Improve Membrane Performance Research Articles

Performance of PVDF-La dope TiO2 Membrane Photocatalytic Under Visible Light Irradiation for Produced Water Treatment

Membrane technology has been widely applied in water management systems for production, but is still hindered by fouling phenomena and low selectivity. Improving membrane performance through modification, such as the addition of photocatalytic materials, has been explored. In this research, La@TiO2 composite was incorporated into PVDF membranes for the treatment of produced water. Lanthanum doping on TiO2 effectively inhibits carrier recombination and enhances photocatalytic activity. According to the research results, adding the La@TiO2 composite to the membrane matrix increased the porosity value and membrane pore size. The PVDF-La@TiO2 1.5%wt membrane exhibited the highest flux values, specifically 20.59 L.m-2.h-1 and 40 L.m-2.h-1 in dark conditions and visible light irradiation. The rejection rates for COD, TDS, and ammonia were 69.89%, 57.77%, and 69.65%. The photocatalytic degradation effect of PVDF-La@TiO2 is proven by a significant difference in the filtration results under vis-light irradiation. The kinetics of COD removal are better described by a pseudo-first-order model. The degradation of PVDF-La@TiO2 1.5% pollutant demonstrated significant results, confirming its photocatalytic activity under irradiation. Overall, the membrane exhibited good performance and proved to be reusable after 6 hours of photofiltration. This research holds promise for enhancing the use of membrane photocatalytics in the treatment of produced water.

Intricacies of CO2 removal from mixed gases and biogas using polysulfone/ZIF-8 mixed matrix membranes - part 1: experimental.

In this work, we explore the potential of polysulfone/ZIF-8 mixed matrix membranes (MMMs) for the enrichment of biogas to biomethane. To this end, we present data for these MMMs on permeability and selectivity as function of pressure and feed composition, at different loadings of ZIF-8. Specifically, we study dense polysulfone membranes prepared by solvent evaporation, with a ZIF-8 loading in the range 0.5-5 wt% for separation of CO2 from artificial mixtures of CO2 and CH4, and also biogas from an operating plant. The MMMs with 1 wt% filler loading gave the highest enhancement in permeability and selectivity, of 56.8% and 41% respectively, as compared to pure PSF membranes. At higher loadings, a tendency for the ZIF-8 particles to agglomerate was seen, which may compromise the ability of the filler to improve membrane performance. With mixed gases, increases in CO2 permeability of about 8 to 34% were observed depending on the gas composition, the enhancement being the higher, the lower the CO2 content. For biogas, permeability and selectivity of the 1% ZIF-8 loaded MMMs were found to be 14.6% and 39.64% lesser respectively than the pure gas values. The study thus throws light on the differences in membrane performance with mixtures as compared to ideal values obtained with pure gases and hence underlines the importance of lab-scale testing of the membranes with actual gas mixtures in the intended applications.

Current Trend of MOFs Incorporated Membranes for Advanced Wastewater Treatment

Membrane technology has gained attention in wastewater treatment due to its great potential for producing high-grade water products for reuse. The membrane also effectively removes persistent pollutants in water effluent. However, their application is constrained by low productivity due to fouling formation. Incorporating functionalized nanoparticles into polymeric membranes has attracted much attention due to the improved membrane performance and additional features. Metal-organic frameworks (MOFs) incorporated into polymeric membranes have been widely applied in reverse osmosis (RO), forward osmosis (FO), nanofiltration (NF), and microfiltration (MF) for water and wastewater treatment. This short review presented recent findings, fabrication methods, and a systematic understanding of transport mechanisms under various operating conditions. This study also focused on several important parameters, such as improving physicochemical properties, membrane features, and performance enhancement in wastewater treatment. The reported studies show that MOFs incorporated membranes have reached >95% organic pollutants and 100% suspended solids. The membrane durability was also enhanced up to 140%, and the flux recovery can be maintained at 98% after several cycles. Even some MOFs, such as ZIF-8 and UiO-66, exhibited excellent performance in harsh conditions (pH < 4). The prospects and challenges of MOFs-incorporated membranes in industrial applications were also provided in this study.

