Antifouling Mechanism Research Articles

Zwitterionic Nanochannels in Covalent Organic Framework Membranes for Improved Flux and Antifouling Property.

Zwitterionic membranes demonstrate excellent antifouling property in water purification. The covalent organic frameworks (COFs), due to the ordered channels and abundant organic functional groups, have distinct superiority in constructing zwitterionic surfaces.Here, the zwitterionic COF membrane is prepared with precise framework structures and uniform charge distribution. The negatively charged 4,4'-diaminobiphenyl-2,2'-sisulphonic acid sodium (SA) and positively charged ethidium bromide (EB) fragments are used to react with 1,3,5-triformylphloroglucinol (TP) at the gas-liquid interface to prepare zwitterionic COF membrane. The complementary charged fragments in the inter-layer and inner-layer facilitate the formation of continuous and tight hydration layer on the membrane surface and pore walls to resist the adsorption of pollutants. The zwitterionic COF membrane effectively resists both negatively charged bovine serum albumin and positively charged lysozyme pollutants with flux recovery ratio (FRR) of 97% and 85%, respectively. Furthermore, the regular nano-channels and balanced interactions between water and surface/pore walls of the zwitterionic membrane result in outstanding permeability of up to 146 L m-2 h-1 bar-1 and excellent dye/salt separation selectivity. The water permeation and antifouling mechanism of membranes are elucidated by experimental and molecular dynamics calculation. Zwitterionic COF membranes can find promising applications in preparing high-performance antifouling membranes.

1-(3-Aminopropyl) imidazole (APIm) modified ultrafiltration (UF) membrane for mitigating alginate fouling caused by calcium

UF is widely used as a wastewater treatment and recycling technology. However, membrane fouling is still an important factor affecting the wide application. In this study, APIm with positive amino group was adsorbed to the surface of the carboxylated polyacrylonitrile (PAN) membrane by electrostatic force to reduce the fouling of sodium alginate (SA) caused by Ca2+. The results show that 1 v/v% APIm was selected as the optimal dosage, accompanied by the highest water flux of 330.5 L·m-2h−1 bar−1 and bovine serum albumin (BSA) rejection rate of 91.0 %. When the concentration of Ca2+ was increased to 10 mM, the Ca2+ catch amount increased to 48.25 mg/cm2. The main anti-fouling mechanism was that APIm captured a certain amount of Ca2+ in situ, destroyed the complex structure of sodium alginate (SA) and Ca2+. Then the fouling layer was easy to be removed by physical cleaning. At the concentration of 10 mM Ca2+, the membrane flux recovery rate of 1 v/v% APIm membrane was increased to 80.1 %. This study demonstrates a fouling control strategy for in-situ removal of Ca2+ bound SA fouling, providing a new approach for the future development of UF membrane.

Development and characterization of an asymmetrical flat microfiltration membrane based on natural phengite clay: Application as a pretreatment for raw seawater reverse osmosis desalination

The work focuses on developing a new asymmetric flat microfiltration membrane using an inexpensive geological material, natural Moroccan phengite clay. The optimal porous ceramic support was prepared by applying the paste casting method and sintering at a low temperature of 1050 °C for 2 h. Secondly, the microfiltration layer was developed by the spin coating method. The layer was then dried and sintered at 850 °C/2h. SEM analysis revealed that the morphological structure of the layer is homogeneous and free from cracks. Furthermore, the microfiltration layer has an average pore size of 1.23 μm, a thickness ranging from 30.3 μm to 31.3 μm, a water permeability of 258.1 L/h.m2.bar, and good chemical stability against corrosion. The performance of the manufactured membrane was evaluated by filtering raw seawater (RSW1 and RSW2) as a potential application for seawater pretreatment before desalination by reverse osmosis. The prepared membrane significantly reduced turbidity concentrations by 98.7 % for RSW1 and 96.8 % for RSW2. The fouling and antifouling mechanisms were also examined. Finally, the preparation cost of the phengite membrane was estimated to be 125 $/m2.

