Facile synthesis of flexible macroporous polypropylene sponges for separation of oil and water

Fluorescent Nanoporous Materials from Polypropylene-Based Covalent Adaptable Networks

Fluorescent polypropylene-based aerogels from thermoreversibly crosslinked networks have been developed. This facile and efficient synthesis results in low-cost, recyclable, chemically resistant, and highly porous functional materials. This process includes the chemical crosslinking of polypropylene, followed by thermal phase separation and freeze-drying, yielding aerogels with specific surface areas up to 200 m2/g, according to nitrogen absorption-desorption measurements. This is significantly higher than that previously reported for polypropylene porous materials. Besides characterizations of polymer networks by infrared spectroscopy and differential scanning calorimetry, a suite of analytical techniques was utilized to characterize the skeletal framework of aerogels, including scanning electron microscopy and small-angle X-ray scattering. These methods revealed the highly porous nanostructural features of interconnected 3D networks. The modulation of the excited-state properties of the incorporated luminophore is demonstrated and provides insights into their potential applications. Importantly, the aerogels have a pronounced ability to retain toluene, affecting their fluorescence behavior over an extended time scale. This conceptual study presents a low-cost solution for the preparation of highly porous materials that might offer versatility in functionality and may open the door to further exploration and design of high-performance materials that can act very effectively in the sensing and adsorption of organic molecules. The results also provide an intriguing direction for future research focusing on the molecular mechanisms driving the observed fluorescence modulations.

Preparation and Investigation of High Surface Area Aerogels from Crosslinked Polypropylenes

Polypropylene-based aerogels with high surface area have been developed for the first time. By chemical crosslinking of polypropylene with oligomeric capped-end amino compounds, followed by dissolution, thermally induced phase separation, and the supercritical CO2 drying process or freeze-drying method, the aerogels exhibit high specific surface areas up to 200 m2/g. Moreover, the silica-cage multi-amino compound was utilized in a similar vein for forming hybrid polypropylene aerogels. According to the SEM, the developed polypropylene-based aerogels exhibit highly porous morphology with micro-nanoscale structural features that can be controlled by processing conditions. Our simple and inexpensive synthetic strategy results in a low-cost, chemically resistant, and highly porous material that can be tailored according to end-use applications.

Repurposing the single-used-plastic for development of hydrophobic aerogels for remediation of oil spill and organic solvents

Currently, around 400 million tonnes of synthetic polymers are being dumped as waste annually and by this rate by 2050 the ocean would contain more such waste compared to the total weight of fish. As recycling could solve part of this problem, recently such waste is being reused for various purposes like composite preparation, oil production and various other use such as production of foams, sponges, and aerogels. However, there is a relatively limited literature available on the utilization of polyethylene polymer (like LDPE). The study presented in this article indicated that LDPE-based polymers could be reused (after modification) for preparation of hydrophobic, lightweight, and porous aerogels that have oil-spills and organic solvent adsorption capacity. The aerogels showed contact angle of 121.9o, bulk density below 0.25 g/cm3, and were found to be semi-crystalline. The aerogels showed oil and solvent adsorption more than that for their untreated counterparts. Also, the aerogels were found to be recycled for more than five cycles with very minimum loss of efficacy. This area of producing oil sorbents from single used plastic wastes is still very open for further research and seems to be a promising route for both waste reduction, and the synthesis of value-added products. This could be one of the most sustainable approaches for efficient single-used plastic wase management and environment clean-up.

A green strategy to recycle the waste PP melt-blown materials: From 2D to 3D construction

The demand for polypropylene (PP) melt-blown materials has dramatically increased due to the COVID-19 pandemic. It has caused serious environmental problems because of the lack of effective treatment for the waste PP melt-blown materials. In this study, we propose a green and sustainable recycling method to create PP sponges from waste PP melt-blown material for oil spill cleaning by freeze-drying and thermal treatment techniques. The recycling method is simple and without secondary pollution to the environment. The developed recycling method successfully transforms 2D laminar dispersed PP microfibers into elastic sponges with a 3D porous structure, providing the material with good mechanical properties and promotes its potential application in the field of oil spill cleaning. The morphology structure, thermal properties, mechanical properties, and oil absorption properties are tested and characterized. The PP sponges with a three-dimensional porous network structure show an exceedingly low density of >0.014 g/cm³, a high porosity of <98.77 %, and a high water contact angle range of 130.4-139.9°. Moreover, the PP sponges own a good absorption capacity of <47.61 g/g for different oil and solvents. In particular, the compressive modulus of the PP sponges is 33.59-201.21 kPa, which is higher than that of most other fiber-based porous materials, indicating that the PP sponges have better durability under the same force. The excellent comprehensive performance of the PP sponges demonstrates the method developed in this study has large application potential in the field of the recycle of waste PP melt-blown materials.