Enhanced management and antifouling performance of a novel NiFe-LDH@MnO2/PVDF hybrid membrane for efficient oily wastewater treatment

Layered double hydroxides (LDHs) have gained significant recognition for their facile synthesis and super-hydrophilic two-dimensional (2D) structure to fabricate antifouling membranes for oily wastewater separation. However, conventional PVDF membranes, due to their hydrophobic nature and inert matrix, often exhibit insufficient permeance and compatibility. In this study, a novel NiFe-LDH@MnO2/PVDF membrane was synthesized using ultrasonic, redox, and microwave-hydrothermal processes. This innovative approach cultivated grass-like NiFe-LDH@MnO2 nanoparticles within an inert PVDF matrix, promoting the growth of highly hydrophilic composites. The presence of NiFe-LDH@MnO2 resulted in pronounced enhancements in surface morphology, interfacial wettability, and oil rejection for the fabricated membrane. The optimal NiFe-LDH@MnO2/PVDF-2 membrane exhibited an extremely high pure water flux (1364 L m−2•h−1), and increased oil rejection (from 81.2% to 93.5%) without sacrificing water permeation compared to the original PVDF membrane. Additionally, the NiFe-LDH@MnO2/PVDF membrane demonstrated remarkable antifouling properties, evident by an exceptional fouling resistance ratio of 96.8% following slight water rinsing. Mechanistic insights into the enhanced antifouling performance were elucidated through a comparative “semi-immersion” investigation. The facile synthesis method, coupled with the improved membrane performance, highlights the potential application prospects of this hybrid membrane in emulsified oily wastewater treatment and environmental remediation.

Chemical Vapor Functionalization of Polymer Membranes for Water Treatment

Polymer membranes are used extensively in water purification to filter and remove particulate and molecular contaminants. Ideally, these membranes should exhibit high permeance, selectivity, and fouling resistance, but these attributes are rarely achieved simultaneously. One approach to improve membrane performance is to modify the polymer using reactive chemical vapors to impart the desired physiochemical properties. In this presentation, I will describe recent work at Argonne using atomic layer deposition (ALD), sequential infiltration synthesis (SIS), and vapor-phase grafting to modify polymer membranes used for ultra- and nano-filtration in water treatment. These techniques rely on self-limiting chemical reactions between gaseous precursors and a solid surface to grow material in an atomically controlled fashion. We have used ALD to produce ultrathin and conformal inorganic layers allowing the membrane pore size and pore wall composition to be precisely tuned, SIS for the bulk modification of polymers by creating an organic-inorganic hybrid material, and vapor-phase grafting of small molecules to achieve additional control over the membrane surface properties. Our studies employ a suite of in-situ and in-operando measurements to elucidate the surface chemistry for these processes and extensive ex-situ characterization and testing to understand the effects of chemical vapor treatment on polymers and how they impact membrane performance.

Morphology and characteristics of polyethersulfone membrane modified with polyethylene glycol hexadecyl ether and nanocarbon

The development of polyethersulfone (PES) membranes to improve membrane performance can be done in various ways; one is by combining two types of additives (organic and inorganic) in one dope polymer solution. In this study, researchers analyzed the effect of combining polyethylene glycol hexadecyl ether (PEG-HE) as an organic additive and nanocarbon as an inorganic additive on the characteristics and performance of PES membranes. The membrane performance test includes analysis of pure water flux and rejection of synthetic fertilizer factory wastewater (Mg2+) with a concentration of 300 ppm. The membrane characterization was carried out by analyzing the morphology of the membrane structure using Scanning Electron Microscopy (SEM), water contact angle (WCA), porosity, and membrane pore size. Ultrafiltration experiment showed that the modified PES membrane with PEG-HE and Nanocarbon had the highest pure water flux. The most significant rejection coefficient of 96.88% was found in an ultrafiltration experiment using pure PES membranes. The characteristic of other membranes will be described in detail in this article.

Self-Healing Sulfonated Poly(ether ether ketone)-Based Polymer Electrolyte Membrane for Direct Methanol Fuel Cells: Effect of Solvent Content.

Proton exchange membranes (PEMs) with superior characteristics are needed to advance fuel cell technology. Nafion, the most used PEM in direct methanol fuel cells (DMFCs), has excellent proton conductivity but suffers from high methanol permeability and long-term performance degradation. Thus, this study aimed to create a healable PEM with improved durability and methanol barrier properties by combining sulfonated poly(ether ether ketone) (SPEEK) and poly-vinyl alcohol (PVA). The effect of changing the N,N-dimethylacetamide (DMAc) solvent concentration during membrane casting was investigated. Lower DMAc concentrations improved water absorption and, thus, membrane proton conductivity, but methanol permeability increased correspondingly. For the best trade-off between these two characteristics, the blend membrane with a 10 wt% DMAc solvent (SP10) exhibited the highest selectivity. SP10 also showed a remarkable self-healing capacity by regaining 88% of its pre-damage methanol-blocking efficiency. The ability to self-heal decreased with the increasing solvent concentration because of the increased crosslinking density and structure compactness, which reduced chain mobility. Optimizing the solvent concentration during membrane preparation is therefore an important factor in improving membrane performance in DMFCs. With its exceptional methanol barrier and self-healing characteristics, the pioneering SPEEK/PVA blend membrane may contribute to efficient and durable fuel cell systems.

