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The use of Polypropylene PP in disposable items such as face masks, gloves, and personal protective equipment has increased exponentially during and after the COVID-19 pandemic, contributing significantly to microplastics and nanoplastics in the environment. Upcycling of waste PP provides a useful alternative to traditional thermal and mechanical recycling techniques. It transforms waste PP into useful products, minimizing its impact on the environment. Herein, we synthesized an oil-sorbent pouch using waste PP, which comprises superposed microporous and fibrous thin films of PP using spin coating. The pouch exhibited super-fast uptake kinetics and reached its saturation in fewer than five minutes with a high oil uptake value of 85 g/g. Moreover, it displayed high reusability and was found to be effective in absorbing oil up to seven times when mechanically squeezed between each cycle, demonstrating robust oil-sorption capabilities. This approach offers a potential solution for managing plastic waste while promoting a circular economy. [ABSTRACT FROM AUTHOR]

Mixed polyolefin-based waste needs urgent attention to mitigate its negative impact on the environment. The separation of these plastics requires energy-intensive processes due to their similar densities. Additionally, these materials cannot be blended without compatibilizers, as they are inherently incompatible and immiscible. Herein, non-wettable microporous sheets from recycled polyethylene (PE) and polypropylene (PP) are presented. The methodology involves the application of phase separation and spin-casting techniques to obtain a bimodal porous structure, facilitating efficient oil–water separation. The resulting sheets have an immediate and equilibrium sorption uptake of 100 and 55 g/g, respectively, due to the presence of micro- and macro-pores, as revealed by SEM. Moreover, sheets possess enhanced crystallinity, as evidenced by XRD; hence, they retain their structure during sorption and desorption and are reusable with 98% efficiency. The anti-wetting properties of the sheets are enhanced by applying a silane coating, ensuring waterless sorption and a contact angle of 140°. These results highlight the importance of implementing sustainable solutions to recycle plastics and mitigate the oil spill problem. [ABSTRACT FROM AUTHOR]

Cellulose is widely used as an effective sorbent to treat wastewater. Cellulosic sorbents have the advantage of biodegradability, as they are natural plant-based materials, compared with the synthetic materials such as polypropylene (PP) or polyurethane (PU). Among the raw biomass materials used for cellulose production, rice husk is one of the most cost competitive and widely available. In this work, biological treatments are compared to find the most effective treatment method for cellulose fibre production from rice husk. Using biological delignification, cellulose was extracted from raw rice husk and acetylated to acquire hydrophobicity. Delignification was performed using both bacteria and fungi and their results were compared. The white-rot fungi strain using 'Aspergillus flavus CICC 40258' was found to be the most effective treatment method, achieving a modified product with up to 55% w/w cellulose concentration. Acetylation further facilitated the sorption process and the maximum oil uptake capacity using delignification and acetylation treatment was found to be 20 g/g. The as-prepared sorbents exhibited high oil uptake rates and saturation capacity was reached after 5 min of contact with oil. The kinetic study presents a good correlation with the pseudo-second order model. The isothermal studies demonstrated that the oil sorption capacity of rice husk follows the Langmuir model as compared with the Freundlich model. [ABSTRACT FROM AUTHOR]

The usage of natural and synthetic sorbents in order to control oil spills is gaining increasing attention due to environmental concerns. In particular, polyolefins including polypropylene and polyethylene are the most commonly used oil sorbent materials because of their low cost but suffer from low oil absorption capacity. Attempts at trying to increase the surface-to-thickness ratio for improving uptake capacity makes them vulnerable to breakage and impractical for most oil spill applications. Novel super oil sorbent polymer sheets consisting of porous ultrahigh-molecular-weight polyethylene have been prepared. The presented sorbent exhibits extremely high uptake and retention capacities along with a mechanically strong structure. The combination of these factors as well as the cost effectiveness of the material used makes these sheets viable candidates for widespread production and utilization. [ABSTRACT FROM AUTHOR]

