Recycling and Reutilizing Polymer Waste via Electrospun Micro/Nanofibers: A Review

Waste Plastic to Roads - HDPE-modified Bitumen and PET Plastic Fibres for Road Maintenance in South Africa: A Review

This review article provides a comprehensive analysis of the transformative potential of waste plastic in South Africa, with a specific focus on high-density polyethylene-modified bitumen and polyethylene terephthalate plastic fibres asphalt. The review encompasses a wide range of topics, including the environmental and socio-economic impacts of plastic waste, the current state of plastic waste management practices in South Africa, and the potential use of waste plastic in road construction. The aim is to critically evaluate the compatibility of recycled waste plastics as bitumen modifiers and fibre to enhance road performance. Additionally, it explores the challenges and opportunities associated with the incorporation of waste plastic in road construction, shedding light on the environmental, economic and technological aspects. The review also emphasizes the need for targeted interventions and collaborative efforts from the South African government and industry stakeholders to address plastic waste management challenges and promote sustainable infrastructure development. Overall, this review provides valuable insights into the transformative potential of waste plastic in South African road maintenance and offers a roadmap for future research and initiatives in this critical area of sustainable development.

Management of ibuprofen in wastewater using electrospun nanofibers developed from PET and PS wastes

Electrospinning is a promising technique for the beneficial use and recycling of plastic waste polymers using simple methodologies. In this study, plastic bottles and Styrofoam wastes have been used to develop polyethylene terephthalate (PET) and polystyrene (PS) nanofibers using electrospinning technique separately without any further purification. The effect of the concentration onto the nanofiber's morphology was studied. The fabricated nanofibers were characterized using Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transformed Infrared Spectroscopy (ATR-FTIR), N2 adsorption/desorption analysis, and water contact angle (WCA). Furthermore, the prepared nanofibers were applied for the adsorption of ibuprofen (IBU) from wastewater. Some parameters that can influence the adsorption efficiency of nanofibers such as solution pH, wt.% of prepared nanofibers, drug initial concentration, and contact time were studied and optimized. The results show that the equilibrium adsorption capacity was achieved after only 10 min for 12 wt% PET nanofibers which is equivalent to 364.83 mg/g. For 12 wt% PS nanofibers, an equilibrium adsorption capacity of 328.42 mg/g was achieved in 30 min. The experimental data was fitted to five isotherm and four kinetics models to understand the complicated interaction between the nanofibers and the drug. Langmuir-Freundlich isotherm model showed the best fit for experimental data for both PET and PS nanofibers. The adsorption process was characterized by predominantly physical reaction rather than chemical adsorption for both materials. The reusability study revealed that the synthesized nanofibers maintain their ability to adsorb/desorb IBU for up to five cycles. The results obtained demonstrated that fabricated nanofibers from plastic wastes could perform promising adsorbents for the management of IBU in wastewater. However, further research is needed for the scaling-up the fabrication which is required for real-world applications.

Recent advances in nanotechnology-based modifications of micro/nano PET plastics for green energy applications

Poly(ethylene terephthalate) (PET) plastic is an omnipresent synthetic polymer in our lives, which causes negative impacts on the ecosystem. It is crucial to take mandatory action to control the usage and sustainable disposal of PET plastics. Recycling plastics using nanotechnology offers potential solutions to the challenges associated with traditional plastic recycling methods. Nano-based degradation techniques improve the degradation process through the influence of catalysts. It also plays a crucial role in enhancing the efficiency and effectiveness of recycling processes and modifying them into value-added products. The modified PET waste plastics can be utilized to manufacture batteries, supercapacitors, sensors, and so on. The waste PET modification methods have massive potential for research, which can play major role in removing post-consumer plastic waste. The present review discusses the effects of micro/nano plastics in terrestrial and marine ecosystems and its impacts on plants and animals. Briefly, the degradation and bio-degradation methods in recent research were explored. The depolymerization methods used for the production of monomers from PET waste plastics were discussed in detail. Carbon nanotubes, fullerene, and graphene nanosheets synthesized from PET waste plastics were delineated. The reuse of nanotechnologically modified PET waste plastics for potential green energy storage products, such as batteries, supercapacitors, and sensors were presented in this review.

Physical Properties of Ultrafine Bubbles Generated Using a Generator System

BACKGROUND/AIM

Ultrafine bubbles (UFBs) have been extensively researched owing to their promising physical and biological properties. However, determining the lifespan or ideal concentration of UFBs for various biological events is challenging. This study aimed to determine the maximum concentration and longest lifespan of UFBs and to verify the validity of UFBs for assessing cell properties.

MATERIALS AND METHODS

A generator system (HMB-H0150+P001, TOSSLEC Corporation Limited, Kyoto, Japan) generated UFBs using various gases. The size and concentration of UFBs in ultrapure water and cell culture medium were measured through a nanoparticle tracking analysis method.

RESULTS

The UFB concentration increased when the generator operated in a time dependent manner. The mean size of UFBs was approximately 120 nm. In the UFB lifespan, the concentration decreased by approximately 30% within the first two weeks of generation and was stable for up to 6 months. The UFB size increased by approximately 20% within the first two weeks of generation and demonstrated minor changes until the 6th month. The number of cells differed significantly with various concentrations of nitrogen gas UFBs.

CONCLUSION

The generator system can generate UFBs with multiple concentrations within a suitable temperature. Consequently, the solution containing UFBs could be widely acceptable in cell culture systems.

Adsorbents obtained from recycled polymeric materials for retention of different pollutants: A review

Polymeric waste is an environmental problem, with an annual world production of approximately 368 million metric tons, and increasing every year. Therefore, different strategies for polymer waste treatment have been developed, and the most common are (1) redesign, (2) reusing and (3) recycling. The latter strategy represents a useful option to generate new materials. This work reviews the emerging trends in the development of adsorbent materials obtained from polymer wastes. Adsorbents are used in filtration systems or in extraction techniques for the removal of contaminants such as heavy metals, dyes, polycyclic aromatic hydrocarbons and other organic compounds from air, biological and water samples. The methods used to obtain different adsorbents are detailed, as well as the interaction mechanisms with the compounds of interest (contaminants). The adsorbents obtained are an alternative to recycle polymeric and they are competitive with other materials applied in the removal and extraction of contaminants.

Adsorption of Different Pollutants by Using Microplastic with Different Influencing Factors and Mechanisms in Wastewater: A Review

The studies on microplastics are significant in the world. According to the literature, microplastics have greatly specific surface areas, indicating high adsorption capacities for highly toxic pollutants in aquatic and soil environments, and these could be used as adsorbents. The influencing factors of microplastic adsorption, classification of microplastics, and adsorption mechanisms using microplastics for adsorbing organic, inorganic, and mixed pollutants are summarized in the paper. Furthermore, the influence of pH, temperature, functional groups, aging, and other factors related to the adsorption performances of plastics are discussed in detail. We found that microplastics have greater advantages in efficient adsorption performance and cost-effectiveness. In this paper, the adsorptions of pollutants by microplastics and their performance is proposed, which provides significant guidance for future research in this field.