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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

Different working mechanisms among P, GO-P and GO-P-S membranes during nanoemulsion separation process.(a) The hydrophobicity and underwater oleophilicity of P membrane leads to severe fouling induced by both surfactant and oil. (b) The nano-engineering by introducing GO sheet can increase pure water permeability (PWP) of phase inversion constructed membrane through enlarging selective layer pore radius. However, topography roughness of membrane is also increased with membrane surface remained oleophilic under water. As a result, GO-P membrane is poor in both antifouling capability and rejection of surfactant as well as oil. (c) Surface functionalization with hydrogel macromolecule can tune selective layer pore radius small enough to reject surfactant, reduce topography roughness and endow the resultant GO-P-S membrane with high oleophobicity under water. The synergistic effect of smooth topography and underwater oil-repellency leads to the multipotent antifouling capabilities that resist both oil and surfactant induced fouling. Moreover, GO-P-S membrane also achieves high rejections of both surfactant and oil.
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f7: Different working mechanisms among P, GO-P and GO-P-S membranes during nanoemulsion separation process.(a) The hydrophobicity and underwater oleophilicity of P membrane leads to severe fouling induced by both surfactant and oil. (b) The nano-engineering by introducing GO sheet can increase pure water permeability (PWP) of phase inversion constructed membrane through enlarging selective layer pore radius. However, topography roughness of membrane is also increased with membrane surface remained oleophilic under water. As a result, GO-P membrane is poor in both antifouling capability and rejection of surfactant as well as oil. (c) Surface functionalization with hydrogel macromolecule can tune selective layer pore radius small enough to reject surfactant, reduce topography roughness and endow the resultant GO-P-S membrane with high oleophobicity under water. The synergistic effect of smooth topography and underwater oil-repellency leads to the multipotent antifouling capabilities that resist both oil and surfactant induced fouling. Moreover, GO-P-S membrane also achieves high rejections of both surfactant and oil.

Mentions: Meanwhile, oil rejection follows the order of GO-P-S membrane >P membrane >GO-P membrane. Firstly, GO-P membrane is inferior in oil rejection to P membrane. This is because those big pores (~80 nm in diameter) of GO-P membrane are not effective to reject nanosized oil droplets especially under high TMP (Fig. 7a,b). Secondly and more importantly, GO-P-S membrane outperforms P membrane in oil rejection. This substantiates that surface wettability also has a significant impact on oil rejection besides pore size sieving effect. Our delicate surface functionalization contributes to preventing pressure-squeezed oil intrusion and thus leads to constantly higher oil rejection (Fig. 7c).


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)

Different working mechanisms among P, GO-P and GO-P-S membranes during nanoemulsion separation process.(a) The hydrophobicity and underwater oleophilicity of P membrane leads to severe fouling induced by both surfactant and oil. (b) The nano-engineering by introducing GO sheet can increase pure water permeability (PWP) of phase inversion constructed membrane through enlarging selective layer pore radius. However, topography roughness of membrane is also increased with membrane surface remained oleophilic under water. As a result, GO-P membrane is poor in both antifouling capability and rejection of surfactant as well as oil. (c) Surface functionalization with hydrogel macromolecule can tune selective layer pore radius small enough to reject surfactant, reduce topography roughness and endow the resultant GO-P-S membrane with high oleophobicity under water. The synergistic effect of smooth topography and underwater oil-repellency leads to the multipotent antifouling capabilities that resist both oil and surfactant induced fouling. Moreover, GO-P-S membrane also achieves high rejections of both surfactant and oil.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f7: Different working mechanisms among P, GO-P and GO-P-S membranes during nanoemulsion separation process.(a) The hydrophobicity and underwater oleophilicity of P membrane leads to severe fouling induced by both surfactant and oil. (b) The nano-engineering by introducing GO sheet can increase pure water permeability (PWP) of phase inversion constructed membrane through enlarging selective layer pore radius. However, topography roughness of membrane is also increased with membrane surface remained oleophilic under water. As a result, GO-P membrane is poor in both antifouling capability and rejection of surfactant as well as oil. (c) Surface functionalization with hydrogel macromolecule can tune selective layer pore radius small enough to reject surfactant, reduce topography roughness and endow the resultant GO-P-S membrane with high oleophobicity under water. The synergistic effect of smooth topography and underwater oil-repellency leads to the multipotent antifouling capabilities that resist both oil and surfactant induced fouling. Moreover, GO-P-S membrane also achieves high rejections of both surfactant and oil.
Mentions: Meanwhile, oil rejection follows the order of GO-P-S membrane >P membrane >GO-P membrane. Firstly, GO-P membrane is inferior in oil rejection to P membrane. This is because those big pores (~80 nm in diameter) of GO-P membrane are not effective to reject nanosized oil droplets especially under high TMP (Fig. 7a,b). Secondly and more importantly, GO-P-S membrane outperforms P membrane in oil rejection. This substantiates that surface wettability also has a significant impact on oil rejection besides pore size sieving effect. Our delicate surface functionalization contributes to preventing pressure-squeezed oil intrusion and thus leads to constantly higher oil rejection (Fig. 7c).

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