Enhanced oil removal from water in oil stable emulsions using electrospun nanocomposite fiber mats

Flexible, durable, and anti-fouling maghemite copper oxide nanocomposite-based membrane with ultra-high flux and efficiency for oil-in-water emulsions separation

In this study, we developed a novel nanocomposite-based membrane using maghemite copper oxide (MC) to enhance the separation efficiency of poly(vinyl chloride) (PVC) membranes for oil-in-water emulsions. The MC nanocomposite was synthesized using a co-precipitation method and incorporated into a PVC matrix by casting. The resulting nanocomposite-based membrane demonstrated a high degree of crystallinity and well-dispersed nanostructure, as confirmed by TEM, SEM, XRD, and FT-IR analyses. The performance of the membrane was evaluated in terms of water flux, solute rejection, and anti-fouling properties. The pinnacle of performance was unequivocally reached with a solution dosage of 50 mL, a solution concentration of 100 mg L-1, and a pump pressure of 2 bar, ensuring that every facet of the membrane's potential was fully harnessed. The new fabricated membrane exhibited superior efficiency for oil-water separation, with a rejection rate of 98% and an ultra-high flux of 0.102 L/m2 h compared to pure PVC membranes with about 90% rejection rate and an ultra-high flux of 0.085 L/m2 h. Furthermore, meticulous contact angle measurements revealed that the PMC nanocomposite membrane exhibited markedly lower contact angles (65° with water, 50° with ethanol, and 25° with hexane) compared to PVC membranes. This substantial reduction, transitioning from 85 to 65° with water, 65 to 50° with ethanol, and 45 to 25° with hexane for pure PVC membranes, underscores the profound enhancement in hydrophilicity attributed to the heightened nanoparticle content. Importantly, the rejection efficiency remained stable over five cycles, indicating excellent anti-fouling and cycling stability. The results highlight the potential of the maghemite copper oxide nanocomposite-based PVC membrane as a promising material for effective oil-in-water emulsion separation. This development opens up new possibilities for more flexible, durable, and anti-fouling membranes, making them ideal candidates for potential applications in separation technology. The presented findings provide valuable information for the advancement of membrane technology and its utilization in various industries, addressing the pressing challenge of oil-induced water pollution and promoting environmental sustainability.

Gamma irradiation induced surface modification of (PVC/HDPE)/ZnO nanocomposite for enhancing the oil removal and conductivity using COMSOL multiphysics

Blend nanocomposite film was prepared by loadings of irradiated ZnO in ratios of (5 wt%) inside the PVC/HDPE matrix using a hot-melt extruder technique. The physical and chemical properties of the irradiated and unirradiated ZnO samples are compared. The Vis-UV spectrum of ZnO shows an absorption peak at a wavelength of 373 nm that was slightly red-shifted to 375 nm for an irradiated sample of ZnO at a dose of 25 kGy due to the defect of crystal structure by the oxygen vacancy during gamma irradiations. This growth of the defect site leads to a decrease in energy gaps from 3.8 to 2.08 eV. AC conductivity of ZnO sample increased after the gamma irradiation process (25 kGy). The (PVC/HDPE)/ZnO nanocomposites were re-irradiated with γ rays at 25 kGy in the presence of four different media (silicon oil, sodium silicate, paraffin wax and water). FTIR and XRD were performed to monitor the changes in chemical composition. The new peak at 1723 cm^-1 attributed to C=O groups was observed in irradiated (PVC/HDPE)ZnO samples at only sodium silicate and water media. This process induced new function groups on the surface of the (PVC/HDPE)/ZnO blend sample. This work aims to develop (PVC/HDPE)ZnO for oil/water separation. The highest oil adsorption capability was observed in samples functionalized by C=O groups based on the different tested oils. The results suggest that the surface characterization of the (PVC/HDPE)/ZnO can be modified to enhance the oil adsorption potential. Further, the gamma irradiation dose significantly enhanced the AC conductivity compared to the unirradiated sample. According to COMSOL Multiphysics, the irradiated sample (PVC/HDPE)ZnO in water shows perfect uniform electric field distribution in medium voltage cables (22.000 V).