Modification of Polyvinylidene Fluoride (PVDF) Membrane by Polymer Blending with Phase Inversion Method

One of the simplest approaches to improve membrane performance is to increase the hydrophilicity of the membrane. This article describes the manufacture of activated polyvinylidene fluoride (PVDF) based membranes using PVP and chitosan as organic additives, with the specific aim of increasing the hydrophilicity of the membranes. Variations of dope solution were made by adding 1% by weight of PVP and 1, 2, and 3% by weight of chitosan into three different PVDF polymer solutions. The effect of additives on the membrane was obtained by evaluating chemical functional groups by ATR-FTIR, morphological changes by SEM, and filtration performance. SEM images show that the presence of additives changes the morphological structure of the membrane. This change also had a significant impact on the membrane performance, as evidenced by the increased permeability of the pure water solution and the removal of dissolved humic acid. Overall, modified PVDF membranes with 1% by weight of PVP and 1, 2, and 3% by weight of chitosan resulted in much better permeability than unmodified PVDF membranes due to their excellent hydrophilicity.

Electroactive nanofiltration membranes based on carbon nanostructures for enhanced desalination performance

Recent advancements in materials science has paved the path for creating nanofiltration membranes that are both electrically conductive and suitable for desalination purposes. These smart membranes offer a powerful approach to regulate ion transport and fouling through surface potential variation. Herein, we report the development of an electrically responsive nanofiltration membrane through a novel process involving the physical entrapment of carbon nanostructures (CNS) within a regenerated cellulose network, followed by crosslinking with glutaraldehyde and casting. We investigated different crosslinking conditions to achieve optimal desalination results. Electron microscopy techniques such as, TEM and SEM, were utilized to confirm the successful incorporation of CNS within the cellulose network. Consequently, the resulting membrane exhibited remarkable electrical conductivity (6044 ± 6.404 S/m), which was exploited to improve membrane performance in desalination. Our results showed that applying an external voltage of −1 V increased the rejection rates of NaCl from 43.8 % to 54.6 %, and Na2SO4 from 75.6 % to 81.7 %, with insignificant effect on the permeate flux. This enhancement was attributed to the increased Donnan potential difference resulting from the polarization-induced charges generated on the membrane when a negative bias was applied. Moreover, the membrane demonstrated reversible ion transport modulation, excellent recyclability, and self-cleaning capabilities. Overall, our findings highlight the potential of these electroactive nanofiltration membranes for desalination and other ion separation applications.

Intramodule pressure profiles and protein accumulation during tangential flow filtration.

Tangential flow filtration (TFF) through a 30 kDa nominal molecular weight cut-off (MWCO) ultrafiltration membrane is widely employed to concentrate purified monoclonal antibodies (mAbs) to levels required for their formulation into injectable biologics. While TFF has been used to remove casein from milk for cheese production for over 35 years, and in pharmaceutical manufacture of biotherapeutic proteins for 20 years, the rapid decline in filtration rate (i.e., flux) at high protein concentrations is a limitation that still needs to be addressed. This is particularly important for mAbs, many of which are 140-160 kDa immunoglobulin G (IgG) type proteins recovered at concentrations of 200 mg/mL or higher. This work reports the direct measurement of local transmembrane pressure drops and off-line confocal imaging of protein accumulation in stagnant regions on the surface of a 30 kDa regenerated cellulose membrane in a flat-sheet configuration widely used in manufacture of biotherapeutic proteins. These first-of-a-kind measurements using 150 kDa bovine IgG show that while axial pressure decreases by 58 psi across a process membrane cassette, the decrease in transmembrane pressure drop is constant at about 1.2 psi/cm along the 20.7 cm length of the membrane. Confocal laser scanning microscopy of the membrane surface at the completion of runs where retentate protein concentration exceeds 200 mg/mL, shows a 50 μm thick protein layer is uniformly deposited. The localized measurements made possible by the modified membrane system confirm the role of protein deposition on limiting ultrafiltration rate and indicate possible targets for improving membrane performance.

