Membrane Properties Research Articles

Fouling mitigation of microcrystalline cellulose-blended poly(vinylidene fluoride) membranes in protein separation

ABSTRACT Modifications of polymeric membranes are necessary to improve the membrane characteristics. The composite membrane of Poly(vinylidene fluoride)_Microcrystalline cellulose (PVDF_MCC) was prepared using dimethylacetamide/lithium chloride (DMAc/LiCl) as co-solvent to dissolve the MCC in the casting solution. The prepared membrane was characterized by using the FTIR, SEM, contact angle, and the water permeates flux. The improvement of hydrophilicity and pore structure with the incorporation of MCC was observed which led to the increment of the water and permeate flux. Indication from the rheological study suggested that the casting solutions with MCC presented the influence on the composite membrane’s pore structure as a significant viscosity increment was observed. This can be examined from the larger pore and elongated finger-like structure of the membrane morphology compared to the pristine membrane. The rejection rate of the protein increased from 85% to 97% after the incorporation of MCC in the PVDF membrane. The utilization of a low-cost and environmentally friendly additive that MCC has to offer helps to improve the antifouling properties of PVDF membranes for the efficient removal of BSA in water.

Does deacclimation reverse the changes in structural/physicochemical properties of the chloroplast membranes that are induced by cold acclimation in oilseed rape?

Winter crops acquire frost tolerance during the process of cold acclimation when plants are exposed to low but non-freezing temperatures that is connected to specific metabolic adjustments. Warm breaks during/after cold acclimation disturb the natural process of acclimation, thereby decreasing frost tolerance and can even result in a resumption of growth. This phenomenon is called deacclimation. In the last few years, studies that are devoted to deacclimation have become more important (due to climate changes) and necessary to be able to understand the mechanisms that occur during this phenomenon. In the acclimation of plants to low temperatures, the importance of plant membranes is indisputable; that is why the main aim of our studies was to answer the question of whether (and to what extent) deacclimation alters the physicochemical properties of the plant membranes. The studies were focused on chloroplast membranes from non-acclimated, cold-acclimated and deacclimated cultivars of winter oilseed rape. The analysis of the membranes (formed from chloroplast lipid fractions) using the Langmuir technique revealed that cold acclimation increased membrane fluidity (expressed as the Alim values), while deacclimation generally decreased the values that were induced by cold. Moreover, because the chloroplast membranes were penetrated by lipophilic molecules such as carotenoids or tocopherols, the relationships between the structure of the lipids and the content of these antioxidants in the chloroplast membranes during the process of the cold acclimation and deacclimation of oilseed rape are discussed.

Effect of Surfactants on the Permeation Rate and Selectivity of Polyamide Composite Membranes for Organic Solvent Nanofiltration

Solvent-resistant membranes are pivotal in industrial separations. This study aims to develop thin-film composite polyamide (TFC-PA) membranes with enhanced organic solvent nanofiltration (OSN) capabilities. Polyallylamine hydrochloride (PAAH) was used as the aqueous amine and isophthaloyl chloride (IPC) as the crosslinker to form the polyamide active layer by interfacial polymerization (IP) on a polyacrylonitrile (PAN) support. The impact of using anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) to act as phase transfer agents during IP was investigated to understand their potential for facilitating the transfer of PAAH to the organic phase for reaction with IPC. The SDS and CTAB were separately dissolved into the PAAH solutions before IP to evaluate their effects on membrane properties. Extensive characterization including SEM, EDX, AFM, Water Contact Angle, ATR-FTIR, and Solid (CP-MAS) 13C-NMR revealed various chemical and structural features of the membrane. The membrane M2 (PAAH-IPC) (exhibited >98% rejection for various anionic and cationic dyes. The inclusion of SDS during interfacial polymerization led to a substantial 3-fold increase in methanol permeate flux from 31Lm-2 h-1 to 119Lm-2 h-1, at a pressure of 15bar. Conversely, the addition of CTAB resulted in membranes with higher flux but insufficient dye rejection. Moreover, after a three-week period of static aging no significant changes were detected in either permeability or solute rejection, substantiating their stability.

