Graphene oxide-embedded polyamide nanofiltration membranes for selective ion separation

Hu, Ruirui; He, Yijia; Zhang, Cuimiao; Zhang, Rujing; Li, Jing; Zhu, Hongwei

doi:10.1039/c7ta08635k

Cited by 102 publications

(57 citation statements)

References 41 publications

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“…The XPS C 1s peak of GO QDs was deconvoluted and displayed in Figure 2b. [35] The intensity of the peak at 3422 cm −1 indicates that there existed rich hydroxyl groups in GO QDs, which render them good hydrophilicity by forming hydrogen bonds with water. The surface functional groups of GO QDs are revealed in the FTIR spectrum ( Figure 2c).…”

Section: Wwwadvmatinterfacesdementioning

confidence: 99%

Physically Coating Nanofiltration Membranes with Graphene Oxide Quantum Dots for Simultaneously Improved Water Permeability and Salt/Dye Rejection

Zhao

et al. 2019

Adv Materials Inter

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strategy to produce fresh water from seawater and polluted water, without generating harmful by-products. [3] Among them, thin-film composite nanofiltration (TFC NF) membranes are an important component. They can produce higher water flux with lower energy consumption compared with reverse osmosis membranes. They are efficient in removal of both conventional and emerging contaminants from water. In addition, the higher rejection of divalent ions compared with monovalent ones makes them promising in the application of water softening. [4][5][6] Generally TFC NF membranes are prepared through the interfacial polymerization (IP) method, forming a structure of an ultrathin polyamide (PA) selective layer on the surface of a porous substrate. The structure and physiochemical properties of the PA selective layer and the underlying substrate can be individually modified to improve the overall membrane performance. [7] However, the trade-off between water permeability and salt rejection, a so-called "upper bound" relation, is one of the key problems faced by TFC membranes. [8][9][10] It is highly desirable that we can fabricate TFC PA NF membranes with improved water permeability and salt/dye rejection for promoting both energy effectiveness and water quality.Incorporating hydrophilic nanoparticles (NPs), such as TiO 2 , [11] SiO 2 , [12,13] Al 2 O 3 , [14] Ag, [15] nanozeolite, [16,17] and graphene oxide quantum dots (GO QDs), [18] into the top PA selective layer to form thin-film nanocomposite (TFN) membranes has been demonstrated as an effective strategy to improve the water permeability of membranes. The improvement is resulted from the increased membrane hydrophilicity and additional water pathways introduced by the NPs. However, NPs tend to interfere the IP process of the PA selective layer, leading to undesired changes in pore structure, thickness, and surface roughness of membranes. [19,20] Besides, the incompatibility between inorganic NPs and the organic polymer matrix results in microporous defects. [21,22] Both of them account for the decrease in membrane salt rejection. Additionally, NPs are mainly embedded inside the polymer matrix, so that they are not effectively available for surface-based interactions.A physically bound coating of graphene oxide quantum dots (GO QDs) on thin-film composite polyamide nanofiltration (NF) membranes is prepared through a pressure-assisted filtration method to simultaneously improve the membranes' water permeability and salt/dye rejection. It is the first attempt to use carbon-based nanoparticles as surface coating to improve the efficiency of water filtration membranes. Influences of the GO QDs' coating on the hydrophilicity and surface charge of the membranes are investigated by water contact angle and zeta potential measurements. With the GO QDs' coating, the surface roughness and hydrophilicity of the membranes increase, and the membrane surface becomes more negatively charged. Water permeability and salt/dye rejection of GO QD-coated NF membranes increase simultaneously ...

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Section: Wwwadvmatinterfacesdementioning

confidence: 99%

Physically Coating Nanofiltration Membranes with Graphene Oxide Quantum Dots for Simultaneously Improved Water Permeability and Salt/Dye Rejection

Zhao

et al. 2019

Adv Materials Inter

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“…This is because the isoelectric point (IEP) of the three membranes is approximately 4. Thus, the membrane surface is positively charged when the pH value is 2 and 3, and the rejection rate of SO 4 2− decreases due to the electrostatic attraction effect 33 . When the pH value is higher than 4, the membrane surface is negatively charged, thus the rejection rate is increased.…”

Section: Resultsmentioning

confidence: 96%

Graphene oxide/multi‐walled carbon nanotubes nanocompsite polyamide nanofiltration membrane for dyeing‐printing wastewater treatment