Nickel-cobalt hydrogen phosphate membrane with outstanding anti-crude oil-fouling capability and its microscopic anti-fouling mechanism

Oil/water separation membranes with superior anti-fouling properties against highly viscous oils are crucial for the efficient treatment of oily wastewater. Herein, the effects of functional groups in an inorganic superhydrophilic membrane on the anti-fouling properties of the membrane are investigated. Using a facile one-step electrochemical deposition method, Ni1-xCoxHPO4·3H2O membranes were formed on a Cu(OH)2 microneedle-coated copper mesh (CCNC–P) with superhydrophilic and underwater superoleophobic properties. All CCNC–P membranes with different Co2+ contents showed outstanding anti-fouling capability for oily wastewater such as those containing crude oil. The CCNC–P(x = 0.5) membrane exhibited high separation efficiency reaching 99.7 % across five oil–water mixtures and oil-in-water emulsions, concurrently presenting an ultrahigh flux of 61695 L m−2 h−1 for crude oil–water mixture. Moreover, the membrane consistently maintained its separation performance during the long-term crude oil–water separation process. The flux decline ratio was below 1 %, and the flux recovery ratio approached 99.4 %. The CCNC–P membranes possessed superior chemical, thermal, and mechanical stability, suggesting significant potential for the industrial treatment of oily wastewater. Density functional theory calculation revealed that the HPO42− group in CCNC–P can strongly adsorb water molecules. The resultant stabilized hydration layer impeded the contact between the membrane surface and oil droplets, while the metal ions scarcely influenced the adsorption of water molecules on CCNC–P. These findings provide new insights into the development of novel oil–water separation membranes with higher anti-fouling capabilities against high-viscosity oils.

Research Progress of Marine Anti-Fouling Coatings

The extended immersion of ships in seawater frequently results in biofouling, a condition characterized by the accumulation of marine organisms such as barnacles and algae. To combat this issue, the application of anti-fouling coatings to the hull surfaces of vessels has emerged as one of the most effective strategies. In response to the increasing global emphasis on environmental sustainability, there is a growing demand for anti-fouling coatings that not only demonstrate superior anti-fouling efficacy but also adhere to stringent environmental standards. The traditional use of organotin-based self-polishing anti-fouling coatings, known for their high toxicity, has been prohibited due to environmental concerns. Consequently, there is a progressive shift toward the development and application of environmentally friendly anti-fouling coatings. This paper reviews the toxicity and application limitations associated with conventional anti-fouling coatings. It provides a comprehensive overview of recent advancements in the field, including the development of novel self-polishing anti-fouling coatings, low surface energy coatings, biomimetic coatings, and nanostructured coatings, each leveraging distinct anti-fouling mechanisms. The paper evaluates the composition and performance of these emerging coatings and identifies key technical challenges that remain unresolved. It also proposes a multi-faceted approach to addressing these challenges, suggesting potential solutions for enhancing the effectiveness and environmental compatibility of anti-fouling technologies. The paper forecasts future research directions and development trajectories for marine anti-fouling coatings, emphasizing the need for continued innovation to achieve both environmental sustainability and superior anti-fouling performance.

Electrochemical flow-through disinfection of Escherichia coli versus Staphylococcus aureus: Identifying impacts of flow patterns on efficiency

While Ti4O7 reactive electrochemical membrane (REM) treatment exhibits high efficiency in inactivating bacteria, it remains obscure about the disinfection and antifouling mechanism. Herein, we highlighted the decisive impact of flow patterns on the electrochemical inactivation of both Escherichia coli and Staphylococcus aureus during dead-end filtration mode. Specifically, 5.22 and 5.47 log removal for E. coli and S. aureus were achieved by a single pass under anode-to-cathode (AC) flow pattern at 7 mA cm−2 respectively, while the inactivation rates immediately decreased to less than one log for cathode-to-anode (CA) flow pattern. Further analysis demonstrated that the remarkable inactivation efficiency in neutral condition, the complete inactivation of E. coli and S. aureus in the parallel plate batch mode were achieved in 15 min and 30 min at 7 mA cm−2 respectively, was significantly inhibited during alkaline and acidic exposure, thereby which explained the slow disinfection rates in CA flow pattern due to the formed alkaline experiment near anodic reaction section. The disinfection efficiency and comparative differences of E. coli and S. aureus were also affected by their hydraulic condition and cell wall structure. Functional groups model substances experiments and molecular dynamics simulation elucidated that the response changes of cell structure especially denser membrane protein complex under alkaline and acidic exposure resisted electrooxidation attack to the membrane structure. These findings here provide insights into the application of Ti4O7 REM technologies in controlling waterborne disease transmission.

