Graphene Oxide Nanosheet Framework on the Surface of Polyvinylidene Fluoride-co-Polyacrylic Acid Composite Membrane for Water Purification (original) (raw)
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Performance improvement of reduced graphene oxide blended PVDF ultrafiltration membrane
DESALINATION AND WATER TREATMENT
The performance of a novel polyvinylidene fluoride (PVDF) membrane with high hydrophilicity and enhanced separation ability was discussed with the addition of a small amount of reduced graphene oxide nanoparticles (rGO). The PVDF-rGO ultrafiltration composite membrane was effectively synthesized, by incorporating rGO (0.1% wt) as nanoparticles by the phase inversion process. The impact of these modifications was studied. The morphological structure of the membranes was evaluated by scanning electron microscopy (SEM). The changes in the chemical structure were investigated using Fourier-transform infrared spectroscopy. The SEM images revealed that in the PVDF membrane, the diameter of the pores increased after rGO grafting. Performance tests showed that the PVDF membrane has flux and a rejection of bovine serum albumin about 92% at an optimum transmembrane pressure of 4 bar. The incorporation of rGO improved the protein rejection, reaching a rejection rate of around 92% at 4 bar. These results suggest that incorporating rGO nanoparticles can enhance the permeability of the membrane. The PVDF membrane modified with 0.1 wt.% rGO showed a considerably higher flux than the unmodified membrane.
Journal of Environmental Management, 2020
This work investigates the performance and structure of polyamide thin film nanocomposite (PA-TFN) membrane incorporated with triethylenetetramine-modified graphene oxide (GO-TETA). The embedment of GO-TETA nanosheets within the structure of PA-TFN membrane was evaluated at different concentrations (0.005, 0.01, 0.03 wt%; in aqueous piperazine (PIP)) through interfacial polymerization (IP). The physicochemical properties of the prepared membrane were investigated by SEM, AFM, water contact angle, and zeta potential as well as ATR-IR spectroscopy. The presence of longer chains of amino groups (in comparison with the directly linked amino ones) among the stacked GO nanosheets was assumed to increase interlayer spacing, resulting in remarkable changes in water permeance and separation behavior of modified polyamide (PA) membrane. It is seen that GO-TETA nanosheets were uniformly distributed in the matrix of PA layer. With increasing the concentration of GO-TETA, the flux of TFN membranes under 6 bar was increased from 49.8 l/m 2 h (no additive) to 73.2 l/m 2 h (TFN comprising 0.03 wt% GO-TETA. In addition, more loading GO-TETA resulted in a significant decrease in the average thickness of the polyamide layer from ~380 to ~150 nm. Furthermore, addition of GO-TETA improved the hydrophilicity of nanocomposite membranes, resulting in superb water flux recovery (antifouling indicator) as high as 95% after filtration of bovine serum albumin solution. Also, the retention capability of the TFN membranes towards some textile dyes increased as high as 99.6%.
Chemical Engineering Science, 2018
A membrane usually suffers from a reduction in membrane rejection performance when exposed to a concentrated salt solution. A fabricated polyimide (PI)/graphene oxide (GO) mixed matrix membrane (MMM) was prepared at different GO/PI concentrations (ranging from 0 to 3.5 wt%) to investigate membrane performance in diluted and concentrated salt solutions. Results showed that the MMM possess nanofiltration (NF) properties with high water permeability and excellent salt rejection (99%) in diluted conditions regardless of the applied filtration pressure. The water and permeate permeability increased with the increase in GO content. Interestingly, for concentrated salt solutions, PI/GO MMM only showed at most 4% reduction in rejection, unlike in pure PI membrane, which experienced 16% reduction. A higher amorphous region of the MMM compared to the pure PI in salt solutions was found through XRD. The ionization of GO increases the amorphous structure thus enhances the effective thickness of membrane maintaining the MMM rejection performance. 0.9 wt% GO/PI in MMM showed the highest rejection (98%) in 0.15 M Na 2 SO 4. The presence of GO with its unique properties and highly porous structure was found to retain the membrane rejection properties, especially in concentrated solution.
