Antifouling Behavior Research Articles

Anti-Fouling Behaviors of a Modified Surface Induced by an Ultrasonic Surface Rolling Process for 304 Stainless Steel

This research aimed to investigate the effects of an ultrasonic surface rolling process (USRP) on the deposition behaviors in CaCO3 crystallization fouling for 304 stainless steel (304SS). The microstructure, surface morphology, and hydrophobic properties of the modified layer were characterized with optical microscopy, a roughness profile measurement instrument, and a contact angle measurement instrument. The corrosion and fouling behaviors of different surfaces were studied in simulated cooling water. The polarization curves and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical properties. The results showed that USRP-treated surfaces had better anti-corrosion and anti-fouling performance. The improvement in anti-fouling performance was attributed to the weakening of peaks and valleys, the reduction of surface defects, and the improvement of corrosion resistance.

Fouling Resistance and Release Properties of Poly(sulfobetaine) Brushes with Varying Alkyl Chain Spacer Lengths and Molecular Weights

We examined the effects of alkyl carbon spacer length (CSL) and molecular weight on fouling resistance and release properties of zwitterionic poly(sulfobetaine methacrylate) brushes. Using surface-initiated atom transfer radical polymerization, we synthesized two series of brushes with CSL = 3 and 4 and molecular weight from 19 to 1500 kg ·mol-1, corresponding to dry brush thickness from around 6 to 180 nm. The brush with CSL = 3 was nearly completely wet with water (independent of molecular weight), whereas the brush with CSL = 4 exhibited a strong increase in water contact angle with molecular weight. Though the two-brush series had distinct wetting properties, both series of brushes exhibited similarly great resistance against fouling by Staphylococcus epidermidis bacteria and Aspergillus niger fungi spores when submerged in water, indicating that neither molecular weight nor CSL strongly affected the antifouling behavior. We also compared the efficacy of brushes against fouling by fungi and silicon oil in air. Brushes grafted to filter paper were strongly fouled by fungi and silicon oil in air. Grafting the polymers to the filter paper, however, greatly enhanced removal of the foulant upon rinsing. The removal of fungi and silicon oil when rinsed with a salt solution was enhanced by 219 and 175%, respectively, as compared to a blank filter paper control. Thus, our results indicate that these zwitterionic brushes can promote foulant removal for dry applications in addition to their well-known fouling resistance in submerged conditions.

Modified Graphene Oxide/Polyvinyl Chloride Membranes for Wastewater Treatment

AbstractGraphene oxide (GO) was modified by citric acid (CA) and embedded into polyvinyl chloride (PVC) membranes. The PVC/GO‐CA (0.15 wt %) membrane showed the best hydrophilicity, porosity, and tensile strength. The results of membranes' performance in a membrane bioreactor (MBR) system demonstrated that the critical flux had a noticeable improvement after adding 0.15 wt % GO‐CA. Also, the irreversible fouling ratio of PVC/GO‐CA membranes was lower than that of the neat PVC membrane, indicating an improvement in antifouling properties of the nanocomposite membrane. Moreover, the soluble microbial product (SMP) and the extracellular polymeric substance (EPS) of the cake layer reduced for the PVC/GO‐CA (0.15 wt %) membrane because of its higher hydrophilicity and better antifouling behavior.

Enhancing the Total Salt Adsorption Capacity and Monovalent Ion Selectivity in Capacitive Deionization Using a Dual-Layer Membrane Coating Electrode

Capacitive deionization (CDI) is highly attractive for seawater desalination, while the trade-off between total salt adsorption capacity (SAC) and monovalent ion selectivity is a big challenge for current electrodes, especially facing solution containing organics. Herein, a simple approach was used to prepare a novel dual-layer membrane coating electrode (D-MCE) by depositing ion exchange polymers onto activated carbon fiber (ACF) to overcome this issue. Performances of the ACF, single-layer MCE, anion exchange membrane ACF, and D-MCE were investigated. Compared to ACF, the single-layer MCE showed an increased total SAC from 435.7 to 593.0 μmol/g with a reduced Cl–/SO42– selectivity from 0.9 to 0.4. The introduction of the membrane increased total SAC to 524.3 μmol/g and decreased Cl–/SO42– selectivity to 0.7. The D-MCE exhibited an improved total SAC to 679.5 μmol/g by inhibiting the co-ion repulsion and Faradaic reaction. Meanwhile, the D-MCE enabled fast Cl– diffusion and presented a high selectivity (3.8). After 50 cycles, the D-MCE exhibited an almost unchanged total SAC and selectivity even in the presence of organics. The narrowed pores and negative outermost layer endowed the D-MCE with an outstanding anti-fouling behavior, which well explained its stable performance. These findings confirmed the high potential of the D-MCE in addressing the trade-off and provided valuable insights into the design of the CDI electrode for desalination.