The preparation of CaCO3-polyalkoxysilane porous nanocomposites as effective sorbent for oil spill removal

The novel porous nanocomposite sorbent was synthesized by the condensation of the diol monomer with the alkoxysilane cross-linker at moderately high temperatures in the presence of nano-CaCO₃ particles. The structural, thermal, and morphological properties of the nanocomposite sorbents were determined by using Fourier transform infrared spectroscopy (FTIR), solid-state CPMAS ¹³C and ²⁹Si NMR, scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). Adding nano-CaCO₃ to the network structure of the polymer not only provided pores to the sorbent but also enhanced its sorption capacity towards various oils and toxic organic solvents. The nanocomposite sorbent exhibited excellent absorption capacity for different toxic organic solvents and oils and great reusability for ten cycles. Moreover, the obtained sorbent material selectively absorbed organic liquids from the surface and bottom of the water without any capacity change owing to their hydrophobicity and oleophilicity. These features of the nanocomposite make it a potential sorbent for the cleaning of oils and oil derivative organic contaminants from the environment.

Superhydrophobic Nanodiamond-Functionalized Melamine Sponge for Oil/Water Separation

Fabrication of absorbent materials foroil/water separation is an important ecological pursuit for oil spill clean-up and organic pollutants' removal. In this study, nanodiamonds (NDs), a promising member of the carbon family, were functionally modified by the covalent linking of octadecylamine (ODA). Subsequently, the superhydrophobic sponge with hierarchical microstructures was fabricated by embedding ND-ODA into a melamine sponge (MS) skeleton via a simple immersion-drying process. The as-prepared sponge (ND-ODA@PDMS@MS) showed superhydrophobic properties with a water contact angle of 155 ± 2°. For various oils and organic solvents, ND-ODA@PDMS@MS possesses excellent absorption capacity (26.65-55.64 g/g) and oil/water separation efficiency (above 98.6%). Furthermore, the adsorption capacity to crude oil remained relatively stable in highly acidic, alkaline, and salty conditions, ensuring the application in the clean-up of industrial oily sewages and marine oil spills. Besides absorbing oil for a single time, ND-ODA@PDMS@MS also exhibited satisfactory performance in continuous oil/water separation. Therefore, this work provides a facile strategy to produce robust and efficient absorbent materials for oil/water separation in large-scale oil and organic solvent clean-ups.

Processable Conjugated Microporous Polymer Gels and Monoliths: Fundamentals and Versatile Applications

Conjugated microporous polymers (CMPs) as a new type of conjugated polymers have attracted extensive attention in academia and industry because of the combination of microporous structure and π-electron conjugated structure. The construction and application of gels and monoliths based on CMPs constitute a fertile area of research, promising to provide solutions to complex environmental and energy issues. This review summarizes and objectively analyzes the latest advances in the construction and application of processable CMP gels and monoliths, linking the basic and enhanced properties to widespread applications. In this review, we open with a summary of the construction methods used to build CMP gels and monoliths and assess the feasibility of different preparation techniques and the advantages of the products. The CMP gels and monoliths with enhanced properties involving various special applications are then deliberated by highlighting relevant scientific literature and discussions. Finally, we present the issues and future of openness in the field, as well as come up with the major challenges hindering further development, to guide researchers in this field.

Sorption as a rapidly response for oil spill accidents: A material and mechanistic approach

Accidents involving oil transportation has increase due to directly connection with the elevation of global energy demand. The environmental losses are tremendous and brings huge economic issues to remediate the spilled oil. This report presents an up-to-date review on an overall aspects of oil spill remediation techniques, the fundamentals and advantages of sorption, the most applied materials through diverse types of oil spill sites and oils with variety features, highlight to natural materials and future prospective. As the environment preservation progressively becomes a major social concern issue, the achievement of a worldwide distribution process aligned with environmental legislation and economic viability is crucial to the oil industry. For this, a specific preparation considering several scenarios must be carried out regarding minimization of oil spillages. Since the sorbent materials are decisive for sorption, it was approached the main sorbents: natural, graphenic, nano, polymeric and waste materials, and future trends.

