Lignin@Fe 3 O 4 nanoparticles adsorb at oil–water interfaces, form Pickering emulsions, induce on-demand magnetic responses to break emulsions, and can sequester oil from water. Lignin@Fe 3 O 4 nanoparticles were prepared using a pH-induced precipitation method and were fully characterized. These were used to prepare Pickering emulsions with castor oil/Sudan red G dye and water at various oil/water volume ratios and nanoparticle concentrations. The stability and demulsification of the emulsions under different magnetic fields generated with permanent magnets (0–540 mT) were investigated using microscopy images and by visual inspection over time. The results showed that the Pickering emulsions were more stable at the castor oil/water ratio of 50/50 and above. Increasing the concentration of lignin@Fe 3 O 4 improved the emulsion stability and demulsification rates with 540 mT applied magnetic field strength. The adsorption of lignin@Fe 3 O 4 nanoparticles at the oil/water interface using 1-pentanol evaporation through Marangoni effects was demonstrated, and magnetic manipulation of a lignin@Fe 3 O 4 stabilized castor oil spill in water was shown. Nanoparticle concentration and applied magnetic field strengths were analyzed for the recovery of spilled oil from water; it was observed that increasing the magnetic strength increased oil spill motion for a lignin@Fe 3 O 4 concentration of up to 0.8 mg mL −1 at 540 mT. Overall, this study demonstrates the potential of lignin-magnetite nanocomposites for rapid on-demand magnetic responses to externally induced stimuli.
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Robust, sustainable and multifunctional nanofibers with smart switchability for water-in-oil and oil-in-water emulsion separation and liquid marble preparation
Various membranes have been developed for the separation of oil/water mixtures; however, their fabrication requires toxic reagents, multiple processing steps, and advanced technologies. Nature not only precisely generates unique materials but also provides tremendous examples in the environment that can be used as inspiration for the development and creation of smart and green materials. In this study, we prepare multifunctional nanobiofibers (NBFs) from grape seeds by a one-pot reaction using green solvents that, when made into a smart layer, can switch between a state of underwater superoleophobic wetting to a state of underoil superhydrophobicity and back without any external stimuli. The several μm length and 50 nm width NBFs exhibit robust stability and provide a porous NBF layer, suggesting their potential for the simultaneous separation of various surfactant-stabilized water-in-oil and oil-in-water emulsions while showing high dye adsorption from water (100% for methylene blue). Furthermore, by rolling water droplets on the surface of NBF powder, an effective microreactor, known as a liquid marble, is prepared for the first time using a bio-originated, superamphiphilic material in air, rather than hydrophilic or hydrophobic materials, and it can be used to remove dye within 30 s. Moreover, based on the ability of NBFs to encapsulate a high volume of water (120 μL), we demonstrate another application of the NBF powder as an additive to soil for maintaining soil moisture under arid conditions, allowing us to successfully demonstrate the growth of a lentil seed. This multi-functional, low-cost, and green NBF material shows excellent sustainability and mechanical/chemical stability for multiple promising environmental remediation applications.
