Superoleophilic Sponge Research Articles

Hydrophobic modified melamine sponge for highly effective remediation of crude oil in water and soil

Crude oil pollution in water and soil has resulted in considerable environmental damage. The utilization of hydrophobic and oleophilic sponge materials for the treatment of crude oil pollution has garnered significant interest, owing to their excellent selective adsorption performance. In this paper, superhydrophobic and superoleophilic sponges (SMF) are prepared by a simple silane hydrolysis-thermal curing method, which is low-cost, environmentally friendly, large-scale preparation, acid and alkali-resistant, and mechanically stable. They can be used for the remediation of oil pollutants in water and soil simultaneously, and show high efficiency, excellent stability, and biosafety. Under appropriate circumstances, SMF is capable of adsorbing up to 82.7 g/g of crude oil in water and eliminating over 70.0 % of crude oil in soil, while exhibiting exceptional recycling performance. Notably, this study introduces a novel technique that alters soil viscosity by controlling soil water content, in conjunction with SMF, for the removal of crude oil in soil. Consequently, SMF shows great promise for practical application in the remediation of oil pollutants in both water and soil.

Nanoparticle-decorated and poly(dimethyl siloxane)-modified superhydrophobic melamine sponge for efficient oil/water separation

A superhydrophobic and superoleophilic sponge (MS/UIO-66(F4)/RGO/PDMS) was fabricated by decorating the skeleton of a melamine sponge (MS) with UIO-66(F4) nanoparticles and reduced graphene oxide (RGO) nanosheets layer by layer, and then hydrophobic modification with polydimethylsiloxane (PDMS). The composition, morphology, thermal stability, and wettability of the modified sponge were characterized, and its oil/water separation application was investigated. Characterization results reveal that compared with the hydrophilic pure MS, the fiber surface of the prepared sponge becomes rough and demonstrates remarkable super-hydrophobicity with a water contact angle of 153.5°. The modified sponge can efficiently separate water-in-diesel emulsion (flux of 3665 L· m−2 · h−1) and multiple stratified oil-water mixtures via the auxiliary device with a separation efficiency above 98.3%, which has no significant change after 25 cycles. The modified sponge can absorb oils or organic solvents 48–100 times higher than its weight, with a stable absorption capacity after 20 cycles. Moreover, it can be applied in handling flammable oils, showing good flame retardancy. Considering it also possesses excellent chemical stability, extreme environmental stability (resistance to high/low temperature, UV irradiation and load-bearing) and mechanical durability under harsh conditions, the modified sponge is a promising candidate in the field of oily wastewater treatment.

Mechanically durable anti-bacteria non-fluorinated superhydrophobic sponge for highly efficient and fast microplastic and oil removal

Microplastics (MPs) pollution evolves into a global environmental problem to be solved urgently. Although many studies are exploring ways to remove MPs from water environment, most of them are lack of selectivity and low efficiency. Herein, considering the fascinating absorption selectivity of superwetting materials, a robust magnetic-responsive superhydrophobic and superoleophilic sponge was firstly used to quickly eliminate MPs from water with very high efficiency. The functional sponge was fabricated by a non-fluorinated coating technique that consisted of polydimethylsiloxane (PDMS) grafted Fe3O4 particle, PDMS grafted halloysite nanotubes, and PDMS binder. The coated sponge achieved excellent mechanically durable and chemically stable superhydrophobicity that resisted a series of severe treatments. It was unquestionable to show very fast oil absorption. What's more, it especially showed very high adsorption capacity (24.3–48.2 mg/g) and could quickly adsorb almost 100% MPs (polypropylene, polyvinyl chloride, and polyethylene) from aqueous suspensions. Moreover, the removal rates remained almost 100% for these MPs after 50 cycles. Besides, the coated sponge had excellent salt tolerance and antibacterial activity to Escherichia coli (E. coli) (99.91%) and Staphylococcus aureus (S. aureus) (90.46%). The adsorption mechanism of the coating was discussed from the perspectives of molecular structure, electronic effect, steric hindrance, and size-scale effect. The absorption driving force mainly derived from the intra-particle diffusion under capillary attraction, whilst slight electrostatic interaction, hydrogen bond interaction, and σ-p (or p-p) conjugation between PDMS and MPs. This functional sponge was destined to be a new strategy in the removal of MPs and other solid pollutants, especially in the high-salinity and rich-microorganism water environment.

