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1
Shetty, Nitin, Marappagounder Ramasamy, and Rajashekhar Pendyala. "Effect of Bulk Temperature on Formation of Crude Oil Fouling Precursors on Heat Transfer Surfaces." Applied Mechanics and Materials 625 (September 2014): 482–85. http://dx.doi.org/10.4028/www.scientific.net/amm.625.482.
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Temperature plays a very important role in the formation of fouling precursors in crude oils which is considered to be the first step before the precursors are either attached to the wall as a deposit or transferred back to the bulk fluid by diffusion. In order to investigate the formation characteristics of fouling precursors in crude oils at different bulk temperatures, a custom-design thin film microreactor is constructed. It is observed during the experiments that tendency to form fouling precursors is higher at higher surface temperatures. The precursor particles once formed continue to grow in size with time at constant surface temperatures. It is also observed that the particles tend to grow in size while it is cooled when the temperatures are below 55 oC.
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Wray, Heather E., Robert C. Andrews, and Pierre R. Bérubé. "Coagulation optimization for DOC removal: pilot-scale analysis of UF fouling and disinfection byproduct formation potential." Water Supply 16, no. 2 (October 26, 2015): 473–80. http://dx.doi.org/10.2166/ws.2015.157.
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A pilot-scale study was performed to evaluate a coagulant dose which had been optimized for biopolymer (i.e., foulant) removal on subsequent ultrafiltration (UF) fouling, as well as disinfection by-product (DBP) precursor removal. Polyaluminum chloride (PACl) dosages were selected based on a point of diminishing returns for biopolymer removal (0.5 mg/L) and directly compared to that applied at full-scale (6 mg/L). Membrane fouling (reversible and irreversible) was measured as resistance increase over a 48 hour filtration period. DBP formation potential (total trihalomethanes (TTHMs), haloacetic acids (HAA9) and total adsorbable organic halides (AOX)) were measured in both raw and treated waters. Results of the study indicate that application of a PACl dose optimized for biopolymer reduction (0.5 mg/L) resulted in 65% less irreversible UF fouling when compared to 6 mg/L. The addition of PACl prior to the membrane resulted in up to a 14% reduction in DBP precursors relative to the UF membrane alone. A similar level of DBP precursor reduction was achieved for both 0.5 and 6 mg/L dosages. The results have implications for cost savings, which may be realized due to decreased chemical use, as well as increased membrane life associated with lower irreversible fouling rates.
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Ramasamy, M., and Umesh B. Deshannavar. "Effect of Bulk Temperature and Heating Regime on Crude Oil Fouling: An Analysis." Advanced Materials Research 917 (June 2014): 189–98. http://dx.doi.org/10.4028/www.scientific.net/amr.917.189.
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Semi-empirical threshold fouling models predict higher fouling rates at high surface or film temperatures. Several experimental fouling data reported in literature and from our study were analyzed with respect to increase in surface and bulk temperatures that showed a decrease in fouling rates. The existing threshold fouling models do not adequately describe the phenomenon of decreasing fouling rates with increase in surface or bulk temperatures. The possible causes including the effect of temperature difference, heating regime and solubility of fouling precursors were analyzed and reported.
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Takeuchi, Haruka, Naoyuki Yamashita, Norihide Nakada, and Hiroaki Tanaka. "Removal Characteristics of N-Nitrosamines and Their Precursors by Pilot-Scale Integrated Membrane Systems for Water Reuse." International Journal of Environmental Research and Public Health 15, no. 9 (September 7, 2018): 1960. http://dx.doi.org/10.3390/ijerph15091960.
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This study investigated the removal characteristics of N-Nitrosamines and their precursors at three pilot-scale water reclamation plants. These plants applies different integrated membrane systems: (1) microfiltration (MF)/nanofiltration (NF)/reverse osmosis (RO) membrane; (2) sand filtration/three-stage RO; and (3) ultrafiltration (UF)/NF and UF/RO. Variable removal of N-Nitrosodimethylamine (NDMA) by the RO processes could be attributed to membrane fouling and the feed water temperature. The effect of membrane fouling on N-Nitrosamine removal was extensively evaluated at one of the plants by conducting one month of operation and chemical cleaning of the RO element. Membrane fouling enhanced N-Nitrosamine removal by the pilot-scale RO process. This finding contributes to better understanding of the variable removal of NDMA by RO processes. This study also investigated the removal characteristics of N-Nitrosamine precursors. The NF and RO processes greatly reduced NDMA formation potential (FP), but the UF process had little effect. The contributions of MF, NF, and RO processes for reducing FPs of NDMA, N-Nitrosopyrrolidine and N-Nitrosodiethylamine were different, suggesting different size distributions of their precursors.
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Azzeh, Jamal, Lizbeth Taylor-Edmonds, and Robert C. Andrews. "Engineered biofiltration for ultrafiltration fouling mitigation and disinfection by-product precursor control." Water Supply 15, no. 1 (September 10, 2014): 124–33. http://dx.doi.org/10.2166/ws.2014.091.
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A pilot-scale study was conducted to evaluate the impact of several biofiltration enhancement strategies in terms of organic removal to reduce disinfection by-product (DBP) formation potential and mitigate ultrafiltration (UF) fouling. Strategies included nutrient addition (nitrogen and phosphorus) to optimize metabolic degradation of organics, use of hydrogen peroxide (H2O2, peroxide) to improve filter run times, and the application of in-line aluminum sulphate (alum) for biopolymer removal. The impact of media type on performance was also examined (anthracite versus granular activated carbon (GAC)). Passive biofiltration (without enhancement) reduced dissolved organic carbon (∼5%), biopolymers (∼20%), and trihalomethane and haloacetic acid precursors (∼20% and ∼12%, respectively) while mitigating UF irreversible fouling (∼60%). Nutrient addition was not observed to enhance biological performance. Addition of 0.5 mg/L hydrogen peroxide decreased head loss by up to 45% without affecting organic removal; however at a dosage of 1 mg/L, it negatively impacted both UF fouling and DBP precursor removal. In-line alum addition prior to biofiltration (<0.5 mg/L) improved UF fouling control by up to 40%, without sacrificing head loss. Overall, GAC provided superior performance when compared to anthracite.
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Millanar-Marfa, Jessa, Laura Borea, Mark de Luna, Florencio Ballesteros, Vincenzo Belgiorno, and Vincenzo Naddeo. "Fouling Mitigation and Wastewater Treatment Enhancement through the Application of an Electro Moving Bed Membrane Bioreactor (eMB-MBR)." Membranes 8, no. 4 (November 22, 2018): 116. http://dx.doi.org/10.3390/membranes8040116.
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High operational cost due to membrane fouling propensity remains a major drawback for the widespread application of membrane bioreactor (MBR) technology. As a result, studies on membrane fouling mitigation through the application of integrated processes have been widely explored. In this work, the combined application of electrochemical processes and moving bed biofilm reactor (MBBR) technology within an MBR at laboratory scale was performed by applying an intermittent voltage of 3 V/cm to a reactor filled with 30% carriers. The treatment efficiency of the electro moving bed membrane bioreactor (eMB-MBR) technology in terms of ammonium nitrogen (NH4-N) and orthophosphate (PO4-P) removal significantly improved from 49.8% and 76.7% in the moving bed membrane bioreactor (MB-MBR) control system to 55% and 98.7% in the eMB-MBR, respectively. Additionally, concentrations of known fouling precursors and membrane fouling rate were noticeably lower in the eMB-MBR system as compared to the control system. Hence, this study successfully demonstrated an innovative and effective technology (i.e., eMB-MBR) to improve MBR performance in terms of both conventional contaminant removal and fouling mitigation.
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Jamieson, Tamar, Harriet Whiley, Jason R. Gascooke, and Sophie C. Leterme. "Can Aggregate-Associated Organisms Influence the Fouling in a SWRO Desalination Plant?" Microorganisms 10, no. 4 (March 22, 2022): 682. http://dx.doi.org/10.3390/microorganisms10040682.
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This pilot study investigates the formation of aggregates within a desalination plant, before and after pre-treatment, as well as their potential impact on fouling. The objective is to provide an understanding of the biofouling potential of the feed water within a seawater reverse osmosis (SWRO) desalination plant, due to the limited removal of fouling precursors. The 16S and 18S rRNA was extracted from the water samples, and the aggregates and sequenced. Pre-treatment systems, within the plant remove < 5 µm precursors and organisms; however, smaller size particles progress through the plant, allowing for the formation of aggregates. These become hot spots for microbes, due to their nutrient gradients, facilitating the formation of niche environments, supporting the proliferation of those organisms. Aggregate-associated organisms are consistent with those identified on fouled SWRO membranes. This study examines, for the first time, the factors supporting the formation of aggregates within a desalination system, as well as their microbial communities and biofouling potential.
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Bu, Fan, Baoyu Gao, Qinyan Yue, Caiyu Liu, Wenyu Wang, and Xue Shen. "The Combination of Coagulation and Adsorption for Controlling Ultra-Filtration Membrane Fouling in Water Treatment." Water 11, no. 1 (January 8, 2019): 90. http://dx.doi.org/10.3390/w11010090.
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Ultra-filtration technology has been increasingly used in drinking water treatment due to improvements in membrane performance and lowering of costs. However, membrane fouling is the main limitation in the application of ultra-filtration technology. In this study, we investigated the impact of four different pre-treatments: Coagulation, adsorption, coagulation followed by adsorption (C-A), and simultaneous coagulation and adsorption (C+A), on membrane fouling and natural organic matter removal efficiency. The results showed that adsorption process required a large amount of adsorbent and formed a dense cake layer on the membrane surface leading to severe membrane fouling. Compared to adsorption alone, the coagulation and C-A processes decreased the transmembrane pressure by 4.9 kPa. It was due to less accumulation of particles on the membrane surface. As for water quality, the C-A ultra-filtration process achieved the highest removal efficiencies of natural organic matter and disinfection by-product precursors. Therefore, the addition of adsorbent after coagulation is a potentially important approach for alleviating ultra-filtration membrane fouling and enhancing treatment performance.