Abstract: 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, researchers have been looking for various ways to overcome the problems of such large quantities of waste plastics. On the other hand, carbon nanotubes (CNTs) are materials with extraordinary physical and chemical properties which often have energy- and resource-intensive production processes. In recent years, some researchers have suggested the idea of using plastic polymers as the carbonaceous feed of CNT production. The studies undertaking such a feat are rather scattered. This review paper is the first of its kind reporting, compiling and reviewing these various processes. The production of multi-walled carbon nanotubes (MWCNTs) from plastic polymers is seen to be satisfactorily achievable through a variety of different catalytic and thermal methods in autoclaves, quartz tube reactors, muffle furnaces, fluidized beds, amongst others. Still, much work needs to be done regarding the further investigation of the numerous parameters influencing production yields and qualities. For example, differences in results are seen in varying operating conditions, experimental setups, catalysts, and virgin or waste plastics being used as feeds. The area of producing CNTs from plastic wastes is still very open for further research, and seems as a promising route for both waste reduction, and the synthesis of value-added products such as carbon nanotubes. [Copyright &y& Elsevier]

The global pollution crisis arising from the accumulation of plastic in landfills and the environment necessitates addressing plastic waste issues. Notably, polypropylene (PP) waste accounts for 20% of total plastic waste and holds promise for hydrophobic applications in the realm of recycling. Herein, the transparent and non-transparent superhydrophobic films made from waste PP are reported. A hierarchical structure with protrusions is induced through spin-casting and thermally induced phase separation. The films had a water contact angle of 159° and could vary in thickness, strength, roughness, and hydrophobicity depending on end-user requirements. The Bode plot indicated enhanced corrosion resistance in the superhydrophobic films. Antibacterial trials with Escherichia coli and Staphylococcus aureus microbial solutions showed that the superhydrophobic film had a significantly lower rate of colony-forming units compared to both the transparent surface and the control blank sample. Moreover, a life cycle assessment revealed that the film production resulted in a 62% lower embodied energy and 34% lower carbon footprint compared to virgin PP pellets sourced from petroleum. These films exhibit distinctiveness with their dual functionality as coatings and freestanding films. Unlike conventional coatings that require chemical application onto the substrate, these films can be mechanically applied using adhesive tapes on a variety of surfaces. Overall, the effective recycling of waste PP into versatile superhydrophobic films not only reduces environmental impact but also paves the way for a more sustainable and eco-friendly future. [Display omitted] • Waste PP is transformed into superhydrophobic films—transparent and non-transparent. • Films are suitable for weather resistance and self-cleaning applications. • Films demonstrate improved corrosion resistance compared to bare carbon steel. • Reduced microbial growth in films makes them suitable for antibacterial use. • Films show lower embodied energy and fewer carbon emissions than virgin PP pellets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polypropylene waste upcycled into superhydrophobic membranes. • A bio-based derived solvent (Cymene) was employed. • Surface roughness and hydrophobicity of the top layer enhanced selectivity. • The presence of micropores ensured efficient liquid passage and high permeability. • Membranes featuring 14,000 Lm-2hr-1 organic solvent flux (96 % water rejection). A key aspect of advancing sustainable membrane technology is to source eco-friendly polymers, such as recycled plastic waste, use renewable plant-based solvents, and limit the number of solvents used in dissolution-precipitation processes. In this study, we upcycle polypropylene PP waste into bi-layered microporous superhydrophobic membranes using a single plant-based solvent, Cymene, through tandem spin-casting and annealing. The surface roughness and hydrophobicity of the top layer enhance selectivity, while the presence of micropores ensures efficient liquid passage and high permeability. The microporous bottom layer serves as a substrate for the top layer, providing structural support. Various annealing conditions were employed to optimize hydrophobicity, roughness, porosity and strength of as-prepared membranes, yielding high permeance and outstanding separation efficiency. The fabricated membranes were subjected to oil–water emulsion separations, demonstrating a contact angle exceeding 155° and a surface roughness of 123 nm, resulting in an organic solvent flux of 14,000 Lm-2h−1 with a 96 % water rejection. Tensile strength and strain % were found to be 13–28 MPa and 20–27 %, respectively. This research provided access to environmentally friendly membranes, adding value to plastic waste with potential benefits to both the polymer and membrane industries as they transition towards a circular economy. [ABSTRACT FROM AUTHOR]