CuO-Fe3C-C modified PVDF membrane for catalysis and antifouling

Modification of membranes is an effective method for degrading organic pollutants and alleviating membrane fouling. In this study, CuO-Fe3C-C catalyst was prepared by high-temperature pyrolysis. The membrane modified by CuO- Fe3C-C was prepared by vacuum filtration. The bacteriostatic rate of the modified membrane can reach to 96.8 %. Compared to the pristine membrane, the pure water flux of the modified membrane increased from 223.43 L m−2h−1 bar−1 to 422.27 L m−2h−1 bar−1, the flux recovery ratio (FRR) of modified membranes increased from 39.7 % to 79.25 %. Removal rate of TC (Tetracycline) by modified membrane activated PMS can reach to 90.75 %. After 5 cycles, the degradation efficiency of modified membranes was still 83.77 %, which was only 6.39 % lower than that of the first cycle. Free radical quenching experiments and ESR tests explored the possible catalysis and antifouling mechanisms of the modified membrane system, the results showed main active species were SO4−•, OH•, O2−• and 1O2. This study prepared membranes with excellent antifouling properties, providing a theoretical reference for alleviating membrane fouling in membrane-based water treatment.

Real-time induced magnetic vibrational based antifouling mechanism for ultrafiltration (UF) membrane

Despite the widespread adoption of membrane technologies for efficient water treatment, membrane fouling remains a significant challenge, reducing separation efficiency, shortening lifespan, and increasing operational costs. Various studies have explored chemical membrane modifications to mitigate fouling, often resulting in adverse effects on flux and selectivity. Based on numerical modeling and experimental investigation, this work introduces real-time induced magnetic vibration as a sustainable approach for membrane antifouling without compromising permeability and selectivity. By preventing or delaying particle deposition on the membrane surface, magnetic vibration reduces fouling intensity. Experimental results demonstrated that different frequencies of magnetic vibration influenced the deposition of foulants (Humic Acid and Sodium Alginate) on the membrane surface. Notably, vibrating the membrane at 10 Hz with centrally attached iron particles led to a 22.4 % reduction in flux when treated with Humic Acid, compared to a 33.9 % reduction without vibration. Exposure to vibrations at the resonance frequency (5 Hz) for 6 h resulted in only a 10 % reduction in flux, effectively preventing the formation of a dense cake layer. Similarly, in the case of Sodium Alginate, a 10 Hz vibration for 2 h decreased the flux reduction from 21.4 % without vibration to 7.3 %, suggesting the preventive effect of vibration on aggregated SA deposition or facilitating continuous displacement for flux retention. Moreover, the study examined the influence of the configuration of iron particles attached to the membranes on the effectiveness of vibration. The study revealed that a striped configuration was more effective than a centralized configuration, owing to the distributed vibration effect across each part of the membrane. Furthermore, the fouling mechanism and rejection percentage were further investigated to enhance understanding of the fouling processes.