Mixed-matrix membrane designed with water channels and sieving effect for effective removal of heavy metals

The challenge of eliminating heavy metal ions from water has been addressed using Polysulfone (PSf) membranes, which have demonstrated significant potential in treating contaminated solutions. This research aimed to improve the permeability and separation performance of PSf membranes by incorporating Al2SiO6 into their structure. The introduction of Al2SiO6 into the membrane matrix was achieved through the nonsolvent-induced phase separation (NIPS). The resulting mixed-matrix membrane (MMM) exhibited improved efficiency in water filtration. The inclusion of Al2SiO6 led to desirable changes in membrane properties such as hydrophilicity, contact angle and porosity, thereby enhancing the performance of heavy metal ion removal capability. Under a pressure of 2 bar, the mixed matrix membranes achieved rejections exceeding 95 % for lead and 70 % for arsenic. Furthermore, the occurrence of Al2SiO6 enhanced the anti-fouling assets of the PSf membrane by increasing its hydrophilic nature and facilitating the development of a hydration layer, which tends to prevent the interactions between the membrane surface and foulant. These properties make these membranes suitable candidates for separating toxic ions from water.

Improving membrane distillation performance by Fe(II) activated sodium percarbonate oxidation during the treatment of shale gas produced water

Membrane distillation (MD) offers promise for recycling shale gas produced water (SGPW), while membrane fouling is still a major obstacle in standalone MD. Herein, sodium percarbonate (SPC) oxidation was proposed as MD pretreatment, and the performance of the single MD, SPC-MD hybrid process and Fe(II)/SPC-MD hybrid process for SGPW treatment were systematically evaluated. Results showed that compared to raw SGPW, the application of SPC and Fe(II)/SPC led to the decrease of the fluorescent organics by 28.54% and 54.52%, respectively. The hydrophobic fraction decreased from 52.75% in raw SGPW to 37.70% and 27.20% for SPC and Fe(II)/SPC, respectively, and the MD normalized flux increased from 0.19 in treating raw SGPW to 0.65 and 0.81, respectively. The superiority of SPC oxidation in reducing the deposited membrane foulants and restoring membrane properties was further confirmed through scanning electron microscopy observation, attenuated total reflection fourier transform infrared, water contact angle and surface tension analyses of fouled membranes. Correlation analysis revealed that hydrophobic/hydrophilic matters and fluorescent organics in SGPW took a crucial role in MD fouling. The mechanism of MD fouling mitigation by Fe(II)/SPC oxidation was attributed to the decrease in concentrations and hydrophobicity of organic by synergistic oxidation, coagulation and adsorption.

Effect of Viscosity and Air Gap within the Spinneret on the Morphology and Mechanical Properties of Hollow-Fiber Polymer Membranes for Separation Performance

Hollow-fiber membranes for nanofiltration were prepared from the blending of Poly (ethylene glycol) (PEG) with Poly (vinyl chloride) (PVC) with different PEG molecular weights (400 and 4000 g/mol) and PVC via a dry/wet spinning process. In the spinning process, the effects of air gap, wind-up speed, dope extrusion rate, and bore extrusion rate were examined. In addition, the different lengths of the center tube, which acted as the inner-side fiber diameter during the preparation of hollow-fiber membranes, were studied. This research was investigated in order to observe the morphological, dielectric, and dynamic mechanical thermal properties to identify a suitable preparation of a hollow-fiber membrane for feasible applications. The morphology of the PVC-580 blended PEG-400 5 weight percent hollow-fiber membrane was seen to have a dense skin on both the inner and outer fiber surface, along with a suitable dope viscosity. Moreover, it offered finger-like substructures that could provide a high applicable feed-stream permeability and selectivity. Finger-like substructures were present on the near inner fiber surface at the controlled center-tube length of 0.3 cm, more so than at the center tube of 1 cm. This was because the solvent and non-solvent in the lumen tube exchanged more quickly than they did in the coagulant bath. The effect of the wind-up speed during the spinning process was significantly influenced by an affordable hollow fiber that can be indicated by the drawing ratio . It was found that the drawing ratio of 3.3 showed a thickness thinner than 2.6 and 2.0, respectively. In summary, a controlled wind-up speed, an acceptable dope viscosity, and—most importantly—an agglomerated time resulted in membrane preparation.

