Antifouling Effect Research Articles

An antifouling electrochemical biosensor based on chondroitin sulfate-functionalized polyaniline and DNA-peptide conjugates for cortisol determination in body fluids.

An antifouling electrochemical biosensor was constructed based on chondroitin sulfate (CS)-functionalized polyaniline (CS/PANI) and DNA-peptide conjugates that is capable of assaying cortisol directly in human fluids. First, a CS-doped PANI nanocomposite (sensing substrate) was electrodeposited onto a bare glassy carbon electrode to promote electron transport, providing the sensing signal from high peak currents of PANI to improve the sensitivity of the biosensor. Dendritic DNA-peptide conjugates were assembled onto the CS/PANI by exploiting the highly specific and strong interactions between biotin and streptavidin, which amplified the sensing signals toward cortisol. The integration of the DNA-peptide conjugates into the CS/PANI nanocomposite ensured that the biosensor had a synergistic antifouling effect and was capable of detecting cortisol directly in body fluids (sweat, saliva, and tears). When assaying cortisol levels, the biosensor exhibited a linear range over the cortisol concentrations of 1 × 10-12-1 × 10-7 M and a low limit of detection (0.333 × 10-12 M). In the detection of cortisol in real samples, the relative standard deviation (RSD) of the biological samples ranged from 2.94 to 4.23%, and the recovery were calculated to be in the range 95.2-103.2%.

Antimicrobial and Antifouling Effects of Petal-Like Nanostructure by Evaporation-Induced Self-Assembly for Personal Protective Equipment.

Although the personal protective equipment (PPE) used by healthcare workers (HCWs) effectively blocks hazardous substances and pathogens, it does not fully rule out the possibility of infection, as pathogens surviving on the fabric surface pose a substantial risk of cross-infection through unintended means. Therefore, PPE materials that exhibit effective biocidal activity while minimizing contamination by viscous body fluids (e.g., blood and saliva) and pathogen-laden droplets are highly sought. In this study, petal-like nanostructures (PNSs) are synthesized through the vertical rearrangement of colloidal lamellar bilayers via evaporation-induced self-assembly of octadecylamine, silica-alumina sol, and diverse photosensitizer. The developed method is compatible with variousfabrics and imparts visible-light-activated antimicrobial and superhydrophobic-basedantifouling activities. PNS-coated fabrics could provide a high level of protection and effectively block pathogen transmission as exemplified by their ability to roll off viscous body fluidsreducingbacterial droplet adhesion and to inactivate various microorganisms. The combination of antifouling and photobiocidal activities results in the complete inactivation of sprayed pathogen-laden droplets within 30min. Thus, this study paves the way for effective contagious disease management and the protection of HCWs in general medical environments, inspiring further research on the fabrication of materials that integrate multiple useful functionalities.

P. pavoninus‐Inspired Smart Slips Marine Antifouling Coating Based on Coumarin: Antifouling Durability and Adaptive Adjustability of Lubrication

AbstractSlippery liquid‐infused porous surface (SLIPS) is received widespread attention in the antifouling field because of its dynamic slippery surface, but the limited effect of physical “anti‐adherence” and the problem of lubricant loss restrict its application for practical marine antifouling. Inspired by the self‐defensive function of P. pavoninus’s poisonous mucus, a SLIPS based on the reversible chemical bonds and the antibacterial effect of coumarin (CmSLIPS) is prepared, which addresses these disadvantages by responsively adaptive lubricity and durability. The CmSLIPS enables the “locking” and “unlocking” mode between lubricant and matrix via the reversible photodimerization of coumarin. It regulates the surface lubricity to adapt to the antifouling demand. The reversible chemical bonds of lubricant and matrix reduce lubricant loss and enhance the lubricant stability and antifouling durability. In addition to the physical anti‐adhesive barrier of SLIPS, the excellent antimicrobial property of coumarin groups further enhances the “biocidal” antifouling effect to improve long‐term antifouling durability. In summary, the CmSLIPS has surface stability, durability, responsively adaptive lubricity, efficient self‐cleaning, anti‐protein, anti‐bacterial, anti‐algae, self‐healing (92.85%) properties and 150‐day marine field antifouling performance during boom seasons, which maintains the satisfactory antifouling performance in the harsh marine environment and demonstrates the promising application in neritic sea equipment.