Journal of Materials Science
In this paper, we present novel semi-permeable graphene-based membranes. Composite filters were designed and fabricated on polysulfone porous scaffolding using combinations of polycrystalline large-area High Strength Metallurgical Graphene (HSMG®), graphene oxide, hydrazine and an in-situ interfacial polymerized polyamide. The naturally occurring defects in HSMG® (which were tenths of a nanometer) were the clue in fabricating a filtering membrane. The performance of graphene membranes was evaluated in forward osmosis test. The prepared composites were proved to be semi-permeable membranes with great ions blocking efficiency (over 95%) and water flux only one order of magnitude lower than the commercial reverse osmosis membranes. The experiments’ results demonstrated that the solutions proposed in this work indicate that graphene-based membranes can be used in water treatment technology.
Scientific Reports, 2017
In the present study, graphene oxide (GO) was incorporated as a nanoadditive into a polyphenylsulfone (PPSU) to develop a PPSU/GO nanocomposite membrane with enhanced antifouling properties. A series of membranes containing different concentrations (0.2, 0.5 and 1.0 wt.%) of GO were fabricated via the phase inversion method, using N-methyl pyrrolidone (NMP) as the solvent, deionized water as the non-solvent, and polyvinylpyrrolidone (PVP) as a pore forming agent. The prepared nanocomposite membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and were also characterized with respect to contact angle, zeta potential and porosity, mean pore radius, tortuosity and molecular weight cutoff (MWCO). Thermogravimetric analysis (TGA) and tensile testing were used to measure thermal and mechanical properties. The membrane performance was evaluated by volumetric flux and rejection of proteins, and antifouling properties. According to the results, the optimum addition of 0.5 wt% GO resulted in a membrane with an increased flux of 171 ± 3 Lm −2 h −1 with a MWCO of ~40 kDa. In addition, the GO incorporation efficiently inhibited the interaction between proteins and the membrane surface, thereby improving the fouling resistance ability by approximately 58 ± 3%. Also, the resulting membranes showed a significant improvement in mechanical and thermal properties. Membrane technology has shown great promise in all types of separation such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO). This technology has a number of attractive features such as simplicity of operating conditions, low energy consumption, no phase change, compact design and environmental friendliness 1,2. Despite its great promise, membrane technology has a key limitation of membrane fouling. This is due to membrane surface properties including hydrophobicity, surface charge and roughness 3-6. Fouling results in an increase in the operational cost, as well as decreased membrane life. Therefore, a large part of research in membrane technology is focused on the development of so-called antifouling membranes. To date, a number of techniques to develop antifouling membranes have been employed. They include hydrophilic surface modification by coating, grafting and the concept of making thin film composite (TFC) membranes, bulk modification by blending and mixing hydrophilic polymers, and incorporation of nanomaterials into membrane matrices for developing nanocomposite membranes 1,7-10. Recently, the study of nanocomposite membranes has grown as an active area of membrane materials research and development. The nanomaterials of greatest interest for nanocomposite membrane development are titanium dioxide (TiO 2), aluminium oxide (Al 2 O 3), zinc oxide (ZnO), silicon dioxide (SiO 2), carbon nanotubes (CNT) and graphene oxide (GO) 11-18. Among them, GO is an emerging nanomaterial that has shown great promise in the development of anti-fouling nanocomposite membranes 17,19-23. During the past few years, several investigators have studied the incorporation of GO into commonly used polymeric membrane matrices like polysulfone (PSF), polyethersulfone (PES), polyvinylidene difluoride (PVDF), polyacrylonitrile (PAN), and their copolymers, with the aim developing antifouling nanocomposite membranes 19,24-27. The additional advantages of using GO as nanoadditive is that it can be processed
Membranes
Emergence of membrane technology for effective performance is qualified due to its low energy consumption, no use of chemicals, high removal capacity and easy accessibility of membrane material. The hydrophobic nature of polymeric membranes limits their applications due to biofouling (assemblage of microorganisms on surface of membrane). Polymeric nanocomposite membranes emerge to alleviate this issue. The current research work was concerned with the fabrication of sulfonated graphene oxide doped polyvinylidene fluoride (PVDF) membrane and investigation of its anti-biofouling and anti-bacterial behavior. The membrane was fabricated through phase inversion method, and its structure and morphology were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-rays diffraction (XRD) and thermo gravimetric analysis (TGA) techniques. Performance of the membrane was evaluated via pure water flux; anti-biofouling behavior was determined through ...