A Comprehensive Examination of Low GO-Silica Loading in Pebax1657/PEI Thin Film Nano-composite Membranes for Gas Dehydration

The aim of this study was to assess the effectiveness of blending Pebax1657 polymer with SiO2-GO nanoparticles in the production of TFN membranes for N2 gas dehydration. By utilizing dip coating, nanoparticles were incorporated at varying concentrations. The resulting nanocomposites were subjected to thorough analysis to investigate their chemical structure, physical morphology, surface topology, and thermal stability. This examination encompassed the application of FTIR, SEM, CA, AFM, and TGA techniques. The results demonstrated that the samples displayed good thermal stability and a highly hydrophilic surface. The investigation concluded that the dehydration properties of TFN membranes are influenced by a variety of factors, such as morphology, plasticization, and hydrophilic attributes. The effectiveness of the system is contingent upon the contribution made by each individual nanoparticle. The impact of SiO2 nanoparticles in their pure form is clearly evident in the 0.5 wt% loaded composite membrane membrane. When 0.5% of SiO2 nanoparticles are introduced into the composite membrane, the morphology closely resembles the ideal state due to the non-porous nature of SiO2 and the low concentration of nanoparticles, hence a selectivity of ~560 is experienced. Fortunately this selectivity is beyond the need of the industries. Consequently, there was a reduction in water vapor and nitrogen permeability, resulting in a heightened selectivity ratio. These discoveries hold considerable importance in industrial settings, as they offer a more comprehensive understanding of the topic.

Optical Characteristics of a New Molecular Complex: “Nafion–Colloidal CdSe/CdS/ZnS Nanocrystals”

Here, the optical properties of the Nafion polymer membrane containing colloidal CdSe/CdS/ZnS nanocrystals embedded by diffusion have been studied. The CdSe/CdS/ZnS nanocrystals have a core/shell/shell appearance. All experiments were carried out at room temperature (22 ± 2) °C. A toluene solution was used to provide mobility to the active sulfone groups of the Nafion membrane and to embed the nanocrystals inside the membrane. The diffusion process of colloidal CdSe/CdS/ZnS nanocrystals into Nafion proton exchange membrane has resulted in a new molecular complex “Nafion–colloidal CdSe/CdS/ZnS nanocrystals”. The kinetics of the nanocrystals embedding into the membrane matrix was investigated using luminescence analysis and absorption spectroscopy techniques. The embedding rate of CdSe/CdS/ZnS nanocrystals into the Nafion polymer membrane was approximately 4·10−3 min−1. The presence of new luminescence centers in the membrane was proved independently by laser emission spectroscopy. The luminescence spectrum of the resulting molecular complex contains intensity maxima at wavelengths of 538, 588, 643 and 700 nm. The additional luminescence maximum observed at the 643 nm wavelength was not recorded in the original membrane, solvent or in the spectrum of the semiconductor nanoparticles. The luminescence maximum of the colloidal CdSe/CdS/ZnS nanocrystals was registered at a wavelength of 634 nm. The intensity of the luminescence spectrum of the membrane with embedded nanocrystals was found to be higher than the intensity of the secondary emission peak of the initial nanocrystals, which is important for the practical use of the “Nafion–colloidal nanocrystals” complex in optical systems. The lines contained in the luminescence spectrum of the membrane, which has been in solution with colloidal nanocrystals for a long time, registered upon its drying, show the kinetics of the formation of the molecular complex “Nafion membrane–nanocrystals”. Colloidal nanocrystals located in the Nafion matrix represent an analog of a luminescent transducer.