Fabrication of negatively charged nanofiltration membrane of modified polystyrene intercalated graphene oxide for pervaporation desalination

Polystyrene intercalated graphene oxide (GO) membranes with and without sulfonation were successfully prepared for pervaporation desalination applications. The membrane was deposited on nylon support and linked with Zn2+ (c) as a crosslinker. To improve membrane performance, modification of polystyrene via sulfonation was also carried out to convert polystyrene (PS) into polystyrene sulfonic acid (PSSA). The interlayer spacing (d-spacing), hydrophilicity, and stability were observed as the membrane characteristics which greatly influenced the desalination performance. Experimental results show that intercalation of GO with PS and PSSA increases the interlayer spacing and membrane stability. The addition of PS decreased the hydrophilicity of the membrane, while the addition of PSSA increased the hydrophilicity. Calculations for optimizing desalination using Central Composite Design (CCD) on c-PSSA-GO/Nylon membranes show that the optimum temperature and time can be achieved at 57 °C and 71 min. The c-PSSA-GO/Nylon membrane showed the best results with a NaCl rejection value of > 99% and a water flux of 15.56 ± 0.6 kg m-2h−1, which was applied to 1% NaCl feed. The c-PSSA-GO/Nylon membrane also shows consistent NaCl rejection and water flux when applied for an extended period. So, the c-PSSA-GO/Nylon membrane has excellent potential for pervaporation desalination.

Photoelectrocatalytic modification of nanofiltration membranes with SrF2/Ti3C2Tx to simultaneously enhance heavy metal ions rejection and permeability

Heavy metal pollution can significantly harm water systems and human health. Combining photoelectrocatalytic (PEC) and nanofiltration (NF) membrane separation technologies can effectively remove heavy metal ions from wastewater. In this study, a water bath method was used to form SrF2/Ti3C2Tx (ST) nanoparticles on the surface of polyvinylidene fluoride (PVDF) membranes and an additional polyamide (PA) functional layer was formed at the interface by crosslinking. ST@PA composite NF membranes (STPP) with good photocatalytic performance were obtained. The separation and catalytic properties of the STPP membranes were controlled by the ST content, which modifies the surface structure and properties of the membranes. The membrane with optimal ST crosslinking exhibited a water contact angle of 50.8°, pure water flux of 24.6 L·m−2·h−1·bar−1, and rejection rates of Mn2+, Ni2+, Cu2+, and Zn2+ of 98.8%, 95.3%, 95.7%, and 97.3%, respectively, under PEC-assisted separation with visible light illumination from a Xe lamp (300 W) and an applied voltage (2 V). The STPP membranes showed improved rejection rates of heavy metal ions under PEC-assisted operation. The mechanism for the improved membrane performance under PEC conditions was preliminarily clarified considering the relationship between the photocatalytic and filtration properties of STPP membranes along with the influence of light irradiation and an external voltage on the heavy metal ions. The generation of electrons, holes, superoxide radicals, and hydroxyl radicals during membrane operation enhances the rejection rates of heavy metal ions. Based on these results, STPP membranes are considered a promising technology for industrial applications in heavy metal removal.

Improvement of anti-wetting and anti-scaling properties in membrane distillation process by a facile fluorine coating method

In this work, a fluorine coating material has been employed to improve membrane performance during membrane distillation process. The coating operation is easy and fast without additional modification of membrane morphology nor chemistry. After coating, pore structure of the membrane has remained unchanged, while surface free energy of the membrane has been drastically lowered. Low surface free energy endows the coated membrane with exceptional high anti-wetting and anti-scaling property. In membrane distillation test with the presence of surfactant or scaling agent, the coated membrane has significantly outperformed the pristine membrane. Moreover, the coated membrane has exhibited excellent performance in water recovery test from synthetic seawater, showing great promise for practical applications.

Next-Generation Water Treatment: Exploring the Potential of Biopolymer-Based Nanocomposites in Adsorption and Membrane Filtration.

This review article focuses on the potential of biopolymer-based nanocomposites incorporating nanoparticles, graphene oxide (GO), carbon nanotubes (CNTs), and nanoclays in adsorption and membrane filtration processes for water treatment. The aim is to explore the effectiveness of these innovative materials in addressing water scarcity and contamination issues. The review highlights the exceptional adsorption capacities and improved membrane performance offered by chitosan, GO, and CNTs, which make them effective in removing heavy metals, organic pollutants, and emerging contaminants from water. It also emphasizes the high surface area and ion exchange capacity of nanoclays, enabling the removal of heavy metals, organic contaminants, and dyes. Integrating magnetic (Fe2O4) adsorbents and membrane filtration technologies is highlighted to enhance adsorption and separation efficiency. The limitations and challenges associated are also discussed. The review concludes by emphasizing the importance of collaboration with industry stakeholders in advancing biopolymer-based nanocomposites for sustainable and comprehensive water treatment solutions.

