Silver nanoparticles separation from the water using nanofiltration membranes: the role of mono- divalent salts and NOM (original) (raw)
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Journal of Membrane Science, 2014
The aim of this study was to evaluate the application of dead-end ultrafiltration for the preparation of silver nanoparticles (AgNPs) with narrow size polydispersity. Aspects as the reaction yield, purification, size-based fractionation, and fouling mechanisms were analyzed. AgNPs were synthesized by chemical reduction, and diafiltration experiments were performed by the washing method. Our results suggest that the cutoff size of the membrane can be used as a primary criterion to define the particle size in the permeate, and eliminate Ag þ from a colloidal dispersion of AgNPs by removing NPs with a size less than the exclusion limit of the membrane. In addition, it was evidenced that ultrafiltration is not an effective method for elimination of AgNPs from aqueous effluents or for exact determination of reaction yield. In the prediction of J 0 , the lowest error was obtained for the cake formation (7.6% and J 0 ¼ 1.36 Â 10 À 2 m/s) followed by internal and intermediate pore blocking models with 32.5 (J 0 ¼ 9.91 Â 10 À 3 m/s) and 29.1% (J 0 ¼1.04 Â 10 À 2 m/s), respectively. Cake formation was identified to be the main fouling mechanism associated with the filtration of the AgNP colloidal dispersion.
Versatile Silver-Nanoparticle-Impregnated Membranes for Water Treatment: A Review
Membranes
Increased affordability, smaller footprint, and high permeability quality that meets stringent water quality standards have accelerated the uptake of membranes in water treatment. Moreover, low pressure, gravity-based microfiltration (MF) and ultrafiltration (UF) membranes eliminate the use of electricity and pumps. However, MF and UF processes remove contaminants by size exclusion, based on membrane pore size. This limits their application in the removal of smaller matter or even harmful microorganisms. There is a need to enhance the membrane properties to meet needs such as adequate disinfection, flux amelioration, and reduced membrane fouling. To achieve these, the incorporation of nanoparticles with unique properties in membranes has potential. Herein, we review recent developments in the impregnation of polymeric and ceramic microfiltration and ultrafiltration membranes with silver nanoparticles that are applied in water treatment. We critically evaluated the potential of these...
Journal of Water Process Engineering, 2020
Silver/silver oxide nanoparticles (AgNPs) is one of the most effective inorganic compounds that acts as an antibacterial agent against Escherichia coli (E. coli) bacteria. In this study, bio-silver or-silver oxide (bio-AgNPs) was synthesised from the seeds and peels of the Parkia speciosa (P. speciosa) plant, a green reducing agent. The seeds and peels were extracted separately via facile methods using a solution of silver nitrate (AgNO 3). The seeds were soaked and peels mixed with the AgNO 3 solution. The resulting bio-AgNPs were then incorporated into polysulfone (PSf) membranes at different weight percentages (0.1, 0.3, 0.5, and 1.0 wt%). The results showed that the PSf mixed matrix membrane (MMM) with 1.0 wt% of P. speciosa peel-derived bio-AgNPs (PP1.0) had the most optimum properties with a smaller crystallite size of 51.60 nm, an average diameter of finger-like cavities of 15.23 μm, the smallest mean pore size of 10.20 nm and the highest surface roughness of 39.90 nm. PP1.0 was also found to be highly hydrophilic since it had the lowest contact angle (63.30 •) which was corroborated by the highest hydroxyl (− OH) peak (3454.21 cm − 1) seen during Fourier-transform infrared (FTIR) spectroscopy analysis. PP1.0 also had the highest water permeation flux (327.73 L m − 2 h − 1), lowest rejection rate (67.21%), lowest bio-AgNP leaching after water filtration (1.56 μg/L) and the formation of a 16.34 mm 2 antibacterial inhibition ring. This proved that PP1.0 had the potential to be applied as an antibacterial membrane for water separation.
Application of Silver Nanoparticles in Drinking Water Purification
Proceedings of MOL2NET'22, Conference on Molecular, Biomedical & Computational Sciences and Engineering, 8th ed. - MOL2NET: FROM MOLECULES TO NETWORKS, 2022
The use of nanotechnology for drinking water purification becomes the emerging field around the world. Usually the nanoparticles are synthesized by variety of chemicals which are quite toxic, flammable in nature and their modes of working are unethical for mankind. The extensive application of the AgNP results in their inevitable release into the environment. Silver nanoparticle is known as excellent antimicrobial agents and therefore they could be used as alternative disinfectant agents. It was found that the aggregation of AgNPs depends on the properties of the background ions, such as Na + and Ca 2+ at different water chemistry conditions. The antimicrobial properties of AgNPs when coated with different organic compounds using natural water conditions. The results obtained showed that silver nanoparticles in surface water and ground water are stable. The composition of AgNPs-impregnated RO-filters and silver-impregnated RO-filters. This study was performed using different water chemistry condition and different manufacturing materials. The results showed that AgNPs-impregnated RO Water filters are more appropriate for this application due to the lesser amount of silver nitrate treated filters. The bacterial removal performance of the AgNPs-treated RO-Water filters and concentration of viable bacteria in the filters are dose-dependent on the amount of silver applied.