Asymmetric PDMS/PVDF Pervaporation Membrane for Separation of Ethanol/Water System

AbstractPreparing asymmetric pervaporation membranes is a kind of promising method to enhance pervaporation membrane flux. Hydrophobic PVDF polymer can be used to prepare asymmetric pervaporation membranes, but its separation factor is relatively low. In this work, to improve the performance of PVDF membrane pervaporation, PDMS polymer was added to the PVDF membrane, and asymmetric PDMS/PVDF permeable membranes were prepared by the non‐solvent induced phase separation (NIPS) method. The effects of mass ratios of PDMS to PVDF on the membrane structures and the membrane properties were characterized by SEM, XRD, FTIR, TGA, water contact angle and mechanical strength. The results showed that the ratios of the PDMS: PVDF affect its phase‐separation behavior. As the addition of PDMS increased, the finger‐like pores on the membrane section gradually became longer, the upper surface changed from less porous to porous structure, and the lower surface structure changed from interconnected flocculent structure to porous, and the best structure of the blend membrane was achieved when the PDMS: PVDF mass ratio was 1 : 5. Therefore, the membrane had the best separation performance in separating 15 wt. % ethanol aqueous solution with a permeate total flux of 273.65 g/(m2 h) and a separation factor of 9.09 when the mass ratio of PDMS: PVDF was 1 : 5.

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

A new paradigm for energy is underway demanding decarbonized energy systems. Some of them rely on emerging electrochemical devices, crucial in hydrogen technologies, including fuel cells, CO2 and water electrolysers, whose applications and performances depend on key components such as their separators/ion-exchange membranes. The most studied and already commercialized Nafion membrane shows great chemical stability, but its water content limits its high proton conduction to a limited range of operating temperatures. Here, we report the synthesis of a new series of triazinephosphonate derivatives and their use as dopants in the preparation of new modified Nafion membranes. The triazinephosphonate derivatives were prepared by substitution of chlorine atoms in cyanuric chloride. Diverse conditions were used to obtain the trisubstituted (4-hydroxyphenyl)triazinephosphonate derivatives and the (4-aminophenyl)triazinephosphonate derivatives, but with these amino counterparts, only the disubstituted compounds were obtained. The new modified Nafion membranes were prepared by casting incorporation of the synthesized 1,3,5-triazinephosphonate (TPs) derivatives. The evaluation of the proton conduction properties of the new membranes and relative humidity (RH) conditions and at 60 °C, showed that they present higher proton conductivities than the prepared Nafion membrane and similar or better proton conductivities than commercial Nafion N115, in the same experimental conditions. The Nafion-doped membrane with compound TP2 with a 1.0 wt % loading showed the highest proton conductivity with 84 mS·cm−1.

Bio‐degradable fibrous membranes for oil/water separation by melt electrospinning

AbstractVarious electrospun fibrous membranes have been addressed for oil/water separation owing to their advantages of high specific surface ratio, lightweight, and high porosity. However, they are commonly obtained by solution electrospinning of non‐green raw materials, which could cause serious environmental issues. To realize effective oil/water separation, the optimal processing parameters for melt electrospun polylactic acid (PLA) were determined through orthogonal experiments. Subsequently, PLA fibrous films with cellulose nanofiber (CNF) or sodium chloride (NaCl) for oil/water separation were produced via melt electrospinning. The effects of incorporating CNF or NaCl on the physiochemical properties of melt electrospun PLA fibrous membranes were investigated. In contrast to the pure PLA membranes, the obtained PLA/CNF and PLA/NaCl composite membranes exhibit a finer average fiber diameter and an increased porosity. Also, the oil absorption characteristics and oil/water separation abilities of these fibrous membranes were experimentally studied. In contrast to the 84.55% oil/water separation efficiency of melt‐electrospun PLA fibrous membranes, PLA/CNF exhibits the highest oil/water separation efficiency at 93.54%, whereas PLA/NaCl achieves a maximum efficiency of 90.29%. These findings show the applicability of the eco‐friendly PLA‐based melt electrospun fibrous membrane in the treatment of oily wastewater.