Encapsulation of Copper Nanoparticles in Electrospun Nanofibers for Sustainable Removal of Pesticides

The excellent catalytic properties of copper nanoparticles (CuNPs) for the degradation of the highly toxic and recalcitrant chlorpyrifos pesticide are widely known. However, CuNPs generally present low stability caused by their high sensitivity to oxidation, which leads to a change of the catalytic response over time. In the current work, the immobilization of CuNPs into a polycaprolactone (PCL) matrix via electrospinning was demonstrated to be a very effective method to retard air and solvent oxidation and to ensure constant catalytic activity in the long term. CuNPs were successfully anchored into PCL electrospun fibers in the form of Cu₂O at different concentrations (from 1.25 wt % to 5 wt % with respect to the PCL), with no signs of loss by leaching out. The PCL mats loaded with 2.5 wt % Cu (PCL-2.5Cu) almost halved the initial concentration of pesticide (40 mg/L) after 96 h. This process was performed in two unprompted and continuous steps that consisted of adsorption, followed by degradation. Interestingly, the degradation process was independent of the light conditions (i.e., not photocatalytic), expanding the application environments (e.g., groundwaters). Moreover, the PCL-2.5Cu composite presents high reusability, retaining the high elimination capability for at least five cycles and eliminating a total of 100 mg/L of chlorpyrifos, without exhibiting any sign of morphological damages.

Unique Fiber Morphologies from Emulsion Electrospinning—A Case Study of Poly(ε-caprolactone) and Its Applications

The importance of electrospinning to produce biomimicking micro- and nano-fibrous matrices is realized by many who work in the area of fibers. Based on the solubility of the materials to be spun, organic solvents are typically utilized. The toxicity of the utilized organic solvent could be extremely important for various applications, including tissue engineering, biomedical, agricultural, etc. In addition, the high viscosities of such polymer solutions limit the use of high polymer concentrations and lower down productivity along with the limitations of obtaining desired fiber morphology. This emphasizes the need for a method that would allay worries about safety, toxicity, and environmental issues along with the limitations of using concentrated polymer solutions. To mitigate these issues, the use of emulsions as precursors for electrospinning has recently gained significant attention. Presence of dispersed and continuous phase in emulsion provides an easy route to incorporate sensitive bioactive functional moieties within the core-sheath fibers which otherwise could only be hardly achieved using cumbersome coaxial electrospinning process in solution or melt based approaches. This review presents a detailed understanding of emulsion behavior during electrospinning along with the role of various constituents and process parameters during fiber formation. Though many polymers have been studied for emulsion electrospinning, poly(ε-caprolactone) (PCL) is one of the most studied polymers for this technique. Therefore, electrospinning of PCL based emulsions is highlighted as unique case-study, to provide a detailed theoretical understanding, discussion of experimental results along with their suitable biomedical applications.

Electrospinning fabrication of magnetic nanoparticles-embedded polycaprolactone (PCL) sorbent with enhanced sorption capacity and recovery speed for spilled oil removal

The use of oil-soaked sorbents in the recovery and cleaning of oil spills presents challenges due to disposal. Recently, magnetic nanoparticle (MNP) based collection has been gaining interest as a new technique to lower the amount of labor required to treat oil spills. In this study, we devised a new method for the preparation of a magnetic nanoparticle (MNP) embedded polycaprolactone (PCL) sorbent with oleophilic and environmentally friendly features, capable of bring easily collected under a magnetic field. Compared with conventional polypropylene sorbents, the MNP embedded PCL sorbent (MNP/PCL) displayed excellent Arabian light (AL) crude oil sorption capacity (45.7 g g^-1) and decreased the absorption time of the oil-soaked sorbent due to its electrospun structure and efficient distribution of hydrophobic MNPs. Furthermore, the MNP/PCL based sorbent became fully pyrolyzed under certain temperatures and conditions. The MNP embedded PCL-based sorbent demonstrated broad applicability and utility in large scale oil spill projects.

Rational design of Janus nanofibrous membranes with novel under-oil superhydrophilic/superhydrophobic asymmetric wettability for water-in-diesel emulsion separation

Endowing nanofibrous membranes with special wettability has always been the dominant strategy to improve the separation performance for water-in-oil emulsions. In this work, a rational design of deacetylated cellulose acetate/polyvinylidene fluoride (dCA/PVDF) Janus nanofibrous membrane, with asymmetric wettability in either air, water or diesel environment, was developed via sequential electrospinning PVDF and CA membranes followed by alkali treatment. In the process of water-in-diesel emulsion separation, the under-diesel superhydrophilic dCA layer is able to capture the emulsified water and strengthens the demulsification ability of the Janus membrane, while the under-diesel superhydrophobic PVDF layer acts as a water barrier and further improves the separation ability. The Janus membrane therefore exhibited prominent separation performance not only for the water/diesel mixture (separation efficiency 99.98%) but also for the surfactant-stabilized water-in-diesel emulsion with l vol% water (separation efficiency 97.74%). Moreover, the Janus membrane maintained high separation efficiency over 96% after repeated use for 50 times or soaking in corrosive solutions for 24 h. The Janus dCA/PVDF nanofibrous membrane possesses competitive efficiency, reusability and acid/alkali resistance, making it a promising candidate as the separation membrane for the surfactant-stabilized water-in-diesel emulsion.