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Davies, S. H., M. J. Baumann, S. Byun, L. M. Corneal, V. V. Tarabara, and S. J. Masten. "Fabrication of catalytic ceramic membranes for water filtration." Water Supply 10, no. 1 (March 1, 2010): 81–86. http://dx.doi.org/10.2166/ws.2010.789.
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The paper describes the use of the layer-by-layer technique to coat ceramic membranes with iron and manganese oxide nanoparticles. The coatings are thin (<50 nm) and relatively uniform. These coatings enhance the performance of the hybrid ozonation-filtration process. With the coated membranes it is possible to significantly reduce fouling, improve the removal of DBP precursors and more effectively kill Escherichia coli bacteria.
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Sfameni, Silvia, Giulia Rando, Maurilio Galletta, Ileana Ielo, Marco Brucale, Filomena De Leo, Paola Cardiano, et al. "Design and Development of Fluorinated and Biocide-Free Sol–Gel Based Hybrid Functional Coatings for Anti-Biofouling/Foul-Release Activity." Gels 8, no. 9 (August 26, 2022): 538. http://dx.doi.org/10.3390/gels8090538.
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Biofouling has destructive effects on shipping and leisure vessels, thus producing severe problems for marine and naval sectors due to corrosion with consequent elevated fuel consumption and higher maintenance costs. The development of anti-fouling or fouling release coatings creates deterrent surfaces that prevent the initial settlement of microorganisms. In this regard, new silica-based materials were prepared using two alkoxysilane cross-linkers containing epoxy and amine groups (i.e., 3-Glycidyloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively), in combination with two functional fluoro-silane (i.e., 3,3,3-trifluoropropyl-trimethoxysilane and glycidyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononylether) featuring well-known hydro repellent and anti-corrosion properties. As a matter of fact, the co-condensation of alkoxysilane featuring epoxide and amine ends, also mixed with two opportune long chain and short chain perfluorosilane precursors, allows getting stable amphiphilic, non-toxic, fouling release coatings. The sol–gel mixtures on coated glass slides were fully characterized by FT-IR spectroscopy, while the morphology was studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). The fouling release properties were evaluated through tests on treated glass slides in different microbial suspensions in seawater-based mediums and in seawater natural microcosms. The developed fluorinated coatings show suitable antimicrobial activities and low adhesive properties; no biocidal effects were observed for the microorganisms (bacteria).
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Shevate, Rahul, Vepa Rozyyev, Rajesh Pathak, Anil U. Mane, Seth B. Darling, and Jeffrey W. Elam. "Tailoring the Interfacial Interactions of Porous Polymer Membranes to Accelerate Atomic Layer Deposition: The Latent Path to Antifouling Membranes." ECS Meeting Abstracts MA2022-02, no. 31 (October 9, 2022): 1160. http://dx.doi.org/10.1149/ma2022-02311160mtgabs.
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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.
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Li, Sheng, Harvey Winters, Sanghyun Jeong, Abdul-Hamid Emwas, Saravanamuthu Vigneswaran, and Gary L. Amy. "Marine bacterial transparent exopolymer particles (TEP) and TEP precursors: Characterization and RO fouling potential." Desalination 379 (February 2016): 68–74. http://dx.doi.org/10.1016/j.desal.2015.10.005.
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Corsino, Santo Fabio, Gaetano Di Bella, Francesco Traina, Lucia Argiz Montes, Angeles Val del Rio, Anuska Mosquera Corral, Michele Torregrossa, and Gaspare Viviani. "Membrane Fouling Mitigation in MBR via the Feast–Famine Strategy to Enhance PHA Production by Activated Sludge." Membranes 12, no. 7 (July 12, 2022): 703. http://dx.doi.org/10.3390/membranes12070703.
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Fouling is considered one of the main drawbacks of membrane bioreactor (MBR) technology. Among the main fouling agents, extracellular polymeric substances (EPS) are considered one of the most impactful since they cause the decrease of sludge filterability and decline of membrane flux in the long term. The present study investigated a biological strategy to reduce the membrane-fouling tendency in MBR systems. This consisted of seeding the reactor with activated sludge enriched in microorganisms with polyhydroxyalkanoate (PHA) storage ability and by imposing proper operating conditions to drive the carbon toward intracellular (PHA) rather than extracellular (EPS) accumulation. For that purpose, an MBR lab-scale plant was operated for 175 days, divided into four periods (1–4) according to different food to microorganisms’ ratios (F/M) (0.80 kg COD kg TSS−1 d−1 (Period 1), 0.13 kg COD kg TSS−1 d−1 (Period 2), 0.28 kg COD kg TSS−1 d−1 (Period 3), and 0.38 kg COD kg TSS−1 d−1 (Period 4)). The application of the feast/famine strategy favored the accumulation of intracellular polymers by bacteria. The increase of the PHA accumulation inside the cells corresponded to the decrease of EPS and an F/M of 0.40–0.50 kg COD kg TSS−1 d−1 was found as optimum to maximize the PHA production, while minimizing EPS. The lowest EPS content in the sludge (18% of total suspended solids) that corresponded to the maximum content of PHA (9.3%) was found in Period 4 and determined significant mitigation of the fouling rate, whose value was close to 0.10 × 1011 m−1 h−1. Thus, by imposing proper operating conditions, it was possible to drive the organic matter toward PHA accumulation. Moreover, a lower EPS content corresponded to a decrease in the irreversible fouling mechanism, which would imply a lower frequency of the extraordinary cleaning operations. This study highlighted the possibility of obtaining a double benefit by applying an MBR system in the frame of wastewater valorization: minimizing the fouling tendency of the membrane and recovery precursors of bioplastics from wastewater in line with the circular economy model.
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Hou, An-Li, Szu-Yi Wang, Wen-Pin Lin, Wei-Hsuan Kuo, Tsung-Jen Wang, and Meng-Jiy Wang. "Surface Antifouling Modification on Polyethylene Filtration Membranes by Plasma Polymerization." Materials 13, no. 21 (November 6, 2020): 5020. http://dx.doi.org/10.3390/ma13215020.
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Surface modification on microporous polyethylene (PE) membranes was facilitated by plasma polymerizing with two hydrophilic precursors: ethylene oxide vinyl ether (EO1V) and diethylene oxide vinyl ether (EO2V) to effectively improve the fouling against mammalian cells (Chinese hamster ovary, CHO cells) and proteins (bovine serum albumin, BSA). The plasma polymerization procedure incorporated uniform and pin-hole free ethylene oxide-containing moieties on the filtration membrane in a dry single-step process. The successful deposition of the plasma polymers was verified by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses. Water contact angle measurements and permeation experiments using cell and protein solutions were conducted to evaluate the change in hydrophilicity and fouling resistance for filtrating biomolecules. The EO1V and EO2V plasma deposited PE membranes showed about 1.45 fold higher filtration performance than the pristine membrane. Moreover, the flux recovery reached 80% and 90% by using deionized (DI) water and sodium hydroxide (NaOH) solution, indicating the efficacy of the modification and the good reusability of the modified PE membranes.
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Rittschof, Daniel, Tara Essock-Burns, Gary Dickinson, S. Zmina, and N. Alberman. "Natural glues and fouling management by interfering with glue curing." Journal of Agricultural and Marine Sciences [JAMS] 20 (January 1, 2015): 34. http://dx.doi.org/10.24200/jams.vol20iss0pp34-39.
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Multidisciplinary approaches and modern technology provide insights to glue curing that are stimulatingand controversial. Our team applies classic and modern theory and techniques to the study of barnacle glue. Techniques include physical measures, bacteriology, behavior, physiology, biochemistry, microscopy, spectroscopy, tomography, tandem mass spectrometry, molecular biology and proteomics. Theory is grounded in evolution and previous literature. Here, we use data from these techniques to support the hypothesis that barnacle glue curing is similar toblood clotting and propose a model for how glue cures. Similar to blood clotting, barnacle glue curing involves enzymatic activation of precursors and rearrangement of structural molecules to form a crosslinked material. Barnacle larval settlement, bacteriology and biochemical data show glue contains large amounts of small peptides. Their role in glue curing has been overlooked. The peptides comprise 15 to 30% of partially cured glue. Because they have little secondary structure, the peptides can associate with binding domains on the substrate and interface with the larger, well-described structural proteins known in barnacle glue. Enzymes participate in curing of barnacle glue. Siloxanes impact glue-curing enzymes. They potentiate trypsin activity and inhibit transglutaminase activity. Changing enzymeactivity impacts how glue cures. Disrupting the curing process of biological glues is central to effective cleaning strategies for fouling management. Thus silicones that interfere with enzyme activity have potential as additives in easy cleansurfaces. The environmental impacts of organosilicones that are generated by biological processes need to be addressed
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Ahmad, Abdul Latif, Nuur Fahanis Che Lah, Nur Amelia Norzli, and Wen Yu Pang. "A Contrastive Study of Self-Assembly and Physical Blending Mechanism of TiO2 Blended Polyethersulfone Membranes for Enhanced Humic Acid Removal and Alleviation of Membrane Fouling." Membranes 12, no. 2 (January 29, 2022): 162. http://dx.doi.org/10.3390/membranes12020162.