Superhydrophilic fluorinated heterogeneous membranes with boosting antifouling property and high stable permeance for efficient emulsion separation

It is yet a query that whether chemically heterogeneous superwetting surface is able to enhance the permeability and anti-fouling capability of membrane contemporaneously, heretofore which is lacking and well worth creating. Here, we propose a bio-adhesion coupled with self-assembly strategy, to construct superhydrophilic fluorinated heterogeneous membranes, through in-situ biomimetic adhesion of the hydrophilic polyphenol-silane coating (TAT) on the porous PVDF membrane, as a secondary reaction platform, and subsequently self-assembly of amphoteric fluorocarbon surfactant (FS-50). Unsurprisingly, we find that introducing FS-50 not only significantly strengthens the permeability, but also improves the anti-fouling self-cleaning, thanks to the formation of robust hydration layer and slippery micro-domains with low friction, to realize the dual anti-fouling effects of pollution resistance and release. The champion PVDF/TAT/FS-2.0 % composite membrane exhibits superhydrophilic and underwater superoleophobic (oil contact angle above 162.3°) property with very low oil-adhesion. This composite membrane possesses an ultrahigh water permeance of 29214.6 L m−2 h−1 bar−1, which is 2.8 times larger than that of pristine PVDF membrane. The PVDF/TAT/FS-2.0 % composite membrane presents the high separation efficiencies (above 99.5 %) for various surfactant-stabilized oil-in-water emulsions and high permeances of 3193.2–4212.3 L m−2 h−1 bar−1. Especially, the membrane at continuous operation for 1.0 h can reach a high stable permeance of 2505.1 L m−2 h−1 bar−1. Moreover, this composite membrane shows strong chemical stability and robustness. This research answers the initial question, and provides the insight for further design and production of chemically heterogeneous superwetting membranes with high permeability, selectivity and antifouling ability.

A highly antifouling and eco-friendly hydrogel coating based on capsaicin derivative -functionalized polymer

Antifouling hydrogels have received extensive attention in the field of marine antifouling due to their excellent hydrophilicity and environmental friendliness. However, the antifouling applications of traditional hydrogels are limited by their poor antibacterial properties, and capsaicin derivatives, as nontoxic and environmentally friendly antifoulants, can be used to improve the antibacterial properties of hydrogels. From the perspective of practical application, hydrogels were obtained by crosslinking the copolymer of the capsaicin derivative N,N'-((4,5,6-trihydroxy-1,3-phenylene) bis (methylene)) diacrylamide (TPA), lipophilic monomers and hydrophilic monomers. This hydrogel exhibited anti-protein performance due to its hydrophilicity, and the capsaicin derivative caused the hydrogel coating to exhibit excellent algae inhibition performance (the minimum adhesion density of diatoms on the surface of the hydrogel coating was less than 440 cells/mm2), better algae anti-adhesion abilities than hydrogel reported in the other paper, and antibacterial effects (the antibacterial rate was more than 95%). After 73 d of panel testing in a real marine environment, there was still a good antifouling effect in the hydrogel coating. Hence, the antifouling performance was improved significantly by capsaicin derivative (TPA)-functionalized hydrogel coating. A new strategy is provided in this study for the preparation of hydrogels with superior marine antifouling properties.

Homogeneous Electrochemical Aptasensor for Sensitive Detection of Zearalenone Using Nanocomposite Probe and Silica Nanochannel Film.