Multiphase media superwettability regulated by coexisting prewetting phase

Understanding the wetting behaviors of a given superwetting surface in multiphase media is important for elaborately tailoring superwettability. Here the surface chemistry of two types of superhydrophobic surfaces was programmed to reveal crucial effect of a coexisting prewetting phase rather than the prewetting process on their wetting states in water and oil–water separation application. After prewetting with ethanol to remove the air layer, underwater contact angles of superhydrophobic surfaces for oil droplet and bubble gradually decreased from over 150° along with the reduced surface energy. When the superhydrophobic surfaces were directly immersed in water or prewetted with oil, a stable air layer or infused oil as the prewetting phase enabled oil droplet and bubble to rapidly spread out. Moreover, air-prewetting superhydrophobic/underwater superoleophobic fabric can selectively adsorb oils from water, whereas it showed an excellent antifouling property without the air layer. For the separation of oil-in-water emulsions using superhydrophobic/underwater superoleophilic sponge, the stable air layer obstructed emulsions into three-dimensional porous structures. After removing the air layer, emulsion separation can be efficiently realized. This discovery provides a feasible approach for the regulation and development of unusual superwettability in multiphase media.

Superhydrophobic ODT-TiO2 NW-PDA nanocomposite-coated polyurethane sponge for spilled oil recovery and oil/water separation

Frequent occurrences of accidental oil spills, chemical leakages and oily water discharge make the development of effective and efficient methods for spilled oil and organic pollutants clean-ups extremely critical and urgent. Here, a novel superhydrophobic octadecanethiol-TiO2 nanowires-polydopamine nanocomposites-modified polyurethane sponge was fabricated by a facile and cost-effective synthesis process, wherein, self-polymerization of dopamine was coated on the polyurethane skeleton structure, followed by direct incorporation of TiO2 nanowires to enhance surface roughness and lastly, surface coating with the low surface energy octadecanethiol molecules. The resultant PU-PDA-TiO2-ODT sponge showed superhydrophobic and superoleophilic with the water contact angle (WCA) of 154.0 ± 2° and the oil contact angle of 0°, as well as self-cleaning and anti-fouling capabilities. The as-fabricated sponge demonstrated high oil adsorption capacity for a broad variety of oils and organic solvents, also exhibiting good reusability of more than 30 cycles without diminishing adsorption performance. The potential for practical applications was demonstrated through gravity-driven and vacuum assisted continuous separations, yielding more than 99.9% oil purity. Moreover, the as-prepared sponge exhibited superior mechanical strength through exceptional performance in compression, ultrasonication and frictions tests, and consistent superhydrophobicity in harsh environments including exposure to pH, temperature and NaCl concentration variations. Thus, the novel superhydrophobic and superoleophilic sponge has great potential for practical application in oil-water separations.

Highly Efficient Amorphous Carbon Sphere-Based Superhydrophobic and Superoleophilic Sponges for Oil/Water Separation.

In this experimental study, a commercially available polyurethane (PU) sponge coated with amorphous carbon spheres (ACSs) is investigated for oil/water separation. The ACSs synthesized using chemical vapor deposition are embedded in the PU sponge by a simple dip-coating method. The superhydrophobic ACS-PU sponge exhibits a water contact angle (WCA) of 156.2 ± 1° and a sliding angle <5°. The prepared sponge exhibits high absorption capacity, removal of oil spills from water, and demulsification of an oil-in-water emulsion. Absorption capacities of 32-68 times the ACS-PU sponge weight were obtained for different organic solvents and oils. It was found that the prepared ACS-PU sponge can effectively absorb oils under both static and turbulent conditions. Compared with the reported studies on the loading of different carbon materials in sponges for oil/water separation, ACSs in PU have a low loading percentage of ∼7 wt % and better absorption recyclability. The method proposes a simple and cost-effective preparation technique of highly hydrophobic and oleophilic ACS-PU sponges for effective oil/water separation.

