Superhydrophobic Melamine Sponge Research Articles

An environmentally friendly and superhydrophobic melamine sponge self-roughened by in-situ controllably grown polydopamine nanoparticle for efficient oil-water separation

The preparation of conventional superhydrophobic sponges inevitably requires the involvement of noxious and non-degradable raw materials，thus threatening ecosystems. As reported herein, an environmentally friendly and superhydrophobic melamine sponge is facilely prepared for efficient oil-water separation, which is completely derived from eco-friendly substances. The formation of a hierarchical structure on the sponge skeleton was achieved via the in-situ controllable growth of polydopamine nanoparticles in mildly alkaline solution. In addition, octadecyl amines (ODA) with long chains of hydrophobic alkyl groups were grafted onto the polydopamine coating to reduce the surface energy through Schiff base or Michael addition reactions. Ultimately, the resulted sponge possessed extreme water repellency with a water contact angle (WCA) of 153.21 ± 1.31° and could retain its superhydrophobicity when it was exposed to solutions with different pH values and high temperature. Moreover, the resultant sponge exhibited fully reversible compressibility with up to 80 % strain and excellent structural stability after 200 cyclic compression tests. Meanwhile, distinct organic liquid absorption experiments were conducted to confirm the resulted sponge with excellent oil absorption capacity (73.46–119.66 g/g) and oil-water separation properties. Therefore, the as-prepared superhydrophobic sponge provides valuable insight into efficient oil-water separation.

Facile preparation of photothermal and superhydrophobic melamine sponge for oil/water separation and anti-icing

The preparation of superhydrophobic sponges with excellent physiochemical performance, affordability, and versatility is still a big challenge. Herein, a photothermal and superhydrophobic melamine sponge has been successfully achieved by decorating lignin particles (LPs)@MXene composite onto the skeletons of melamine sponge (MS) via the self-polymerization of dopamine. The obtained superhydrophobic MS (labeled as MS@PDA/LPs@MXene) shows a water contact angle of 153.7°, and maintains surface superhydrophobicity under harsh conditions (i.e., acidic, alkaline environments, high temperatures, frictional damage, and icing/de-icing cycles). Notably, the MS@PDA/LPs@MXene exhibits an exceptional oil adsorption capacity of carbon tetrachloride up to 143.6 times of its own weight, a high separation efficiency of 99.3 %, and a retained separation efficiency of 98.9 % after 15 cyclic adsorption processes, respectively. Owing to a synergistic photothermal effect of PDA and LPs@MXene, the MS@PDA/LPs@MXene possesses a maximum surface temperature of 62.8 °C under solar irradiation (1.0 kW/m2, 1 sun), and realizes the ice-free property at a low temperature of −17.9 °C (relative humidity, 90 %) on a continuous cooling stage under solar irradiation (0.5 sun). Furthermore, the LPs@MXene composite coating can be applied on various substrates (i.e., Al sheet, Cu sheet, filter paper, carbon cloth, steel mesh and NdFeB magnet) to obtain surface superhydrophobicity, showing excellent anti-corrosion property for the permanent NdFeB magnet. Thus, this paper proposes a facile and cost-effective strategy to prepare superhydrophobic melamine sponge with multifunctional properties, and provides new insights into the rational design of high-performance superhydrophobic sponges for their applications in oil/water separation and anti-icing.

Remediation of seawater polluted by oil spills via integrating porous materials with phase-change materials