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In this study, membrane fabrication was achieved by two different methods: (i) self-assembly and (ii) physical blending of TiO2 in PES membrane for humic acid filtration. The TiO2 nanoparticles were self-assembled by using TBT as the precursor and pluronic F127 as triblock copolymers around the membrane pores. This was achieved by manipulating the hydrolysis and condensation reaction of TBT precursors during the non-solvent induced phase separation (NIPS) process. On the other hand, the TiO2 was physically blended as a comparison to the previous method. The characteristic of the membrane was analysed to explore the possibility of enhancing the membrane antifouling mechanism and the membrane flux. The membrane morphology, pore size, porosity, and contact angle were characterised. Both methods proved to be able to enhance the antifouling properties and flux performance. The HA rejection increased up to 95% with membrane flux 55.40 kg m−2 h−1. The rejection rate was not significantly improved for either method. However, the antifouling characteristic for the self-assembly TiO2/PES membrane was better than the physically blended membrane. This was found to be due to the high surface hydrophilicity of the MM membrane, which repelled the hydrophobic HA and consequently blocked the HA adsorption onto the surface.
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Castaldo, Rachele, Mariagrazia Iuliano, Mariacristina Cocca, Veronica Ambrogi, Gennaro Gentile, and Maria Sarno. "A New Route for Low Pressure and Temperature CWAO: A PtRu/MoS2_Hyper-Crosslinked Nanocomposite." Nanomaterials 9, no. 10 (October 17, 2019): 1477. http://dx.doi.org/10.3390/nano9101477.
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PtRu/MoS2 nanoparticles (NPs) (PtRu alloy partially coated by one-layer MoS2 nanosheets) were prepared through a ‘wet chemistry’ approach. The obtained NPs were directly embedded, at 5 parts per hundred resin/rubber (phr) loading, in a poly (divinylbenzene-co-vinyl benzyl chloride) hyper-crosslinked (HCL) resin, synthesized via bulk polymerization of the resin precursors, followed by conventional FeCl3 post-crosslinking. The obtained HCL nanocomposites were characterized to evaluate the effect of the NPs. It shows a high degree of crosslinking, a good dispersion of NPs and a surface area up to 1870 ± 20 m2/g. The catalytic activity of the HCL nanocomposite on phenol wet air oxidation was tested at low air pressure (Pair = 0.3 MPa) and temperature (T = 95 °C), and at different phenol concentrations. At the lower phenol concentration, the nanocomposite gives a total organic carbon (TOC) conversion of 97.1%, with a mineralization degree of 96.8%. At higher phenol concentrations, a phenol removal of 99.9%, after 420 min, was achieved, indicating a quasi-complete depletion of phenol, with a TOC conversion of 86.5%, corresponding to a mineralization degree of 84.2%. Catalyst fouling was evaluated, showing good reusability of the obtained nanocomposite.
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Lebedev, Denis, Maxim Novomlinsky, Vladimir Kochemirovsky, Ilya Ryzhkov, Irina Anfimova, Maxim Panov, and Tatyana Antropova. "Glass/Au Composite Membranes with Gold Nanoparticles Synthesized inside Pores for Selective Ion Transport." Materials 13, no. 7 (April 9, 2020): 1767. http://dx.doi.org/10.3390/ma13071767.
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Nanocomposite membranes have been actively developed in the last decade. The involvement of nanostructures can improve the permeability, selectivity, and anti-fouling properties of a membrane for improved filtration processes. In this work, we propose a novel type of ion-selective Glass/Au composite membrane based on porous glass (PG), which combines the advantages of porous media and promising selective properties. The latter are achieved by depositing gold nanoparticles into the membrane pores by the laser-induced liquid phase chemical deposition technique. Inside the pores, gold nanoparticles with an average diameter 25 nm were formed, which was confirmed by optical and microscopic studies. To study the transport and selective properties of the PG/Au composite membrane, the potentiometric method was applied. The uniform potential model was used to determine the surface charge from the experimental data. It was found that the formation of gold nanoparticles inside membrane pores leads to an increase in the surface charge from −2.75 mC/m2 to −5.42 mC/m2. The methods proposed in this work allow the creation of a whole family of composite materials based on porous glasses. In this case, conceptually, the synthesis of these materials will differ only in the selection of initial precursors.
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Gheata, Adrian, Alessandra Spada, Manon Wittwer, Ameni Dhouib, Emilie Molina, Yannick Mugnier, and Sandrine Gerber-Lemaire. "Modulating the Surface Properties of Lithium Niobate Nanoparticles by Multifunctional Coatings Using Water-in-Oil Microemulsions." Nanomaterials 13, no. 3 (January 28, 2023): 522. http://dx.doi.org/10.3390/nano13030522.
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Inorganic nanoparticles (NPs) have emerged as promising tools in biomedical applications, owing to their inherent physicochemical properties and their ease of functionalization. In all potential applications, the surface functionalization strategy is a key step to ensure that NPs are able to overcome the barriers encountered in physiological media, while introducing specific reactive moieties to enable post-functionalization. Silanization appears as a versatile NP-coating strategy, due to the biocompatibility and stability of silica, thus justifying the need for robust and well controlled silanization protocols. Herein, we describe a procedure for the silica coating of harmonic metal oxide NPs (LiNbO3, LNO) using a water-in-oil microemulsion (W/O ME) approach. Through optimized ME conditions, the silanization of LNO NPs was achieved by the condensation of silica precursors (TEOS, APTES derivatives) on the oxide surface, resulting in the formation of coated NPs displaying carboxyl (LNO@COOH) or azide (LNO@N3) reactive moieties. LNO@COOH NPs were further conjugated to an unnatural azido-containing small peptide to obtain silica-coated LNO NPs (LNO@Talys), displaying both azide and carboxyl moieties, which are well suited for biomedical applications due to the orthogonality of their surface functional groups, their colloidal stability in aqueous medium, and their anti-fouling properties.
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Bouzid, Habib, Murielle Rabiller-Baudry, Lydie Paugam, Florence Rousseau, Zoubir Derriche, and Nourre Eddine Bettahar. "Impact of zeta potential and size of caseins as precursors of fouling deposit on limiting and critical fluxes in spiral ultrafiltration of modified skim milks." Journal of Membrane Science 314, no. 1-2 (April 2008): 67–75. http://dx.doi.org/10.1016/j.memsci.2008.01.028.
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Chaudhary, Rimsha, Khadija Nawaz, Amna Komal Khan, Christophe Hano, Bilal Haider Abbasi, and Sumaira Anjum. "An Overview of the Algae-Mediated Biosynthesis of Nanoparticles and Their Biomedical Applications." Biomolecules 10, no. 11 (October 30, 2020): 1498. http://dx.doi.org/10.3390/biom10111498.
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Algae have long been exploited commercially and industrially as food, feed, additives, cosmetics, pharmaceuticals, and fertilizer, but now the trend is shifting towards the algae-mediated green synthesis of nanoparticles (NPs). This trend is increasing day by day, as algae are a rich source of secondary metabolites, easy to cultivate, have fast growth, and are scalable. In recent era, green synthesis of NPs has gained widespread attention as a safe, simple, sustainable, cost-effective, and eco-friendly protocol. The secondary metabolites from algae reduce, cap, and stabilize the metal precursors to form metal, metal oxide, or bimetallic NPs. The NPs synthesis could either be intracellular or extracellular depending on the location of NPs synthesis and reducing agents. Among the diverse range of algae, the most widely investigated algae for the biosynthesis of NPs documented are brown, red, blue-green, micro and macro green algae. Due to the biocompatibility, safety and unique physico-chemical properties of NPs, the algal biosynthesized NPs have also been studied for their biomedical applications, which include anti-bacterial, anti-fungal, anti-cancerous, anti-fouling, bioremediation, and biosensing activities. In this review, the rationale behind the algal-mediated biosynthesis of metallic, metallic oxide, and bimetallic NPs from various algae have been reviewed. Furthermore, an insight into the mechanism of biosynthesis of NPs from algae and their biomedical applications has been reviewed critically.
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Jain, A. "Algae-mediated synthesis of biogenic nanoparticles." Advances in Natural Sciences: Nanoscience and Nanotechnology 13, no. 4 (October 26, 2022): 043001. http://dx.doi.org/10.1088/2043-6262/ac996a.
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Abstract In recent era, green trend of synthesising biogenic nanoparticles (NPs) is a sustainable, safe, environment-friendly, and relatively inexpensive substitute to conservative routes of NPs making. Biosynthesis route showcases significant properties such as the absence of poisonous chemical compounds used as stabilising or reducing agents, lack of toxic yields generated from the process, reduced energy consumption, inexpensiveness, and high scalability. This has made green synthesis methods more attractive than other traditional methods. Synthesis of nanomaterials (NMs) using algae extracts is a substantiating ecological, simple, low-priced biosynthesis process. The secondary metabolites from algae have been reported to reduce metal precursors to nanoparticles (metal, metal oxide, or bimetallic NPs). Moreover, they cap and stabilise. Depending on the site of NP formation, synthesis could occur intra or extra-cellularly. Among the varied series of algae mediated synthesis, the most commonly biosynthesised NPs are silver, gold, copper oxide, cuprous oxide and zinc oxide. The algal biosynthesised NPs have been reviewed for numerous biomedical applications, which comprise anti-cancerous, anti-fouling, anti-bacterial, anti-fungal, bioremediation, and biosensing activities. The current review draws the major stress on the basis behind the algal-mediated biosynthesis of metallic and metallic oxide NPs from various algae. Furthermore, special attention to critical understanding of biosynthesis mechanism of NPs from algae and their biomedical applications has been reviewed critically.
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Niemann, Hendrik, Andreas Marmann, Wenhan Lin, and Peter Proksch. "Sponge Derived Bromotyrosines: Structural Diversity through Natural Combinatorial Chemistry." Natural Product Communications 10, no. 1 (January 2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000143.
