Synthesis, characterization and permeation performance of cellulose acetate/polyethylene glycol-600 membranes loaded with silver particles for ultra low pressure reverse osmosis (original) (raw)
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Self-sterilized composite membranes of cellulose acetate/polyethylene glycol for water desalination
Carbohydrate Polymers, 2016
Cellulose acetate/Polyethylene glycol-600 composite membranes were fabricated by two step phase inversion procedure and modified by in-situ reduction of silver nitrate. FTIR spectra demonstrated the existence of functional groups for bonding of silver with oxygen at 370 cm −1 , 535 cm −1. The XRD diffractogram indicates characteristic peaks at 2 values of 38.10 • , 44.30 • , 64.40 • , and 77.30 • which confirm the successful incorporation of silver within matrix of composite membranes. The morphology of composite membranes with appearances of spongy voids was exemplified from the scanning electron microscope. The atomic force microscopy was used to determine the increase in the surface roughness of the membranes. The increase in hydrophilicity, measured through contact angle, is rendered to the embedment of silver. The modification of membranes increased the flux from 0.80 to 0.95 L/hr.m 2. The resulting membranes have outstanding ability to fight against gram negative Escherichia Coli and Bacillus Sabtilus. The novel cellulose acetate/polyethylene glycol membranes customized with silver have paved the path for evolution of axenic membranes.
In this work, a number of cellulose acetate/polyethylene glycol-600 membranes, with different ratios were prepared by 2-stage phase inversion protocol. The permeation propertieswere studied by subjecting membranes in indigenously fabricated reverse osmosis plant. The flux and salt rejection of membranes were determined. The membrane with highest salt rejection was selected for modification with chitosan. The modified membranes were characterized for their compositional analysis, surface roughness, surface morphology, permeation properties, membrane hydraulic resistance and antibacterial activity. The presence of functional group was determined by FTIR spectra. Chitosan was found to significantly enhance the salt rejection and membrane hydraulic resistance. All modified membranes exhibited remarkable antibacterial properties. The varying nature of nodules and interstices spaces was observed in the images obtained by the atomic forced microscopy. The asymmetric surface morphology of membranes was elucidated from the scanning electron microscope. The synthesis of cellulose acetate membrane, doped with polyethylene glycol and modified with chitosan, provides a convenient access towards the development of sustainable chemistry.
Cellulose, 2017
In this research work, silver nanoparticles/ polyethylene glycol/cellulose acetate ultrafiltration (Ag-NPs/PEG/CA UF) composite membranes were synthesized and characterized. The Ag-NPs were embedded in the polymer matrix by two methods: in situ and ex situ; varying the type of solvent used (dimethylformamide, DMF; or N-methyl-2-pyrrolidone, NMP). The Ag-NPs used in the ex situ method were synthesized by a green chemistry reduction method. The composite membranes were characterized by Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis-derivative thermogravimetric analysis (TGA-DTG); the molecular weight cutoff and permeability were also determined. Moreover, the antibacterial efficiency of the composite membranes was measured against bacteria like Escherichia coli and Staphylococcus aureus. By FTIR-ATR analysis it was possible to observe that the Ag-NPs embedded in membranes changed the membrane morphology. The SEM-EDS analysis showed that the in situ composite membranes have good dispersity of Ag-NPs, DMF FB being the most densely populated obtained. By another hand, the ex situ DMF NP composite membrane presented the highest amount of silver signals per unit area (lm 2). The permeability of the membrane was affected by the presence of the Ag-NPs; the DMF NP composite membrane had the highest permeate flow, while DMF FB had the highest antibacterial activity.
In this work, a series of cellulose acetate/polyethylene glycol-600 membranes, with varying ratios were prepared by 2-stage phase inversion protocol. The permeation properties were studied by subjecting membranes in indigenously fabricated reverse osmosis plant. After optimization of different CA/PEG ratios, themembranewith highest salt rejection capacity was selected and modified with varying amount of silica. The Modified membranes were characterized for their permeation properties, hydrophilicity, compositional analysis, thermal stability,mechanical strength and morphological studies. Silica significantly influenced the permeation performance of composite membrane. The flux enhanced from 0.35 to 2.46 L/h m2 along with an 11.41% relative increase in salt rejection. The hydrophilicity was significantly enhanced by the addition of silica. In FTIR spectra, the broadening of the peak around 3500 cm−1 and emergence of peak at 950 cm−1 specified the incorporation of silica particles. The thermal analysis indicated the relative increase in degradation temperature (Tmax) and glass transition temperature (Tg) for CPS-5 membrane. The mechanical stability of the modified membranes, increased initially, but declined with further addition of silica. The results indicated that the incorporation of SiO2 content in the casting solution improved the fouling resistance of the membranes.