Developing rapid and efficient analytical methods is of great importance for food safety Herein, we present a novel homogeneous electrochemical aptasensor for ultrasensitive quantitative determination of zearalenone (ZEN) based on a nanocomposite probe and silica nanochannel film. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and UV-Vis characterization techniques confirm that graphene oxide (GO) bears an aromatic conjugated structure, along with hydroxyl and carboxyl groups, facilitating the subsequent adsorption of cationic redox hexa-ammine-ruthenium (III) (Ru(NH3)63+) and anionic ZEN aptamer, to form a Ru(NH3)63+-ZEN aptamer-GO nanocomposite probe in a homogeneous solution. Vertically-ordered mesoporous silica films (VMSF) bearing silanol groups can be simply grown on the solid indium tin oxide (ITO) electrode surface and enable the selective preconcentration of Ru(NH3)63+, eventually leading to signal amplification. Since the detachment of Ru(NH3)63+ from the GO surface by the recognized ZEN aptamer in the presence of ZEN, more free Ru(NH3)63+ is released in solution and produces enhanced redox signals at the VMSF modified ITO electrode, allowing quantitative detection of ZEN. On the basis of the above sensing strategy, the proposed homogeneity, due to the assistance of graphene, as well as of the signal amplification and anti-fouling effects of VMSF, accurate analysis of ZEN can be realized in maize and Chinese chestnut samples.

Highly strong bio-inspired ZnO/PDMS superhydrophobic surface with drag reduction and antibacterial properties

Maintaining the long-term stability of water repellency and antifouling remains a challenge. This study presents the fabrication of a solid sharkskin-inspired surface exhibiting superhydrophobic and antifouling properties by polydimethylsiloxane (PDMS) and zinc oxide (ZnO) nanostructures through the simple microcasting and hydrothermal methods. The ZnO grown under optimal reaction parameters showed a remarkable contact angle of 151°, signifying the emergence of superhydrophobicity. Furthermore, the ZnO/PDMS sharkskin surface was found to reduce drag by up to 12.2%. Notably, the bacterial adhesion was decreased on the sharkskin-like PDMS surface with ZnO nanostructures by 96.5% compared to smooth PDMS. This resulted from the combined antifouling effects of ZnO photocatalytic property and the microstructure-induced hydrophobicity. Additionally, the ZnO nanostructures demonstrated exceptional mechanical stability and robustness.

Surface-Active Ionic-Liquid-Based Coatings as Anti-Biofilms for Stone: An Evaluation of Their Physical Properties

The biodeterioration of stone surfaces can be a threat to the conservation of built heritage. Much effort has been put into finding treatments and processes to mitigate biocolonization and its effects, both in terrestrial and underwater environments. Recently, the use of surfactant ionic liquids has been shown to have biocidal and antifouling effects on stone. However, little information is currently available on the morphological and physical properties of such coatings. In this paper, we report on the physical characterization of coatings based on an ionic liquid (IL) consisting of N-(2-hydroxyethyl)-N,N-dimethyl-1-do-decanaminium cation and a combination of bromide and dodecylbenzenesulfonate (DBS) anions in a molar ratio of 3:1, respectively. Nanosilica and tetraethyl orthosilicate were used as binders to promote the adhesion of the ionic liquid to the stone surface. The coatings were applied on Carrara marble samples and analyzed using Scanning Electronic Microscopy (SEM), static contact angles, colorimetric measurements and capillary water absorption. The resistance to UV radiation and seawater was also investigated. The results show that the IL behaves differently depending on the binder. The latter influences the arrangement of the IL and its wettability, which decreases in the case of NanoEstel, whereas this parameter increases in the case of Estel. In addition, the coatings show good resistance to the degradation agents.

Self-healing and durable antifouling zwitterionic hydrogels based on functionalized liquid metal microgels

Hydrogels are a promising new class of antifouling materials. But their utility is constrained by low mechanical strength and unsatisfactory antifouling performance over the long term. Herein, we successfully prepared zwitterionic polymer PEIS cross-linked gallium-based liquid metal microgels-based (PEIS-Gel@PMPC-GLM) hydrogels via UV-curing and amidation reaction. The as-prepared hydrogels showed preferable mechanical properties and superior hydrophilicity to the original hydrogels. The PEIS-Gel@PMPC-GLM hydrogels could prevent the adhesion of more than 90 % of microalgae and nearly 100 % of bacteria in a short-term antifouling test. PEIS-Gel@PMPC-GLM hydrogels also performed exceptionally well in the high concentration antibacterial test and the long-term antifouling test (remove more than 90 % bacteria and 80 % microalgae). In addition to releasing a high concentration of gallium ions, as shown by the ICP-OES test, PEIS-Gel@PMPC-GLM hydrogels also exhibitedexcellent lubrication performance, as demonstrated by the friction test (coefficient of friction as low as 0.023). Therefore, the antifouling effect of gallium ions combined with the strong hydration ability of the surfaces endowed the hydrogels remarkable antibacterial and antifouling properties. As a result of the exposed gallium atoms inducing further crosslinking of residual vinyl monomer in hydrogels, PEIS-Gel@PMPC-GLM hydrogels revealed certain self-healing performance.