Superoleophilic polyurethane sponge for highly efficient oil/water separation

A superoleophilic polyurethane sponge had been constructed by means of an immersion method in an ethanol solution of n-octadecyltrichlorosilane. SEM, FTIR, TGA, and XPS unanimously confirmed that PODS had been successfully coated onto the skeleton of polyurethane sponge. The PODS-modified sponge displayed both excellent hydrophobicity with high water contact angle of 152° and good oil affinity. The PODS-modified sponge took the high adsorptive capabilities for the silicone oil, toluene, and peanut oil with 62.1, 73.7, and 98.2 g · g–1 after 50 cycles of extrusion-release, respectively. The superoleophilic sponge in this work exhibited promising opportunities on the oil/water separation and the oil spill remediation.

Novel magnetic and flame-retardant superhydrophobic sponge for solar-assisted high-viscosity oil/water separation

The development of new multifunctional adsorbent sponge with superhydrophobic, magnetic drive, flame retardancy and efficient adsorption of high viscosity oils display an attractive potential for oil/water separation. In this work, the Fe3O4 nanoparticles with photothermal and magnetic effect were used to achieve solar-assisted efficient adsorption of high-viscosity oil and controlled magnetic drive adsorption and recovery. Using intrinsic flame-retardant melamine-formaldehyde (MF) sponge as the skeleton, the Fe3O4 nanoparticles and polydimethylsiloxane solution (Fe3O4/PDMS) were used to modify superhydrophilic sponges into superhydrophobic (WCA = 158°) and superoleophilic (OCA = 0°) sponges with excellent flame-retardant property. Due to the chemical stability, low density and high porosity, the modified sponge exhibits excellent oil and organic solvent adsorption properties and reusability. Owing to the excellent photothermal performance of Fe3O4/PDMS modified MF (Fe3O4/PDMS@MF) sponge, the sponge was heated rapidly with solar-assisted and decreased the viscosity of the high-viscosity oil, which allowed the high-viscosity oil to be absorbed efficiently. At the same time, the Fe3O4/PDMS@MF sponge can be controlled by the remote magnetic field and enters the special oil pollution area for oil adsorption and recovery. This superhydrophobic multifunctional sponge has great potential for high-viscosity oil adsorption, magnetic drive recovery and flame-retardant applications.

Highly efficient oil-in-water emulsion and oil layer/water mixture separation based on durably superhydrophobic sponge prepared via a facile route

The fabrication of the materials with special wettability being capable of removing oil layer on water surface and oil droplets in oil-in-water emulsion is an important issue for water pollution. So far, it still remains challenging to explore a simple, facile, environmentally friendly approach for achieving this goal. Herein, inspired by the adhesion of marine mussels, the polydopamine (PDA) coating with hierarchical structure was directly fabricated onto the surface of melamine (MF) sponge by facile self-polymerization in dopamine solution. Then, a superhydrophobic and superoleophilic sponge was successfully obtained after the modification by dodecanethiol (DDT) at ambient temperature. The as-prepared sponge can selectively separate a series of oil droplets in oil-in-water emulsion with high efficiency (transparency: 76.6–93.8%) and absorb various oils or organic solvents up to 45.2–98.6 times of its own weight. Moreover, in conjunction with a vacuum system, great amounts of oils up to 20 times its own weight can be effectively separated from water surface within 1s by the sponge. Due to low cost, simple process, and easy accessibility, the as-prepared sponge has potential applications in oil-in-water emulsion separation and oil spill cleanup.

One-step fabrication of novel superhydrophobic and superoleophilic sponge with outstanding absorbency and flame-retardancy for the selective removal of oily organic solvent from water