Multifunctional membranes with super-wetting interface and in-situ Fenton-like sites for efficient oil-in-water emulsion separation

The surge in oil-in-water (O/W) emulsions poses a threat to the ecological environment. Membrane separation technology can achieve complete O/W emulsion separation through size sieving; however, its efficiency is limited by membrane fouling. In this study, an efficient O/W separation membrane with passive and positive anti-fouling properties was fabricated using Fe3O4 functionalized attapulgite (ATP) nanofibers. The anti-fouling mechanism of the multifunctional membranes for the separation of various O/W emulsions was studied. During separation process, a hydration layer, which mitigates oil adhesion with binding energy as low as −169 kcal·mol−1, forms on the interface of Fe3O4-ATP. When a cationic surfactant is present, positively charged oil droplets are attracted to the membrane surface, where they compress against each other, leading to demulsification and escape. Synergistic effects including electrostatic shielding, interaction energy, and steric hindrance were demonstrated through characterization and simulation. Our findings showed that the membrane exhibited a high filtration efficiency with an oil rejection of over 99 % and a steady flux of over 73 % of its initial value. After filtration, oil fouling degraded into smaller sizes and escaped from the membrane structure through the Fenton-like catalytic function of Fe3O4, resulting in a flux recovery ratio of up to 90 %. This study provides a reference for the construction of multifunctional membranes for efficient separation processes and advancing anti-fouling research on membrane interfaces.

Construction of zwitterionic surface of PVDF hollow fiber membrane and the study on the mechanism of “autonomy-response” synergistic enhancement anti-fouling

In this study, polyvinylidene fluoride (PVDF)/styryl maleic anhydride (SMA) hollow fiber membrane was fabricated using the Thermally Induced Phase Separation (TIPS) technique. Subsequently, zwitterion-sulfobetaine methacrylate (SBMA) was introduced to the membrane surface through a Michael addition reaction to create a nearly electrically neutral membrane surface. This modification effectively mitigated the high adsorption of differently charged protein pollutants on the membrane surface, thereby enhancing its anti-fouling performance. Simultaneously, the membrane surfaces with positive and negative charges were separately constructed, and the impact of membrane surface charge properties on the anti-fouling performance against positively and negatively charged foulants was investigated. Furthermore, detailed studies were conducted on the chemical structure, surface morphology, performance, and anti-fouling mechanism of the modified membranes. The results indicate that the electrically neutral membrane modified by zwitterionic SBMA exhibited excellent anti-fouling properties against both bovine serum albumin (BSA) and lysozyme (LYZ), with a flux recovery rate (FRR) reaching 96.5 % and 94.6 %, respectively. The static adsorption capacities of BSA and LYZ on the membrane surface decreased to 5.89 μg cm−2 and 9.53 μg cm−2, respectively. Furthermore, the study investigated the structure of the hydration layer formed by zwitterionic SBMA on the membrane surface, as well as its hydration capacity and anti-fouling mechanism. Subsequently, through an assessment of the long-term stability of the modified membrane and its flux recovery rate (FRR), in conjunction with theories related to hydration layers and thermodynamics, it elucidated the anti-fouling mechanism involving “autonomy-response” synergistic enhancement of zwitterions. These findings will offer new strategies for researching hollow fiber membranes with superior anti-fouling properties and for applying zwitterions in membrane technology.

Quaternary Ammonium Salts-Based Materials: A Review on Environmental Toxicity, Anti-Fouling Mechanisms and Applications in Marine and Water Treatment Industries.

The adherence of pathogenic microorganisms to surfaces and their association to form antibiotic-resistant biofilms threatens public health and affects several industrial sectors with significant economic losses. For this reason, the medical, pharmaceutical and materials science communities are exploring more effective anti-fouling approaches. This review focuses on the anti-fouling properties, structure-activity relationships and environmental toxicity of quaternary ammonium salts (QAS) and, as a subclass, ionic liquid compounds. Greener alternatives such as QAS-based antimicrobial polymers with biocide release, non-fouling (i.e., PEG, zwitterions), fouling release (i.e., poly(dimethylsiloxanes), fluorocarbon) and contact killing properties are highlighted. We also report on dual-functional polymers and stimuli-responsive materials. Given the economic and environmental impacts of biofilms in submerged surfaces, we emphasize the importance of less explored QAS-based anti-fouling approaches in the marine industry and in developing efficient membranes for water treatment systems.

