The widespread use of plastics, particularly polypropylene (PP), in disposable items like face masks has dramatically increased plastic waste, contributing significantly to environmental microplastic pollution. Traditional recycling methods for PP are often inefficient and costly. This research addresses this challenge by exploring the upcycling of waste PP face masks into a functional product—an oil absorbent for oil spill management. The increasing global production of plastics, reaching 360 million tons annually and with 50% becoming waste after single use, highlights the urgency for innovative solutions. The COVID-19 pandemic further exacerbated the problem, with the exponential increase in single-use PPE, like face masks (estimated 289.63 billion annually in Asia alone), significantly adding to the plastic waste burden. This study investigates a sustainable alternative: transforming this waste into a valuable oil-sorbent, addressing both plastic pollution and the environmental consequences of oil spills. Current oil-spill remediation methods often involve expensive, less sustainable materials like polyurethane (PU), which is both costly and constitutes a small percentage of plastic waste compared to PP. Existing polymer-based aerogels show limited oil uptake. Graphene aerogels, while efficient, have low mechanical strength and require complex chemical treatments for oil extraction, making them impractical. Therefore, this research aims to develop a cost-effective, highly efficient, and reusable oil sorbent from readily available waste PP face masks, promoting a circular economy and mitigating the environmental impact of both plastic waste and oil spills. The collected waste was carefully treated to mitigate any potential pathogen risks before processing, ensuring a safe and environmentally responsible approach.

The literature extensively documents the environmental challenges posed by plastic pollution and the rising concerns regarding microplastics and nanoplastics from single-use plastics, particularly those generated during the COVID-19 pandemic. Several studies focus on various recycling and upcycling strategies for plastic waste, including thermal and mechanical recycling techniques, and chemical recycling approaches. Prior research has explored using modified PP face masks as oil sorbents, but these methods often involved complex surface modifications using multiple organic solvents and expensive nanoparticles, limiting their scalability and cost-effectiveness. Existing oil sorbents, such as polyurethane (PU) aerogels and those using graphene or carbon nanotubes, have either limited uptake capacity, poor reusability, or high production costs. The study highlights the need for a low-cost, readily available, and highly efficient oil sorbent derived from abundant waste materials, underscoring the environmental and economic benefits of upcycling waste PP from face masks into a practical solution for oil-spill management. This is emphasized by the large amount of research into similar solutions to reduce plastic pollution such as chemical recycling of waste plastics, strategies to reduce the global carbon footprint of plastics and utilization of plastic wastes for sustainable environmental management.

The study involved the collection of waste PP face masks, followed by a 14-day quarantine period to minimize pathogen risks. The PP was then dissolved in xylene at 130 °C. Spin coating was employed to create a uniform microporous thin film on a heated glass substrate. This process involved three stages with varying rotational speeds (400, 1000, and 3000 rpm) to optimize film formation. Annealing at 160 °C enhanced film properties. A PP fibrous thin film was prepared by heating a non-woven PP sheet at 80 °C. The microporous and fibrous thin films were superposed and sealed within a pouch constructed from the fibrous thin film, creating a five-layered oil-sorbent structure. The porosity of the sorbent was determined by measuring the volume of N-Methyl-2-pyrrolidone absorbed into the porous structure. Contact angle measurements were conducted with various oils (toluene, sunflower oil, engine oil, and paraffin oil) to assess the superoleophilic nature of the pouch. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyzed the morphology and surface roughness. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) characterized the chemical composition. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) determined the crystallinity and melting point. Oil saturation and dripping kinetics were assessed using engine oil to determine the absorption capacity and retention time. Oil-water separation efficiency was evaluated using different oil-water mixtures. Finally, the recyclability of the pouch was tested using both mechanical squeezing and hexane washing to determine reusability and oil recovery.

SEM analysis revealed a porous structure with elliptical pores (0.5 µm to 5 µm) and approximately 40% porosity. AFM showed a surface roughness (RMS) of 749 nm. XPS analysis confirmed the complete removal of xylene solvent and indicated minimal oxidation. FT-IR spectra confirmed the presence of characteristic PP peaks. DSC analysis indicated a melting point of 168 °C and a crystallinity of 57%, corroborated by XRD (60% crystallinity). Contact angle measurements showed a superoleophilic nature (<1° for toluene, 11°–19.9° for other oils). The oil-sorbent pouch exhibited rapid saturation kinetics (<5 min) and a high immediate oil uptake capacity of 85 g/g with engine oil, reaching equilibrium uptake capacity at 55 g/g. The pouch demonstrated high oil retention capacity and excellent oil-water separation efficiency (99.5% at lower oil concentration and 100% at oil concentration above 8%). The pouch showed high reusability, maintaining 91% efficiency after seven cycles of mechanical squeezing and 100% efficiency with hexane washing. These results highlighted the exceptional oil sorption capacity of the developed oil sorbent pouch.

The results demonstrate the successful upcycling of waste PP face masks into a highly effective and reusable oil sorbent. The superposed microporous and fibrous structure, created through a simple and cost-effective method, contributed to the exceptional oil uptake capacity and rapid absorption kinetics. The superoleophilic nature of the material and its high porosity facilitated efficient oil absorption. The high reusability through both mechanical squeezing and hexane washing showcases the potential for this approach to significantly reduce waste and provide a sustainable solution for oil spill remediation. Compared to other oil sorbents reported in the literature, the proposed material provides a significant improvement in terms of cost-effectiveness, performance, and environmental impact. The findings highlight the feasibility of transforming abundant waste plastic into a useful product, aligning with principles of the circular economy.

This study successfully upcycled waste polypropylene face masks into a highly efficient and reusable oil-sorbent pouch. The pouch demonstrated superior oil uptake (85 g/g), rapid absorption kinetics, and excellent reusability (up to seven cycles). This innovative approach offers a sustainable solution for managing plastic waste while simultaneously addressing the environmental challenge of oil spills. Future research could explore scaling up the production process, testing the effectiveness with different types of oils, and evaluating the long-term durability and environmental impact of the material.

The study primarily focused on engine oil. Further investigation with a broader range of oil types is necessary to confirm the versatility of the oil-sorbent pouch. The long-term durability and potential degradation of the material under various environmental conditions require further evaluation. The scalability of the current production method to industrial levels needs assessment.