Polypropylene/lignin blend monoliths used as sorbent in oil spill cleanup

With increasing industrial development, frequent oil spillages in water; therefore, it is imperative and challenging to develop absorbents materials that are eco-efficiency, cost-effective, and pollution prevention. In this study, sorbents obtained from Lignin incorporated with Polypropylene in different levels loading 0, 10, 20 % wt using thermally induced phase separation Technique (TIPS). The Polypropylene/Lignin blend monoliths were fabricated and compared in terms of morphological, thermal, and wetting characterizations. The successfully blending of different lignin concentrations with preserved the chemical structure of the polymer was confirmed by FTIR analysis. Thermogravimetric tests displayed that the existence of Lignin has changed the onset temperature (Tonset) of the blending sorbents, decreasing as the loading of Lignin is increased. The contact angle measurement showed a decrease in the hydrophobicity of sorbents with increasing lignin loading, Polypropylene/Lignin blend monoliths showed better absorption toward oils (soybean - engine) as compared to Polypropylene itself. PP10L showed an improvement in the oil sorption capacity around 2 times compared to the Polypropylene. These excellent features make Polypropylene/Lignin blend monoliths more competitive promising candidates than commercial absorbent.

One-pot fabrication of reusable hybrid sorbents for quick removal of oils from wastewater

The leaking of harmful organic liquids into water resources has had hazardous impacts on living organisms. Herein, we demonstrated the fabrication of hybrid sorbents using s-PPG and organosilane cross-linker. The final product exhibited high, quick absorption capacity, great reusability and excellent oil separation performance from wastewater. They also selectively absorb different oils from the bottom and surface of water without any capacity change, even in harsh conditions like wavy and sub-zero water environment. Experimental results demonstrated that the obtained sorbents are efficient to successfully remove oil from water surface, even at harsh conditions, and float on the water surface before and after oil sorption without any capacity loss and structural change. Simple preparation by avoiding time consuming multistep process, initiator, solvent, activator free reaction medium, high and selective sorption characteristics and great reusability could make these sorbents a promising candidate for the cleaning of water from harmful organic liquids, by absorbing them.

Superhydrophobic Polypropylene Functionalized with Nanoparticles for Efficient Fast Static and Dynamic Separation of Spilled Oil from Water

Frequent oil spills not only threaten the ecosystem, but they are also a waste of a valuable source of energy. There is an urgent need to develop materials that can readily remove spilled oil from water bodies and also have the capacity to collect it for energy applications. Herein, a superhydrophobic fiber of functionalized polypropylene is engineered with the help of palmitic acid interaction with incorporated copper oxide nanoparticles. The successful development of functionalized polypropylene is confirmed by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The scanning electron microscopy images reveal that the surface roughness of the polypropylene is enhanced after functionalization. The optimized functionalized polypropylene displays an ultrahydrophobic surface with a water contact angle of 162.42°. The functionalized polyprolyene displays good absorption capacity. It has the capacity to take 30 to 40 times its own weight in oils and nonpolar organic solvents, which makes it useful for small spills. With a flux of 11 204 Lm-2 h-1, functionalized polypropylene is as an ideal material for the dynamic separation of oil spills from water. It also has excellent selectivity towards oil, water rejection, and oil absorption capacity.

Facile Fabrication of Superhydrophobic and Eco-Friendly Poly(lactic acid) Foam for Oil-Water Separation via Skin Peeling

Superhydrophobic polymer foams are a good candidate for oil absorption because of their lightweight and tunable porosity and have promising applications in the long-term application of oil-water separation. However, developing a facile and green strategy to fabricate pure polymer foams with superhydrophobicity and eco-friendliness for large-scale oil-water separation remains a challenge. Here, a facile template-free water-assisted thermally impacted phase separation approach combined with skin peeling for the fabrication of superhydrophobic and eco-friendly pure poly(lactic acid) (PLA) foam for oil-water separation is proposed for the first time. The PLA foam with special micro- and nanostructures possesses a water contact angle of 151°, and the maximum saturated adsorption capacity is 31.5 g/g. More importantly, during the continuous oil-water pumping experiment, the foam has an efficiency of 98% and could maintain for more than 15 h, showing a promising prospect for cleaning large-scale oil pollution.

Cost-Effective, Highly Selective and Environmentally Friendly Superhydrophobic Absorbent from Cigarette Filters for Oil Spillage Clean up

Ecological and environmental damage caused by oil spillage has attracted great attention. Used cigarette filters (CF) have also caused negative environmental consequences. Converting CF to economical materials is a feasible way to address these problems. In this study, we demonstrate a simple method for production of a highly hydrophobic absorbent from CF. CF was modified by using different volume ratios of octadecyltrichlorosilane and methyltrimethoxysilane. When the volume ratio was 3:2, the modified CF had the high water contact angle of 155°. It could selectively and completely absorb silicone oil from an oil-water mixture and showed a good absorption capacity of 38.3 g/g. The absorbed oil was readily and rapidly recovered by simple mechanical squeezing, and it could be reused immediately without any additional treatments. The as-obtained superhydrophobic modified CF retained an absorption capacity of 80% for pump oil and 82% for silicone oil after 10 cycles. The modified CF showed good elasticity in the test of repeated use. The present study provides novel design of a functional material for development of hydrophobic absorbents from used CF via a facile method toward oil spillage cleanup, as well as a new recycling method of CF to alleviate environmental impacts.