The cleanup of viscous oil spills, especially in frigid regions, presents significant challenges due to the low fluidity of the oil. While the integration of absorption materials with photo/electric thermal conversion has shown significant promise, its effectiveness can be greatly influenced by environmental factors. To address these challenges, this study introduces an innovative solution: three-dimensional porous materials (3D-PMs) combined with phase change materials (PCMs). By utilizing energy pre-stored in PCMs through sunlight irradiation or electric heating, heat can be efficiently released when 3D-PMs come into contact with crude oil. A novel superhydrophobic melamine sponge (PPCPP@MS), composed of polypyrrole (PPy) and polyethylene glycol (PEG), has been developed for this purpose. The PPy polymerization layer reliably converts light/electricity into heat, while the PEG‑carbon nanotube (CNT) composite coating layer facilitates heat storage and release. This innovative design significantly enhances safety, energy utilization efficiency, and operational effectiveness. Furthermore, COMSOL simulation was employed to the interfacial heat transfer and phase transformation process of PPCPP@MS during crude oil absorption. Demonstrating stable heat release and oil-adsorbing performance in simulated low-temperature marine environments, PPCPP@MS exhibits great potential for addressing oil spills in extreme climates. The innovative design of PPCPP@MS offers crucial insights for managing viscous oil spills, particularly in frigid regions, providing a promising approach in environmental protection and remediation efforts.

Superhydrophobic melamine sponge prepared by radiation-induced grafting technology for efficient oil–water separation

Superhydrophobic melamine sponge prepared by radiation-induced grafting technology for efficient oil–water separation

Solar-heating superhydrophobic sponge based on size-controllable polydopamine nanoparticles for fast crude oil recovery and photothermal deicing

In the wake of recurring oil spills causing devastating environmental and ecological damage, there is an urgent need for efficient oil spill remediation strategies. Conventional absorbents are often ineffective in harsh environments and struggle with the recovery of high-viscosity crude oil at room temperature. Although photothermal absorbents can greatly improve the fluidity of crude oil, their practical applications are still limited due to complicated preparation processes, hazardous fluorinated reagents, and secondary pollution. This study introduces a facile, one-step dip-coating method to develop a photothermal superhydrophobic melamine sponge (MS), incorporating a fluorine-free suspension of polydimethylsiloxane (PDMS), siloxane-containing acrylate copolymers (SAC), and polydopamine nanoparticles (PDA NPs). The resulting PDMS/SAC-PDA@MS shows an exceptional water contact angle (WCA) and significant self-cleaning abilities due to its superhydrophobicity. With superior mechanical and chemical durability, the sponge achieves remarkable oil absorption (up to 102.6 times its weight) and efficient oil/water separation. Crucially, under solar irradiation, the sponge’s surface temperature reaches 87.6 °C, effectively reducing oil viscosity and enabling rapid cleanup of oil spills and active deicing. This study presents a green, economical approach to synthesizing photothermal superhydrophobic adsorbents with potential applications in environmental cleanup and active deicing.

Enhanced superhydrophobic melamine sponge with bimetal organic framework for simultaneous oil-water separation and microplastic removal

The escalating problem of oily wastewater and microplastic pollution poses a significant threat to our environment. Addressing this challenge has been hampered by the lack of sustainable materials capable of handling multiple pollutants effectively. However, this research introduces a groundbreaking approach for designing a superhydrophobic composite sponge, MS@ZnCo-ZIF@HDTMS. Utilizing a straightforward layer-by-layer self-assembly strategy, this work achieved the robust integration of bimetallic organic framework (ZnCo-ZIF) onto the sponge surface. This integration was facilitated by the adhesive and ion exchange properties of polydopamine (PDA), thereby constructing intricate micro- and nanocomposite structures. The immense specific surface area of ZnCo-ZIF offered numerous absorption sites for the assembly of PDA and hexadecyltrimethoxysilane (HDTMS). Remarkably, the composite sponge exhibits superhydrophobic and superoleophilic properties, demonstrating exceptional oil absorption capacities ranging from 55 g/g to 96 g/g, even after enduring 50 cycles. Moreover, MS@ZnCo-ZIF@HDTMS possesses remarkable mechanical and chemical stability. Its gravity-driven oil-water separation capabilities are noteworthy, achieving a permeate flux of 10,000 L m-2 h-1 and a removal rate of up to 99.2 %. Crucially, the superhydrophobic nature of the composite sponge, coupled with capillary effect, Van der Waals forces, hydrogen bonding, and other interactions, enables MS@ZnCo-ZIF@HDTMS to capture a diverse range of microplastics from water relatively swiftly. Therefore, this work not only provides effective candidates for the sustainable treatment of oil and microplastics in water but also opens new avenues for the restoration of aquatic environments.