Bacterial outer membrane vesicle nanorobot

Autonomous nanorobots represent an advanced tool for precision therapy to improve therapeutic efficacy. However, current nanorobotic designs primarily rely on inorganic materials with compromised biocompatibility and limited biological functions. Here, we introduce enzyme-powered bacterial outer membrane vesicle (OMV) nanorobots. The immobilized urease on the OMV membrane catalyzes the decomposition of bioavailable urea, generating effective propulsion for nanorobots. This OMV nanorobot preserves the unique features of OMVs, including intrinsic biocompatibility, immunogenicity, versatile surface bioengineering for desired biofunctionalities, capability of cargo loading and protection. We present OMV-based nanorobots designed for effective tumor therapy by leveraging the membrane properties of OMVs. These involve surface bioengineering of robotic body with cell-penetrating peptide for tumor targeting and penetration, which is further enhanced by active propulsion of nanorobots. Additionally, OMV nanorobots can effectively safeguard the loaded gene silencing tool, small interfering RNA (siRNA), from enzymatic degradation. Through systematic in vitro and in vivo studies using a rodent model, we demonstrate that these OMV nanorobots substantially enhanced siRNA delivery and immune stimulation, resulting in the utmost effectiveness in tumor suppression when juxtaposed with static groups, particularly evident in the orthotopic bladder tumor model. This OMV nanorobot opens an inspiring avenue to design advanced medical robots with expanded versatility and adaptability, broadening their operation scope in practical biomedical domains.

Sex differences in membrane properties and cellular excitability of dopamine D1 receptor-expressing neurons within the shell of the nucleus accumbens of pre- and mid-adolescent mice

BackgroundThe transition from childhood to adulthood, or adolescence, a developmental stage, is characterized by psychosocial and biological changes. The nucleus accumbens (NAc), a striatal brain region composed of the core (NAcC) and shell (NAcSh), has been linked to risk-taking behavior and implicated in reward seeking and evaluation. Most neurons in the NAc are medium spiny neurons (MSNs) that express dopamine D1 receptors (D1R +) and/or dopamine D2 receptors (D2R +). Changes in dopaminergic and glutamatergic systems occur during adolescence and converge in the NAc. While there are previous investigations into sex differences in membrane excitability and synaptic glutamate transmission in both subdivisions of the NAc, to our knowledge, none have specified NAcSh D1R + MSNs from mice during pre- and mid-adolescence.MethodsSagittal brain slices containing the NAc were prepared from B6.Cg-Tg(Drd1a-tdTomato)6Calak/J mice of both sexes from postnatal days 21–25 and 35–47, representing pre- and mid-adolescence, respectively. Whole-cell electrophysiology recordings were collected from NAcSh D1R + MSNs in the form of membrane-voltage responses to current injections, to assess membrane properties and action potential waveform characteristics, and spontaneous excitatory postsynaptic currents (sEPSCs) to assess glutamatergic synaptic activity.ResultsRelative to pre-adolescent males, pre-adolescent female NAcSh D1R + MSNs exhibited a less hyperpolarized resting membrane potential, increased input resistance, and smaller action potential afterhyperpolarization amplitudes. During mid-adolescence, decreased input resistance and a shorter action potential duration in females were the only sex differences observed.ConclusionsTaken together, our results indicate that NAcSh D1R + MSNs in mice exhibit sex differences in membrane properties and AP waveform during pre-adolescence that are overall indicative of increased cellular excitability in females and are suggestive of possible sex differences in glycine receptors, inwardly-rectifying potassium channels, and large conductance voltage-gated potassium channels. These differences do not appear to persist into mid-adolescence, when sex was observed to affect input resistance oppositely to that of pre-adolescence and AP waveform in a manner suggestive of differences in voltage-gated potassium channels.

Investigations of nanomaterial-based membranes for efficient removal of contaminants from wastewater via membrane distillation: a critical review