Steam-side heat transfer analysis in spirally corrugated tube for grate furnace superheater

In the case of low Reynolds number, the structure of the spirally corrugated tube will make the solid particles in the fluid be affected by the centrifugal force, and be more evenly distributed in the fluid to achieve anti-fouling effect. Therefore, it can be used in heat exchangers with serious fouling problems to improve heat exchange efficiency. In this paper, the first stage low-temperature superheater in the grate furnace is selected as application equipment. The local resistance coefficient, local Nusselt number and local heat flux are analyzed, the thermal-hydraulic characteristics of different sample points are evaluated. Combinatorial method of central composite design and Latin hypercube design is used to select four representative sample points, and effect of the corrugation pitch ratio and depth ratio on the convective heat transfer intensity, fluid resistance and fluid work consumption of the steam side is studied. The research results show that as the corrugation depth increases, the local heat transfer coefficient in the circumferential direction increases, and more heat is transferred from the flue gas to the steam, but the pump power consumed in the flow process has also increased. Due to the existence of spiral structure, the local heat flux density of the wall is symmetrically distributed in the circumferential direction, which represents that the temperature gradient increases, and the heat flow is improved.

Capsaicin-based silicone antifouling coating with enhanced interlocking adhesion via SIPN

Silicone-based coatings generally exhibit excellent dynamic fouling release due to their low surface energy and elastic modulus. However, the poor adhesion of these coatings at the interface between the coating and the substrate, as well as deficient static antifouling capabilities, severely deteriorate their antifouling properties over extended periods. Herein, an epoxy-poly(dimethylsiloxane)/capsaicin (EP-PDMS/CAP) coating with highly enhanced interfacial adhesion and remarkable antifouling performances was prepared. The coating adhesion strength of the EP-PDMS/CAP has been improved by more than 5 times compared to a PDMS control coating (from 0.4 MPa to 2.04 MPa) by forming a semi-interpenetrating polymer network (SIPN) structure between the epoxy and PDMS layers. The EP-PDMS/CAP coating achieved the superior antifouling effects in both static and dynamic conditions, the anti-bacterial rate was as high as 96.8 %, and the anti-algal adhesion rate to the green algae Chlorella increased by 95.7 %, due to the synergistic effects of the fouling release performance from the PDMS coating and the fouling prevention of capsaicin. Furthermore, the EP-PDMS/CAP coating was proven to be extremely stable in different treatments such as acid/basic solutions, air oven heating test, and cyclic sand abrasion, showing great potential for anti-biofouling under aggressive conditions. This work provides a promising pathway towards the development of high-performance silicone-based composite coatings for efficient marine anti-biofouling.

Arginine-Functionalized Thin Film Composite Forward Osmosis Membrane Integrating Antifouling and Antibacterial Effects.