Membranes
The emergence of mixed matrix membranes (MMMs) or nanocomposite membranes embedded with inorganic nanoparticles (NPs) has opened up a possibility for developing different polymeric membranes with improved physicochemical properties, mechanical properties and performance for resolving environmental and energy-effective water purification. This paper presents an overview of the effects of different hydrophilic nanomaterials, including mineral nanomaterials (e.g., silicon dioxide (SiO2) and zeolite), metals oxide (e.g., copper oxide (CuO), zirconium dioxide (ZrO2), zinc oxide (ZnO), antimony tin oxide (ATO), iron (III) oxide (Fe2O3) and tungsten oxide (WOX)), two-dimensional transition (e.g., MXene), metal–organic framework (MOFs), covalent organic frameworks (COFs) and carbon-based nanomaterials (such as carbon nanotubes and graphene oxide (GO)). The influence of these nanoparticles on the surface and structural changes in the membrane is thoroughly discussed, in addition to the perfo...
Algal Research, 2017
This study investigated the characteristics of various graphene oxide (GO) nanohybrid membranes and their performance in algal organic matter (AOM) filtration. The membranes were fabricated by phase inversion method. The effect of GO and its nanohybrids embedded in membranes was investigated in terms of wettability, porosity, pore size, surface charge, composition, morphology, permeability, fouling resistance and antimicrobial ability. In addition, the rejection of protein and carbohydrate as critical foulants in AOM was studied. Based on the findings, all the composite membranes showed lower flux decline than PVDF membrane. Composite membranes maintained higher protein (81-86%) and carbohydrate (77-83%) rejection compared with PVDF membrane (64% for protein and 63% for carbohydrate). However, the reversible to irreversible fouling ratio of PVDF, ZnO/GO-PVDF, Ag/GO-PVDF and GO-PVDF membranes was 3.07, 1.53, 0.86 and 1.09, respectively. This scenario implied that more hydrophilic substances in small molecular weight (MW) contained in AOM had plugged the composite membranes' pores and resulted in irreversible fouling. On the other hand, ZnO/GO-PVDF and Ag/GO-PVDF membranes exhibited superior antimicrobial ability and showed great potential in anti-biofouling mitigation.
Evaluating graphene oxide and holey graphene oxide membrane performance for water purification
Journal of Membrane Science, 2019
Graphene oxide (GO) membranes have demonstrated desirable performance for purifying water, matching or exceeding the ion rejection and water flux properties of reverse osmosis (RO) membranes. Though previous methods (e.g., surface decoration and d-space tuning) have been investigated to improve GO membranes, thermal treatment can induce the formation of holes in GO nanosheets in a controlled manner. The resulting holey-GO (hGO) membranes are hypothesized to have improved water permeability via decreasing the pathlength that water molecules must travel through the membrane; specifically, through cross-sheet junctions, which is currently one of the main bottlenecks in other GO membranes. GO and hGO membranes with varying thicknesses were fabricated on polycarbonate supports and evaluated with ion transport tests in a diffusion cell via permeate conductivity. Permeability tests were conducted using a dead-end filtration cell (0.27 MPa-0.48 MPa). Produced hGO membranes demonstrated up to 3.8 times higher permeability relative to GO membranes, despite being up to 4 times thicker. Additionally, the empirical upper bound for a modified Robeson plot measuring permeability and selectivity was exceeded by both GO and hGO membranes demonstrated in this work.