Abstract Absorbent materials integrated with superhydrophobicity, superoleophilicity and flame-retardancy are highly desired in the adsorption/removal of flammable oils/organic compounds as well as reducing the risk of fire and explosion. Here, one-step fabrication of novel superhydrophobic and superoleophilic sponge with outstanding absorbency and flame-retardancy was presented. Using raw melamine (ME) sponge as the supporting matrix, the formation of polydopamine (PDA) nanoaggregates via in-situ self-polymerization of high-concentrated dopamine and the covalent grafting of hydrophobic n-dodecylthiol (DT) onto PDA were combined in a feasible alkaline water/ethanol medium. As investigated by scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS), the as-prepared ME/PDA/DT sponge possessed hierarchical structure with submicron PDA nanoaggregates containing DT motif (low surface energy) on 3D interconnected porous network. It exhibited superhydrophobic (water contact angle 157.7°) and superoleophilic (oily/organic solvent contact angle 0° properties. Owing to the highly porous structure, superhydrophobic property, chemical and mechanical stability, the ME/PDA/DT sponge exhibited outstanding absorbency properties of oily organic solvents including fast absorption kinetics, high absorption capacity, and easy reusability. Also, the ME/PDA/DT sponge could be used for one-line continuous organic solvent/water separation. More interestingly, the ME/PDA/DT sponge demonstrated improved flame-retardant property as compared to the intrinsic flame-retardant nature of the raw melamine sponge. Consequently, the risk of fire and explosion was expected to reduce when the fabricated sponge was used as an absorbent for flammable oils and organic compounds. The ease of the one-step superhydrophobic/superoleophilic modification and the promising feature of the obtained materials exhibit great potential for application in oils/organic solvents clean-up.

Spongy Structures Coated with Carbon Nanomaterials for Efficient Oil/Water Separation

Rapid progress of processing and transportation of oil and petroleum products may cause disaster for environment like oil spill. Oil booms, combustion, and oil skimmer vessels are usually used to clean up the oil spill, but often with poor efficiency and even with undesirable environmental side effects. With obtaining of carbon nanomaterials (CNMs) (graphene, carbon nanotubes) and developing inexpensive technologies for their synthesis it has become perspective to use them for creation of 3D structures which may serve as a hydrophobic sorbents for oil and petroleum products. In this study, sponges coated with carbon nanomaterials were obtained using “dip-coating” method. Walls of commercially available polyurethane (PU) and melamine sponges were coated with reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs). The resulting sponges are characterized by excellent mechanical properties, they are superhydprophobic, and they fully repel water and at the same time selectively absorb oil and organic liquids of different densities. We believe that superhydrophobic and superoleophilic sponges, the walls of which are coated with CNMs, are perspective candidates for reusable sorbents for collection of oil and petroleum products from the surface of water and moreover due to its excellent mechanical properties they can serve as a hydrophobic filtering materials for separation of oil from the surface of water.

Preparation of MCC/MC Silica Sponge and Its Oil/Water Separation Apparatus Application

A novel superoleophilic sponge, which has been prepared by a simple sol–gel process using microcrystalline cellulose (MCC) and methyl cellulose (MC), and its oil/water separation apparatus application are presented here. The samples were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectra (FTIR), and so on. The results indicated that MCC/MC silica sponge (MCC-CH3) had been successfully introduced C═O and methyl groups and exhibits better mechanical properties, absorption capacity, and high oil selectivity. Besides, a novel oil–water separation apparatus was designed to make MCC-CH3 a further practical application. Based on this simple but flexible and intelligent design, oil collection, sorption materials regeneration, and free navigation can be simultaneously achieved in the remediation of oil spills. The results showed the discharge flow of n-hexane was about 11700 g·h–1·g–1, and the oil ratio of the discharge mixture reached 99% under a conti...

Oil/water mixtures and emulsions separation of stearic acid-functionalized sponge fabricated via a facile one-step coating method

Abstract Superhydrophobic and superoleophilic sponge was prepared by facile dip coating in a stearic acid (SA) solution and subsequent heat treatment. The obtained sponge exhibits excellent superhydrophobic stability and selectively sorption ability for oil pollutants on water surface. Also, the sponge is capable of separating huge amounts of oils from water continuously via a vacuum system and oil droplets in oil-in-water emulsions. After the separation by the coated sponge, the transparency for the emulsions (n-Hexane-in-water and toluene-in-water) can increase to over 80% from below 14.7%. The oil sorption capacity of as-prepared sponge for various types of oils and organic solvents can reach 17.4–41.6 times of its own weight, and the absorbed oils are easy to be recovered by a simple squeezing process. Moreover, the recovered sponge can repeatedly absorb/desorb the oils for at least 100 times, demonstrating slightly decrease in sorption capacities and hydrophobicity. The proposed approach for fabricating superhydrophobic sponges is simple and inexpensive so that the as-prepared sponge has great potential as an efficient sorbent in oily wastewater filtration and oil spill clean-up.