Membrane fouling is an inevitable obstacle of polyamide composite forward osmosis (FO) membranes in oily wastewater treatment. In this study, zwitterionic arginine (Arg) is grafted onto nascent self-made FO polyamide poly(ether sulfone) (PA-PES) membrane, imparting superior hydrophilic, antifouling, and antibacterial properties to the membrane. Detailed characterizations revealed that the Arg-modified (Arg-PES) membrane presented obviously surface positively charged and unique morphology. Results showed that our strategy endowed the optimized membrane, the water flux increased by 113.2% compared to the pristine membrane, respectively, meanwhile keeping high NaCl rejection > 93.9% (with DI water as feed solution and 0.5 M NaCl as draw solution, FO mode). The dynamic fouling tests indicated that the Arg-PES membranes exhibited much improved antifouling performance towards oily wastewater treatment. The flux recovery ratios of the membrane were as high as 92.0% for cationic emulsified oil (cetyl pyridinium chloride, CPC), 87.0% for neutral emulsified oil (Tween-80), and 86.0% for anionic emulsified oil (sodium dodecyl sulfate, SDS) after washing, respectively. Meanwhile, the Arg-PES membranes assembled with guanidine cationic groups exhibited an enhanced antibacterial property against E. coli, which exhibited a high antibacterial efficiency of approximately 96%. Consequently, the newly arginine functionalized FO membrane possesses impressive antifouling performance, while simultaneously resisting bacterial invasion, thus rendering it an ideal alternative for oily wastewater treatment in the FO process.

Fabrication of an anti-fouling coating based on epoxy resin with a double antibacterial effect via an in situ polymerization strategy

The hull and subsea equipment are often plagued by widespread marine biofouling, so developing a sustainable environmental protection antifouling paint is urgent. The study designed and developed an antifouling composite coating system (E44-Ag-PGI) with a synergistic antibacterial effect based on the dual strategy of the bacteriostatic effect of stereochemical structure on polymer surface and release sterilization of metal nanoparticles. Firstly, an antifouling agent (PGI) was prepared by simple radical polymerization by combining glycidyl methacrylate with borneol, a complex bicyclic monoterpene structure extracted from plants. Then bisphenol A epoxy resin with strong adhesion to metal was selected as the base material. The synthetic antifouling agent with epoxy groups was polymerized in situ into the epoxy resin network, and compared with pure epoxy resin, the elongation at break of E44-Ag-PGI coating with 20 % PGI content increased from 40.37 % to 124.8 %, which was mainly attributed to the introduction of a soft chain of antifouling agent polymer, which improved the flexibility of the coating. Meanwhile, the antibacterial efficiency of the coating against Pseudomonas aeruginosa and Staphylococcus aureus was 97.69 % and 95.9 %, respectively. This excellent antibacterial performance was mainly attributed to the synergistic antibacterial action of natural borneol and AgNPs. In addition, the biofilm and diatom resistance experiments of the coating showed that the coating also has an excellent antifouling effect. This provided a new research idea for environmentally friendly antifouling coatings.

Exploring the low cell adhesion of photoinduced superhydrophilic surfaces for improving the effect of antifouling protective coatings on porous building materials

The susceptibility of building materials to biological colonization is associated with accelerated decay processes, aesthetical alterations and health risks. Thus, preventive measurements involving the use of coatings with passive (bioreceptivity decrease) and active (biocides) antifouling mechanisms are common. Hydrophobic and superhydrophobic coatings that decrease water availability are the most common anti-fouling strategies, although they can promote cell adhesion under the right circumstances and lose effectiveness after the initial biofilm setting.In this work, we explore an innovative alternative strategy to improve the anti-fouling effect of a hydrophobic coating through surface modification to grant low cell-adhesion superhydrophilic properties (while preserving its low water absorption) and its combination with nano-biocides. This is achieved by the incorporation of Ag or CuO-modified TiO2 into an ormosil sol–gel matrix. Irradiation with UV–Vis light activates the superhydrophilic surface while maintaining a decrease in capillary water absorption of >90% and accelerated algal exposure tests showed a markedly lower colonization rate compared to the superhydrophobic surface, owing to the modifications in cell-water-surface interfacial tensions. The nano-biocides showed a dual effect, promoting the transition to superhydrophilic and further decreasing colonization. Furthermore, the superhydrophilic surfaces enhance the biocide effect by promoting the interaction of the nanoparticles with the surrounding media.

