Immobilization Of Silver Nanoparticles Research Articles

Green construction of self-floating polysaccharide-based hydrogels with catalytic activity for efficient organic pollutants reduction

This study employed an anionic heteropolysaccharide extracted from overgrown Enteromorpha and homopolysaccharide pullulan to fabricate a self-floating hydrogel by introducing bubble templates. Subsequently, green in-situ reduction and immobilization of silver nanoparticles (Ag NPs) in the hydrogel were successfully achieved without additional reducing agents. The heteropolysaccharide from Enteromorpha provides carboxyl and sulfate groups for Ag+ ions complexation, which is beneficial for the in-situ reduction of Ag NPs and inhibits their aggregation. The incorporation of bubble templates facilitates the creation of a hierarchical pore structure in the hydrogel, giving it self-floating properties for easy recycling, while the hierarchical network with rich anchor sites ensuring adequate traction for Ag NPs dispersion and stabilization. By adjusting polysaccharide content and using bubble templates, Ag NPs smaller than 10 nm can be obtained. The composite hydrogel exhibits tunable catalytic activity and excellent degradation towards Rhodamine B, Methyl Orange, and 4-Nitrophenol, with the normalized rate constant (knor) of 78.89, 59.08, and 30.42 min−1 g−1, respectively. Notably, the reduction efficiency remained above 98 % after 6 recycles with little leaching of Ag NPs, benefiting from its self-floating ability for easy recovery in practical applications.

Improving antifouling performance of FO membrane by surface immobilization of silver nanoparticles based on a tannic acid: diethylenetriamine precursor layer for municipal wastewater treatment.

In this study, a facile method for multifunctional surface modification on forward osmosis (FO) membrane was constructed by surface immobilization of AgNPs based on tannic acid (TA)/diethylenetriamine (DETA) precursor layer. The cellulose triacetate (CTA) FO membranes modified by TA and DETA with different co-deposition time (6 h, 12 h, 24 h) were investigated. Results indicated that the TA/DETA (24)-Ag CTA membrane with a TA/DETA co-deposition time of 24 h was identified to be optimal, which attained more hydrophilic. And it had the bacterial mortality of Escherichia coli and Staphylococcus aureus reaching 98.23% and 99.83% respectively and possessed excellent physical and chemical binding stability. Meanwhile, the coating layer resulted in the antifouling ability without damaging the membrane intrinsic transport characteristics. As for synthetic municipal wastewater treatment, the water flux of CTA FO membrane decreased approximately 49% of the initial flux after running for 14 days. In contrast, the flux decline rate of TA/DETA (24)-Ag CTA membrane was about 37%. Furthermore, less foulant deposition and higher recovery rate of water flux was observed for TA/DETA (24)-Ag CTA membrane, implying that the modified membrane effectively alleviated membrane fouling and processed a lower flux decline during municipal wastewater treatment. It was attributed to the enhanced surface hydrophilicity and antibacterial property of the coating layer, which improved antifouling property.

Photothermal controlled antibacterial Ta4C3Tx-AgNPs/nanocellulose bioplastic food packaging

Uncontrolled antibacterial, insufficient barrier and low strength are the bottlenecks of food packaging applications. Herein, Ta4C3Tx nanosheet as a template was used to prepare Ta4C3Tx immobilized silver nanoparticles (Ta4C3Tx-AgNPs), which was compounded with nanocellulose to obtain high-strength and high barrier controllable bactericidal nanocellulose-based bioplastic packaging (CTa-Ag). The results indicated that due to the hydrogen bonding between nanocellulose and Ta4C3Tx, the bridging effect of QCS (quaternized chitosan) and the filling of Ta4C3Tx-AgNPs, the CTa-Ag had tightly stacked microstructure, which endowed them with excellent mechanical properties (4.0 GPa), ultra-low oxygen permeability (0.009 cm3/m2·d·atm) and stable photothermal conversion efficiency. Importantly, the packaging exhibits the ability to control the release of antibacterial active ingredients. Moreover, the synergistic effects of controllable release of nano active factors, photothermal and photocatalysis in CTa-Ag gave it long-lasting antibacterial properties. This study brings new insights into the design and manufacture of multifunctional, controllable and long-lasting antibacterial bioplastic food packaging.