High dye separation performance of novel Cu‐BTC/PES MMMs with water‐stabilized Cu‐BTC nanoparticles

AbstractMetal–organic frameworks (MOFs), as porous materials, have been extensively applied in a variety of realms, but little of these has been reported used in sewage disposal field owing to its precariousness toward water. Herein, a novel mixed matrix membrane of polyethersulfone (PES) was synthesized using Cu‐BTC‐IPA, a hydrolytic resistance MOF modified with isopropanol (IPA), which exhibits high permeability and water stability. A significant increase in hydrophilicity of the membrane was found in the modified membranes compared with the pure membrane. The porosity measurement confirmed the increased efficiency of mass transfer in the modified membranes. An enhancement in membrane performance was observed by introducing the Cu‐BTC‐IPA filler into the PES matrix, with a remarkable increase (207%) in pure water flux observed compared to that of the pristine PES membrane (264.2 L m−2 h−1 bar−1), reaching 546.4 L m−2 h−1 bar−1. Meanwhile, it exhibited superior rejection of dyestuffs (98.4% for Congo red and 98.9% for Coomassie brilliant blue). In addition, the Cu‐BTC‐IPA/PES mixed matrix membrane demonstrated remarkable anti‐biofouling properties, as evidenced by its high flux recovery rates of bovine serum albumin (BSA) solutions. The consequences indicate that introducing stable MOF into mixed matrix membranes (MMMs) is extremely effective in improving membrane performance for sewage treatment.

Adsorption of heavy metals on the surface of nanofiltration membranes: “A curse or blessing”?

Adsorptive membranes, formed by dispersing adsorbent particles in a the polymer matrix of ultrafiltration (UF) membranes, are among a number of promising technologies for removing heavy metal ions from water. They offer much higher water permeability compared to nanofiltration (NF) membranes. However, because of a limited adsorption capacity, adsorptive membranes require frequent regenerations to maintain their selective properties. In contrast, NF membranes rely on size/steric exclusion and electrostatic repulsion. Moreover, by incorporating adsorptive nanoparticles into, for example, the polyamide (PA) layer in thin film nanocomposite (TFN) membranes, NF membranes, in addition to size/steric exclusion and electrostatic repulsion, can also reject heavy metal ions by adsorption. Some TFN-NF membranes for processing feed solutions containing heavy metal ions require regeneration, implying a detrimental effect of heavy metal adsorption on their performance. Still, some do not, which leads to the question stated in the title of this article.In this study, we examined the role of heavy metal ions (Cu2+ and Pb2+) in feed solutions on their rejection and water permeability TFN membranes containing cellulose nanocrystals (CNCs), acetylated CNCs (ACNCs) and CysCNCs in the PA layer. We performed NF experiments of durations ranging from 1 to 16 h. At the end of each experiment, we measured the membranes' heavy metal adsorption, contact angle, and zeta potential and correlated them with time-dependent water permeability and heavy metal rejection. An increase in heavy metal adsorption with time was associated with a desirable simultaneous increase in water permeability and heavy metal rejection. The equilibrium adsorption was reached 8–12 h from the start of the experiments, while membrane performance remained constant. Therefore, membrane regeneration was not only unnecessary but would be undesirable because the adsorbed heavy metals improve membrane performance. In other words, the adsorption of heavy metals on the surface of NF membranes appears to be a “blessing” rather than a “curse."

Membrane modification in enhancement of virus removal: A critical review

Many waterborne diseases are related with viruses, and COVID-19 worldwide has raised the concern of virus security in water into the public horizon. Compared to other conventional water treatment processes, membrane technology can achieve satisfactory virus removal with fewer chemicals, and prevent the outbreaks of viruses to a maximal extent. Researchers developed new modification methods to improve membrane performance. This review focused on the membrane modifications that enhance the performance in virus removal. The characteristics of viruses and their removal by membrane filtration were briefly generalized, and membrane modifications were systematically discussed through different virus removal mechanisms, including size exclusion, hydrophilic and hydrophobic interactions, electronic interactions, and inactivation. Advanced functional materials for membrane modification were summarized based on their nature. Furthermore, it is suggested that membranes should be enhanced through different mechanisms mainly based on their ranks of pore size. The current review provided theoretical support regarding membrane modifications in the enhancement of virus removal and avenues for practical application.

