrication methods, characterization, and PV performance, are summarized.

Tailor‐made FAU zeolite composite membrane for wastewater treatment

In this work, a novel multipurpose Faujasite (FAU) zeolite composite membrane was fabricated by in-situ hydrothermal method to separate different solute molecules such as vanillic acid, phenol, and brilliant green from the aqueous solution. The coal fly ash based ceramic substrate was synthesized and used as substrate for preparing the zeolite composite membrane. The X-ray diffraction (XRD) pattern confirmed the crystalline nature of membranes and the presence of Quartz and hematite in the composite membrane. The presence of Si-O and Al-O in zeolite coated composite membrane was confirmed by Fourier Transform infrared spectroscopy (FTIR) analysis. Scanning electron microscope (SEM) analysis showed the porous structure and 8.34 μm thickness of zeolite coating on membrane. The isoelectric point of composite membrane was observed at pH 2.07 through zeta potential analysis. Brunauer-Emmett-Teller (BET) surface area, average pore volume and pore diameter of zeolite composite membrane were estimated as 6.406 m2/gm, 0.0070 cm3/gm, and 4.371 nm, respectively. The hydraulic pore radius and porosity of composite membranes were 27.7 nm and 20.1%. The maximum separation efficiency of FAU zeolite composite membrane towards vanillic acid, phenol and brilliant green was estimated as 78.67%, 89.13%, and 94.28%, respectively, for 200 mg/L feed concentration at 276 kPa applied pressure. The results obtained in this study reveals that the multipurpose FAU zeolite composite membrane fabricated in this study can be effectively used for separation of various solutes molecules present in the wastewater.

Construction of Micropore Membranes for Efficient Separation of Chiral Pesticides Based on Layer-by-Layer Technology

Construction of Micropore Membranes for Efficient Separation of Chiral Pesticides Based on Layer-by-Layer Technology

Highly selective membrane for efficient separation of environmental determinands: Enhanced molecular imprinting in polydopamine-embedded porous sleeve

• Highly selective MIM was approached for efficient separation of determinand. • Dopamine-embedded porous sleeve was proposed for enhanced molecular imprinting. • Homogeneous imprinted sites spread throughout interpenetrating-bicontinuous porous. • Stable selectivity in regeneration cycles ensures the long-term availability. • Insight of polymerization mechanisms were obtained by DFT calculations. The molecularly imprinted membrane has shown irreplaceable superiority in advanced water treatment, biochemical purification, and in most cases, pretreatment of environmental determinands. However, effective and controllable construction of imprinted sites in membrane-based interpenetrating pores is as yet the significant bottleneck. Herein, we proposed a thermally induced strategy on the polydopamine-embedded molecularly imprinted membrane (DEMIM) for enhanced selective separation of Ciprofloxacin (CIP). The porous sleeve was constructed with polyvinylidene fluoride (PVDF), together with the integrated β-cyclodextrin (β-CD) for hydrophilicity and anti-fouling requirements. Based on the thermally induced operation, polydopamine (PDA) embedded in the membrane matrix acted as a secondary reaction platform, effectively improving the interpenetrating-bicontinuous porous morphology and enhancing the availability of imprinted sites in microchannels. The imprinting polymerization was carried out by the efficient thiol-ene Click reaction, which was investigated in depth by density functional theory (DFT) calculations. The impressive relative separation factor (2.33–4.59) and permselectivity (9.50–12.50) indicated the superior availability of DEMIM for the selective separation. The remarkable regeneration performance (fluctuation in 8.4%∼10.8%) demonstrated the feasibility of the porous membrane-based sleeve for regeneration of molecular imprinting. The approach and methodologies achieved in this work will potentially promote the development of novel molecularly imprinted membranes for advanced applications.

Amino-functionalized graphene oxide membranes for efficient separation of Sr2+ ions

Graphene oxide (GO) membranes were integrated with diverse nitrogen functional groups by subjecting to ammonia (NH3) vapours and evaluated for resultant changes in their chemical functioning and strontium (Sr) adsorption performance. Exposure to NH3 vapours amends the functional groups of GO, introduces amine, amide, ammonium functionalities and generates abundant sites prone to react with Sr2+ ions. The extent of GO restructuring and repercussions on Sr adsorption behaviour were examined using different GO precursors, NH3 treatment methods, membranes with varying GO mass and other nitrogen reagents namely, tri-isooctyl amine, pyridine, N,N-dimethyl acetamide. Nitrogen group functionalization enhances the Sr adsorption capacity of GO membranes nearly by two times, irrespective of the NH3 exposure duration and nature of precursor GO membranes. These NH3 subjected GO membranes displayed optimum Sr adsorption performance of ~475 mg/g, reusable at least for nine filtration cycles and importantly, capable of discharging 35–60 % of adsorbed Sr. The N-group supported Sr separation demonstrated in the present work is an energy efficient solid state membrane based procedure, which also lays a road map for development of amine, amide, ammonium functionalized GO layers and provides flexible platform for separation of all those toxic elements displaying affinity to complex with N-groups.