The production of bacterial cellulose from coconut water and its application as a green photocatalyst composite membrane

AbstractIn this research work, bacterial cellulose was produced from the fermentation of coconut water and incubated for 4, 5, and 6 days. The bacterial cellulose membrane was utilized as immobilized silver nanoparticles (AgNPs). A green photocatalyst membrane was prepared by reducing silver ions in the bacterial cellulose matrix structure using local fruit extracts, tomatoes, Citrus hystrix fruit, and mangosteen peel as a reducing agent. The composite was dried in the oven to obtain a more durable fixed structure. The properties of produced bacterial cellulose were determined by measuring the thickness, water retention capacity (WRC), cellulose content, and swelling. The functional group and crystallinity index of bacterial cellulose were observed by FTIR and XRD instrument analysis. The SEM EDX analysis confirms that the silver ions were successfully reduced in the BC matrix, and the UV–Vis spectrum showed that the composite membrane has the ability to degrade the methylene blue solution under sunlight irradiation. The maximum degradation efficiency of the composite membrane against 5 ppm methylene blue solution was achieved by the composite membrane reduced by tomatoes, with a value of 93%. This result proved that the composite membrane produced in this research has excellent capabilities as a green photocatalyst for degrading wastewater containing dye pollutants.

Obtaining of Antibacterial Nanoporous Layer on Ti7.5Mo Alloy Surface Combining Alkaline Treatment and Silver: In Vitro Studies

In the present study, a combination of alkaline treatment and silver was used to produce an antibacterial nanolayer on the Ti7.5Mo alloy surface. The antibacterial response and osteogenesis were evaluated by assessing the adhesion and proliferation of S. aureus and S. epidermidis, as well as the adhesion, viability, and expression levels of genes involved in osteogenic differentiation in the mouse pre-osteoblast cell line MC3T3-E1. The potential stimulus of extracellular remodeling was evaluated using zymography. Our results showed that there is no difference in cytotoxicity after silver immobilization. Protein activity (MMP9) progressively increased for theTi7.5Mo alloy, both untreated and after alkaline treatment. However, the highest increase in protein activity was observed when the alloy was in direct contact with immobilized silver nanoparticles. The surfaces containing silver showed a better response in terms of colony formation, meaning that less bacterial adhesion was detected. The results showed that the layer formed was effective in reducing bacterial activity without altering cell viability.

Knitted Structures Made of Antibacterial Fibers Intended for Protective Gloves

At a time of growing epidemic hazards caused by a very rapid evolution of dangerous pathogens, there is a pressing demand for bioactive textiles. Therefore, the development of high-quality knitted structures that could be used as bioactive protective materials has become a priority. This publication describes the fabrication of functional knitted structures from previously prepared antibacterial cellulose fibers containing nanosilica with immobilized silver nanoparticles. The structural and physical parameters of knitted fabrics made from them were studied with a view to their potential application in bioactive protective gloves. Tests of the basic structural and physical parameters of the knitted fabrics did not show that the nanomodifier applied in fibers significantly impacts the physical properties of the resulting fabrics. Moreover, water vapor permeability, cut resistance, and pH test results relevant to the functional and protective properties of interest and to user comfort showed that the obtained fabrics can be used in the production of bioactive protective gloves.

Simultaneous generation and immobilization of silver nanoparticles on cellulose membranes by hydrogen bond-assisted in-situ reaction for colorimetric detection of mercury ions and hydrogen peroxide

The present study has verified that silver nanoparticles (AgNPs) can be simultaneously generated and immobilized in the micro-nanopores of regenerated cellulose membranes (CMs) via a simple in-situ synthesis, which can be used for colorimetric detection of mercury ions (Hg2+) and hydrogen peroxide (H2O2). The findings showed that the high-loose interpenetrating porous structure and abundant hydroxyl groups of CMs can serve as both micro-reaction spaces and immobilized sites for the in-situ synthesis of AgNPs. The Ag@CMs, composed of well-dispersed, firmly-fixed, and quantity controlled AgNPs functionalized CMs, have excellent Hg2+ colorimetric detection capabilities with a visual limit of detection (VLOD) as low as 5 nM. It can efficiently complete early-warning and semi-quantitative Hg2+ recognition, and exhibits high storage stability for more than 180 days. Moreover, the Ag@CMs exhibited peroxidase mimic behavior and catalyzed the oxidation reaction of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to produce a blue solution. This work proposes a simple “green” approach for the heterogeneous synthesis of controllable and stable AgNPs immobilized on CMs and explores their application in chemosensing.

