Plastics waste management: A review of pyrolysis technology

<abstract> <p>The world is today faced with the problem of plastic waste pollution more than ever before. Global plastic production continues to accelerate, despite the fact that recycling rates are comparatively low, with only about 15% of the 400 million tonnes of plastic currently produced annually being recycled. Although recycling rates have been steadily growing over the last 30 years, the rate of global plastic production far outweighs this, meaning that more and more plastic is ending up in dump sites, landfills and finally into the environment, where it damages the ecosystem. Better end-of-life options for plastic waste are needed to help support current recycling efforts and turn the tide on plastic waste. A promising emerging technology is plastic pyrolysis; a chemical process that breaks plastics down into their raw materials. Key products are liquid resembling crude oil, which can be burned as fuel and other feedstock which can be used for so many new chemical processes, enabling a closed-loop process. The experimental results on the pyrolysis of thermoplastic polymers are discussed in this review with emphasis on single and mixed waste plastics pyrolysis liquid fuel.</p> </abstract>

A market-oriented database design for critical material research

<abstract> <p>Material databases are important tools to provide and store information from material research. Rising concerns about supply-chain risks to raw materials presents a need to incorporate raw-material market and end-use application data, beyond basic chemical and physical properties, into a material database. One key challenge for researchers working on critical materials is information scarcity and inconsistency. This paper introduces, as a result of a two-year project, a critical-material commodity database (CMCD) incorporated with a low-code web-based platform that allows easy access for users and simple updates for the authors. The main goal of this project was to educate material scientists on the applications having the most impact on the supply chain and current industrial specifications/markets for each application. The objective was to provide material researchers with harmonized information so that they could gain a better understanding of the market, focus their technologies on an application with a high potential for commercialization, and better contribute to supply-chain risk reduction. While the goal was met with high receptivity, several limitations stemmed from query design, distribution platform, and quality of data source. To overcome some of these limitations and expand on CMCD's potential, we are building a public webpage with an improved interface, better data organization, and higher extensibility.</p> </abstract>

Sustainable management of textile and clothing

<abstract> <p>Textile and clothing industry (T&amp;C) is the second largest industry in the manufacturing sector. Currently, the industry operates on a linear model. Its value-chain is associated with several problems such as environment pollution (solid wastes, effluent discharges, air pollution, and emission of greenhouse gases), and resources extraction and depletion (raw materials, water, energy). These problems present the challenges that are addressed in this paper. These problems are further exacerbated by the rapid growth in population and attendant need for economic growth. There is therefore need to begin to address how to make the industry more sustainable. This will entail reviewing the entire T&amp;C value chain from raw material extraction to post-consumption of its products. Nigeria, an emerging economy is used as a proxy for the study. The management of textile/clothing wastes in Nigeria does not follow best practices, as the wastes are generally, disposed at dumpsites. Even though Nigeria is rich in natural resources to produce textiles, the country largely depends on importation of finished T&amp;C goods. This paper uses three models namely: new business model, efficient waste management system, and regenerative production processes and materials to demonstrate how the industry can become more sustainable. This effort will focus on reuse and recycling of textile and clothing products. Emphasis is built on eco-design to encourage proper waste management system to support recovery, reprocessing, reuse, and recycling of textile and clothing products.</p> </abstract>

Recent advances in acid-free dissolution and separation of rare earth elements from the magnet waste

<abstract> <p>The availability of REEs is limiting the successful deployment of some environmentally friendly and energy-efficient technologies. In 2019, the U.S. generated more than 15.25 billion pounds of e-waste. Only ~15% of it was handled, leaving ~13 billion pounds of e-waste as potential pollutants. Of the 15% collected, the lack of robust technology limited REE recovery for re-use. Key factors that drive the recycling of permanent magnets based on rare earth elements (REEs) and the results of our research on magnet recycling will be discussed, with emphasis on neodymium and samarium-based rare earth permanent magnets.</p> </abstract>

Value recovery from spent lithium-ion batteries: A review on technologies, environmental impacts, economics, and supply chain

<abstract> <p>The demand for lithium-ion batteries (LIBs) has surged in recent years, owing to their excellent electrochemical performance and increasing adoption in electric vehicles and renewable energy storage. As a result, the expectation is that the primary supply of LIB materials (e.g., lithium, cobalt, and nickel) will be insufficient to satisfy the demand in the next five years, creating a significant supply risk. Value recovery from spent LIBs could effectively increase the critical materials supply, which will become increasingly important as the number of spent LIBs grows. This paper reviews recent studies on developing novel technologies for value recovery from spent LIBs. The existing literature focused on hydrometallurgical-, pyrometallurgical-, and direct recycling, and their advantages and disadvantages are evaluated in this paper. Techno-economic analysis and life cycle assessment have quantified the economic and environmental benefits of LIB reuse over recycling, highlighting the research gap in LIB reuse technologies. The study also revealed challenges associated with changing battery chemistry toward less valuable metals in LIB manufacturing (e.g., replacing cobalt with nickel). More specifically, direct recycling may be impractical due to rapid technology change, and the economic and environmental incentives for recycling spent LIBs will decrease. As LIB collection constitutes a major cost, optimizing the reverse logistics supply chain is essential for maximizing the economic and environmental benefits of LIB recovery. Policies that promote LIB recovery are reviewed with a focus on Europe and the United States. Policy gaps are identified and a plan for sustainable LIB life cycle management is proposed.</p> </abstract>

Electrospun nanofibers for efficient adsorption of heavy metals from water and wastewater

<abstract> <p>Heavy metals (HMs) are persistent and toxic environmental pollutants that pose critical risks toward human health and environmental safety. Their efficient elimination from water and wastewater is essential to protect public health, ensure environmental safety, and enhance sustainability. In the recent decade, nanomaterials have been developed extensively for rapid and effective removal of HMs from water and wastewater and to address the certain economical and operational challenges associated with conventional treatment practices, including chemical precipitation, ion exchange, adsorption, and membrane separation. However, the complicated and expensive manufacturing process of nanoparticles and nanotubes, their reduced adsorption capacity due to the aggregation, and challenging recovery from aqueous solutions limited their widespread applications for HM removal practices. Thus, the nanofibers have emerged as promising adsorbents due to their flexible and facile production process, large surface area, and simple recovery. A growing number of chemical modification methods have been devised to promote the nanofibers' adsorption capacity and stability within the aqueous systems. This paper briefly discusses the challenges regarding the effective and economical application of conventional treatment practices for HM removal. It also identifies the practical challenges for widespread applications of nanomaterials such as nanoparticles and nanotubes as HMs adsorbents. This paper focuses on nanofibers as promising HMs adsorbents and reviews the most recent advances in terms of chemical grafting of nanofibers, using the polymers blend, and producing the composite nanofibers to create highly effective and stable HMs adsorbent materials. Furthermore, the parameters that influence the HM removal by electrospun nanofibers and the reusability of adsorbent nanofibers were discussed. Future research needs to address the gap between laboratory investigations and commercial applications of adsorbent nanofibers for water and wastewater treatment practices are also presented.</p> </abstract>