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- Award ID(s):
- 1719875
- NSF-PAR ID:
- 10146555
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 7
- Issue:
- 46
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 26456 to 26468
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT In this study, the cost‐effective graphite powder (GPd)‐coated polyurethane (PGPd‐PU) sponge hollow tube (PGPd‐PUHT) was prepared for high‐efficient continuous oil removal, the hydrophobicity‐superoleophilicity PGPd‐PU sponge was fabricated through a simple dip‐coating method, which dipping PU sponge into GPd dispersion and drying, then coating polydimethylsiloxane (PDMS) on sponge skeleton, as‐prepared sponge could selectively absorb a variety of oils up to 34 times of its own weight for dimethyl sulfoxide (DMSO). The PGPd‐PUHT was prepared
via wrapping PGPd‐PU sponge on porous tubular support. The obtained PGPd‐PUHT could continuously collect various types of oils from water surface with flux as high as 1.52 kL/m2h, and excellent separation efficiency (up to 97.7%) for toluene, as well as remarkable reusability. Moreover, a continuous floating oil collection device based on PGPd‐PUHT was designed which showed excellent floating oil collection ability. In addition, our strategy possesses the advantages of low cost, simple preparation, highly efficient, and easily scale‐up, showing a great potential for dealing with practical oil spill remediation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020 ,137 , 48921. -
The separation of oil from water and filtration of aqueous solutions and dispersions are critical issues in the processing of waste and contaminated water treatment. Membrane-based technology has been proven as an effective method for the separation of oil from water. In this research, novel vertical nanopores membrane, via oriented cylindrical block copolymer (BCP) films, suitable for oil/water filtration has been designed, fabricated and tested. We used a ∼100 nm thick model poly(styrene- block -methymethacrylate) (PS- b -PMMA) BCP as the active top nanofiltration layer, processed using a roll-to-roll (R2R) method of cold zone annealing (CZA) to obtain vertical orientation, followed by ultraviolet (UV) irradiation selective etch of PMMA cylinders to form vertically oriented nanopores as a novel feature compared to meandering nanopores in other reported BCP systems. The cylindrical nanochannels are hydrophilic, and have a uniform pore size (∼23 nm), a narrow pore size distribution and a high nanopore density (∼420 per sq. micron). The bottom supporting layer is a conventional microporous polyethersulfone (PES) membrane. The created asymmetric membrane is demonstrated to be effective for oil/water extraction with a modestly high throughput rate comparable to other RO/NF membranes. The molecular weight dependent filtration of a water soluble polymer, PEO, demonstrates the broader applications of such membranes.more » « less
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Abstract Methods for the efficient and affordable remediation of oil spills and chemical leaks are crucially needed in today’s environment. In this study, we have developed a simple, magnetic, porous material based on polydimethylsiloxane (PDMS) and steel wool (SW) that can fulfill these needs. The PDMS-SW presented here is superhydrophobic, superoleophilic, and capable of absorbing and separating oils and organic solvents from water. The material is mechanically and chemically stable, even in salty environments, and can be magnetically guided. It exhibits good selectivity, recyclability, and sorption capacity, and can quickly and continuously absorb and remove large amounts of oils and organic solutions from stationary and turbulent water. In addition, PDMS-SW’s inherently high porosity enables direct, gravity-driven oil-water separation with permeate flux as high as ~32,000 L/m2·h and separation efficiency over 99%. The solution immersion process used to prepare the material is easily scalable and requires only a single step. Thus, with its demonstrated combination of affordability, efficiency, and ease of use, PDMS-SW has the potential to meet the demands of large-area oil and chemical clean-ups.
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Abstract Biodiesel inherently contains more water than mineral diesel and as a result microbial contamination is a major problem that hinders its widespread application. The current method of removing the microbial contamination is direct addition of biocide. However, this method cannot enrich the water phase with biocide rapidly enough, leading to unavoidable overdosing of biocide and environmental issues. Here, biocide is encapsulated within hydrogel microparticles with a water‐triggered release feature to improve antimicrobial efficiency of biocide in biodiesel. To demonstrate the water‐triggered release mechanism, a green dye is encapsulated within the microparticles. The encapsulated dye remains inside the microparticles for more than 6 weeks when the microparticles are stored in oil phase; however, the dye releases in 4 min when the microparticles contact water. Using this water‐triggered release strategy, biocide is successfully delivered to the water phase in biodiesel. The encapsulated biocide shows higher antimicrobial efficacy than that of free biocide, in both short‐term and long‐term experiments. The possibility of scaling up the production of hydrogel microparticles using bulk emulsification method is also explored. Moreover, the water‐triggered release strategy can be used for releasing other water‐soluble functional materials. This opens opportunities for a wide range of encapsulation and controlled delivery applications.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c9ta10320a