Preparation of PVDF@TiO2 hybrid membrane and the research of the “hydration layer & rigid layer obstruction-electrostatic coalescence” anti-oil fouling mechanism

In this study, the 3-Aminopropyltriethoxysilane (APTES) was first grafted onto TiO2 nanoparticles (APTES-TiO2 nanoparticles), which were then introduced the membrane surface by reacting with anhydride on the membrane surface and Schiff base reaction with the PEI-TA. There are two types of hollow fiber hybrid membranes with varying nanoparticle distributions were constructed. The influence of hybrid mode on the ability of anti-oil fouling was researched. The results indicated that the PVDF@TiO2 hybrid membrane has a flux recovery rate of 96.68 % and a total flux decline rate of 15.52 %, indicating a good anti-emulsified oil fouling performance. By characterizing the anti-oil droplets adhesion, water-binding capacity, surface charge of membrane and concentrate system coacervate size, the coalescence ability of the hybrid membrane to the oil droplets and the spreading behavior of oil droplets on the surface were uncovered. Ultimately, the anti-fouling mechanism “hydration layer &rigid layer obstruction-electrostatic coalescence” was proposed, which can reasonably explain the weakness of the interplay between the membrane surface and oil droplets, thus slowing down the attaching and spreading of emulsified oil droplets. This study laid the foundation for developing hybrid membranes with high resistance to emulsified oil fouling ability. The proposed anti-fouling mechanism can provide new ideas for the efficient purification of oily wastewater.

Bio-inspired multimimimetic synergistic strategies Cs3Bi2Br9/ZnS organosilicon antifouling flexible films: Coupled micro/nanostructured surfaces, fluorescence, and reactive oxygen species mechanisms

Constructing multifaceted bio-inspired environmentally friendly films combining the synergistic advantages of multiple bionics can improve the static antifouling effect of antifouling-releasing silicones and mitigate the toxicity to marine ecology. In this work, based on the multiple anti-fouling mechanisms of fluorescent corals, designed Cs3Bi2Br9/ZnS/PDMS (CZP) flexible fluorescent films with surface microstructures and interpenetrating network Moreover, the blue fluorescence in the CZP films can be maintained for a long time in seawater environment (attributed to bismuth-based chalcogenides), and the formation of the heterostructure of Cs3Bi2Br9/ZnS (CBB/ZS) improves the ability of releasing reactive oxygen species (hydroxyl radical, superoxide radical, and singlet-linear oxygen).The CZP films obtained excellent antifouling effect under static conditions with antimicrobial rate up to 90.51 % and anti-algae adhesion to diatoms up to 96.60 %, which was attributed to the synergistic effect of the fluorescence functionality, micronized structure, and free radical release. Consequently, this work provides a promising avenue for the development of marine antifouling silicon-based films for efficient and environmentally friendly applications.

Dynamic antifouling strategies of soft corals: Disrupting the flow field by tentacles

As permanently attached organism, soft corals can prevent fouling organisms from attaching to them through its anti-fouling mechanisms. In this paper, the antifouling mechanism of soft coral tentacles was revealed through the combination of numerical simulation and laboratory experiment. The results indicated that the interaction between tentacle structures and fluid medium affects the distribution and adhesion of bacteria. At the microscopic level, the boundary layer of low normal flow velocity forms a "water film" near the tentacles, preventing bacteria from approaching the tentacle surface. From the macro perspective, coral tentacles can disrupt the flow field through vortex streets, disrupt water flow stability, and make it difficult for bacteria to attach. The new discovery of bacterial movement and attachment behavior in the flow around a circular cylinder provides theoretical guidance for the design of antifouling surfaces.

Molecular Interaction Mechanisms Between Lubricant-Infused Slippery Surfaces and Mussel-Inspired Polydopamine Adhesive and DOPA Moiety.