Hierarchical porous alumina ceramics as multi-functional support with excellent performance

Hierarchical porous nanostructure alumina ceramics (HP-Al2O3) were prepared through a novel approach involving polymer-assisted freeze-drying and subsequent calcination. The resulting material exhibits interconnected micro-meso-macro pores, distinguishing it from traditional Al2O3 nanoparticles (Al2O3-Nps) prepared without freeze-drying. By manipulating freeze-drying precursors and calcination temperatures, we tailor the morphology and structure of HP-Al2O3. Notably, the HP-Al2O3 demonstrates a remarkable 5.3-fold increase in adsorption efficiency for Congo red compared to Al2O3-Nps, attributed to its significantly larger specific surface area. The HP-Al2O3 is a versatile platform for building multi-functional composites, proved by immobilizing silver nanoparticles (AgNps) and graphitized carbonitride (g-C3N4) through chemical reduction and gas-solid reaction methods, respectively. When employed for the reduction of 4-nitrophenol and the degradation of Rhodamine B, Ag/HP-Al2O3 and g-C3N4/HP-Al2O3 display approximately 2.5 and 2.4 times higher reaction rate constants compared to Ag/Al2O3-Nps and g-C3N4/Al2O3-Nps. This enhanced catalytic performance is attributed to several key factors: the 3D porous framework of the HP-Al2O3 facilitates efficient catalyst immobilization, the microporous and mesoporous nature increases the active site and specific surface area, and the hierarchical porous structure enhances mass diffusion and light capture. Moreover, the self-supporting nature of the HP-Al2O3 simplifies separation and recovery from reaction solutions. With the integration of its hierarchical porous structure and commendable recovery properties, HP-Al2O3 emerges as a promising candidate for various functional applications, particularly in catalysis.

Green Immobilized Silver Nanoparticles Over Mentha spicata Flower Extract Modified Reduced Graphene Oxide: Investigation of its Antioxidant and Anti-liver Cancer Effects

Green Immobilized Silver Nanoparticles Over Mentha spicata Flower Extract Modified Reduced Graphene Oxide: Investigation of its Antioxidant and Anti-liver Cancer Effects

Cardiopulmonary protective properties of decorated Ag NPs on lignin modified magnetic nanoparticles mediated by Cydonia in CCD-19Lu, WI-38, BEAS-2B, HCASMC, HCAEC, and HPAEC cell lines

Advances in silver nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of cardiopulmonary diseases. The present investigation describes a green procedure for the in situ immobilizing silver nanoparticles over calcium lignosulfonate modified Fe3O4 magnetic nanoparticles mediated by Cydonia root extract (Fe3O4@lignosulfonate-Ag NPs) and its catalytic and subsequent biological performances. The characterization of synthesized Fe3O4@lignosulfonate-Ag NPs were analyzed using XRD, VSM, ICP, SEM, EdaX, elemental mapping and TEM. In the medicinal part of the present research, the lung (CCD-19Lu, WI-38, and BEAS-2B) and heart (HCASMC, HCAEC, and HPAEC) cell viability was determined by trypan blue assay. The caspase activity colorimetric assay kit and Rhodamine123 fluorescence dye were used to determine the caspase-3 activity and mitochondrial membrane potential, respectively. Apoptosis and DNA fragmentation were determined by the TUNEL test. In addition, the inflammatory cytokines concentrations were evaluated by the Rat inflammatory cytokine assay kit. Fe3O4@lignosulfonate-Ag NPs-treated cell cutlers decreased significantly (p ≤ 0.01) the caspase-3 activity, inflammatory cytokines concentrations, and DNA fragmentation, and enhanced the mitochondrial membrane potential and cell viability in the high concentration of Methotrexate-treated CCD-19Lu, WI-38, BEAS-2B, HCASMC, HCAEC, and HPAEC cells. In the antioxidant test, the IC50 of Fe3O4@lignosulfonate-Ag NPs and BHT against DPPH free radicals were 168 and 54 µg/mL, respectively. Finally, Fe3O4@lignosulfonate-Ag NPs may be used as a cardiopulmonary protective supplement to treat cardiopulmonary diseases.