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Sponge derived bromotyrosines are a multifaceted class of marine bioactive compounds that are important for the chemical defense of sponges but also for drug discovery programs as well as for technical applications in the field of antifouling constituents. These compounds, which are mainly accumulated by Verongid sponges, exhibit a diverse range of bioactivities including antibiotic, cytotoxic and antifouling effects. In spite of the simple biogenetic building blocks, which consist only of brominated tyrosine and tyramine units, an impressive diversity of different compounds is obtained through different linkages between these precursors and through structural modifications of the side chains and/or aromatic rings resembling strategies that are known from combinatorial chemistry. As examples for bioactive, structurally divergent bromotyrosines psammaplin A, Aplysina alkaloids featuring aerothionin, aeroplysinin-1 and the dienone, and the bastadins, including the synthetically derived hemibastadin congeners, have been selected for this review. Whereas all of these natural products are believed to be involved in the chemical defense of sponges, some of them may also be of particular relevance to drug discovery due to their interaction with specific molecular targets in eukaryotic cells. These targets involve important enzymes and receptors, such as histone deacetylases (HDAC) and DNA methyltransferases (DNMT), which are inhibited by psammaplin A, as well as ryanodine receptors that are targeted by bastadine type compounds. The hemibastadins such as the synthetically derived dibromohemibastadin are of particular interest due to their antifouling activity. For the latter, a phenoloxidase which catalyzes the bioglue formation needed for firm attachment of fouling organisms to a given substrate was identified as a molecular target. The Aplysina alkaloids finally provide a vivid example for dynamic wound induced bioconversions of natural products that generate highly efficient chemical weapons precisely when and where needed.
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Zahoor, Muhammad, Azmat Ullah, Sultan Alam, Mian Muhammad, Roy Hendroko Setyobudi, Ivar Zekker, and Amir Sohail. "Novel Magnetite Nanocomposites (Fe3O4/C) for Efficient Immobilization of Ciprofloxacin from Aqueous Solutions through Adsorption Pretreatment and Membrane Processes." Water 14, no. 5 (February 24, 2022): 724. http://dx.doi.org/10.3390/w14050724.
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The release of antibiotics into the aquatic environment enhances the drug resistance capabilities of microorganisms, as in large water reservoirs, their concentrations are lesser than their minimum bactericidal concentration, and microorganisms living there become resistant to such antibiotics. Therefore, robust hybrid technologies, comprising of efficient conventional adsorption processes and modern membranes processes, are needed to effectively remove such pollutants from industrial effluents. The present study is an attempt where iron-based magnetic carbon nanocomposites (Fe3O4/C) were prepared from mango biomass precursors and utilized as an adsorbent for the removal ciprofloxacin from wastewater in combination with three types of membranes that are robust but fouled by organic matter. The Fe3O4/C composite was characterized using energy dispersive X-Ray (EDX) technique, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), Barrett–Joyner-Halenda (BJH) surface area, Thermogravimetric (TG)/Thermal differential analysis (DTA) and point of zero charge pH analyses. Initially, batch adsorption experiments were used to determine adsorption parameters. Then the adsorption unit was coupled with membrane pilot plant where the adsorption role was to adsorb CIPRO before entering into the membrane unit to control fouling caused by selected antibiotic. In batch experiments, the equilibrium time was found as 60 min and kinetics data were more favorably accommodated with the pseudo-2nd-order model (R2 = 0.99). Langmuir model (R2 = 0.997) more favorably accommodated the equilibrium data in comparison to other models used such as the Freundlich (R2 = 0.86), Temkin (R2 = 0.91) and Jovanovich (R2 = 0.95) models. The thermodynamic aspects of the adsorption process were also evaluated and the process was found to be spontaneous, feasible and exothermic. The influence of adsorbent dosage and pH, were also investigated, where the optimal adsorption conditions were: optimum pH = 7 and optimum Fe3O4/C dosage = 0.04 g. The CIPRO-loaded nanocomposite was regenerated with NaOH, CH3OH and distilled water several times. Improved percent rejections of CIPRO and permeate fluxes with the membrane/adsorption operation were observed as compared to naked membrane operations. Magnetic adsorbent was found as a best solution of foul control; a defect in the modern robust technology of membranes. However, further experimentation is needed to validate the present findings.
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Suhaimi, A., E. Mahmoudi, K. S. Siow, and M. F. Mohd Razip Wee. "Surface Modification of Polyamide Ultrafiltration Membrane by Plasma Polymerisation of Acrylic Acid." Sains Malaysiana 49, no. 12 (December 31, 2020): 3043–50. http://dx.doi.org/10.17576/jsm-2020-4912-17.
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Increase in hydrophilicity of the filtration membrane could attribute to the fouling reduction and overall filtration performance. In this study, we employ a surface modification on polyamide (PA) membrane by using plasma polymerization with acrylic acid as the precursor by varying the deposition time from 1 to 10 min to induce hydrophilic surface of the membrane without changing the bulk properties of PA membrane. Cross-flow filtration of humic acid using the modified PA membrane was conducted to measure permeates flux and rejection. We calculate the fouling tendencies of each membrane and the result indicates the best performance from sample with 7 min deposition time in terms of permeate flux, rejection and the lowest fouling tendencies. Therefore, this proposed technique could be useful to further improve the commercial filtration membrane; without changing the membrane fabrication process.
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Varcoe, John, Rachida Bance-Souahli, Arup Chakraborty, Mehdi Choolaei, Carol Crean, Carlos Giron Rodriguez, Bjørt Óladóttir Joensen, et al. "The Latest Developments in Radiation-Grafted Anion-Exchange Polymer Electrolytes for Low Temperature Electrochemical Systems." ECS Meeting Abstracts MA2022-01, no. 35 (July 7, 2022): 1443. http://dx.doi.org/10.1149/ma2022-01351443mtgabs.
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Anion-exchange membranes (AEM) are being developed for use in electrochemical technologies including fuel cells (AEMFC),water electrolysis (AEMWE for green hydrogen), electrolysers for CO2 reduction (CO2RR), and reverse electrodialysis (RED). Radiation-grafted AEMs (RG-AEM) represent a promising class of AEM that can exhibit high conductivities (OH- conductivities of > 200 mS cm-1 at temperatures above 60 °C) and favourable in situ water transport characteristics). Hence, RG-AEMs have shown significant promise when tested in AEMFCs alongside powdered radiation-grafted anion-exchange ionomers (RG-AEI), producing high performances and promising durabilities [Energy Environ. Sci., 12, 1575 (2019) and Nature Commun., 11, 3561 (2020)], even at temperatures above 100 °C [Dekel et al., J. Power Sources Adv., 5, 100023 (2020)]. An Achilles heel with RG-AEM types is that they can swell excessively in water and have large dimensional changes between the dehydrated and hydrated states. This limits the ion-exchange capacities (IEC) that can be used: excessive IECs in RG-AEM will cause excessive swelling and poorer robustness. This clearly indicates that additional crosslinking is needed. As Kohl et al. have highlighted, optimised crosslinking can lead to production of high-IEC AEMs that are both robust enough to be < 20 µm in thickness and also low swelling [e.g. J. Electrochem. Soc., 166, F637 (2019)], allowing truly world-leading AEMFC performances. RG-AEMs are also being used as a screening platform for down-selecting different (cationic) head-group chemistries for use in RED cells (a salinity gradient power technology), where different head-groups may lead to different AEM characteristics such as: in-cell resistance (when in contact with aqueous electrolytes), permselectivity, and fouling characteristics (when real world waters such as industrial brines, seawater and freshwater are used). It was evident very early on in these studies that RG-AEMs (desirably) exhibit extremely low resistances but also (undesirably) very low permselectivities when un-crosslinked (less than the required 90%+ permselectivity). Our work on RG-type cation-exchange membranes [Sustainable Energy Fuels, 3, 1682 (2019)] clearly shows that introduction of crosslinking can improve permselectivity. Crosslinking always involves a compromise, where its introduction can improve a membrane characteristic (e.g. reduced swelling or improved permselectivity) but also leads to lower conductivities or poorer transport of chemical species through the membranes. Hence, crosslinking types and levels need to be carefully controlled. With RG-AEMs (made by electron-beam activation (peroxidation) of inert polymer films, followed by grafting of monomers and post-graft amination), we have a choice of introducing crosslinking at various stages. The figure below summarises the two different approaches to crosslinking that will be discussed in the presentation: adding a divinyl-type crosslinker into the grafting mixture or adding a diamine-type crosslinker into the amination step. This presentation will present a selection of recent RG-AEM and RG-AEI developments from a number of projects: (1) REDAEM: AEMs for RED cells [EPSRC Grant EP/R044163/1]; (2) CARAEM: Novel RG-AEMs for AEMFCs and AEMWE [EPSRC Grant EP/T009233/1]; (3) SELECTCO2: RG-AEMs being tested in CO2RR cells [EU Horizon 2020 grant agreement 851441]. This presentation will show: (a) RG-AEMs made from thin high density polyethylene (HDPE) precursors appear better for application in AEMFCs, while RG-AEMs from made from thicker ETFE precursors appear to be better for CO2RR cells and RED; (b) RG-AEMs can be made using a variety of crosslinking strategies; (c) RG-AEIs can be made using ETFE powders and give optimal performance after cryogrinding down to micrometer sizes; Figure 1
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Su, Fei, Ying-Hua Li, Wen-He Deng, Hai-Bo Li, Lei Yang, and Tian-yu Chen. "Study on mitigating membrane fouling based on precursor and flocculant Alb matching in EC/O-UF system." Water Science and Technology 80, no. 9 (November 1, 2019): 1715–24. http://dx.doi.org/10.2166/wst.2019.422.
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Abstract One of the effective ways to remove halogenated disinfection by-products (DBPs) from drinking water is the application of ultrafiltration technology. However, membrane fouling is an important factor affecting the service life and treatment effect. In this study, the electrocoagulation/oxidation-ultrafiltration (EC/O-UF) process was used to remove the precursor substance that produced DBPs, i.e. dissolved organic matters (DOMs). Operating parameters were optimized from the matching of different flocculant morphology to low concentration DOM. The degree of membrane fouling was characterized by analyzing DOMs concentration and membrane flux. The results showed that the optimal conditions for the production of Alb were: current density 10 A/m2, hydraulic retention time 10 min, and initial pH 5.0–7.0. Under these conditions, the production of flocculant Alb could reach 58–61%, 94–97% DOMs were removed by EC/O-UF.