Lubricant-infused slippery surfaces have recently emerged as promising antifouling coatings, showing potential against proteins, cells, and marine mussels. However, a comprehensive understanding of the molecular binding behaviors and interaction strength of foulants to these surfaces is lacking. In this work, mussel-inspired chemistry based on catechol-containing chemicals including 3,4-dihydroxyphenylalanine (DOPA) and polydopamine (PDA) is employed to investigate the antifouling performance and repellence mechanisms of fluorinated-based slippery surface, and the correlated interaction mechanisms are probed using atomic force microscopy (AFM). Intermolecular force measurements and deposition experiments between PDA and the surface reveal the ability of lubricant film to inhibit the contact of PDA particles with the substrate. Moreover, the binding mechanisms and bond dissociation energy between a single DOPA moiety and the lubricant-infused slippery surface are quantitatively investigated employing single-molecule force spectroscopy based on AFM (SM-AFM), which reveal that the infused lubricant layer can remarkably influence the dissociation forces and weaken the binding strength between DOPA and underneath per-fluorinated monolayer surface. This work provides new nanomechanical insights into the fundamental antifouling mechanisms of the lubricant-infused slippery surfaces against mussel-derived adhesive chemicals, with important implications for the design of lubricant-infused materials and other novel antifouling platforms for various bioengineering and engineering applications.

Fluorescent zinc acrylate resins containing coumarin structures with enhanced antifouling performance

The demand for non-toxic antifouling coatings has led to the development of multifunctional antifouling coatings. In this work, a series of coumarin acids with fluorescence were first prepared via the Knoevenagel condensation reaction. Then, multifunctional zinc acrylate resins were produced successfully by employing an acrylic acid monomer, ZnO, and coumarin acids by free radical polymerization and polycondensation processes. The self-polishing and antifouling properties of the resins were investigated by dynamic simulation experiments, E. coli growth inhibition experiments, algae adhesion inhibition experiments, and marine environment antifouling experiments. The results show that the zinc acrylate resins containing the coumarin structures not only have good self-polishing performance but also have better antifouling performances than the zinc acrylate resin containing benzoic acid. This work not only reveals the antifouling mechanism of the multifunctional resins, but also provides a new strategy for the development of environmentally friendly antifouling coatings.

Mechanisms and Strategies of Advanced Oxidation Processes for Membrane Fouling Control in MBRs: Membrane-Foulant Removal versus Mixed-Liquor Improvement.

Membrane bioreactors (MBRs) are well-established and widely utilized technologies with substantial large-scale plants around the world for municipal and industrial wastewater treatment. Despite their widespread adoption, membrane fouling presents a significant impediment to the broader application of MBRs, necessitating ongoing research and development of effective antifouling strategies. As highly promising, efficient, and environmentally friendly chemical methods for water and wastewater treatment, advanced oxidation processes (AOPs) have demonstrated exceptional competence in the degradation of pollutants and inactivation of bacteria in aqueous environments, exhibiting considerable potential in controlling membrane fouling in MBRs through direct membrane foulant removal (MFR) and indirect mixed-liquor improvement (MLI). Recent proliferation of research on AOPs-based antifouling technologies has catalyzed revolutionary advancements in traditional antifouling methods in MBRs, shedding new light on antifouling mechanisms. To keep pace with the rapid evolution of MBRs, there is an urgent need for a comprehensive summary and discussion of the antifouling advances of AOPs in MBRs, particularly with a focus on understanding the realizing pathways of MFR and MLI. In this critical review, we emphasize the superiority and feasibility of implementing AOPs-based antifouling technologies in MBRs. Moreover, we systematically overview antifouling mechanisms and strategies, such as membrane modification and cleaning for MFR, as well as pretreatment and in-situ treatment for MLI, based on specific AOPs including electrochemical oxidation, photocatalysis, Fenton, and ozonation. Furthermore, we provide recommendations for selecting antifouling strategies (MFR or MLI) in MBRs, along with proposed regulatory measures for specific AOPs-based technologies according to the operational conditions and energy consumption of MBRs. Finally, we highlight future research prospects rooted in the existing application challenges of AOPs in MBRs, including low antifouling efficiency, elevated additional costs, production of metal sludge, and potential damage to polymeric membranes. The fundamental insights presented in this review aim to elevate research interest and ignite innovative thinking regarding the design, improvement, and deployment of AOPs-based antifouling approaches in MBRs, thereby advancing the extensive utilization of membrane-separation technology in the field of wastewater treatment.

