Beads-on-String Structured Nanofibers for Smart and Reversible Oil/Water Separation with Outstanding Antifouling Property

Abstract

It is challenging to explore a unified solution for the treatment of oily wastewater from complex sources. Thus, membrane materials with flexible separation schemes are highly desired. Herein, we fabricated a smart membrane by electrospinning TiO2 doped polyvinylidene fluoride (PVDF) nanofibers. The as-formed beads-on-string structure and hierarchical roughness of the nanofibers contribute to its superwetting/resisting property to liquids, which is desirable in oil/water separation. Switched simply by UV (or sunlight) irradiation and heating treatment, the smart membrane can realize reversible separation of oil/water mixtures by selectively allowing water or oil to pass through alone. Most importantly, the as-prepared nanofiber membrane possesses outstanding antifouling and self-cleaning performance resulting from the photocatalytic property of TiO2, which has practical significance in saving solvents and recycling materials. This work provides a route for fabricating cost-effective, easily scaled up, and recyclable membranes for on-demand oil/water separation in versatile situations, which can be of great usage in the new green separation technology.

Preparation of Fouling-Resistant Nanofibrous Composite Membranes for Separation of Oily Wastewater

“…The resultant membrane showed effective oil-water emulsion separation due to the hydrophilicity of PEG and low surface energy of PTFOA. Wang et al [24] prepared titanium dioxide (TiO 2 ) doped polyvinylidene fluoride (PVDF) nanofibers to prevent fouling of membranes in oil-water separation. TiO 2 gel was prepared and mixed with the PVDF solution before the spinning process.…”

Fabrication of Photocontrolled Surfaces for Oil/Water Separation through Sulfur(VI) Fluoride Exchange

“…The resulting material displayss witchable wettability between hydrophobic and hydrophilic states when subjected to ultraviolet or visible irradiation. [29,30] However,b ys imply irradiating these materials with light, their wettability can be easily transitioned betweenh ydrophobicity and hydrophilicity.H owever,i no rder to recover their hydrophobic state, ZnO and TiO 2 must be stored in the dark for prolonged time periods, whichrestricts their applications.I nc ontrast, photoresponsive organic chemicals, such as azobenzenea nd spiropyran, can easily transition betweenh ydrophobic and hydrophilics tates under ultraviolet (UV) or visible light irradiation. [1][2][3][4][5][6][7] To address this issue, we need more effective methods of collecting and recovering insoluble oils ando rganics olvents from polluted water.R esearchers have developed numerous products and approaches forw ater purification, such as oil-containment booms, [8][9][10] absorbent compounds, [11][12][13] and variouso il/water separation techniques, [14][15][16][17] particularly those that are based on materialw ettability.F or example, severals uperhydrophobic/superoleophilic materials, including polyester-based compounds, [18,19] surfacemodified metal meshes, [20,21] and textiles, [22,23] have shown sat-isfactoryp erformancei ni solating oils that have ah igher density than water.…”

“…[29,30] However,b ys imply irradiating these materials with light, their wettability can be easily transitioned betweenh ydrophobicity and hydrophilicity.H owever,i no rder to recover their hydrophobic state, ZnO and TiO 2 must be stored in the dark for prolonged time periods, whichrestricts their applications.I nc ontrast, photoresponsive organic chemicals, such as azobenzenea nd spiropyran, can easily transition betweenh ydrophobic and hydrophilics tates under ultraviolet (UV) or visible light irradiation. For example, researchers have studied inorganic oxides, such as ZnO and TiO 2 ,f or wastewatert reatmenta nd self-cleaning purposes.…”

Core‐sheath structured TiO2@PVDF/PAN electrospun membranes for photocatalysis and oil‐water separation

“…Moreover, PVDF is cheap and have an easy access, which enables its application to different fields and makes it the most common polymer that is combined with TiO 2. In addition, hydrophobic PVDF allows nonpolar organic solvents to aggregate over its surface, which in turn obtains good oil‐water separation function, exemplified by PVDF/TiO 2 oil‐water separating membranes that correspond to the temperature and UV lights . Polyacrylonitrile (PAN) is a polymer that is also commonly used in electrospinning due to its hydrophilicity, flexibility, and density, and PAN is used as a fixing photocatalytic model polymer with an attempt to separate oil from water and purify water .…”