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Giacobbo, Alexandre, Andréa Moura Bernardes, Maria Filipe Rosa, and Maria de Pinho. "Concentration Polarization in Ultrafiltration/Nanofiltration for the Recovery of Polyphenols from Winery Wastewaters." Membranes 8, no. 3 (July 21, 2018): 46. http://dx.doi.org/10.3390/membranes8030046.
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Concentration polarization is intrinsically associated with the selective character of membranes and often means flux decline and which causes a subsequent decrease of ultrafiltration and nanofiltration performance. More important is the fact that it acts as a precursor of membrane fouling and creates severe fouling problems in the longer times range. The quantification of its dependence on the operating parameters of cross-flow velocities and transmembrane pressures makes recourse to the film theory to introduce mass-transfer coefficients that generally are calculated by dimensionless correlations of the Sherwood number as a function of the Reynolds and Schmidt numbers. In the present work, the mass-transfer coefficients are obtained through the fitting of experimental results by the pressure variation method. The ultrafiltration/nanofiltration of the winery wastewaters from the racking operation is carried out with the membranes ETNA 01PP (Alfa Laval) and NF 270 (Dow Filmtec) under a wide range of cross-flow velocities and transmembrane pressures up to 15 bar.
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Ayu Lestari, Riani, Muthia Elma, Erdina Lulu Atika Rampun, Anna Sumardi, Adhe Paramitha, Aptar Eka Lestari, Sadidan Rabiah, Zaini Lambri Assyaifi, and Gesit Satriaji. "Functionalization of Si-C Using TEOS (Tetra Ethyl Ortho Silica) as Precursor and Organic Catalyst." E3S Web of Conferences 148 (2020): 07008. http://dx.doi.org/10.1051/e3sconf/202014807008.
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Silica network was tailored configuring siloxane (Si-O-Si) and silanol (Si-OH) groups which are essential to produce porous-structured materials. As silanols are hydrophilic, react with water to form fouling. This research address to actualize strategy for synthesizing highly functionalized silica carbon (Si-C) using hybrid organic-inorganic structures as the primary method for improving hydro-stability by employing precursor TEOS and organic catalyst through a sol-gel process. Catalysis employs citric acid or citric acid-ammonia whereas carbon templated into silica network. The synthesis scheme involves: a) sol-gel process at 0°C and b) calcination. Silica sol dried into xerogels were prepared and calcined at 200°C and 250°C. Characterization of xerogels showed the infrared band areas of the organic groups to evaluate the thermal stability. For xerogel employed single (pH 5.5) and dual (pH 7.65) catalyst, infrared spectra showed mostly look similar Si-C area at similar wavelength. Silica xerogel is more effectively prepared from TEOS with one-step single acid catalyst including calcination.
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Ahmad, Kim, Kim, and Kim. "Diethylene Glycol-Assisted Organized TiO2 Nanostructures for Photocatalytic Wastewater Treatment Ceramic Membranes." Water 11, no. 4 (April 10, 2019): 750. http://dx.doi.org/10.3390/w11040750.
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A high-performance photocatalytic ceramic membrane was developed by direct growth of a TiO2 structure on a macroporous alumina support using a hydrothermal method. The morphological nanostructure of TiO2 on the support was successfully controlled via the interaction between the TiO2 precursor and a capping agent, diethylene glycol (DEG). The growth of anatase TiO2 nanorods was observed both on the membrane surface and pore walls. The well-organized nanorods TiO2 reduced the perturbation of the alumina support, thus controlling the hydrolysis rate of the TiO2 precursor and reducing membrane fouling. However, a decrease in the amount of the DEG capping agent significantly reduced membrane permeability, owing to the formation of nonporous clusters of TiO2 on the support. Distribution of the organized TiO2 nanorods on the support was very effective for the improvement of the organic removal efficiency and antifouling under ultraviolet illumination. The TiO2 nanostructure associated with the reactive crystalline phase, rather than the amount of layered TiO2 formed on the support, which was found to be the key to controlling photocatalytic membrane reactivity. These experimental findings would provide a new approach for the development of efficacious photocatalytic membranes with improved performance for wastewater treatment.
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Gerasimova, Lidia G., Anatoly I. Nikolaev, Ekaterina S. Shchukina, Marina V. Maslova, Galina O. Kalashnikova, Gleb O. Samburov, and Gregory Yu Ivanyuk. "Hydrochloric Acidic Processing of Titanite Ore to Produce a Synthetic Analogue of Korobitsynite." Minerals 9, no. 5 (May 22, 2019): 315. http://dx.doi.org/10.3390/min9050315.
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The modal composition of (apatite)-nepheline-titanite ore and its geological setting within apatite deposits of the Khibiny Massif allow selective mining of titanite ore and its hydrochloric acidic processing. The reaction of titanite with concentrated hydrochloric acid produces hydrated titanosilicate precipitate (TSP) which, in turn, can be a precursor in titanosilicate synthesis. It is particularly noteworthy that a synthetic analogue of korobitsynite, Na5(Ti3Nb)[Si4O12]2O2(OH)2·7H2O, was synthesized by means of TSP alteration by alkaline hydrothermal solution at 200 °C within three days. The titanosilicate obtained this way has comparatively weak cation-exchange properties regarding Cs+ and Sr2+ cations and considerable photocatalytic activity occurring under visible light, which allows the use of a synthetic korobitsynite analogue (SKR) for production of self-cleaning, sterilizing, and anti-fouling building materials.
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Cheng, Yi-Hsuan, Cheng-Ta Wu, and Lung-Hao Hu. "Dual functional low surface energy coating of anti-corrosion / fouling via crosslinking polysilazane preceramic precursor incorporated with fluorine." Progress in Organic Coatings 177 (April 2023): 107409. http://dx.doi.org/10.1016/j.porgcoat.2023.107409.
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Thoutam, Pranav, Parvin Ahmadi Sefiddashti, Faizan Ahmad, Hani Abulkhair, Iqbal Ahmed, Abdulmohsen Al-saiari, Eydhah Almatrafi, Omar Bamaga, and Sina Rezaei Gomari. "Integration of Hydrate-Based Desalination (HBD) into Multistage Flash (MSF) Desalination as a Precursor: An Alternative Solution to Enhance MSF Performance and Distillate Production." Water 15, no. 3 (February 2, 2023): 596. http://dx.doi.org/10.3390/w15030596.
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This study considers the integration of multistage flash (MSF) desalination with hydrate-based desalination (HBD) precursor to improve MSF performance in terms of distillate production, longevity, and operational conditions. This is accomplished by a comprehensive analysis of the rate of scale formation, distillate production, and the MSF performance ratio by means of mathematical modelling conducted in Simulink software. To calibrate the effectiveness of HBD as precursor to the MSF desalination process, two MSF models were created: the once-through (OT) and brine recycle (BR) configurations. The MSF models were validated in terms of stagewise distillate production, brine temperature, and coolant temperatures with data from the literature, while neglecting the non-equilibrium allowance. The operational performance of the proposed integration approach was evaluated in terms of the deposition rates of CaCO3, scale thickness, fouling resistance, overall heat transfer coefficient, performance ratio, and production ratio. The examination was conducted from the perspective of water salinity and stream temperature for the integrated HBD-MSF systems. The results show that due to the quality of output water in terms of salinity and temperature, the integration of HBD and MSF improved the performance of MSF by substantially reducing scale formation rates as well as increasing the production of distillate where the scale formation rates were 40.6% and 36.3% lower for the hybrid HBD-MSF-OT and HBD-MSF-BR systems, respectively.
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Deng, Ai Hua, Hui Min Huang, and Wen Jin Ji. "Influence of Magnetic Field on Calcium Carbonate Precipitation in the Presence of Foreign Ions." Advanced Materials Research 554-556 (July 2012): 649–56. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.649.
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In this paper, the effect of the adjustable permanent magnetic field with the maximum magnetic flux density as 4100mT on the calcium carbonate(CaCO3) precipitation process was investigated from hard water in the absence and in the presence of foreign ions Al3+、Fe2+、Mg2+、SO42+. By changing the strength of the magnetic field, the fouling resistance efficiency, the total CaCO3precipitation and precipitation in the bulk solution were determined by measurement of the mass of CaCO3precipitation, and the polymorph composition of CaCO3precipitated in bulk solution and particle size fouling on the loading slice was determined by XRD and electron microscope. The effect of MF on the precipitation process of CaCO3was tested by degassifying dissolved CO2in calcocarbonic pure water containing foreign ions. The results showed that magnetic water treatment increased the total precipitation and favored the precipitation in bulk solution instead of precipitating on the walls regardless the presence of foreign ions. The effect is intensifying with the strengthening of the magnetic flux indendity. The Magnetic field (MF) did not affect the polymorph composition of CaCO3in the absence of foreign ions. While in the presence of foreign ions, the precipitation and structure of precipitated CaCO3were significantly affected. The MF favored the precipitation of aragonite and inhibited the formation of calcitein the presence of Mg2+and SO42-. In the case of Al3+and Fe2+, the precipitation of aragonite is favored, calcite and vaterite is inhibited. The MF influenced CaCO3precipitation process by influencing the hydration process of the ions in the solution and changing the dehydration process of hydrated CaCO3as the precursor of crystal nuclei for the magnetic field change the structure of water cluster. The reason that foreign ions can change the polymorph composition of CaCO3is probably owing to its hydration and dehydration.
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Goyat, Rohit, Yajvinder Saharan, Joginder Singh, Ahmad Umar, and Sheikh Akbar. "Synthesis of Graphene-Based Nanocomposites for Environmental Remediation Applications: A Review." Molecules 27, no. 19 (September 29, 2022): 6433. http://dx.doi.org/10.3390/molecules27196433.