Carbon and polymer-based magnetic nanocomposites for oil-spill remediation-a comprehensive review

Oil spills are a major contributor to water contamination, which sets off a significant impact on the environment, biodiversity, and economy. Efficient removal of oil spills is needed for the protection of marine species as well as the environment. Conventional approaches are not efficient enough for oil-water separation; therefore, effective strategies and efficient removal techniques (and materials) must be developed to restore the contaminated marine to its normal ecology. Several research studies have shown that nanotechnology provides efficient features to clean up these oil spills from the water using magnetic nanomaterials, particularly carbon/polymer-based magnetic nanocomposites. Surface modification of these nanomaterials via different techniques render them with salient innovative features. The present review discusses the advantages and limitations of conventional and advanced techniques for the oil spills removal from wastewater. Furthermore, the synthesis of magnetic nanocomposites, their utilization in oil-water separation, and adsorption mechanisms are discussed. Finally, the advancement and future perspectives of magnetic nanocomposites (particularly of carbon and polymer-based magnetic nanocomposites) in environmental remediation are presented.

Review on Electrospun Nanofiber-Applied Products

Electrospinning technology, which was previously known as a scientific interdisciplinary research approach, is now ready to move towards a practice-based interdisciplinary approach in a variety of fields, progressively. Electrospun nanofiber-applied products are made directly from a nonwoven fabric-based membranes prepared from polymeric liquids involving the application of sufficiently high voltages during electrospinning. Today, electrospun nanofiber-based materials are of remarkable interest across multiple fields of applications, such as in electronics, sensors, functional garments, sound proofing, filters, wound dressing and scaffolds. This article presents such a review for summarizing the current progress on the manufacturing scalability of electrospun nanofibers and the commercialization of electrospun nanofiber products by dedicated companies globally. Despite the clear potential and limitless possibilities for electrospun nanofiber applications, the uptake of electrospinning by the industry is still limited due to the challenges in the manufacturing and turning of electrospun nanofibers into physical products. The recent developments in the field of electrospinning, such as the prominent nonwoven technology, personal views and the potential path forward for the growth of commercially applied products based on electrospun nanofibers, are also highlighted.

A new generation of hollow polymeric microfibers produced by gas dissolution foaming

A new and straightforward route to produce polymeric hollow microfibers has been proposed. Polycaprolactone (PCL) hollow fibers are obtained for the first time using an environmentally friendly gas dissolution foaming approach, overcoming its limitations to induce porosity on samples in the micrometric range. Different porous morphologies are achieved from solid PCL microfibers with a well-controlled diameter obtained by conventional electrospinning. The optimization of the foaming parameters provides two sets of well-defined hollow fibers, one showing smooth surfaces and the other presenting an enhanced surface porosity. Accordingly, gas dissolution foaming proves to be not only suitable for the production of hollow polymeric microfibers, but is also capable of providing diverse porous morphologies from the same precursor, solid fibers. Moreover, a preliminary study about the suitability of this new generation of foamed hollow polymeric fibers for drug delivery is carried out, aiming to take advantage of the enhanced surface area and tunable morphology obtained by using the proposed new production method. It is found that the foamed microfibers can be loaded with up to 15 wt% of ibuprofen while preserving the morphology of each kind of fiber. Then, foamed PCL fibers presenting a hollow structure and surface porosity show a remarkable constant release of ibuprofen for almost one and a half days. In contrast, the original solid fibers do not present such behavior, releasing all the ibuprofen in about seven hours.

Facile Oil Removal from Water-in-Oil Stable Emulsions Using PU Foams

Superhydrophobic and oleophilic polyurethane foams were obtained by spray-coating their surfaces with solutions of thermoplastic polyurethane and hydrophobic silicon oxide nanoparticles. The developed functionalized foams were exploited as reusable oil absorbents from stable water-in-oil emulsions. These foams were able to remove oil efficiently from a wide range of emulsions with oil contents from 10 to 80 v.%, stabilized using Span80. The modified foams could reach oil absorption capacities up to 29 g/g, becoming a suitable candidate for water-in-oil stable emulsions separation.