TEMPO-oxidized nanocellulose immobilized AgNPs modified chitosan composite film with durable antibacterial and preservative properties for fruits and vegetables package

Film preservative packaging is one of common techniques to solve rot problem of fruits and vegetables in transit, storage and sale process. But traditional petroleum-based films have no long-lasting antibacterial properties and they are difficult to biodegrade. Herein, TEMPO-oxidized nanocellulose (TCNF) was used as green reducer and stabilizer to synthesize and immobilize silver nanoparticles (AgNPs) in one-pot method. Next the TCNF immobilized AgNPs was combined with chitosan to form antibacterial preservative composite film (CS/TCNF@AgNPs). The results show that CS/TCNF@AgNPs exhibited satisfied preservative effects for cherry tomatoes and strawberries. Notably, the composite film showed excellent antibacterial properties against E. coli and S. aureus and the accumulated release amount of AgNPs was only about 2.05% after 264 h. Furthermore, the composite film degraded almost completely in soil within 25 days. The cytotoxicity assay also exhibited favorable biocompatibility. Therefore, the composite film has potential application as a packaging material for fruit and vegetable antibacterial preservation.

Nanosilver-decorated covalent organic frameworks for enhanced photodynamic, photothermal, and antibacterial properties

Bacterial infections caused by multidrug-resistant bacteria pose an extremely serious treat to human health However, nanoscale antibacterial materials can effectively inhibit bacterial growth without inducing bacterial resistance. Herein, we have developed a highly effective antibacterial agent by immobilizing silver nanoparticles (AgNPs) within a novel covalent organic framework (COF). The COFBDP/CD-S-3-Ag system was synthesized in situ using BODIPY phoyosensitizer (BDP) and carbon quantum dots (CD-S-3) as precursors. The optimized COFBDP/CD-S-3-Ag system exhibited excellent photodynamic therapy (PDT) and photothermal therapy (PTT). Importantly, the COFBDP/CD-S-3-Ag system, with many active groups, can capture and kill bacteria effectively by interacting with them, thereby contributing to improved antibacterial efficacy. As expected, the designed COFBDP/CD-S-3-Ag system combines the advantages of COFBDP/CD-S-3 (preventing the aggregation of AgNPs and having the ability to capture bacteria) and AgNPs (antibacterial ability), demonstrating excellent antibacterial efficacy. This study developed a new class of antibacterial materials and took an important step forward in promoting the application of COF-based antibacterial materials.

Green synthesized Ag nanoparticles decorated on the surface of Hibiscus tea leaf extract modified reduced graphene oxide: Investigation of its anti-lung carcinoma effects

An eco-friendly green decorated of Ag NPs on the surface of graphene oxide (RGO/Ag NPs) has been described using Hibiscus tea leaves extract. The Hibiscus tea leaves extract was applied as a reducing and stabilizing agent for immobilizing silver nanoparticles without aggregation with spherical shape and uniform sizes. The as-synthesized nanocomposite (RGO/Ag NPs) was characterized using FE-SEM, EDX, elemental mapping, TEM, XRD and ICP analysis. The synthesized nanocomposite had very low cell viability and high anti-lung carcinoma activities dose-dependently against HLC-1, PC-14, LC-2/ad and NCI-H322 cell lines without any cytotoxicity on the normal cell line (HUVEC). The IC50 of the nanocomposite were 500, 327, 204, and 542 µg/mL against HLC-1, PC-14, LC-2/ad and NCI-H322 cell lines, respectively. The synthesized nanocomposite inhibited half of the DPPH molecules in the concentration of 141 µg/mL. Perhaps notable anti-lung carcinoma activities of the synthesized nanocomposite against common lung carcinoma cell lines are linked to their antioxidant activities.

Self-Sanitizing Polycaprolactone Electrospun Nanofiber Membrane with Ag Nanoparticles.

The objective of this research was to develop an environment-friendly and scalable method for the production of self-sanitizing electrospun nanofibers. This was achieved by immobilizing silver nanoparticles (Ag NPs) onto plasma-treated surfaces of biodegradable polycaprolactone (PCL) nanofibers. The plasma deposited polymer layer containing carboxyl groups played a critical role in providing a uniform distribution of Ag NPs on the nanofiber surface. Ag ions were absorbed by electrostatic interaction and then reduced under the action of UV-light. The concentration and release of Ag ions were analyzed using the EDXS/XPS and ICP AES methods, respectively. Although high levels of Ag ions were detected after 3 h of immersion in water, the material retained a sufficient amount of silver nanoparticles on the surface (~2.3 vs. 3.5 at.% as determined by XPS), and the release rate subsequently decreased over the next 69 h. The antipathogenic properties of PCL-Ag were tested against gram-negative and gram-positive bacteria, fungi, and biofilm formation. The results showed that the PCL-Ag nanofibers exhibit significant antimicrobial activity against a wide range of microorganisms, including those that cause human infections. The incorporation of Ag NPs into PCL nanofibers resulted in a self-sanitizing material that can be used in variety of applications, including wound dressings, water treatment, and air filtration. The development of a simple, scalable, and environmentally friendly method for the fabrication of these nanofibers is essential to ensure their widespread use in various industries. The ability to control the concentration and release rate of Ag ions in the PCL nanofibers will be critical to optimize their efficacy while minimizing their potential toxicity to human cells and the environment.