Ultrastable superhydrophobic melamine sponge via a one-step aqueous solution-based approach for oil/water separation

In this study, an eco-friendly aqueous solution-dipping method was developed for the synthesis of an ultrastable superhydrophobic melamine sponge (MS). The MS exhibits not only a high oil adsorption capacity of 46.3–149.5 times of its own weight, but also a good reusability with a slight decrease in adsorption capacity after 20 absorption-desorption cycles. Moreover, the continuous separation of immiscible oils/organic solvents and water with vacuum assistance is also realized. Besides, the material also features with exceptional physicochemical stability and fire-retardant performance, enabling its potential applications in extreme environments (high temperature, strong wind and waves, strong acids and alkalis, UV radiation, etc.). The as-established synthesis pathway has its chance in simplifying the industrial fabrication processes of composited functional sponges.

Hierarchical 0D CuO Wrapped by Petal-like 2D ZnO: A Strategic Approach of Superhydrophobic Melamine Sponge toward Wastewater Treatment.

In addressing the pressing environmental challenges posed by frequent oil spills, this work presents a novel approach of synthesizing a superhydrophobic three-dimensional (3D) porous melamine sponge (MS). CuO and ZnO nanoparticles were grown on the MS via a hydrothermal method to create MS/CuO/ZnO with multiscale hierarchical nanostructures. The resulting material exhibited a stable water contact angle of 155° through various tests. MS/CuO/ZnO demonstrated exceptional oil absorption capacities (40-145 g/g and 0.83-0.99 mL.cm-3), surpassing 98% efficiency in oil separation, and retained reusability for 10 cycles. Impressively, the sponge achieved successful separation of oil/water emulsions with a permeation flux of 14870 L m-2 h-1. The composite sponge, distinguished by its high photodegradation ability, can degrade both water- and oil-targeted pollutants under visible light irradiation from light-emitting diode (LED). With its remarkable attributes including superior oil absorption, excellent oil/water separation, mechanical resistance, and excellent photocatalytic ability, it exhibits considerable potential for applications in both wastewater treatment and large-scale marine oil spill response. The easily prepared MS/CuO/ZnO emerges as a versatile solution capable of addressing pressing challenges and marking a significant leap toward sustainable and impactful environmental remediation.

Facile Preparation of Photothermal Superhydrophobic Melamine Sponge Decorated with MXene and Lignin Particles for Efficient Oil/Water Separation, Fast Crude Oil Recovery, and Active Deicing.

Frequent oil spills and the discharge of oily wastewaters have caused a serious threat to the environment, ecosystems, and human beings. Herein, a photothermal and superhydrophobic melamine sponge (MS) decorated with MXene and lignin particles has been prepared for the separation of oil/water mixtures, the recovery of crude oils, and active deicing. The obtained superhydrophobic melamine sponge shows a water contact angle (WCA) of 152.3° and an oil contact angle of ∼0° and possesses good chemical stability, thermal stability, and mechanical durability in terms of being immersed in various liquids (i.e., corrosive solutions, organic solvents, and boiling water) and being abrased by sandpapers. This superhydrophobic MS displays a high oil adsorption capacity of CCl4, up to 91.6 times its own weight and a high separation efficiency of 99.4%. Furthermore, the maximum surface temperature of the superhydrophobic MS reaches 57.5 °C under sunlight irradiation (1.0 kW/m2) due to the excellent photothermal heating conversion performance of MXene and lignin particles. When exposed to sunlight, the superhydrophobic MS can quickly absorb viscous crude oils up to 72 times its own weight. Also, the WCA of the superhydrophobic MS remains above 146° after 50 icing/deicing cycles, showing excellent photothermal anti-icing properties. Thus, this study presents an easy and low-cost method for designing photothermal superhydrophobic melamine sponges and opens a new avenue to the applications of efficient oil/water separation, fast crude oil recovery, and active deicing.