Oil sorbents from plastic wastes and polymers: A review

A large volume of the waste produced across the world is composed of polymers from plastic wastes such as polyethylene (HDPE or LDPE), polypropylene (PP), and polyethylene terephthalate (PET) amongst others. For years, environmentalists have been looking for various ways to overcome the problems of such large quantities of plastic wastes being disposed of into landfill sites. On the other hand, the usage of synthetic polymers as oil sorbents in particular, polyolefins, including polypropylene (PP) and polyethylene (PE) have been reported. In recent years, the idea of using plastic wastes as the feed for the production of oil sorbents has gained momentum. However, the studies undertaking such feasibility are rather scattered. This review paper is the first of its kind reporting, compiling and reviewing these various processes. The production of an oil sorbent from plastic wastes is being seen to be satisfactorily achievable through a variety of methods Nevertheless, much work needs to be done regarding further investigation of the numerous parameters influencing production yields and sorbent qualities. For example, differences in results are seen due to varying operating conditions, experimental setups, and virgin or waste plastics being used as feeds. The field of producing oil sorbents from plastic wastes is still very open for further research, and seems to be a promising route for both waste reduction, and the synthesis of value-added products such as oil sorbents. In this review, the research related to the production of various oil sorbents based on plastics (plastic waste and virgin polymer) has been discussed. Further oil sorbent efficiency in terms of oil sorption capacity has been described.

Low-Density Open Cellular Sponges as Functional Materials

Low-density macroporous sponges with densities less than 100 mg cm^-3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation of the sponges with property combinations that lead to novel applications. Bottom-up and top-down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed.

Template-free synthesis of polystyrene monoliths for the removal of oil-in-water emulsion

Oil-in-water emulsions are harmful to both humankind and environment. Frequent oil spill disasters make it urgent to develop low cost and high-efficiency materials for the treatment of oil-in-water emulsions. In this study, we report the facile template-free synthesis of macroporous polystyrene (PS) monolith from PS solution using a thermally-induced phase separation (TIPS) technique. The fabricated monolith showed high hydrophobicity, superoleophilicity, and macroporous structure. Moreover, the monolith exhibited high removal efficiency toward different oil-in-water emulsions. The monolith can be fabricated from cheap and commonly-used plastic. Thus, we anticipate that this research will contribute to both the recycling of PS and the treatment of oil spill accidents.

Preparation of Superwetting Porous Materials for Ultrafast Separation of Water-in-Oil Emulsions

Functional materials with a superwetting surface property have been extensively explored to achieve emulsion separation. In this paper, we report a simple and inexpensive method for fabricating superhydrophobic/superoleophilic porous materials from polymeric sponges. These microstructured porous materials, which do not contain any fluorinated compounds, maintain their superhydrophobicity and superoleophilicity after long-term organic solvent immersion and display environmental stability. These superhydrophobic porous materials can effectively separate a wide range of water-in-oil emulsions including surfactant-free and surfactant-stabilized water-in-oil emulsions with high efficiency (>99.98%) and high flux (up to 155 000 L m^-2 h^-1 bar^-1). Meanwhile, these materials exhibited excellent pH resistance and antifouling properties. The high performance of our superhydrophobic porous materials and their efficient, low-energy, cost-effective preparation suggest that they have a great potential for practical applications.

Flexible Superhydrophobic and Superoleophilic MoS2 Sponge for Highly Efficient Oil-Water Separation

Removal of oils and organic solvents from water is an important global challenge for energy conservation and environmental protection. Advanced sorbent materials with excellent sorption capacity need to be developed. Here we report on a superhydrophobic and superoleophilic MoS₂ nanosheet sponge (SMS) for highly efficient separation and absorption of oils or organic solvents from water. This novel sponge exhibits excellent absorption performance through a combination of superhydrophobicity, high porosity, robust stability in harsh conditions (including flame retardance and inertness to corrosive and different temperature environments) and excellent mechanical properties. The dip-coating strategy proposed for the fabrication of the SMS, which does not require a complicated process or sophisticated equipment, is very straightforward and easy to scale up. This finding shows promise for water remediation and oil recovery.

Cellulose-based aerogel from Eichhornia crassipes as an oil superabsorbent

Cellulose-based aerogels (CBAs) were prepared based on Eichhornia crassipes as a raw material and a paper wet-strengthening agent as a cross-linker via a green and simple process.