Control the hydrophilic layer thickness of Janus membranes by manipulating membrane wetting in membrane distillation

Janus membranes with asymmetric wettability have attracted wide attentions for their robust anti-oil-wetting/fouling abilities in membrane distillation (MD). Compared to traditional surface modification approaches, in this study, we provided a new approach which manipulated surfactant-induced wetting to fabricate Janus membrane with a controllable thickness of the hydrophilic layer. The membranes with 10, 20, and 40 μm of wetted layers were obtained by stopping the wetting induced by 40 mg L−1 Triton X-100 (J = 25 L m−2 h−1) at about 15, 40, and 120 s, respectively. Then, the wetted layers were coated using polydopamine (PDA) to fabricate the Janus membranes. The resulting Janus membranes showed no significant change in porosities or pore size distributions compared with the virgin PVDF membrane. These Janus membranes exhibited low in-air water contact angles (< 50°), high underwater oil contact angles (> 145°), and low adhesion with oil droplets. Therefore, they all showed excellent oil-water separation performance with ∼100% rejection and stable flux. The Janus membranes showed no significant decline in flux, but a trade-off existed between the hydrophilic layer thicknesses and the vapor flux. Utilizing membranes with tunable hydrophilic layer thickness, we elucidated the underlying mechanism of such trade-off in mass transfer. Furthermore, the successful modification of membranes with different coatings and in-situ immobilization of silver nanoparticles indicated that this facile modification method is universal and can be further expanded for multifunctional membrane fabrication.

Antimicrobial andUVprotective chitosan/lignin multilayer nanocoating with immobilized silver nanoparticles

AbstractPoor antimicrobial activity and lack of protection against UV irradiation are weaknesses of cotton textiles. In an attempt to impart superior antimicrobial and UV‐protective properties to cotton, layer‐by‐layer deposition of chitosan and magnesium lignosulfonate, and in situ synthesis of silver (Ag) nanoparticles (NPs), was performed. Lignin, in a chitosan/lignin multilayer, simultaneously acts as a UV protective macromolecule and natural reducing and stabilizing agent, allowing formation of Ag NPs. Four bilayers of this coating is sufficient for fabrication of a chitosan/lignin/Ag‐NP textile nanocomposite treatment with 50+ UV protection. 100% reduction of Gram‐negative bacteriaEscherichia coli, gram‐positive bacteriaStaphylococcus aureus,and yeastCandida albicanscan be achieved with a 12‐bilayer coating, when 20 mM silver nitrate solution and sodium borohydride are applied. On the other hand, four bilayers impregnated with Ag NPs, using 10 mM silver nitrate solution, provides sufficient antimicrobial activity independent of an added reducing agent. This treatment exhibits no inhibition of human keratinocyte cells growth on the skin, indicating low cytotoxicity.

Enzyme assisted magnetic hybrids as self-activated cascade reagent with synergistic activity for antimicrobial application

The abuse of antibiotics seriously threatens the public health, which leads to the urgent need to develop novel antimicrobial strategies. Reactive oxygen species (ROS) have been considered as an alternative approach for bacterial inactivation. At present, magnetic materials, especially iron oxide (Fe3O4) nanoparticles have gained widely application in biomedical field. Owing to the intrinsic peroxidase-like activity, Fe3O4 can catalyze the decomposition of hydrogen peroxide (H2O2) to generate hydroxyl radical (⋅OH) under acidic conditions. Recently, Fe3O4-based peroxidase mimics have been developed for wound infection therapy. However, the direct introduction of H2O2 with relative high concentration may induce undesired effect to normal tissues, and the infection site with near neutral pH still limits the antibacterial efficiency. Herein, carboxyl modified Fe3O4 immobilized silver nanoparticles (Ag NPs) and glucose oxidase (GOx) were synthesized as a self-activated cascade regent. GOx endowed the hybrids with catalytic activity, which could convert glucose into gluconic acid, which activated the peroxidase-like activity of Fe3O4 by decreasing the pH value. Moreover, the self-supplied H2O2 was subsequently catalyzed by Fe3O4 to generate ⋅OH. By combining the excellent antimicrobial performance of Ag NPs, the enzyme assisted magnetic hybrids exhibited robust antibacterial activity, which exhibited a great potential in bacteria-infected wound therapy.