Fabrication of superhydrophobic melamine sponge composite sorbent in supercritical carbon dioxide atmosphere for selective and effective oil removal from water

In this study, both the modification of activated halloysite nanotube (HNT) with methyltriethoxysilane (METES) and the fabrication of durable, superhydrophobic (water contact angle: 153.0°) and superoleophilic (oil contact angle: 0 °) melamine sponge (MS)-HNT-METES sorbent material (MS-METES) were achieved in supercritical carbon dioxide (scCO2) atmosphere. For the coating of MS with clay mineral and METES through sol-gel reaction in scCO2, optimal process conditions were determined to be pressure difference of 60 bars at 35 °C, solvent/METES mass ratio of 7.5, METES/MS mass ratio of 10, and degas time of 400 s. Successful preparation of MS-METES was proven by XPS, FTIR, 29Si-MAS NMR, SEM, and contact angle measurements. MS-METES displayed excellent sorption capacity for various petroleum products, oils, and organic solvents (49.6–122.4 g/g), remarkable oil-water separation efficiency (99.1%, for continuous separation technique), high selectivity for oil/organic solvent in acidic, salty, and alkaline solution conditions, good reusability, chemical stability and robustness, and outstanding flexibility and mechanical stability. We believe that the innovative process used in this study will have great potential to be used by researchers in the direct fabrication of new superhydrophobic and superoleophilic sorbent materials for the selective removal of oil and organic solvent spills from water.

Magnetic superhydrophobic melamine sponges for crude oil removal from water

This paper proposes the preparation of a new sorbent material based on melamine sponges (MS) with superhydrophobic, superoleophilic, and magnetic properties. This study involved impregnating the surface of commercially available MS with eco-friendly deep eutectic solvents (DES) and Fe3O4 nanoparticles. The DES selection was based on the screening of 105 eutectic mixtures using COSMO-RS modeling. Other parameters affecting the efficiency and selectivity of oil removal from water were optimized using the Box-Bhenken model. Menthol:Thymol (1:1)@Fe3O4-MS exhibited the highest sorption capacity for real crude oils (101.7–127.3 g/g). This new sponge demonstrated paramagnetic behavior (31.06 emu/g), superhydrophobicity (151°), superoleophobicity (0°), low density (15.6 mg/cm3), high porosity (99 %), and excellent mechanical stability. Furthermore, it allows multiple regeneration processes without losing its sorption capacity. Based on these benefits, Menthol:Thymol (1:1)@Fe3O4-MS shows promise as an efficient, cost-effective, and eco-friendly substitute for the existing sorbents.

Simple preparation superhydrophobic melamine sponge via one-step emulsion polymerization for continuous oil/water separation in harsh environment

The oil spill and industrial oily wastewater in large quantities has caused severe harm to the environment and human health, which make an urgent requirement to develop low-cost, eco-friendly, stable performance and highly efficient oil/water separation materials. Herein, a superhydrophobic/superlipophilic melamine sponge with excellent hydrophobic stability was successfully fabricated via one-step emulsion polymerization. During polymerization, trimethylolpropane triacrylate (TMPTA) and polyethylene imine (PEI) form robust microspheres, and polydimethylsilane (PDMS) cross-links to form hydrophobic coating on the original sponge skeleton. The modified sponge could continuously separate various immiscible oil/water mixtures under harsh conditions (including strong acids, strong bases, salts). Even after 10 consecutive cycles, the separation efficiency for toluene and petroleum ether exceeds 99.87%. In addition, the as-prepared sponge exhibited extraordinarily high oil absorption capacities (with a maximum saturated oil absorption of 107.31 g/g for chloroform) and excellent reversible compressibility (up to 100 compression cycles). More importantly, the pore size of modified sponge was adjusted through a simple mechanical compression strategy so that the compressed sponge met the particle size screening requirements to effectively separate the surfactant-stabilized water-in-oil emulsions. Based on the simple preparation protocol, fluorine-free raw materials, and excellent properties, the MS-TMPTA/PEI-PDMS sponge presented here have extremely promising application potential in oil/water separation.