Study of antifouling and decolorization effect in polyethersulfone membranes improved with dendrimer‐modified metal–organic frameworks

AbstractThe Mil‐125(Ti) metal–organic framework nanoparticles were modified with different compounds i.e. polyamidoamine dendrimer (Mil‐Den), chitosan (Mil‐CS) and Mil‐CS‐Den to prepare functional and hydrophilic nanocomposites. These nanocomposites were characterized and applied for modification of polyethersulfone (PES) membrane by blending them in the dope solutions. The mixed matrix PES membranes were manufactured by the nonsolvent‐induced phase inversion method. The introduction of the nanocomposites into the membrane structure led to positive alterations such as the improvement of hydrophilicity and morphology causing the development of permeability and antifouling properties. The bare PES membrane contact angle was decreased from 60° to 34.5° by adding 0.5 wt% of Mil‐CS‐Den nanocomposite. Applications of novel structures with special absorption in 0.5 wt% of Mil‐CS‐Den membrane, caused an increment of porosity, mean pore size and reduction of surface roughness. The permeability was enhanced from 4.2 to 21.43 L/m2 h bar, while fouling was reduced from 48.5% to 13.5% which indicates the strengthening of the antifouling feature of the hydrophobic PES membrane. Also, the flux recovery ratio was enhanced from 66.7% to 89.3% by blending 0.5 wt% of Mil‐CS‐Den. The modified membranes showed an excellent dye separation performance. The attachment of dendrimer and chitosan to the Mil‐125(Ti) surface increased the efficiency of Mil‐125(Ti) in the modification of the PES membrane. The utilization of nanomaterial features can reduce the limitation of membrane processes and reach desirable outcomes. The results of this work indicate the high potential of the modified MOF for the removal of dye contaminants as well as provide a suitable perspective for water purification with the help of membrane processes.

Light-settable polybenzoxazines for marine antifouling coatings

Building benzoxazine coatings on large equipment is of great practical importance and challenging. In this work, a main-chain type benzoxazine (MCBZ) resin that can be quickly shaped under UV light was successfully synthesized and can be directly coated into a film. In addition, it had a wide processing window, low curing temperature, excellent static antifouling effect, and sterilization effect. The d12-DHBP-MCBZ resin was prepared from dodecamine, which ensured the sterilization effect, and 4, 4′-dihydroxy-benzophenone provided the photoinitiation sites and activated the oxazine ring. By adjusting the ratio of d12-DHBP-MCBZ to TMPTMA, hydrophilic benzoxazine coatings can be prepared, suitable for fouling-resisting coatings. The results indicated that the d12-DHBP-MCBZ resin could be quickly shaped under UV light, and the post-curing temperature was only 140 °C. In particular, the coatings' excellent hydrophilicity can effectively prevent fouling organisms' adhesion and improve the static antifouling effect. It was worth mentioning that Poly (BZ/20 %TMA) coating achieved a high sterilization performance of >99 %. These works gave us a new strategy to solve application problems of benzoxazine coatings on large equipment and antifouling coating efficiency problems.

Wear‐resistant/antifouling integrated coating protection technology of polyethylene cable

AbstractPolymer cables are being applied increasingly in fields such as deep‐sea mooring and cage culture. How to improve their wear resistance and prevent microbial adhesion is an urgent problem to be solved. In this work, the surface of the cable was treated by the polyvinylpyrrolidone cross‐linking method and the anchoring effect of one‐dimensional linear nanomaterials, which improved the adhesion of the water‐based coating. Meanwhile, the protective effect of the coating was improved through the addition of antifouling agents and wear‐resistant agents. The microstructure and intermolecular forces of the coating were characterized by scanning electron microscopy and infrared spectroscopy. The net hanging test results show that the surface‐treated cable exhibits better abrasion resistance and antifouling effects, and the shedding phenomenon is significantly improved.