Inducing SERS activity at graphitic carbon using graphene-covered Ag nanoparticle substrates: Spectroelectrochemical analysis of a redox-active adsorbed anthraquinone.

Graphitic carbon electrodes are central to many electrochemical energy storage and conversion technologies. Probing the behavior of molecular species at the electrochemical interfaces they form is paramount to understanding redox reaction mechanisms. Combining surface-enhanced Raman scattering (SERS) with electrochemical methods offers a powerful way to explore such mechanisms, but carbon itself is not a SERS activating substrate. Here, we report on a hybrid substrate consisting of single- or few-layer graphene sheets deposited over immobilized silver nanoparticles, which allows for simultaneous SERS and electrochemical investigation. To demonstrate the viability of our substrate, we adsorbed anthraquinone-2,6-disulfonate to graphene and studied its redox response simultaneously using SERS and cyclic voltammetry in acidic solutions. We identified spectral changes consistent with the reversible redox of the quinone/hydroquinone pair. The SERS intensities on bare silver and hybrid substrates were of the same order of magnitude, while no discernible signals were observed over bare graphene, confirming the SERS effect on adsorbed molecules. This work provides new prospects for exploring and understanding electrochemical processes in situ at graphitic carbon electrodes.

Immobilization of silver nanoparticles on cellulose nanofibrils incorporated into nanofiltration membrane for enhanced desalination performance

Nanofiltration (NF) membranes circumventing global water scarcity with excellent separation and antibacterial performances are highly desirable for efficient water treatment but remain a great challenge. Herein, a nanofiltration membrane was fabricated by in situ immobilizing silver nanoparticles (AgNPs) on sulfated cellulose nanofibril incorporated during interfacial polymerization. AgNPs were confirmed to be uniformly distributed and in situ grown on sulfated cellulose nanofibril (SCNF) due to its abundant sulfate and hydroxyl groups by mixing them with anhydrous piperazine solution as inorganic phase and homophenyl chloride n-hexane solution as the organic phase on the surface of a polyethersulfone microporous membrane. The attributes of SCNF, excellent hydrophilicity, and highly negative charges enhanced both the rejection and water permeability. As the SCNF charge increased, the roughness of SCNF increased and the contact angle decreased, and the maximum values were 203 nm and 17.67°, respectively. Among all the composite NF membranes, H-SCNF/Ag-0.01 had better rejection of Na2SO4 and NaCl, with a maximum rejection of 97.11% and 32.55%, respectively. Meanwhile, it also maintained high water permeability. Antibacterial experiments indicated that the composite NF membrane had effective inhibition against Escherichia coli and exhibited an expected slow-release capability of Ag+, which made it have long-term antibacterial properties. It was estimated that the antibacterial effect could last for 90 days. This work demonstrated that AgNPs in situ immobilization on SCNF could be used as promising nanofillers for designing advanced functional NF membranes.

High performance antibiofouling hollow fiber polyethersulfone nanocomposite membranes incorporated with novel surface-modified silver nanoparticles suitable for membrane bioreactor application

Surface-modified silver nanoparticles with amine, thiol, carboxyl, and the thiol-polyvinylpyrroldidone (PVP) functional groups were synthesized as functional filler for nanocomposite membranes for membrane bioreactor (MBR), with the aims to enhance antimicrobial effect of silver, while immobilizing silver nanoparticles inside the matrix of the membrane. Analyses by fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DLS) proved successful surface modification for each type of nanoparticles, with average particle sizes of 69, 20, 33, and 34 nm for amine, carboxyl, thiol and thiol-PVP modified silver nanoparticles, respectively. Polyethersulfone (PES) based nanocomposite hollow fiber membranes showed different morphology and performance in ultrafiltration and MBR experiments. The surface modifications were able to immobilize silver nanoparticles inside the membrane by providing proper interactions between the nanoparticles and polymer, reducing silver release compared to the unmodified nanoparticles. Modified nanoparticles changed the phase inversion, resulting in different morphology and average pore size in the range of 7.6–28.0 nm. The surface-modified nanoparticles with enhanced antimicrobial activity improved antifouling properties of the nanocomposite membranes, leading to interesting MBR performance improvements, with 122 % increase of flux, 23 % increase of chemical oxygen demand (COD) removal and flux recovery by over 30 %.