The requirement for wastewater treatment is paramount in ensuring environmental sustainability and safeguarding public health. As industrialization and urbanization accelerate, the volume of wastewater generated continues to increase, containing a diverse range of pollutants and contaminants. Untreated wastewater poses serious threats to ecosystems, water bodies, and human communities, leading to pollution, waterborne diseases, and ecological imbalances. Effective wastewater treatment becomes essential to mitigate these adverse effects by removing or reducing pollutants before discharge into natural water sources. This process helps to preserve water quality, protect aquatic life, and maintain the overall health of ecosystems. Membrane distillation (MD) has emerged as a promising technology for wastewater treatment, offering an innovative approach to address the challenges associated with conventional treatment methods. In MD, a hydrophobic membrane serves as a selective barrier, allowing water vapor to pass through while preventing the passage of contaminants. This paper offers an extensive overview of the latest advancements in nanotechnology and membrane distillation applied in wastewater treatment. We will delve into different types of nanomaterials that have been used to enhance the properties of MD membranes, such as nanocomposites, nanoparticles, and nanofiber membranes. We also explore the mechanisms by which these nanomaterials improve the separation efficiency, anti-fouling properties, and durability of MD membranes. Additionally, we highlight the potential of hybrid membranes that combine different types of nanomaterials for further improving the performance of MD in wastewater treatment. We provide examples of recent studies that have investigated the use of hybrid membranes, including carbon nanotube-graphene oxide hybrid membranes, nanocomposite nanofiber membranes, and silver nanoparticle-embedded membranes. We also identify some areas for future research and development, such as the scale-up and commercialization of nanotechnology-based MD systems. In summary, this review paper highlights the potential of nanotechnology to enhance the performance of MD in wastewater treatment, leading to improved water quality and a cleaner environment.

Effect of Plasticizer Type on Polymer Inclusion Membranes Properties and Performance for Zinc Separation

Effect of Plasticizer Type on Polymer Inclusion Membranes Properties and Performance for Zinc Separation

Experimental Study of Needle Insertion into Gerbil Tympanic Membrane.

The perforation characteristics and fracture-related mechanical properties of the tympanic membrane (TM) greatly affect surgical procedures like myringotomy and tympanostomy performed on the middle ear. We analyzed the most important features of the gerbil TM perforation using an experimental approach that was based on force measurement during a 2-cycle needle insertion/extraction process. Fracture energy, friction energy, strain energy, and hysteresis loss were taken into consideration for the analysis of the different stages of needle insertion and extraction. The results demonstrated that (1) although the TM shows viscoelastic behavior, the contribution of hysteresis loss was negligible compared to other irreversible dissipated energy components (i.e., fracture energy and friction energy). (2) The TM puncture force did not substantially change during the first hours after animal death, but interestingly, it increased after 1week due to the drying effects of soft tissue. (3) The needle geometry affected the crack length and the most important features of the force-displacement plot for the needle insertion process (puncture force, puncture displacement, and jump-in force) increased with increasing needle diameter, whereas the insertion velocity only changed the puncture and jump-in forces (both increased with increasing insertion velocity) and did not have a noticeable effect on the puncture displacement. (4) The fracture toughness of the gerbil TM was almost independent of the needle geometry and was found to be around 0.33 0.10kJ/m2.

A Critical Review of Short Antimicrobial Peptides from Scorpion Venoms, Their Physicochemical Attributes, and Potential for the Development of New Drugs.

Scorpion venoms have proven to be excellent sources of antimicrobial agents. However, although many of them have been functionally characterized, they remain underutilized as pharmacological agents, despite their evident therapeutic potential. In this review, we discuss the physicochemical properties of short scorpion venom antimicrobial peptides (ssAMPs). Being generally short (13-25 aa) and amidated, their proven antimicrobial activity is generally explained by parameters such as their net charge, the hydrophobic moment, or the degree of helicity. However, for a complete understanding of their biological activities, also considering the properties of the target membranes is of great relevance. Here, with an extensive analysis of the physicochemical, structural, and thermodynamic parameters associated with these biomolecules, we propose a theoretical framework for the rational design of new antimicrobial drugs. Through a comparison of these physicochemical properties with the bioactivity of ssAMPs in pathogenic bacteria such as Staphylococcus aureus or Acinetobacter baumannii, it is evident that in addition to the net charge, the hydrophobic moment, electrostatic energy, or intrinsic flexibility are determining parameters to understand their performance. Although the correlation between these parameters is very complex, the consensus of our analysis suggests that there is a delicate balance between them and that modifying one affects the rest. Understanding the contribution of lipid composition to their bioactivities is also underestimated, which suggests that for each peptide, there is a physiological context to consider for the rational design of new drugs.

Ion-Selective Metathesis Design of Flow-Electrode Capacitive Deionization for Energy-Saving and Anti-Scaling Softening of Brackish Water.