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The term graphene was coined using the prefix “graph” taken from graphite and the suffix “-ene” for the C=C bond, by Boehm et al. in 1986. The synthesis of graphene can be done using various methods. The synthesized graphene was further oxidized to graphene oxide (GO) using different methods, to enhance its multitude of applications. Graphene oxide (GO) is the oxidized analogy of graphene, familiar as the only intermediate or precursor for obtaining the latter at a large scale. Graphene oxide has recently obtained enormous popularity in the energy, environment, sensor, and biomedical fields and has been handsomely exploited for water purification membranes. GO is a unique class of mechanically robust, ultrathin, high flux, high-selectivity, and fouling-resistant separation membranes that provide opportunities to advance water desalination technologies. The facile synthesis of GO membranes opens the doors for ideal next-generation membranes as cost-effective and sustainable alternative to long existing thin-film composite membranes for water purification applications. Many types of GO–metal oxide nanocomposites have been used to eradicate the problem of metal ions, halomethanes, other organic pollutants, and different colors from water bodies, making water fit for further use. Furthermore, to enhance the applications of GO/metal oxide nanocomposites, they were deposited on polymeric membranes for water purification due to their relatively low-cost, clear pore-forming mechanism and higher flexibility compared to inorganic membranes. Along with other applications, using these nanocomposites in the preparation of membranes not only resulted in excellent fouling resistance but also could be a possible solution to overcome the trade-off between water permeability and solute selectivity. Hence, a GO/metal oxide nanocomposite could improve overall performance, including antibacterial properties, strength, roughness, pore size, and the surface hydrophilicity of the membrane. In this review, we highlight the structure and synthesis of graphene, as well as graphene oxide, and its decoration with a polymeric membrane for further applications.
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Wu, Junhui, Zhi Wang, Wentao Yan, Yao Wang, Jixiao Wang, and Shichang Wang. "Improving the hydrophilicity and fouling resistance of RO membranes by surface immobilization of PVP based on a metal-polyphenol precursor layer." Journal of Membrane Science 496 (December 2015): 58–69. http://dx.doi.org/10.1016/j.memsci.2015.08.044.
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Giacobbo, Alexandre, Elisa Veridiani Soares, Andréa Moura Bernardes, Maria João Rosa, and Maria Norberta de Pinho. "Atenolol removal by nanofiltration: a case-specific mass transfer correlation." Water Science and Technology 81, no. 2 (January 15, 2020): 210–16. http://dx.doi.org/10.2166/wst.2020.073.
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Abstract Concentration polarization is a phenomenon inherent to membrane separation operations and as a precursor of membrane fouling is frequently related to the decrease in the performance of these operations. In the present work, a case-specific mass transfer correlation was developed to assess the concentration polarization when nanofiltration, in different operating conditions, was applied to treat a pharmaceutical wastewater containing atenolol. NF runs with two membranes, two atenolol concentrations and three feed circulating velocities were conducted, and the corresponding experimental mass transfer coefficients were determined using film theory to describe the concentration polarization phenomenon. Higher velocities led to higher mass transfer coefficients and, consequently, lower concentration polarization. These mass transfer coefficients were correlated with the circulating velocity (Re), the solute diffusivity (Sc) and the membrane permeability (LP+) (the membrane is a permeable interface with effect on the concentration profiles developed from the interface towards the bulk feed), yielding the following correlation Sh = 1.98 × 104Re0.5Sc0.33LP+0.32. The good agreement between the calculated and the experimental results makes this correlation a valuable tool for water practitioners to predict and control the concentration polarization during atenolol-rich wastewater treatment by nanofiltration, thereby increasing its productivity and selectivity.
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Moghimifar, Vahid, Ahmadreza Raisi, Abdolreza Aroujalian, and Niloofar Bayani Bandpey. "Preparation of Nano Crystalline Titanium Dioxide by Microwave Hydrothermal Method." Advanced Materials Research 829 (November 2013): 846–50. http://dx.doi.org/10.4028/www.scientific.net/amr.829.846.
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Titanium dioxide (TiO2) nanoparticles due to their exclusive physical, chemical and electrical properties are widely used as a heterogeneous catalyst and catalytic support in the chemical reactions, a semiconductor for photocatalysis reactions and additives in the membrane processes. The TiO2 nanoparticles are also utilized in solar cells, gas sensors, pigments and etc. Efficiency of these nanoparticles in various applications is dramatically dependent on their size. Various techniques such as combustion flame synthesis and conventional hydrothermal methods have been used to prepare TiO2 nanoparticles, but few synthesis techniques can reproducibly produce particles below 10 nm. In this study, the TiO2 nanoparticles in rutile phase were synthesized by microwave assisted hydrothermal method by controlling the crystallization time and temperature. Titanium tetrachloride (TiCl4) was used as a titanium precursor. The synthesized nanoparticles were characterized by X-ray powder diffraction (XRD) and Scanning Electron Microscope (SEM) analysis. The XRD pattern showed that the rutile phase of the TiO2 nanoparticles was successfully synthesized by the proposed method with the average crystal size of 4nm. Finally, the prepared Titanium dioxide (TiO2) nanoparticles were as a hydrophobic additive in the polymeric ultrafiltration membranes in order to reduce the membrane fouling.
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Hastuti, Lathifah Puji, Ahmad Kusumaatmaja, Adi Darmawan, and Indriana Kartini. "Effect of Polymer Concentration on the Photocatalytic Membrane Performance of PAN/TiO2/CNT Nanofiber for Methylene Blue Removal through Cross-Flow Membrane Reactor." Bulletin of Chemical Reaction Engineering & Catalysis 17, no. 2 (April 14, 2022): 350–62. http://dx.doi.org/10.9767/bcrec.17.2.13668.350-362.
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A photocatalytic membrane combining photocatalyst and membrane technology based on polyacrylonitrile (PAN) and TiO2/CNT has been developed. Such combination is to overcome fouling formation on the membrane, thus prolonging the membrane lifetime and enhancing the efficiency on the waste treatment. PAN nanofiber was prepared by electrospinning method. The precursor solution was dissolved PAN and dispersed TiO2/CNT in N,N-Dimethylformamide (DMF). PAN concentration in the precursor solution was varied at 4.5, 5.5, 6.5, 7.5, and 8.5%. The effect of PAN concentration on the fiber morphology and pore size was discussed. The performance of the resulted membrane on methylene blue (MB) removal was also investigated on a cross-flow system. SEM images of the resulted membrane identified that PAN nanofiber was successfully fabricated with random orientation. The PAN 6.5% showed the highest diffraction intensity of the anatase crystalline phase of TiO2. The additions of CNT and TiO2 lead to the formation of a cluster of beads as confirmed by TEM. Increasing the concentration of PAN increased the fiber diameter from 206 to 506 nm, slightly decreased the surface area and pore size, respectively, from 32.739 to 21.077 m2.g−1 and from 6.38 to 4.75 nm. The PAN/TiO2/CNT nanofibers show type IV of the adsorption-desorption N2 isotherms with the H1 hysteresis loops. Membrane PAN/TiO2/CNT at PAN concentration of 6.5% shows the optimum performance on the MB color removal by maintaining the percentage of rejection (%R) at 90% for 240 min and permeability of 750 LMH. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
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Jang, Wongi, Jaehan Yun, Yejun Park, In Kee Park, Hongsik Byun, and Chang Hyun Lee. "Polyacrylonitrile Nanofiber Membrane Modified with Ag/GO Composite for Water Purification System." Polymers 12, no. 11 (October 22, 2020): 2441. http://dx.doi.org/10.3390/polym12112441.
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Silver nanoparticle-modified graphene oxide (Ag/GO) was reliably prepared by using sodium borohydride (NaBH4) in the presence of citric acid capping agent via a simple wet chemistry method. This rapidly formed Ag/GO composite exhibited good dispersity in a solution containing hydrophilic polyacrylonitrile (PAN). Subsequent electrospinning of this precursor solution resulted in the successful formation of nanofibers without any notable defects. The Ag/GO-incorporated PAN nanofibers showed thinner fiber strands (544 ± 82 nm) compared to those of GO-PAN (688 ± 177 nm) and bare-PAN (656 ± 59 nm). Subsequent thermal treatment of nanofibers resulted in the preparation of thin membranes to possess the desired pore property and outstanding wettability. The Ag/GO-PAN nanofiber membrane also showed 30% higher water flux value (390 LMH) than that of bare-PAN (300 LMH) for possible microfiltration (MF) application. In addition, the resulting Ag/GO-PAN nanofiber membrane exhibited antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). Furthermore, this composite membrane exhibited outstanding anti-fouling property compared to the GO-PAN nanofiber membrane in the wastewater treatment. Therefore, the simple modification strategy allows for the effective formation of Ag/GO composite as a filler that can be reliably incorporated into polymer nanofiber membranes to possess improved overall properties for wastewater treatment applications.
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Mustalifah, F. R., A. Rahma, Mahmud, Sunardi, and M. Elma. "Chemical cleaning to evaluate the performance of silica-pectin membrane on acid mine drainage desalination." IOP Conference Series: Materials Science and Engineering 1195, no. 1 (October 1, 2021): 012057. http://dx.doi.org/10.1088/1757-899x/1195/1/012057.
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Abstract Pervaporation process is an excellent and potential way applied for desalting acid mine drainage water. Nevertheless, the water flux was reduced gradually due to the issue of membrane fouling. To resolve this problem, cleaning process was chosen to maintain the water flux of silica-pectin membranes. This study aims to recover the water flux and salt rejection of the silica-pectin membranes via chemical cleaning process applied for acid mine drainage water desalination with various temperature of feed water (25-60 °C). Silica-pectin membrane was formulated by employing TEOS functioning as silica precursor and pectin as carbon template from banana peels. Chemical cleaning of the membrane carried out by employing TiO2 solution + UV light radiation for an hour. Performance of the silica-pectin membrane was evaluated via pervaporation process under dead-end system. The performance of silica-pectin banana peels membrane found flux recovery from 10.6 kg.m− 2.h−1 and flux recovery of 17.54 kg.m− 2.h−1. It shows that flux recovery higher than before backwashing process. Also, silica-pectin membrane results in all of the salt rejection <99 %. It is concluded that the chemical backwashing process is important to apply to recover the water flux of membrane, also, this process considers to save and reduce the operational costs.