Polyurethane Membranes From Red Seaweeds For Ammonia Adsorption

Polyurethane (PU) membranes were prepared from red seaweed (Gracilaria sp.), castor oil, Toluene Diisocyanate (TDI), and added benzoyl peroxide (BPO) additive to improve membrane performance. The membrane is applied for the adsorption of ammonia in the solution. FT-IR analysis showed the presence of functional group N = C = O at a wavenumber of 2276 cm-1 and the O-H functional group at a wave number of 3373.50 cm-1, indicating the urethane group's formation has been formed during membrane polymerization. SEM images showed the morphological structure of the PU membrane, where the more open structure of the PU membrane by the addition of BPO. The DSC and TGA results showed the membrane's thermal stability with the addition of BPO. The PU membrane has an optimum contact time for ammonia uptake of 40 minutes. The adsorption isotherm of ammonia by the PU membrane follows the Freundlich isotherm model. The adsorption capacity of the PU membrane with the addition of BPO additives was 13.2 mg/g, which shows that the adsorption capacity of the PU-BPO membrane has a better performance than a membrane without the addition of the BPO. The PU-BPO membrane could be used as an alternative method of ammonia removal.

Preparation of GO@DCN nanocomposite modified PVDF membranes for improved membrane performance and exploration of formation mechanism

Two-dimensional nanocomposite membranes (NCMs) have attracted increased attention, but the effects of nanomaterials on membranes and phase inversion mechanisms are still unclear. In this study, graphene oxide (GO) was combined with nitrogen defect-modified g-C3N4 (DCN) nanosheets by grinding to obtain GO@DCN, with subsequent doping into polyvinylidene fluoride (PVDF) by non-solvent induced phase separation (NIPS) to prepare a series of hydrophilic NCMs. The thermodynamic ternary phase diagram of NCMs is reported for the first time. Compared with pure PVDF, the phase inversion of NCMs was accelerated with the addition of DCN, GO and GO@DCN nanomaterials, which lead to sequential increment in porosity, providing channels for water molecules. Besides, the Density Function Theory(DFT) calculations indicated a strong interaction between PVDF and GO@DCN, which also contributes to the rapid phase inversion of the PVDF/GO@DCN. Furthermore, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory demonstrates that the attraction between PVDF/GO@DCN2.0 and Bovine Serum Albumin (BSA) is halved compared to PVDF and BSA, indicating superior antifouling ability. At the same time, the negative zeta potential of NCMs rose, which enhanced the repulsion between NCMs and the negatively charged BSA contaminants in water. Thus, in contrast to PVDF, the permeate flux of PVDF/GO@DCN2.0 increased from 161.6 Lm−2h−1 to 387.8 Lm−2h−1 and the rejection of BSA from 80.1% to 91.6%, respectively. The flux recovery ratio (FRR) of PVDF/GO@DCN2.0 improved 30.4%, and irreversible fouling decreased 29.6%. After five cleaning cycles, the NCM still maintained excellent stability.

Minimizing bacterial adhesion on membrane: Multiscale characterization of surface modifications

The control of biofouling is required to improve membrane performance for water filtration. In this context, developing bioinspired approaches to modify membranes and give them antifouling properties is an interesting alternative. In this study, we elaborated new anti-biofouling membranes by coating them with vanillin, a natural bioactive molecule acting as a Quorum Sensing Inhibitor (QSI). The adsorption of vanillin by filtration was optimized to obtain homogeneous surface modifications. The modified membranes were then characterized in terms of physical-chemical properties: the results showed that they were more hydrophobic and exhibited a 14% decrease in pure water flux. Then, their anti-fouling properties were evaluated using complementary multiscale characterization methodologies: AFM single-cell experiments showed that vanillin adsorption had an effect on both the probability of bacterial cells to adhere to the surface, and on the force of adhesion. Direct EFM and SEM observation and adhesion assays further confirmed the effect of vanillin-modified membranes at the population-scale which showed a decrease in the bacterial coverage rate up to 50%. Altogether, it confirms the multifunctionality of vanillin-coated membranes against biofouling: reduction of bacterial initial adhesion by changing the membranes surface properties and reduction of biofilm formation by quorum sensing inhibition.