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A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion.

Qin D, Liu Z, Bai H, Sun DD, Song X - Sci Rep (2016)

Bottom Line: The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization.Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion.Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

View Article: PubMed Central - PubMed

Affiliation: Energy Research Institute @ NTU, Interdisciplinary Graduate School, Nanyang Technological University, 639798, Singapore.

ABSTRACT
Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

No MeSH data available.


Related in: MedlinePlus

The characterizations of oil-in-water nanoemulsions.(a) Optical photo (from left to right, oil concentration is increased from 400 mg/L to 2000 mg/L by 400 mg/L increment for each flask), (b) turbidity data and (c) dynamic light scattering (DLS) result of nanoemulsions under different oil concentrations (The surfactant/oil ratio is kept as 0.15). (d) Optical microscopy image of 2000 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm). (e) Optical photo (from left to right, surfactant/oil ratio is increased from 0.05 to 0.25 by 0.05 increment for each flask), (f) turbidity data and (g) DLS result of nanoemulsions under different surfactant/oil ratios (The oil concentration is kept as 1200 mg/L). (h) Optical microscopy image of 1200 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm).
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f5: The characterizations of oil-in-water nanoemulsions.(a) Optical photo (from left to right, oil concentration is increased from 400 mg/L to 2000 mg/L by 400 mg/L increment for each flask), (b) turbidity data and (c) dynamic light scattering (DLS) result of nanoemulsions under different oil concentrations (The surfactant/oil ratio is kept as 0.15). (d) Optical microscopy image of 2000 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm). (e) Optical photo (from left to right, surfactant/oil ratio is increased from 0.05 to 0.25 by 0.05 increment for each flask), (f) turbidity data and (g) DLS result of nanoemulsions under different surfactant/oil ratios (The oil concentration is kept as 1200 mg/L). (h) Optical microscopy image of 1200 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm).

Mentions: Various oil-in-water nanoemulsions were prepared as the feed solutions for membrane separation. It’s found that both oil concentration and surfactant/oil ratio play an important role in the dispersion of oil droplets in nanoemulsion. Figure 5a–c demonstrates the positive correlation between oil droplet size and oil concentration. Generally, the synthetic nanoemulsions become less transparent as oil concentration increased (Fig. 5a), which is also evidenced by the corresponding increase of turbidity (Fig. 5b). Moreover, dynamic laser light scattering (DLS) result reveals that oil droplet distribution is shifted towards larger sizes along with the increase of oil concentration. Noteworthily, the initial increase of oil concentration from 400 mg/L to 1200 mg/L merely causes a slight increase in average droplet size from 180 nm to 211 nm. While a further increase of oil concentration to 1600 mg/L and 2000 mg/L leads to the remarkable increase in average droplet size to 316 nm and to 479 nm, respectively (Fig. 5c).


A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion.

Qin D, Liu Z, Bai H, Sun DD, Song X - Sci Rep (2016)

The characterizations of oil-in-water nanoemulsions.(a) Optical photo (from left to right, oil concentration is increased from 400 mg/L to 2000 mg/L by 400 mg/L increment for each flask), (b) turbidity data and (c) dynamic light scattering (DLS) result of nanoemulsions under different oil concentrations (The surfactant/oil ratio is kept as 0.15). (d) Optical microscopy image of 2000 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm). (e) Optical photo (from left to right, surfactant/oil ratio is increased from 0.05 to 0.25 by 0.05 increment for each flask), (f) turbidity data and (g) DLS result of nanoemulsions under different surfactant/oil ratios (The oil concentration is kept as 1200 mg/L). (h) Optical microscopy image of 1200 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834549&req=5

f5: The characterizations of oil-in-water nanoemulsions.(a) Optical photo (from left to right, oil concentration is increased from 400 mg/L to 2000 mg/L by 400 mg/L increment for each flask), (b) turbidity data and (c) dynamic light scattering (DLS) result of nanoemulsions under different oil concentrations (The surfactant/oil ratio is kept as 0.15). (d) Optical microscopy image of 2000 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm). (e) Optical photo (from left to right, surfactant/oil ratio is increased from 0.05 to 0.25 by 0.05 increment for each flask), (f) turbidity data and (g) DLS result of nanoemulsions under different surfactant/oil ratios (The oil concentration is kept as 1200 mg/L). (h) Optical microscopy image of 1200 mg/L nanoemulsion with 0.15 surfactant/oil ratio (scale bar, 2 μm).
Mentions: Various oil-in-water nanoemulsions were prepared as the feed solutions for membrane separation. It’s found that both oil concentration and surfactant/oil ratio play an important role in the dispersion of oil droplets in nanoemulsion. Figure 5a–c demonstrates the positive correlation between oil droplet size and oil concentration. Generally, the synthetic nanoemulsions become less transparent as oil concentration increased (Fig. 5a), which is also evidenced by the corresponding increase of turbidity (Fig. 5b). Moreover, dynamic laser light scattering (DLS) result reveals that oil droplet distribution is shifted towards larger sizes along with the increase of oil concentration. Noteworthily, the initial increase of oil concentration from 400 mg/L to 1200 mg/L merely causes a slight increase in average droplet size from 180 nm to 211 nm. While a further increase of oil concentration to 1600 mg/L and 2000 mg/L leads to the remarkable increase in average droplet size to 316 nm and to 479 nm, respectively (Fig. 5c).

Bottom Line: The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization.Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion.Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

View Article: PubMed Central - PubMed

Affiliation: Energy Research Institute @ NTU, Interdisciplinary Graduate School, Nanyang Technological University, 639798, Singapore.

ABSTRACT
Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

No MeSH data available.


Related in: MedlinePlus