Superhydrophobic melamine sponges with high performance in oil/organic solvent sorption

The severe adverse impacts of the frequently occurring marine oil spills call for the urgent development of an efficient approach for oil spill restoration. Here, we prepared a superhydrophobic melamine sponge with water contact angle of 151.6° via a one-step dip-coating process by simply reacting the melamine sponge with stearic anhydride. The as-prepared sponge, MS-4, demonstrates excellent sorption capacities for various organic solvents such as hexane, toluene and chloroform, as well as oils including diesel, mineral oil, and crude oil, with sorption capacities ranging from 78 to 160 times its own mass. Moreover, MS-4 exhibits good recyclability with retention rate of over 93% even after 50 sorption/squeezing cycles, remarkable stability when exposed to challenging conditions such as strong acidic (pH = 1.0) and alkaline (pH = 13.0) environments, as well as high salinity environments. Additionally, MS-4 displays superb selectivity, enabling the continuous oil/water separation when assisted by a vacuum pump, achieving a high flux of approximately 106 L•m−2•h−1, while maintaining a low water content of as minimal as 30 ppm. Notably, through a facile filtration process, MS-4 achieves an exceptional demulsification efficiency of up to 99.7% for water-in-oil emulsions.

A biomimetic design for efficient petrochemical spill disposal: CoFe-PBA modified superhydrophobic melamine sponge with mechanical/chemical durability and low fire risk

Due to frequent petrochemical spills, environmental pollution and the threat of secondary marine fires have arisen, necessitating an urgent need for petrochemical spill treatment strategies with high-performance oil-water separation capabilities. To address the challenges of poor durability, instability in hydrophobic conditions, and difficulty in absorbing high-viscosity crude oil associated with hydrophobic absorbent materials, the authors of this study took inspiration from the unique micro and nanostructures of springtails' water-repellent skin. We engineered a superhydrophobic melamine sponge using interfacial assembly techniques designated as Si@PBA@PDA@MS. This material demonstrated improved mechanical and chemical durability, enhanced photothermal performance, and reduced fire risk. The metal-organic framework (MOF)-derived cobalt-iron Prussian blue analog (CoFe-PBA) was firmly anchored to the sponge framework by the chelation of cobalt ions using polydopamine (PDA). The results demonstrated that Si@PBA@PDA@MS demonstrated excellent superhydrophobicity (WCA=163.5°) and oil absorption capacity (53.4–97.5 g/g), maintaining high durability even after 20 cycles of absorption-squeezing. Additionally, it could still exhibit excellent mechanical properties, hydrophobic stability, and absorption performance across a wide temperature range (0–100 °C), pH range (1−14), and high compression strength (ε = 80%), with excellent mechanical/chemical durability. Furthermore, Si@PBA@PDA@MS demonstrated remarkable photothermal performance and low fire risk, offering efficient, safe, and sustainable practical value for effective petrochemical spill treatment.

Superhydrophobic Sponge for Highly Efficient Separation of Both Stratified and Emulsified Oil–Water Mixtures

Efficient separation of oil–water mixtures, particularly homogeneous and stable emulsions, has always been an industrial challenge. Herein, we report a facile, cost-effective procedure for fabricating superhydrophobic melamine sponges using a single solution–immersion process. The modified sponge has stable superhydrophobicity owing to the synergy of triple hydrophobic mechanisms with a maximum water contact angle of 158°. As an absorbent, the modified sponge block exhibits high porosity, outstanding absorption capacity, excellent mechanical properties, and superior physical and chemical stability, enabling its use for the separation of stratified oil–water mixtures via repeated absorption–extrusion processes with a separation efficiency of nearly 100%. Furthermore, as a filter, the crushed, modified sponge powders exhibit a demulsification efficiency ranging from 97.65 to 99.33% for the separation of ideal water-in-oil emulsions under gravity. Finally, the feasibility of these sponges for oilfield applications is established through the demonstration of the continuous separation of an emulsion of brine in crude oil using the modified sponge powders in conjunction with an in-house built apparatus. This work may open a viable pathway for the efficient separation of both stratified and emulsified oil–water mixtures via wettability, and provide a novel strategy for the reuse of waste sponges.

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.