Electro-responsive OCNT/PPy membrane for efficient irreversible-fouling control through electroregulation of electrostatic and fluid interaction forces

Membrane-based separation process has been proven to be a powerful strategy for low-energy-consumption and high-efficiency water purification. However, the practical application is still subjected to serious membrane fouling. In this study, an impressive approach to alleviate membrane fouling is proposed using an electro-conductive oxygenated carbon nanotube/polypyrrole (OCNT/PPy) membrane combining electrically-regulated electrostatic and fluid forces. Benefiting from the negative potential (−1.18 V vs. SCE) applied on the membrane, the electric polarization effects significantly enhance the repulsive electrostatic force on contaminant. The transmembrane pressure increases at an ignorable rate during the filtration process. Meanwhile, for accumulated irreversible membrane fouling after multi-cycle filtrations, the positive potential (+1.19 V vs. SCE) exerted on OCNT/PPy membrane can decrease the fluid resistances of backwash flow. As a result, the electrically-regulated hydraulic backwash achieves a thorough recovery rate of permeance at 99.1 %. The numerical analysis of the antifouling mechanism reveals that the mitigation of irreversible membrane fouling is mainly attributed to rapid formation of a loose cake layer under electrical assistance. Moreover, the computational fluid dynamics verifies that the reduction of water-channel resistance enhances the elimination of foulants in membrane pores. This work motivates a new thought for membrane fouling control through electroregulation of electrostatic and fluid forces at the membrane-water interface.

Piezoceramic membrane with built-in ultrasound for reactive oxygen species generation and synergistic vibration anti-fouling

Piezoceramic membranes have emerged as a prominent solution for membrane fouling control. However, the prevalent use of toxic lead and limitations of vibration-based anti-fouling mechanism impede their wider adoption in water treatment. This study introduces a Mn/BaTiO3 piezoceramic membrane, demonstrating a promising in-situ anti-fouling efficacy and mechanism insights. When applied to an Alternating Current at a resonant frequency of 20 V, 265 kHz, the membrane achieves optimal vibration, effectively mitigating various foulants such as high-concentration oil (2500 ppm, including real industrial oil wastewater), bacteria and different charged inorganic colloidal particles, showing advantages over other reported piezoceramic membranes. Importantly, our findings suggest that the built-in ultrasonic vibration of piezoceramic membranes can generate reactive oxygen species. This offers profound insights into the distinct anti-fouling processes for organic and inorganic wastewater, supplementing and unifying the traditional singular vibrational anti-fouling mechanism of piezoceramic membranes, and potentially propelling the development of piezoelectric catalytic membranes.

Coke oven wastewater treatment using polymeric and ceramic membranes.

This research is aimed to investigate the efficacy of membrane separation technology in treating coke oven wastewater (COW). A comparative study was conducted using three types of membranes: commercial polymeric (CP) membrane, commercial ceramic (CC) membrane, and synthesized ceramic (SC) membrane. The potential of the SC membrane in COW treatment was assessed in comparison to the CC membrane, which had a molecular weight cut-off (MWCO) of 1 Kilo-Dalton. The experiments were conducted under various trans-membrane pressure (TMP) conditions ranging from 1 to 4bar. Additionally, the effect of the CP membrane on COW treatment was examined at TMP levels ranging from 5 to 25bar. The research findings revealed that the SC membrane exhibited promising results in terms of permeability and flux compared to the CC membrane. Also, a significant reduction was observed in various water parameters such as TSS decreased by 89.74%, chlorides by 8.24%, nitrogen by 10%, and hardness by 22%. Moreover, the study was carried out by implementing an anti-fouling mechanism to mitigate fouling effects on membrane performance.