Chlorine-resistance, reswelling after drying and molecule/ions separation properties of carboxyl multi-walled carbon nanotubes/calcium alginate composite hydrogel membrane

In practice sodium hypochlorite (NaClO) is often used to clean biological contamination from membrane surfaces. It is worth thinking about how to balance the mechanical strength and chlorine resistance of calcium alginate (CaAlg) hydrogel membrane during cleaning. In this study, carboxyl multi-walled carbon nanotubes/calcium alginate (CMWCNT/CaAlg) composite hydrogel membrane with chlorine-resistance ability was prepared. Performance of CMWCNT/CaAlg membrane in various aspects, including morphology and chlorine resistance, were characterized. In addition, vacuum drying and reswelling method enhanced the mechanical strength of the membrane. Moreover, the interactions mechanism between CMWCNT and NaAlg were investigated by isothermal titration calorimetry (ITC) and molecular dynamics (MD) simulation. Subsequently, the factors influencing membrane separation efficiency towards dye molecule/salt ions were analyzed. It turns out that the composite membrane could achieve nearly 100% high efficiency in the rejection of dye molecules with large molecular weight (Mw > 700 Da), while the rejection of salt was below 8%. Our findings demonstrated CMWCNT/CaAlg composite membrane not only has excellent anti-fouling and chlorine resistance, but also has a very broad application prospect in the separation of dye and salt.

A high-toughness anti-pollution polyethersulfone membrane for efficient separation of oil-in-water emulsions

Stable emulsion is the most difficult of all forms of oily wastewater to treat. Membrane separation technology has more advantages in solving related problems because of its high selectivity. The existence of hydroxyapatite containing more hydrophilic groups makes the membrane materials with high hydrophilicity obtained. In this work, hydroxyapatite was modified by strong adsorption of dopamine to prepare modified nanoparticles with good compatibility, which were more easily dispersed in the solution. Then the modified hydroxyapatite was introduced into the casting solution to avoid agglomeration and uneven distribution. The phase separation process was then completed by reverse thermal separation (RTIPS). After water flux and oil-water separation tests, high permeability (1515.46 L/m2 h, 14 times higher than the raw membranes) and high selectivity (99.80 % and 99.92 %) were obtained. At the same time, the membrane materials with the optimal conditions also achieved better performance in the cycle test. In addition, the bond between materials was improved due to the presence of hydroxyapatite, which ultimately makes the membrane materials more ductile and reduces the possibility of breakage.

Functionalized GO Membranes for Efficient Separation of Acid Gases from Natural Gas: A Computational Mechanistic Understanding.

Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion behaviors of several unary gases (N2, CH4, CO2, H2S, and SO2) are explored in the 1,4-phenylenediamine-2-sulfonate (PDASA)-doped GO channels. Molecular insights show that the multilayer adsorption of acid gases evaluates well by the Redlich-Peterson model. A tiny amount of PDASA promotes the solubility coefficient of CO2 and H2S, respectively, up to 4.5 and 5.3 mmol·g-1·kPa-1, nearly 2.5 times higher than those of a pure GO membrane, which is due to the improved binding affinity, great isosteric heat, and hydrogen bonds, while N2 and CH4 only show single-layer adsorption with solubility coefficients lower than 0.002 mmol·g-1·kPa-1, and their weak adsorption is insusceptible to PDASA. Although acid gas diffusivity in GO channels is inhibited below 20 × 10-6 cm2·s-1 by PDASA, the solubility coefficient of acid gases is certainly high enough to ensure their separation efficiency. As a result, the permeabilities (P) of acid gases and their selectivities (α) over CH4 are simultaneously improved (PCO2 = 7265.5 Barrer, αCO2/CH4 = 95.7; P(H2S+CO2) = 42075.1 Barrer, αH2S/CH4 = 243.8), which outperforms most of the ever-reported membranes. This theoretical study gives a mechanistic understanding of acid gas separation and provides a unique design strategy to develop high-performance GO membranes toward efficient natural gas processing.

A highly promoted nanofiltration membrane by incorporating of aminated Zr-based MOF for efficient salts and dyes removal with excellent antifouling properties

Nowadays, effective removal of dye and salt from aqueous solutions has received widespread attention in the field of wastewater treatment. In this study, Zr-based nanofillers were used to create high-flux polyethersulfone nanofiltration membranes with impressive anti-fouling performance. Three different levels of UiO-66-NH2 concentration (0.01, 0.1, 1 wt%) were used in membrane body. Solvothermal method was used to synthesize the nanoparticles, and their physical and chemical characteristics were examined through FTIR, XRD, EDAX, and FESEM analyses. Membranes properties also were investigated by SEM, porosity, water content, roughness, water contact angle, flux, separation efficiency, and fouling studies. The surface roughness of the blended membrane with 0.01 wt% nanoparticles (M2) was almost halved compared to the pristine membrane (M1). The water contact angle was also reduced from 70.98° for M1 to 39.09° for M2. The water flux of M2 with 0.01 wt% nanoparticles was 2.31 times higher than that of the pristine membrane. The MB, RhB, and RB21 dyes, as well as Na2SO4, MgSO4, MgCl2, and NaCl solutions, were used to investigate the membrane separation efficiency. All modified membranes showed significant dye retention for both cationic and anionic dyes, and sodium sulfate rejection reached up to> 93.2%. The M2 exhibited the best performance for removal of MB (95.8%), RhB (94.2%), and RB21 (83.6%). The FRR was 46.51% for bare membrane, whereas it was increased significantly for the modified samples up to> 86%. The total resistance of the optimal membrane was remarkably reduced compared to the PES pristine membrane.