Tailored ultra-low pressure nanofiltration membranes for advanced drinking water treatment

Nanofiltration (NF) membranes featuring high water permeance, excellent antifouling properties, and selective organic matter/minerals separation for drinking water are highly desirable in the environmental water treatment process. In this work, an ultra-permeable NF membrane was tailored via a low temperature-assisted interfacial polymerization (LTIP) method. The surface morphologies, structural compositions, and separation performances of the NF membranes were further regulated by changing the addition of the aqueous monomer. The optimized NF membrane (NFM-0.2) showed ultrahigh water permeance of 31.8 L m−2 h−1 bar−1 and 95.1 % Na2SO4 rejection while maintaining superior antifouling behaviors. During the filtration of natural surface water, NFM-0.2 presented 75.5 % higher removals of DOC, UV254, and bisphenol A. The application of NFM-0.2 for filtrating ground water indicated that NFM-0.2 could remove 50.0 % and 62.9 % of organic matter and total hardness, respectively. The permeate water not only had no potential to form scaling after boiling but also preserved mineral ions, which was helpful for providing high-quality drinking water. Combined with the feasibility and practicability of the LTIP method, the facile strategy provides a facile way for tailoring ultralow pressure NF membranes featuring both highly selective separation of organic matter/minerals and superior antifouling abilities for practical water treatment.

Design and Manufacturing of Antibacterial Electrospun Polysulfone Membranes Functionalized by Ag Nanocoating via Magnetron Sputtering.

Antibacterial properties of engineered materials are important in the transition to a circular economy and societal security, as they are central to many key industrial areas, such as health, food, and water treatment/reclaiming. Nanocoating and electrospinning are two versatile, simple, and low-cost technologies that can be combined into new advanced manufacturing approaches to achieve controlled production of innovative micro- and nano-structured non-woven membranes with antifouling and antibacterial properties. The present study investigates a rational approach to design and manufacture electrospun membranes of polysulfone (PSU) with mechanical properties optimized via combinatorial testing from factorial design of experiments (DOE) and endowed with antimicrobial silver (Ag) nanocoating. Despite the very low amount of Ag deposited as a conformal percolating nanocoating web on the polymer fibers, the antimicrobial resistance assessed against the Gram-negative bacteria E. coli proved to be extremely effective, almost completely inhibiting the microbial proliferation with respect to the reference uncoated PSU membrane. The results are relevant, for example, to improve antifouling behavior in ultrafiltration and reverse osmosis in water treatment.

Polyethylene Glycol-b-poly(trialkylsilyl methacrylate-co-methyl methacrylate) Hydrolyzable Block Copolymers for Eco-Friendly Self-Polishing Marine Coatings.

Hydrolyzable block copolymers consisting of a polyethylene glycol (PEG) first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-methyl methacrylate (MMA)) second block were synthesized by RAFT polymerization. Two PEGs with different molar masses (Mn = 750 g/mol (PEG1) and 2200 g/mol (PEG2)) were used as macro-chain transfer agents and the polymerization conditions were set in order to obtain copolymers with a comparable mole content of trialkylsilyl methacrylate (~30 mole%) and two different PEG mole percentages of 10 and 30 mole%. The hydrolysis rates of PEG-b-(TRSiMA-co-MMA) in a THF/basic (pH = 10) water solution were shown to drastically depend on the nature of the trialkylsilyl groups and the mole content of the PEG block. Films of selected copolymers were also found to undergo hydrolysis in artificial seawater (ASW), with tunable erosion kinetics that were modulated by varying the copolymer design. Measurements of the advancing and receding contact angles of water as a function of the immersion time in the ASW confirmed the ability of the copolymer film surfaces to respond to the water environment as a result of two different mechanisms: (i) the hydrolysis of the silylester groups that prevailed in TBSiMA-based copolymers; and (ii) a major surface exposure of hydrophilic PEG chains that was predominant for TPSiMA-based copolymers. AFM analysis revealed that the surface nano-roughness increased upon immersion in ASW. The erosion of copolymer film surfaces resulted in a self-polishing, antifouling behavior against the diatom Navicula salinicola. The amount of settled diatoms depended on the hydrolysis rate of the copolymers.