Materials Research
Inorganic nanoparticles incorporation in polymer membranes for filtration processes has attracted the attention of researchers in order to improve in some ways their performance. In this work, AgNPs were synthesized "in situ" in cellulose acetate (CA) membrane by chemical reduction of a silver salt. The membranes were prepared by the nonsolvent induced phase inversion method. Asymmetric membranes without (CA-M) and with adsorbed AgNPs (CA-Ag-M) were obtained. Ultrafiltration properties were confirmed for both membranes (16 nm of average pore diameter) and average crystallite size of 21 nm for the adsorbed AgNPs was computed. Contact angle measured with Milli-Q water and dry CA-Ag-M is near zero while for the CA-M is around 80º. The CA-M showed water permeability of 214 Lh-1 m-2 , while the CA-Ag-M permeability was 1651 Lh-1 m-2 .
Water research, 2014
The potential to incorporate silver nanoparticles (Ag-NPs) as biocides in membranes for water purification has gained much interest in recent years. However, a viable strategy for loading the Ag-NPs on the membrane remains challenging. This paper presents a novel, facile procedure for loading Ag-NPs on thin-film composite (TFC) reverse osmosis membranes. Reaction of silver salt with a reducing agent on the membrane surface resulted in uniform coverage of Ag-NPs, irreversibly bound to the membrane, as confirmed by XPS, TEM, and SEM analyses. Salt selectivity of the membrane as well its surface roughness, hydrophilicity, and zeta potential were not impacted by Ag-NP functionalization, while a slight reduction (up to 17%) in water permeability was observed. The formed Ag-NPs imparted strong antibacterial activity to the membrane, leading to reduction of more than 75% in the number of live bacteria attached to the membrane for three model bacteria strains. In addition, confocal microsco...
DESALINATION AND WATER TREATMENT, 2017
Amine functionalized TiO 2 nanoparticles were synthesized via surface reaction with 3-Aminopropyl triethoxysilane. These nanoparticles were added to polysulfone and cellulose acetate blend casting solutions in 1-Methyl-2-pyrrolidone to form hybrid membranes by phase inversion. The amine groups on the surface of the membranes were used as absorption sites for silver nanoparticles. The obtained membranes were characterized using Fourier Transform Infra Red spectroscopy, Scanning electron microscope and X-ray diffraction. Water uptake studies and contact angle measurements were done to evaluate hydrophilicity of the membranes. Pure water flux studies of the membrane were carried out in a dead end filtration unit. Rejection and antifouling studies were carried out using bovine serum albumin as a model protein. The hybrid membranes exhibited better permeability and fouling resistance. The hybrid membranes with silver decoration on the surface showed microbial resistance.
Journal of Membrane Science, 2010
In order to evaluate the effect of membrane surface properties on the initial stage of biofouling, in the reverse osmosis (RO) membrane process, initial bacterial adhesion and biofilm formation experiments were performed under no filtration condition. In this study, five commercialized polyamide thin-film composite RO membranes (SW30HRLE, SW30HR (Dow FilmTec Co., USA), TM820 (Toray Co., Japan), RE-BE, RE-FE (Woongjin Chemical Co., Korea)) were chosen and their surface properties such as surface charge, roughness, hydrophobicity and surface morphology were measured. For examining initial bacterial adhesion, a flow channel reactor was employed for 3 h, while for examining a biofilm formation, the CDC reactor was employed for 48 h. Pseudomonas aeruginosa PAO1 tagged with GFP was selected as a model bacterial strain. Major findings in this study indicate that although the initial bacterial cell adhesion in a flow channel reactor indicated more bacterial cells attachment on the membrane surface with higher hydrophobicity, the extent of biofilm grown in CDC reactor for 48 h became similar regardless of the difference of the membrane surface properties, indicating that the membrane surface properties become a less important factor affecting the biofilm growth on the membrane surface. This finding will be helpful in improving the understanding of biofouling issue occurring in the real RO membrane system, although practical implication is somewhat limited since this study was performed under no filtration condition.