A comparative study on superhydrophobic sponges and their application as fluid channel for continuous separation of oils and organic solvents from water

Abstract This study adopted melamine as core material to prepare porous materials possessing superhydrophobic and superoleophilic property, which is utilized to separate polar and non-polar solvents from polar/non-polar mixture. The sponges were treated by four different methods; (1) acetone treatment, (2) coating of functionalized expanded graphite (FEG), (3) coating of multi-walled carbon nanotubes (MWCNTs) and, (4) coating of reduced graphene oxide (rGO). After treatment, the functional groups on the sponge skeleton were examined and the water contact angles were also measured. Based on the experimental results, sponge treated with acetone showed the best absorption capacity, but worst hydrophobic property; while the sponges coated with FEG and MWCNTs possessed the worst absorption capacity. The sponge coated with reduced graphene oxide showed notable superhydrophobic property, as well as excellent absorption capacity. In this work, we also designed a set-up to separate organic solvents from organic-water mixture using the superhydrophobic and superoleophilic sponge. The basic idea is that, when the mixture of solvent and water was poured in the upstream of the channel, the solvent was absorbed by the treated sponge which was placed at the bottom of the channel, while water flowed down along the channel; as a result, separating the solvent from the mixture.

Unpowered oil absorption by a wettability sponge based oil skimmer

Superhydrophobic–superoleophilic sponges equipped on oil skimmers are obtained after being immersed in a copper stearate solution.

Mussel-inspired fabrication of novel superhydrophobic and superoleophilic sponge modified using a high density of nanoaggregates at low concentration of dopamine

A superhydrophobic/superoleophilic sponge with outstanding adsorbency and flame-retardancy was fabricated by modification using a high density of polydopamine-nanoaggregates at low concentration of dopamine.

Oil Absorbents Based on Melamine/Lignin by a Dip Adsorbing Method

Effective removal of oils and leakage chemicals from water is of significance in oceanography, environmental protection, and industrial production. Materials that can reduce environmental pollution are in high demand. Herein, we have developed a facile synthesis of ultralight, high-hydrophobic, and superoleophilic sponges (UHS sponges) through a dip adsorbing process based on lignin and commercially available melamine sponges. The obtained UHS sponges consist of an interconnected structure with high porosity and ultralow density (6.4 mg cm–3). As the hydrophobic carbon coating of the skeleton and its microstructure trapping the air, the UHS sponge exhibits high-hydrophobicity and superoleophilicity, which are beneficial to its applications in oil–water separation. Besides lignin, other biomass like tannin is also suitable as the modification agent to prepare UHS sponges via a dip adsorbing method. As a result, this novel sponge exhibits excellent oil/water separation performance such as high selectivity, ...

Facile Approach toward the Fabrication of Superhydrophobic and Superoleophilic Sponges for the Removal of Oil from Oil/Water Mixtures

Facile Approach toward the Fabrication of Superhydrophobic and Superoleophilic Sponges for the Removal of Oil from Oil/Water Mixtures

Oil/water separation performances of superhydrophobic and superoleophilic sponges.

Superhydrophobic and superoleophilic sponges were fabricated by immersion in an ethanol solution of octadecyltrichlorosilane. The resulting coating strongly adheres to the sponges after curing at 45 °C for 24 h. Absorption capacities of 42-68 times the polymerized octadecylsiloxane sponge weight were obtained for toluene, light petroleum, and methylsilicone oil. These adsorption capacities were maintained after 50 cycles.

Facile Fabrication of Superhydrophobic Sponge with Selective Absorption and Collection of Oil from Water

A simple vapor-phase deposition process has been developed to fabricate a superhydrophobic and superoleophilic sponge using ordinary commercial polyurethane sponges. The simultaneous properties of superhydrophobicity and superoleophilicity enable the sponge to float on the water surface and selectively absorb oil from water. Its uptake capacities of different oils (motor oil, lubricating oil, pump oil, silicone oil, and soybean oil) in the oil–water mixtures were all above 20 g/g. The absorbed oil could be collected by squeezing the sponge, and the recovered sponge could be reused in oil–water separation for many cycles while still maintaining a high capacity. This is helpful for realizing the proper disposal of the oil and avoiding secondary pollution. A similar experiment was performed using the as-prepared sponge to remove petroleum from contaminated water. The results suggest that our material might find practical applications in the cleanup of oil spills and the removal of organic pollutants from water surfaces.