An eco-friendly process for the elaboration of poly(ethylene terephthalate) surfaces grafted with biobased network embedding silver nanoparticles with multiple antibacterial modes

This paper reports a strategy for the elaboration of highly performing antibacterial PET surfaces according to an eco-friendly photoinduced process. Modified PET surfaces were elaborated through the grafting of a three dimensional (3D) biopolymer derived from vanillin with antibacterial activity. Biobased polymer grafting was performed through a grafting-from photopolymerization approach initiated from a photoinitiator compound preliminary functionalized onto PET surface. Antibacterial activity of the elaborated materials was tested against Gram-positive (Rhodococcus wratislaviensis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) strains. Antibacterial activity of the biopolymer covalently linked onto PET surface was observed for all tested bacterial strains. Antibacterial effect of vanillin derivative coated onto PET material was combined with a multi-scale roughness induced through the grafting process giving antifouling behaviour to the material. Besides, to improve antibacterial activity of the modified material, biobased network was used as binding sites for photoembedding of antimicrobial silver nanoparticles. The hybrid material showed excellent antibacterial properties against Gram-positive and Gram-negative tested cells. The enhancement of material antibacterial activity against this wide range of pathogens resulted of a combination of different effects: the antibacterial activity of coated vanillin derivative and nanosilver combined with a surface nanostructuration imparting antifouling properties.Grafting of biobased polymer network loaded with nanosilver onto PET material was characterized at various stages of the modification by UV–vis spectroscopy, water contact angle measurements, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface topography was studied by atomic force microscopy (AFM).

Exfoliation of MoS2 nanosheets using stimuli responsive poly (N-isopropylacrylamide-co-allylamine) for multi-functional nanofiltration membranes preparation

Exfoliating TMD nanosheets in aqueous solution with stimuli responsive stabilizers could have a synergistic effect on both exfoliation and smart behavior manifestation. Smart porous membranes material permeation management has a significant impact on membrane applications. Herein, stimuli responsive Poly (N-isopropylacrylamide-co-allylamine) exfoliated MoS2 nanosheets laminar membranes were prepared using facile vacuum filtration. The prepared membranes manifested synergistic effect for thermo-responsive, antifouling, and photocatalytic behavior. The use of a solar simulator as a source of both heat and light is a promising feature for improving membrane separation and antifouling ability. The water permeance of the MoS2 laminar membrane is regulated in a reversible way by the thermo-responsive gates. The unique tunability of the membrane also aids in the separation of different sized molecules. In the field of smart gating systems and molecular separation, the modified 2D MoS2 stimuli-responsive membranes expands the utilization range of nano-gating separation.

Tailoring the Interfacial Interactions of Porous Polymer Membranes to Accelerate Atomic Layer Deposition: The Latent Path to Antifouling Membranes

Atomic layer deposition (ALD) is a powerful strategy to engineer hybrid organic-inorganic membranes with emergent functionalities. The combination of atomic-level thickness control, wide materials palette, and unprecedented conformality allow the physiochemical properties (e.g., hydrophilicity) of mesoporous polymer membranes to be precisely tuned. The nucleation of ALD materials growth on polymer surfaces relies on chemical interactions between the ALD metalorganic precursor and functional groups in the polymer structure and these interactions dictate the number of ALD cycles required to achieve a continuous coating. Strategies to enhance these interactions could enable desirable properties such as anti-fouling behavior to be imparted on inert polymer surfaces that lack the necessary functional groups for ALD nucleation. In this study, we demonstrate that the reactivity of polyacrylonitrile (PAN) membranes towards ALD metal oxide (MO) precursors with Lewis acid characteristics is enhanced by introducing Lewis base functional groups (amidoxime: Am) on the PAN backbone. The resulting Lewis acid-base interactions accelerates the MO nucleation in Am-PAN and reduce the number of deposition cycles required to achieve hydrophilicity compared to the untreated PAN membrane. Unveiling the reaction mechanism, the in-situ FTIR intensity changes established enhanced interaction dynamics between the ALD MO precursors and the Am-PAN membrane, unlike the PAN membrane. For similar MO cycles, through both spectroscopic and thermogravimetric analysis, we observe enhanced MO loading in the Am-PAN membrane compared to the PAN membrane. Here we have verified that strong Lewis acid-base interactions led to enhanced loading for a range of ALD MO materials including Al2O3, TiO2, SnO2, and ZnO. Most importantly, the Al2O3-Am-PAN hybrid membrane showed 23.3% higher antifouling capability compared to the pristine PAN membrane. Our approach expands the scope of design options for fouling-resistant porous hybrid inorganic-organic membranes and may reduce manufacturing costs of water treatment membranes.