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Jiménez-Robles, Ramón, Beatriz María Moreno-Torralbo, Jose David Badia, Vicente Martínez-Soria, and Marta Izquierdo. "Flat PVDF Membrane with Enhanced Hydrophobicity through Alkali Activation and Organofluorosilanisation for Dissolved Methane Recovery." Membranes 12, no. 4 (April 15, 2022): 426. http://dx.doi.org/10.3390/membranes12040426.
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A three-step surface modification consisting of activation with NaOH, functionalisation with a silica precursor and organofluorosilane mixture (FSiT), and curing was applied to a poly(vinylidene fluoride) (PVDF) membrane for the recovery of dissolved methane (D-CH4) from aqueous streams. Based on the results of a statistical experimental design, the main variables affecting the water contact angle (WCA) were the NaOH concentration and the FSiT ratio and concentration used. The maximum WCA of the modified PVDF (mPVDFmax) was >140° at a NaOH concentration of 5%, an FSiT ratio of 0.55 and an FSiT concentration of 7.2%. The presence of clusters and a lower surface porosity of mPVDF was detected by FESEM analysis. In long-term stability tests with deionised water at 21 L h−1, the WCA of the mPVDF decreased rapidly to around 105°, similar to that of pristine nmPVDF. In contrast, the WCA of the mPVDF was always higher than that of nmPVDF in long-term operation with an anaerobic effluent at 3.5 L h−1 and showed greater mechanical stability, since water breakthrough was detected only with the nmPVDF membrane. D-CH4 degassing tests showed that the increase in hydrophobicity induced by the modification procedure increased the D-CH4 removal efficiency but seemed to promote fouling.
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Kim, Jaeyun, Hyun Kyong Shon, Sunho Joh, Donggeun Jung, Hee-Kyung Na, and Tae Geol Lee. "One-step fabrication method of non-fouling amine-functionalized polyethylene glycol thin film using a single precursor through plasma-enhanced chemical vapor deposition." Surface and Coatings Technology 403 (December 2020): 126384. http://dx.doi.org/10.1016/j.surfcoat.2020.126384.
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Munir, Muhammad Miftahul, Muhamad Prama Ekaputra, Abdul Rajak, Annisa Rahma, Ade Yeti Nuryantini, and Khairurrijal. "Fabrication of Poly(acrylonitrile)/PAN Nanofiber Using a Drum Collector Electrospinning System for Water Purification Application." Advanced Materials Research 1123 (August 2015): 281–84. http://dx.doi.org/10.4028/www.scientific.net/amr.1123.281.
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The development of filtration technique for water purification has been performed ranging from the conventional to the advanced technique such as coagulation, sedimentation, sand filtration, reverse osmosis and nanofiltration. However, the major challenge to be addressed in the filtration technique is the tendency of membrane fouling or clogging. This effect causes a decreasein the flux and effectiveness of membrane filtration. In this study, we reported the fabrication of poly (acrylonitrile)/PAN nanofiber membrane by electrospinning technique and their application for water purification. A drum collector electrospinning system was used to produce uniform nanofiber membrane. Nanofiber membrane was fabricated from precursor solution which was prepared by dissolving poly (acrylonitrile) that has molecular weight of 150.000 g/mol in n,n-dimethylformamide (DMF). PAN nanofiber membrane were fabricated via electrospinning technique with 8wt% in concentration. The morphology of the membrane was characterized by using Scanning Electron Microscopy (SEM). SEM analysis showed that uniform nanofiber was formed with average fiber diameter of 290-370 nm. Three different concentrations of antacid suspension were prepared as the sample in order to test the performance of PAN nanofiber as membrane filter. Flux test was carried out by applying various pressure against the membrane in order to obtain the flux values of each variation of waste water model. The purity of the filtrate was analyzed by using UV spectrophotometer and the result show a decreased absorbance by 93%.
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Nikiforov, Anton, Rino Morent, and Chuanlong Ma. "(Invited) Plasma Technology in Surface Engineering: From Super-Hydrophilic to Super-Hydrophobic Materials." ECS Meeting Abstracts MA2022-02, no. 18 (October 9, 2022): 865. http://dx.doi.org/10.1149/ma2022-0218865mtgabs.
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Materials surface wettability is a fundamental property of a solid. Wettability plays a paramount role in the everyday applications of solid materials in many fields of science and technology. Numerous examples include advanced membranes (from water purification to biopharmaceuticals), energy storage devices, windows, raincoats, roofs, disposable diapers, microfluidics, bandages, tissue scaffolds, and bio-implants. With the continuous development of modern society, the demand for advanced functional materials with the desirable surface wettability is increasing faster than ever before. This is why precise control over surface wettability is expected to provide materials with superior properties for unprecedented applications in diverse fields. Over the past decade, conventional wet chemistry approaches have been among the most frequently used methods for surface wettability control. However, they are often energy-inefficient, pollute the environment, and rely on harsh synthesis conditions. Recently, low-temperature plasma processing has attracted major attention in surface wettability control. The reason for this particular interest is because plasma processing is highly-selective, environmentally friendly, and low-cost. Plasma processing can uniquely modify both the surface chemistry and surface topography for a wide range of materials. Moreover, it can be operated at very mild conditions such as room temperature, atmospheric pressure, and open-air environments. Plasma can be used as a controlled reactive physicochemical environment for surface activation, coating deposition, and nanostructuring of diverse materials. The unique plasma-specific conditions and effects allow precise control over microscopic surface chemical composition and surface nanostructures by adjusting the macroscopical energy input. Accordingly, effective control over surface wettability can be achieved for a broad range of hard and soft materials. An environmentally friendly, large scale and low-cost wetting control method that does not result in bulk damage, would result in improvement of industrial applications. A possible solution to this wetting control problem is atmospheric-pressure plasma (APP), especially the plasma generated in open-air due to the benefits of solvent-free treatment, requiring no vacuum systems and suitable for in-line processes. In the current work, we will give a comprehensive overview of different atmospheric pressure plasma processes capable to change the surface properties of the polymers with little or no change of the bulk. Two main approaches: (i) plasma activation introducing oxygen-containing groups into the material surface; (ii) plasma polymerization directed to the change of the surface composition will be highlighted and background will be explained. Recently our team developed a new approach based on the use of a combination of plasma activation and plasma polymerization, two different plasma techniques in a single process to achieve different surface wetting properties from hydrophilic to hydrophobic, with the high long-term stability of the coatings in water. Such a type of research approach realized in one plasma source was not yet applied for wettability control and has very promising application potential in the industrial processing of polymers. For surface engineering, and easy to scale-up the radio frequency (RF) plasma system was adopted to perform both plasma activation and plasma polymerization on PET substrate in the atmospheric pressure in the open air. Different characterization methods including WCA measurements, Fourier-transform infrared spectroscopy (FT-IR), XPS, and atomic force microscopy (AFM) were applied to get an insight into surface chemistry and morphology and the effect of the combination of the plasma activation with plasma polymerization. The developed approach has shown the capability of stable coatings deposition with the use of acrylic acid, HMDSO or fluorine-containing precursors PFDA. We demonstrate a single-step, fast, green, cheap, and universal plasma-based approach with potential for large-scale production of oil/water separation membranes, namely aerosol-assisted plasma deposition (AAPD). A hydrophobic polyester membrane is exposed to an in-line atmospheric pressure plasma coupled with an aerosol of a 2-hydroxyethyl methacrylate (HEMA) monomer. A plasma polymerized HEMA thin film is thus successfully coated on the membrane, resulting in an superhydrophilic/underwater superoleophobic surface. With created coating, the water pre-wetted plasma-functionalized polyester membrane shows an ultrahigh separation efficiency above 97.8% towards various oil/water mixtures and a superb water flux above 35.6 L m-2 s-1. Importantly, it also exhibits excellent performance in anti-oil-fouling, recyclability, and durability, indicating its high potential in real-life usage. To further examine the universality of the proposed approach, another hydrophilic monomer (acrylic acid) is also used to functionalize the polyester membranes. The obtained functionalized membranes can also efficiently separate diversified oil/water mixtures. Therefore, this study demonstrates the capability of plasma-based surface engineering methods to manipulate surface properties of materials in a very wide range from superhydrophobic to hydrophilic and even super-hydrophilic which opens new areas of applications.
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Muthia Elma, Aulia Rahma, Uun Kusumawati, Reza Satria Kelik Pratama, and Alya Dita Alyanti. "Single Vs Multichannel Silica-Pectin Ultrafiltration Membranes for Treatment of Natural Peat Water." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 100, no. 2 (December 31, 2022): 33–46. http://dx.doi.org/10.37934/arfmts.100.2.3346.
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A comparative study was undertaken to investigate the potential of silica-pectin ultrafiltration membrane on varied operation pressure (0.1-0.3 MPa). Cross-flow ultrafiltration works were explored with tubular alumina substrates in single and multichannel configuration. The silica-pectin sol was prepared from TEOS as silica precursor by sol-gel method, afterward pectin was templated into the silica sol to induce carbon on it. Thereafter, both of single and multichannel alumina substrates was coated by the silica-pectin sol via inner coating technique. The study exhibited better performance of multichannel silica-pectin ultrafiltration membrane (with 4 bores) compared to the single channel membrane in terms of the permeate quality of UV254 rejection, as well as the permeate flux. The UV254 rejection of multichannel silica-pectin ultrafiltration membranes conducted over 84% in compliance with highest permeate fluxes of 234.3 L.m-2.h-1.bar-1 at high operation pressure (TMP 0.3 MPa). The multichannel ultrafiltration membrane permeate flux in this work is slightly high 60-75% over single channel. Hence, both single and multichannel silica-pectin membranes exhibited steady neutralized permeate fluxes under TMP 0.3 MPa conditions for natural 100% peat water concentration, which indicates that fouling is not occurred during filtration time up to 60 min. Therefore, multichannel silica-pectin ultrafiltration membrane in this work is success to treatment of natural peat water, that the natural organic matter removal was found to be fit for uses as clean water sources.