Separation and Purification Technology, 2001
The recent development of new mineral and organomineral membranes induced an increasing interest in the nanofiltration process. Their better mechanical as well as chemical properties allow them to challenge widely commercialised organic membranes. In this work, the behaviour of both copper and silver in the course of nanofiltration is studied in presence of nitriloacetic acid (NTA) and sodium thiosulphate. Filtrations were performed using two different types of membrane: a mineral gamma alumina membrane with a point of zero charge equal to 8.2, and an organic membrane (MT34). Effects of the nature of ligand, pressure, pH and metal concentration were examined on each studied membrane. Filtrations on organic membrane showed that only the molecular weight can be considered as an preponderant parameter in relation with the rejection yield. On the other hand, based on both electric interaction and molecule size, the mineral amphoteric membrane allowed various possibilities of separation between the two metals according to the pH value.
Nanomaterials
Three types of graphene oxide/silver nanoparticles (GO/AgNPs) composite membranes were prepared to investigate size-effect of AgNPs on nanofiltration ability. The size of AgNPs was 8, 20, and 33 nm, which was characterized by UV-visible spectroscopy and transmission electron microscopy. The morphology and structure of GO and GO/AgNPs composite membranes were characterized by atomic force microscopy, scanning electron microscopy, and X-ray diffraction. The filtration performance of membranes were evaluated on a dead-end filtration device. When the size of AgNPs is 20 nm, the GO/AgNPs composite membrane has the highest water flux (106.1 L m−2 h−1 bar−1) and rejection of Rhodamine B (RhB) (97.73%) among three types of composite membranes. The effect of feed concentration of dye solution and the flux of common solvent was also investigated. The mechanism was discussed, which demonstrated that both interlaying spacing and defect size influence the filtration ability of membrane, which is...
Preparation and Characterization Silver Nanoparticle Embedded Polyamide Nanofiltration (NF) Membrane
MATEC Web of Conferences
In this study, silver nanoparticles (AgNPs) were synthesized from tea leaves extract and its antimicrobial properties was tested on Escherichia coli (E. coli) using agar well method. The synthesized nanoparticles were characterized by using UV-vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The result from XRD analysis shows that the synthesized AgNPs are a face-centered cubic (fcc) structure with an average particle size of 28±15 nm AgNPs which confirmed by TEM. The synthesized AgNPs were then used in the preparation of thin film composite NF membrane via interfacial polymerization method. Separation performance of the produced membrane was evaluated in term of membrane permeability and solute rejection (vitamin B12, NaCl and Na2SO4 solutions). Based on the structural parameters (pore size, rp and Δx/Ak) values obtained from vitamin B12 test, all membranes can be considered as tight NF membranes. From the salts rejection test, membranes with th...
Complex organic fouling and effect of silver nanoparticles on aquaporin forward osmosis membranes
Journal of Water Process Engineering, 2020
Despite the negligible pressure used in forward osmosis (FO), the process still suffers from fouling. Recent studies demonstrated that this issue is common among all FO membrane types, including aquaporin-based filters. To address this problem, various approaches have been proposed. However, despite the biocidal effects of silver, no attempt has been made to apply silver for fouling mitigation in aquaporin FO membranes. Consequently, the present work focuses on the investigation of controlled combined organic fouling of aquaporin FO membranes and the effects of silver nanoparticles on the membrane performance and its properties. The obtained data show that in contrast with unaltered membranes, the membranes doped with silver nanoparticles are much more resistant to fouling. After the first filtration run, pristine membranes exhibited a flux decline of 50%, while the flux decline of the modified membranes was limited to 10%. Physical cleaning restored the flux of both membranes to 100%. Analysis of the membranes showed that the membrane water flux was not affected by the covalent binding of the silver nanoparticles. Further, the membranes' chemistry, zeta potential, contact angle, roughness, and antimicrobial resistance were altered.
Journal of Membrane Science, 2010
Silver nanoparticles (Ag nps) in host poly(perfluorosulfonic) acid membrane (Nafion-117) were formed by in situ reduction of the Ag + ions with ionic (sodium borohydride) and non-ionic (dimethyl formamide, and formamide) reagents. Ag + ions were loaded in the membrane samples by the ion-exchange mechanism. Ag + ions were tagged with 110m Ag radiotracer to monitor the process of Ag nps formation in the membrane matrix. Transmission electron microscopic analyses of cross-section of the reduced membrane samples were carried out to study the shape, size, and positioning of nps in the membrane. This study revealed that the shape of Ag nps in all the cases was spherical, but size and spatial distributions varied depending upon reducing conditions of the membrane. The bulk concentration of Ag nps having 15 ± 4 nm size was found to be located near the surface of BH 4 − ions reduced membrane sample. In case of slow dimethyl formamide reduction, the non-uniform and bimodal size distribution (5 ± 1 and 18 ± 5 nm) of Ag nps was observed in the membrane matrix. The reduction with formamide at 65 • C was found to produce Ag nps dispersed uniformly in the membrane matrix with narrow size distribution (9 ± 2 nm). EDXRF and radiotracer analyses were carried out to quantify Ag contents of the nanoparticles formed in the reduced membrane samples. The mechanism of formation of Ag nps in the membrane by ionic and nonionic reductant was interpreted in terms of ion-exchange process operating during the reduction. The self-diffusion coefficients of Na + , Cs + , and Eu 3+ counterions in the Ag nps embedded membrane samples were measured by the isotopic-exchange method. It was observed that the presence of Ag nps enhanced the diffusion mobility of slow moving Cs + and Eu 3+ counterions ions in the membrane matrix by 2 and 5 times, respectively.