Superhydrophobic sponge with nanoneedle-like surface for efficiently separating immiscible and emulsified oil-water mixtures

To increase the collision probability between emulsified droplets and sponge surface for more efficient separation of emulsions, a durable superhydrophobic melamine sponge (MS) with nanoneedle-like surface was prepared through a simple and inexpensive route in this work. The fabrication processes included the formation of ZnO nanoneedles on MS surface via a hydrothermal method, followed by coating with polybenzoxazine based bisphenol A and dodecylamine (PB-D). As excepted, the resulting superhydrophobic sponge (PB-D/ZnO/MS) could effectively separate various surfactant-stabilized water-in-oil and oil-in-water emulsions, with a high permeation flux of up to 14,050 L m−2 h−1 and separation efficiency above 98.5 %, driven solely by gravity due to its nanoneedle-like surface. Moreover, PB-D/ZnO/MS also displayed outstanding absorption capacities for various oils and organic solvents (57.4–123.0 g/g) as well as prominent reusability, enduring 30 cycles of repeated absorption-squeezing without any evident decrease in water contact angle and absorption capacity (maintaining 90.9–96.6 % of initial value). In addition, the superhydrophobicity of PB-D/ZnO/MS remained almost unchanged after being immersed in strong acidic, alkaline and salty solutions for 48 h. Furthermore, PB-D/ZnO/MS not only showed outstanding flame retardancy but also remained rapid oil absorption rate under combustion conditions. Thus, the obtained superhydrophobic MS is a promising candidate for practical oil/water separation.

Magnetically responsive and durable super-hydrophobic melamine sponge material

Magnetically responsive and durable super-hydrophobic melamine sponge material

Eco‐friendly and facile modified superhydrophobic melamine sponge by molybdenum sulfide for oil/water separation

AbstractOily wastewater has caused serious damage to the human health and ecological environment. It is urgent to develop novel materials for high performance oil/water separation. Porous melamine sponges (MS) are considered as an ideal matrix material for oil/water separation. Herein, molybdenum sulfide (MoS2) modified with tannic acid (TA) and octadecylamine (ODA) was attached to MS framework via a facile dip‐coating method. This novel and eco‐friendly MS@(MoS2@ODA) sponge displays superior superhydrophobicity (WCA = 156.2°) and oil/water separation ability (absorption capacity = 113–145 g g−1). MoS2@ODA not only enhances surface roughness of MS framework, but also raises its specific surface area, causing an increase in the oil adsorption capacity of MS. Moreover, the composite sponge exhibited excellent chemical and mechanical stability. It is envisioned that this work can demonstrate a facile synthesis strategy for producing environmental friendliness MS with stable superhydrophobicity for high‐efficient oil/water separation.

Multi-energies assisted and all-weather recovery of crude oil by superhydrophobic melamine sponge.

Efficient and safe recovery of high-viscosity marine crude oil spills is still a worldwide challenge. High-viscosity crude oil is difficult to be removed by traditional adsorbent materials. Although some recent developments in photothermal or electric-thermal oil-absorbing materials, the vertical heat transfer inside and the potential hazard of electrical leakage are difficult to be guaranteed. In order to overcome these problems, we polymerized dopamine (DA) in situ on the skeleton surface of the commercial melamine sponge (MS), and further coated the full-wavelength light-absorbing Fe3O4 NPs-Graphene (HF-G) on it to obtain the superhydrophobic sponge with excellent photothermal conversion effect, heat conductivity and magnetic heating capabilities (HF-G/PDA@MS). When the thickness of sponge is 5mm, the HF-G/PDA@MS shows excellent vertical heat conductivity ability, and can absorb about 80g/g. It also can be combined with an extra electric-heating device to achieve continuous heating to reduce the viscosity and recover crude oil at night or extreme weather. In addition, the temperature of HF-G/PDA@MS can reach about 40°C by electromagnetic induction heater, indicating that we can use multiple energies-assisted modes to heat the HF-G/PDA@MS to. This work provides a promising solution and theoretical support for all-weather solving offshore crude oil spills pollution and recovery.