Designing of nanotextured inorganic-organic hybrid PVDF membrane for efficient separation of the oil-in-water emulsions

The separation of the emulsified oil/water is one of the critical environmental challenges. The PVDF membranes have been found helpful for separation, but rapid fouling makes them less attractive in treating oil-in-water emulsions. The design of antifouling membranes has become an area of deep interest. Herein, developing a novel modified PVDF ultrafiltration membrane was reported by doping the pyrrole and solidifying it in a ferric-containing coagulation bath, resulting in a unique nanotextured PVDF membrane (CCB–Fe/PPnp-PVDF) to separate the oil/water emulsions. The resultant CCB-Fe/PPnp-PVDF membrane was thoroughly characterized using the FTIR, FE-SEM, EDX, mapping, AFM, and contact analyzer. The hydrophilicity of the CCB-Fe/PPnp-PVDF was substantially improved, and the water contact angle was reduced from 81֯ ± 0.9֯ to 44֯ ± 1.7֯. The CCB-Fe/PPnp-PVDF membrane flux increased by 121% compared to the pristine PVDF membrane, with high separation efficiency of 99%. The hydrophilic nanotextured surface of the CCB-Fe/PPnp-PVDF membrane showed good antifouling behavior, with a flux recovery ratio (FRR) of more than 96%. Irreversible flux was just less than 4%. The high flux recovery ratio indicated that the nanotextured surface produced by the Fe/PPnp had prevented the blockage of the membrane pores and compact cake layer formation, which makes it an excellent membrane for oil/water emulsion separation. This strategy can be adopted for designing advanced membranes for separation applications.

Mechanisms for Reduced Fibrin Clot Formation on Liquid-Infused Surfaces.

Biomedical devices are prone to blood clot formation (thrombosis), and liquid-infused surfaces (LIS) are effective in reducing the thrombotic response. However, the mechanisms that underpin this performance, and in particular the role of the lubricant, are not well understood. In this work, it is investigated whether the mechanism of LIS action is related to i) inhibition of factor XII (FXII) activation and the contact pathway; ii) reduced fibrin density of clots formed on surfaces; iii) increased mobility of proteins or cells on the surface due to the interfacial flow of the lubricant. The chosen LIS is covalently tethered, nanostructured layers of perfluorocarbons, infused with thin films of medical-grade perfluorodecalin (tethered-liquid perfluorocarbon), prepared with chemical vapor deposition previously optimized to retain lubricant under flow. Results show that in the absence of external flow, interfacial mobility is inherently higher at the liquid-blood interface, making it a key contributor to the low thrombogenicity of LIS, as FXII activity and fibrin density are equivalent at the interface. The findings of this study advance the understanding of the anti-thrombotic behavior of LIS-coated biomedical devices for future coating design. More broadly, enhanced interfacial mobility may be an important, underexplored mechanism for the anti-fouling behavior of surface coatings.

Micro-patterned cellulose triacetate membranes for forward osmosis: Synthesis, performance and anti-fouling behavior

Most cellulose triacetate (CTA)-based studies for forward osmosis (FO) have greatly focused on achieving asymmetric membranes with a highly porous sublayer along with a dense selective layer. Such membranes can achieve better fluxes due to improved mass transfer and reduced internal concentration polarization. In this work, patterning of the CTA-membranes via modification of the conventional non-solvent induced phase inversion is explored as an alternative route to increase FO water flux without reducing salt selectivity. The modified way of applying the non-solvent in this method increased the membrane bulk porosity from ~17 % to ~50 %. Such high porosity and reduced tortuosity of the patterned membrane can reduce the internal concentration polarization by back-transport and reduced accumulation of salt and other solutes in the porous support. During FO, the patterned CTA membrane showed a water flux of 30 L m−2 h−1 and reverse salt flux of 25 g m−2 h−1, thanks to the increased effective membrane area, low water transport resistance, and high porosity of the membrane support. The patterned CTA-membranes may have potential in FO for applications with larger draw solutes due to the slightly larger pores on the membrane surface following the non-solvent spraying. Alternatively, some phase inversion parameters can still be further tuned to lower the salt passage.