Wei

Cao

et al. 2020

Polymers for Advanced Techs

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Graphene oxide (GO)/multi‐walled carbon nanotubes (MWCNTs) modified nanofiltration (NF) membranes were successfully fabricated by interfacial polymerization of piperazine (PIP) and 1,3,5‐benzenetricarbonyl trichloride (TMC). Compared with the pristine polyamide (PA) membrane and GO membrane, the typical structure of the granular protrusions on the surface of the GO/MWCNTs membrane gradually disappeared, and a regular ordered morphology appeared. The membrane thickness and surface roughness were increased according to the results of field emission scanning electron microscopy (FE‐SEM) and atomic force microscopy (AFM). The contact angle of GO/MWCNTs NF membranes progressively decreased from 57° to 23°, indicating the enhancement of surface hydrophilicity. The best NF performance was achieved when the ratio of GO to MWCNTs was 6:3 (G‐M‐3). The water flux was 55.6 L/m2.h, which was 33.7% higher than that of the GO membrane, and the rejection rate for Na2SO4 was maintained at approximately 94%. Both modified NF membranes could treat actual dyeing‐printing wastewater effectively. The anti‐fouling performance of G‐M‐3 was better than that of G3. Therefore, GO/MWCNTs‐modified NF membranes have a good application prospects in the field of wastewater treatment and water purification.

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“…In the meanwhile, the signal of pristine RO membranes is still present in Raman spectrum of RO‐GO‐thin, indicating that GO coating is quite thin. With increasing the thickness of GO coating, RO‐GO‐thick shows two typical peaks of D band at 1350 cm −1 and G band at 1600 cm −1 , which are the characteristic peaks of pure GO nanosheets, suggesting that GO coating is thick enough to shelter the signals of pristine RO membranes. The peak intensity at 1350 cm −1 has been used to evaluate the coverage of RO membrane by GO using Raman mapping.…”

Section: Resultsmentioning

confidence: 99%

Facile Fabrication of Unimpeded and Stable Graphene Oxide Coating on Reverse Osmosis Membrane for Dual‐Functional Protection

Wang

Liu

et al. 2018

ChemistrySelect

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Membrane fouling and chlorination have remained the greatest threats to durable reverse osmosis (RO) membrane applications. Here, we report a facile technique of high pressure assisted deposition (HPSD) to physically anchor stable graphene oxide (GO) coatings on RO membranes for simultaneous dual‐functional protection against fouling and chlorination without sacrifice of water flux. Thick coatings were directly prepared by HPSD, and a subsequent “skin‐removing” method was used to obtain GO thin coatings with stronger adhesion. The measurement of GO coating thickness was achieved by a “removing‐transferring” method, demonstrating a thickness of 200 and 50 nm for GO thick and thin coatings, respectively. Benefiting from our coating deposition technique of HPSD, 100% of coverage by GO was achieved for both GO coated membranes. The filtration test showed that GO coating was highly permeable to water resulted from the optimized small size of GO sheets (∼200 nm) and the unique water transport properties through GO laminates. The GO thin coating could effectively alleviate the membrane fouling by rendering membrane surface more hydrophilic and smoother, while the thick coating reversely aggravated the fouling due to the more hydrophobic surface. In addition, GO coating could dramatically improve the chlorine stability of RO membrane by impeding the diffusion of reactive chlorine, with a high level of salt rejection after chlorination for GO coated membranes.

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Graphene oxide-embedded polyamide nanofiltration membranes for selective ion separation

Abstract: Graphene oxide modified piperazine nanofiltration membranes are prepared by in situ interfacial polymerization and show improved water permeability and ion selectivity performance.

Cited by 102 publications

References 41 publications

Physically Coating Nanofiltration Membranes with Graphene Oxide Quantum Dots for Simultaneously Improved Water Permeability and Salt/Dye Rejection

Physically Coating Nanofiltration Membranes with Graphene Oxide Quantum Dots for Simultaneously Improved Water Permeability and Salt/Dye Rejection

Graphene oxide/multi‐walled carbon nanotubes nanocompsite polyamide nanofiltration membrane for dyeing‐printing wastewater treatment

Facile Fabrication of Unimpeded and Stable Graphene Oxide Coating on Reverse Osmosis Membrane for Dual‐Functional Protection

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