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Chik, N. S. I., N. Z. K. Shaari, and S. A. Shamsudin. "The Separation of Oily Water Mixture Using Membrane." IOP Conference Series: Materials Science and Engineering 1176, no. 1 (August 1, 2021): 012003. http://dx.doi.org/10.1088/1757-899x/1176/1/012003.
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Abstract The increment of oil discharge in the water system gives a great impact to the environments. Membrane separation has been widely used to treat the oily water mixture due to its environmentally process, low operating cost and has better efficiency. Polysulfone (PSF) is widely used in the membrane fabrication due to its good physico-chemical, mechanical and hydraulic stability, but its hydrophobicity limits its application in the separation of oily mixture due to the fouling. The blend of PSF with poly (vinyl alcohol) (PVA) could compensate this limitation where the covalent bonding between PSF/PVA could form a protective layer to prevent the deposition of organic foulants on the membrane surface. Furthermore, PVA has been studied intensively for membrane applications because of its good chemical stability, film-forming ability and high hydrophilicity. To ensure the compatibility and high stability of the resultant membrane, the cross linking of the polymer blend (PSF/PVA) with tetraethylorthosilicate as silica nano precursor through sol-gel reaction was conducted in this study. Polyethylene glycol 400 was added as an additive to improve the properties of the integral membrane. The concentration of tetraethylorthosilicate was varied at 0wt.%, 0.5wt.%, and 1wt.% while the concentrations of other polymers are remained constant. Performance testing on the fabricated membrane through pure water flux and rejection of oil particles were conducted. The results exhibited that higher concentration of tetraethylorthosilicate led to higher water flux and higher rejection of oil particles respectively for the fabricated membrane. The crosslinked membranes achieved l00% of oil rejection after 45 minutes filtration time, meanwhile membrane from pure polymer blend only achieved 60.2% of oil rejection. This finding shows the potential of the fabricated membrane to be further explored in the area of oily water mixture treatment process.
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Chik, N. S. I., N. Z. K. Shaari, and S. A. Shamsudin. "The Separation of Oily Water Mixture Using Membrane." IOP Conference Series: Materials Science and Engineering 1176, no. 1 (August 1, 2021): 012003. http://dx.doi.org/10.1088/1757-899x/1176/1/012003.
Full textAbstract:
Abstract The increment of oil discharge in the water system gives a great impact to the environments. Membrane separation has been widely used to treat the oily water mixture due to its environmentally process, low operating cost and has better efficiency. Polysulfone (PSF) is widely used in the membrane fabrication due to its good physico-chemical, mechanical and hydraulic stability, but its hydrophobicity limits its application in the separation of oily mixture due to the fouling. The blend of PSF with poly (vinyl alcohol) (PVA) could compensate this limitation where the covalent bonding between PSF/PVA could form a protective layer to prevent the deposition of organic foulants on the membrane surface. Furthermore, PVA has been studied intensively for membrane applications because of its good chemical stability, film-forming ability and high hydrophilicity. To ensure the compatibility and high stability of the resultant membrane, the cross linking of the polymer blend (PSF/PVA) with tetraethylorthosilicate as silica nano precursor through sol-gel reaction was conducted in this study. Polyethylene glycol 400 was added as an additive to improve the properties of the integral membrane. The concentration of tetraethylorthosilicate was varied at 0wt.%, 0.5wt.%, and 1wt.% while the concentrations of other polymers are remained constant. Performance testing on the fabricated membrane through pure water flux and rejection of oil particles were conducted. The results exhibited that higher concentration of tetraethylorthosilicate led to higher water flux and higher rejection of oil particles respectively for the fabricated membrane. The crosslinked membranes achieved l00% of oil rejection after 45 minutes filtration time, meanwhile membrane from pure polymer blend only achieved 60.2% of oil rejection. This finding shows the potential of the fabricated membrane to be further explored in the area of oily water mixture treatment process.
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Betar, Bashir O., Mohammed A. Alsaadi, Zaira Z. Chowdhury, Mohamed K. Aroua, Farouq S. Mjalli, Kaharudin Dimyati, MHD N. Hindia, Fawzi M. Elfghi, Yehya M. Ahmed, and Hazim F. Abbas. "Bimetallic Mo–Fe Co-Catalyst-Based Nano-Carbon Impregnated on PAC for Optimum Super-Hydrophobicity." Symmetry 12, no. 8 (July 28, 2020): 1242. http://dx.doi.org/10.3390/sym12081242.
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The application of super-hydrophobic nanomaterials for synthesizing membranes with unique physiochemical properties has gained a lot of interest among researchers. The presence of super-hydrophobic materials inside the membrane matrix can play a vital role not only in the separation of toxins, but also to achieve higher water flux with lower fouling tendencies required for an efficient membrane distillation process. In this research, super-hydrophobic carbon nanomaterials (CNMs) were synthesized using powder activated carbon (PAC) as a precursor, whereby the growth was initiated using a bimetallic catalyst of iron (Fe) and molybdenum (Mo). Until recently, no research has been conducted for synthesis and to observe the catalytic influence of bimetallic catalysts on the physiochemical characteristics of the derived CNMs. The synthesis process was carried out using the chemical vapor deposition (CVD) process. The CVD process was optimized using Box–Behnken factorial design (BBD), whereby 15 experiments were carried out under different conditions. Three input variables, which were percentage composition of catalysts (percentage of Fe and Mo) and reaction time (tr), were optimized with respect to their impact on the desired percentage output of yield (CY) and contact angle (CA). Analysis of variance (ANOVA) testing was carried out. It was observed that the developed model was statistically significant. The highest CY (320%) and CA (172°) were obtained at the optimal loading of 5% Fe and 2% Mo, with a reaction time of 40 min. Surface morphological features were observed using field emission scanning electron microscopic (FESEM) and transmission electron microscopic (TEM) analysis. The images obtained from FESEM and TEM revealed the presence of two types of CNMs, including carbon nanofibers (CNFs) and multiwall carbon nanotubes (CNTs). Thermogravimetric analysis was carried out to observe the temperature degradation profile of the synthesized sample. Raman spectroscopic analysis was also used in order to have a better understanding regarding the proportion of ordered and disordered carbon content inside the synthesized sample.
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Son, Heejong, Hoon-Sik Yoom, Chang-Dong Seo, Sang-Goo Kim, and Yong-Soon Kim. "Evaluation of Dissolved Organic Matter Removal Characteristics in GAC Adsorption Process in Drinking Water Treatment Process using LC-OCD-OND." Journal of Korean Society of Environmental Engineers 42, no. 5 (May 31, 2020): 239–50. http://dx.doi.org/10.4491/ksee.2020.42.5.239.
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Objectives:In this study, we used liquid chromatograph-organic carbon detector-organic nitrogen detector (LC-OCD-OND) to evaluate adsorption and breakthrough characteristics of NOM fractions (biopolymers (BP), humic substances (HS), building blocks (BB) and low molecular weight organic substances (LMW-O)) according to the various characteristics of the different materials of granular activated carbons (GACs).Methods:Breakthrough characteristics, adsorption capacity and partition coefficients were evaluated by NOM fractions (BP, HS, BB, and LMW-O) using a lab-scale GAC adsorption column filled with coal-, coconut- and wood-based GAC. The GAC column test was operated with 10 minutes empty bed contact time (EBCT). The pore characteristics of each GAC were evaluated using an automated gas sorption analyzer (Autosorb iQ3, Quantachrome, USA) and the concentrations of NOM fractions in the influent and effluent were analyzed using chromatography LC-OCD-OND (Model 8, DOC-Labor, Germany).Results and Discussion:NOM adsorption capacity was evaluated for different materials of laboratory scale GAC adsorption column test. To study the adsorption behavior of individual NOM fractions according to the operation time, NOM was fractionated into BP, HS, BB and LMW-O by LC-OCD-OND, and the individual NOM fractions were quantified. Higher MW like BP was not adsorbed to GAC, in contrast, HS, BB, and LMW-O were well removed during the initial operation period, the concentrations in the effluent gradually increased as increase the operation period until reaching to the pseudo steady-state. Poor removal of BP in GAC adsorption may be a result of blocking the pores with large MW BP and hinder the access to the pores. However, in the case of HS, BB, and LMW-O, as the molecular size decreased, these organic matters easily access to the pores inside of GAC. It was confirmed through the partition coefficient that the adsorption capacity of these NOM fractions increased in proportion to the MW. In addition, in order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH<sub>zpc</sub> must be higher than the neutral pH level.Conclusions:In order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH<sub>zpc</sub> must be higher than the neutral pH level. In addition, in the NOM fractions, BP were not adsorbed to GAC, while the adsorption capacity of the remaining NOM fractions increased as the MW of the NOM fractions decreased. LMW-O was the most adsorbed, followed by BB, HS and BP. BP and HS play an important role in the membrane fouling that are introduced a lot into domestic and foreign water treatment plants. This study showed that the BP was not removed by the adsorption mechanism of the GAC process. In addition, HS was adsorbed and removed at the beginning of the operation, but the adsorption capacity of HS decreased rapidly as the operation period increased compared to other NOM fractions. Therefore, the GAC adsorption process is not expected to be an effective pre-treatment technology for reducing membrane foulants. Previous studies showed that the yields of DBPs (µmol･DBP/µmol･C) in the high MW humic and low MW non-humic fractions are similar. Therefore, it is suggested that the GAC adsorption process is more effective for DBP precursor control in water containing a larger percentage of LMW NOM.