While flow-electrode capacitive deionization (FCDI) is recognized as an attractive desalination technology, its practical implementation has been hindered by the ease of scaling and energy-intensive nature of the single-cell FCDI system, particularly when treating brackish water with elevated levels of naturally coexisting SO42- and Ca2+. To overcome these obstacles, we propose and design an innovative ion-selective metathesis FCDI (ISM-FCDI) system, consisting of a two-stage tailored cell design. Results indicate that the specific energy consumption per unit volume of water for the ISM-FCDI is lower (by up to ∼50%) than that of a conventional single-stage FCDI due to the parallel circuit structure of the ISM-FCDI. Additionally, the ISM-FCDI benefits from a conspicuous disparity in the selective removal of ions at each stage. The separate storage of Ca2+ and SO42- by the metathesis process in the ISM-FCDI (46.25% Ca2+, 14.25% SO42- in electrode 1 and 4.75% Ca2+, 35.25% SO42- in electrode 2) can effectively prevent scaling. Furthermore, configuration-performance analysis on the ion-selective migration suggests that the properties of the ion exchange membrane, rather than the carbon species, govern the selectivity of ion removal. This work introduces system-level enhancements aimed at enhancing energy conservation and scaling prevention, providing critical optimization of the FCDI for brackish water softening.

Ion-Selective Metathesis Design of Flow-Electrode Capacitive Deionization for Energy-Saving and Anti-Scaling Softening of Brackish Water.

While flow-electrode capacitive deionization (FCDI) is recognized as an attractive desalination technology, its practical implementation has been hindered by the ease of scaling and energy-intensive nature of the single-cell FCDI system, particularly when treating brackish water with elevated levels of naturally coexisting SO42- and Ca2+. To overcome these obstacles, we propose and design an innovative ion-selective metathesis FCDI (ISM-FCDI) system, consisting of a two-stage tailored cell design. Results indicate that the specific energy consumption per unit volume of water for the ISM-FCDI is lower (by up to ∼50%) than that of a conventional single-stage FCDI due to the parallel circuit structure of the ISM-FCDI. Additionally, the ISM-FCDI benefits from a conspicuous disparity in the selective removal of ions at each stage. The separate storage of Ca2+ and SO42- by the metathesis process in the ISM-FCDI (46.25% Ca2+, 14.25% SO42- in electrode 1 and 4.75% Ca2+, 35.25% SO42- in electrode 2) can effectively prevent scaling. Furthermore, configuration-performance analysis on the ion-selective migration suggests that the properties of the ion exchange membrane, rather than the carbon species, govern the selectivity of ion removal. This work introduces system-level enhancements aimed at enhancing energy conservation and scaling prevention, providing critical optimization of the FCDI for brackish water softening.

Structure and thermodynamics of supported lipid membranes on hydrophobic van der Waals surfaces.

Understanding the adsorption and physical characteristics of supported lipid membranes is crucial for their effective use as model cell membranes. Their morphological and thermodynamic properties at the nanoscale have traditionally been studied on hydrophilic substrates, such as mica and silicon oxide, which have proved to facilitate the reconstruction of biomembranes. However, in more recent years, with the advent of the van der Waals crystals technology, two-dimensional crystals such as graphene have been proposed as potential substrates in biosensing devices. Membranes formed on these crystals are expected to behave differently owing to their intrinsic hydrophobicity, however thus far knowledge of their morphological and thermodynamic properties is lacking. Here we present a comprehensive nanoscale analysis of the adsorption of phosphatidylcholine lipid monolayers on two of the most commonly used van der Waals crystals, graphite and hexagonal boron nitride. Both morphological and thermodynamic properties of the lipid membranes were investigated using temperature-controlled atomic force microscopy. Our experiments show that the lipids adsorb onto the crystals, forming monolayers with their orientation dependent upon their concentration. Furthermore, we found that the hydrophobicity of van der Waals crystals determines a strong increase in the transition temperature of the lipid monolayer compared to that observed on hydrophilic substrates. These results are important for understanding the properties of lipid membranes at solid surfaces and extending their use to novel drug delivery and biosensing devices made of van der Waals crystals.