High flux polyaniline-coated ceramic membrane for effective separation of emulsified oil-in-water

Oil separation from oily wastewater is critical for environmental sustainability. In the present study, we report for the first time the facile fabrication of high flux polyaniline-modified ceramic membrane to effectively separate emulsified oil. Aniline was rapidly polymerized in a single step on alumina ceramic support using different monomer concentrations. It was revealed that the alumina membrane modified with 1.0 M aniline monomer is suitable for separating oil/water emulsions with an exceptionally high permeance of 3451 L m −2 .h −1 (L.M.H.) and high separating efficiency. The polyaniline-coated alumina membranes appeared superhydrophilic/superoleophobic w ith negligible fouling behavior. The modified membranes demonstrate a steady oil rejection flux after several cycles with excellent oil-rejection of 97%. The high flux, low operating pressure, and antifouling behavior revealed that these modified membranes are excellent candidates for emulsified-oil separation.

Marine antifouling behavior of the surfaces modified by dopamine and antibacterial peptide

Marine antifouling behavior of the surfaces modified by dopamine and antibacterial peptide

Antifouling nanocomposite polymer coatings for marine applications: A review on experiments, mechanisms, and theoretical studies

• Experimental studies about antifouling nanocomposite polymer coatings are reviewed. • Antifouling mechanisms of nanocomposite polymer coatings are presented. • Metal oxides, metal-organic frameworks, nano-carbons, MXene, and clay are discussed. • Theoretical and simulation studies for antifouling investigations are introduced. • Antifouling behavior is simulated by quantum computations and intermolecular forces. Marine fouling is a worldwide challenge with huge damages on industrial structures, side effects on economics of industries, and environmental and safety-related hazards. Different approaches have been used for combating fouling in the marine environment. Meanwhile, nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application. Nanomaterials such as nano-metals, nano-metal oxides, metal-organic frameworks, carbon-based nanostructures, MXene, and nanoclays have antibacterial and antifouling properties in the polymer coatings. Besides, these nanomaterials can improve the corrosion resistance, mechanical strength, weathering stability, and thermal resistance of the polymer coatings. Therefore, in this review paper, the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed. This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix, the inherent properties of the nanomaterials, the weight percent and the dispersion method of the nanomaterials within the coating matrix, and the chemicals used for modifying the surface of the nanomaterials; meanwhile, the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites. Moreover, the theoretical studies are introduced to pave the way of researchers working on the antifouling coatings, and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency. .

Recycled PET/metal oxides nanocomposite membrane for treatment of real industrial effluents: Membrane fabrication, stability, antifouling behavior, and process modeling and optimization

An environmentally friendly nanofiltration membrane from recycled PET (Polyethylene terephthalate) was fabricated for rejection of Pb (II) and Cr (VI) from synthetic and real industrial effluents. Various ZnO/y-FeOOH NPs concentrations from 0.5 to 1 wt% were investigated as a hydrophilic agent. The membranes were characterized by FE-SEM, XRD, WCA, AFM, and FTIR analysis. Membrane stability in acid/alkaline/boiling water was also studied. The Box–Behnken design (BBD) was used for the optimization of the metals rejection. The influence of the pH, transmembrane pressure (TMP), and heavy metal ion concentrations on the rejection were investigated. The optimal conditions were achieved as; 3.59, 0.5 bar, and 11 mg/L for Pb (II) and 3.9, 0.5 bar, and 10 mg/L for Cr (VI) rejection. The pure water flux (PWF) was 169.39 kg/m2·h, and the rejection rate of Pb (II) and Cr (VI) were 94.7 %, and 63.4 %, respectively. The antifouling behavior of the membranes was also studied by the filtration of milk solution. The rPET/ZnO/y-FeOOH membrane with 0.5 wt% of NPs had a high antifouling capability (FRR 96.2 %, Rr 90.21 %, and Rir 3.001 %). This study confirmed that the fabricated rPET/ZnO/y-FeOOH membrane is a promising filter for the removal of heavy metals from industrial effluents.