Virtual screening of the natural antifoulants: In silico approach to screen lichen metabolites against marine biofoulers

AbstractThe present study aims to explore the inhibitory action of lichen metabolites against important protein targets of marine fouling organisms using computational methods. Lichens with their unique ability to produce various secondary metabolites find versatile applications in Biotechnology and allied fields. The 3D structure of target proteins associated with fouling activity of marine organism were collected from the protein data bank (PDB) and the computational docking analysis was performed using the PyRx software with 40 lichen compounds that are collected from PubChem. The lichen compounds were docked against the following protein targets—mannose‐specific lectin CGL1 of Crassostrea gigas, Proximal thread matrix protein 1 PTMP 1 of Mytilus galloprovincialis, and G protein‐coupled receptor (GPCR) of Balanus amphitrite. As there was no experimentally determined structure available for GPCR of B. amphitrite, homology modeling was performed to predict the protein structure. The docking study showed effective binding of lichen compounds to various fouling targets with the binding energies in the range of −10.1 to −5 kcal/mol. Among the lichen compounds studied, roccanin showed the least binding energy for CGL1, PTMP1 and GPCR. The correlation assessments predict a positive relationship between binding energy, molecular weight and retention time. MD Simulation studies were performed using LARMD online tool and the RMSD and radius of gyration (Rg) values was recorded. This study proves that the compounds produced by lichens have high antifouling effect against marine foulers under in silico conditions.

Influence of an Axial-Electromagnetic Field Treatment Device with a Solenoid Structure on Crystallization Fouling on the Tube Side of a Shell-and-Tube Heat Exchanger.

In this study, the influence of an axial-electromagnetic field treatment device (AEFTD) with a solenoid structure using different electromagnetic frequencies on calcium carbonate (CaCO3) crystallization fouling on the tube side of a shell-and-tube heat exchanger was investigated. The experimental results indicated that the application of the AEFTD could effectively reduce fouling resistance and decelerate the growth rate of CaCO3 fouling. The opposite trend between fouling resistance and the outlet temperature of an experimental fluid indicated that the application of the AEFTD could enhance heat transfer. Meanwhile, the crystal morphologies of the fouling samples were analyzed by means of scanning electron microscopy (SEM). The axial-electromagnetic field favored the formation of vaterite as opposed to calcite. Non-adhesive vaterite did not easily aggregate into clusters and was suspended in bulk to form muddy fouling that could be carried away by turbulent flow. Furthermore, the anti-fouling mechanism of the axial-electromagnetic field is discussed in detail. The anti-fouling effect of the AEFTD on CaCO3 fouling exhibited extreme characteristics in this study. Therefore, the effectiveness of the AEFTD is contingent upon the selection of the electromagnetic parameters.

Hydrophobic DES Based on Menthol and Natural Organic Acids for Use in Antifouling Marine Coatings.

Marine biofouling negatively impacts industries with off-shore infrastructures, such as naval, oil, and aquaculture. To date, there are no ideal sustainable, economic, and environmentally benign solutions to deal with this phenomenon. The advances achieved in green solvents, as well as its application in different industries, such as pharmaceutical and biotechnology, have promoted the emergence of deep eutectic systems (DES). These eutectic systems have applications in various fields and can be revolutionary in the marine-based industrial sector. In this study, the main objective was to investigate the potential use of hydrophobic DES (HDES) based on menthol and natural organic acids for their use as marine antifouling coatings. Our strategy encompassed the physicochemical characterization of different formulations, which allowed us to identify the most appropriate molar ratio and intermolecular interactions for HDES formations. The miscibility of the resulting HDES with the marine coating has been evaluated and proven to be successful. The Men/OL (1:1) system proved to be the most promising in terms of cost-production and thus was the one used in subsequent antifouling tests. The cytotoxicity of this HDES was evaluated using an in vitro cell model (HaCat cells) showing no significant toxicity. Furthermore, the application of this system incorporated into coatings that are used in marine structures was also studied using marine species (Mytilus edulis mussels and Patella vulgata limpets) to evaluate both their antifouling and ecotoxicity effects. HDES Men/OL (1:1) incorporated in marine coatings was promising in reducing marine macrofouling and also proved to be effective at the level of microfouling without viability impairment of the tested marine species. It was revealed to be more efficient than using copper oxide, metallic copper, or ivermectin as antifouling agents. Biochemical assays performed on marine species showed that this HDES does not induce oxidative stress in the tested species. These results are a strong indication of the potential of this HDES to be sustainable and efficiently used in marine fouling control technologies.