Development of Composite Thin-Film Nanofiltration Membranes Based on Polyethersulfone for Water Purification

The development of thin-film composite membranes has gained more importance as they exhibit higher permeability, higher solute rejection and improved antifouling behavior. The incorporation of hydrophilic nanomaterials within the composite thin film has reported to effectively increase the hydrophilicity and improve the membrane performance. In this study novel thin-film composite nanofiltration membranes were prepared by interfacial polymerization of trimesoyl chloride, polyvinylpyrolidone (PVP) and montmorillonite (MMT) composite on the porous polyethersulfone membrane. The effect of preparation parameters was studied as; reaction time, PVP concentration and MMT content. The properties of the prepared composite thin-film membranes were analyzed in terms of their chemical structure, surface morphological features, pure water contact angle, zeta potential, pure water permeation flux (PWP) and solutes rejection. The prepared composite thin-film membranes showed smoother surfaces, different surfaces functionality and amphoteric surfaces with points of zero charge at pH 7–7.5. The PWP was found to increase with increasing MMT content up to 0.10 wt%. The rejection of crystal violet dye (CV) was studied using the prepared membranes. The membrane with 0.5% PVP, 0.10% MMT and 6 min reaction time showed PWP of 18.1 L/m2 h bar and CV rejection of 80.01%. The rejection of Na2SO4 and MgCl2 increased with increasing MMT content and reached 96% and 35.4%, respectively. The steady state flux was decreased by 5% with increasing MMT content from 0.10 to 0.12 wt% indicating improved antifouling behavior with MMT.

Influence of the Zeolite ZSM-22 Precursor on a UF-PES Selective Substrate Layer for Salts Rejection.

Fabrication of the ZSM-22/Polyethersulfone (ZSM-22/PES) membranes as selective salt filters represent a growing membrane technological area in separation with the potential of high economic reward based on its low energy requirements. The incorporation of ZSM-22 zeolite material as additives into the PES polymer matrix has the prospective advantage of combining both the zeolite and polymer features while overcoming the limitations associated with both materials. This work investigated the influence of the nature of the silica precursor on ZSM-22 zeolite hydrothermally synthesised using colloidal (C60) and fumed (C60) silica to Si/Al of 60. The successful synthesis of the highly crystalline zeolitic materials was confirmed through XRD, FTIR, and SEM with EDX. The ZSM-22 additives were directly dispersed into a PES polymeric matrix to form a casting solution for the preparation of the ZSM-22/PES selective substrate layers via a phase inversion method for salts rejection. The polymeric PES was selected as an organic network in which the content of the ZSM-22 zeolite (ranging between 0 and 1.0 wt.%), was obtained and characterised by XRD, FTIR, and SEM analysis, as well as water contact angle (WCA) measurement and dead-end filtration cell. The phase inversion preparation method has induced the resulting ZSM-22/PES NF substrates anisotropy, as attributed to a high water flux to the above 700 L·m−2·h−1; high selectivity and rejection of salts to above 80% is revealed by the obtained results. The materials also exhibited improved antifouling behavior to above 70% flux recovery ratios. As such, the nature of the silica precursor influences ZSM-22 zeolite synthesis as a potential additive in the PES polymer matrix and led to the enhanced performance of the pure PES ultrafiltration membrane.

Cement-Biofouling and Sulfate Resistivity of Hardened Blended Cement Pastes in Marin Environment: A Case Study

In the present study, field examinations are explored on diversed blended cement mixes. The hardened blended pastes are prepared using ordinary Portland cement (OPC), fine metakaolin (MK) and brine chlorine sludge(CLS). Cement fouling features and the attack by SO4-2 ions are studied on the blended samples that are immersed in the sea water for 9 months. The performance of the cured specimens was explored via studying the compressive strength, the percent of mass change and the volume expansion at various curing durations. Besides, the total chlorophyll colonized on the surface of the cured specimens was determined by using spectrophotometeric technique. XRD and SEM techniques are specifed for studying the phase compositions and the morphology of the formed cement hydrates. The results illustrate that the blended mixes show an antifouling behavior higher than the neat OPC. This is related to acquiring a more compact structure of reduced porosities upon OPC blending. Additionally, OPC-MK specimens showed higher SO-42 ions resistance than OPC-CLS or OPC pastes. This is related to the high pozzolanic properties of MK in contrary to brine sludge.