Recycling Potentials of Precious Metals from End-of-Life Vehicle Parts by Selective Dismantling

Advanced membrane-based high-value metal recovery from wastewater

Considering the circular economy and environmental protection, sustainable recovery of high-value metals from wastewater has become a prominent concern. Unlike conventional methods featuring extensive chemicals or energy consumption, membrane separation technology plays a crucial role in facilitating the sustainable and efficient recovery of valuable metals from wastewater due to its attractive features. In this review, we first briefly summarize the sustainable supply chain and significance of sustainable recovery of aqueous high-value metals. Then, we review the most recent advances and application potential in promising state-of-the-art membrane-based technologies for recovery of high-value metals (silver, gold, rhenium, platinum, ruthenium, palladium, iridium, osmium, and rhodium) from wastewater effluents. In particular, pressure-based membranes, liquid membranes, membrane distillation, forward osmosis, electrodialysis and membrane-based hybrid technologies and their mechanism of high-value metal recovery is thoroughly discussed. Then, engineering application and economic sustainability are also discussed for membrane-based high-value metal recovery. The review finally concludes with a critical and insightful overview of the techno-economic viability and future research direction of membrane technologies for efficient high-value metal recovery from wastewater.

Potential prediction and coupling relationship revealing for recovery of platinum group metals from spent auto-exhaust catalysts based on machine learning

As hazardous waste, the massive generation of spent auto-exhaust catalysts (SACs) puts enormous pressure on environmental management, but provides a rare opportunity for platinum group metals (PGMs) recycling. In this study, machine learning (ML) method was firstly applied to accurately predict regional SACs generation in China for 2025-2050 under five shared socio-economic pathways (SSPs) scenarios, based on which economic and carbon emission reduction potential of PGMs recycling were estimated. Population-GDP-GDPII-GDPIII and Random Forest were determined as key variables and the predictive model. Results indicate that SACs will reach 28.15 million sets (1.7 times that of 2020) and PGMs have economic potential of $890 million by 2050 (SSP1). Furthermore, based on environmental impact assessment, the capture enrichment-electrodeposition purification process is proposed as the best low-carbon recycling solution for SACs. And the integrated recovery process based on copper capture can realize 1.51 million tons of carbon emission reduction in China in 2050 (SSP1). This study can provide decision-making guidance for PGMs recovery and environmental management, as well as technical references for SACs recovery program selection.

Incorporating platinum circular economy into China's hydrogen pathways toward carbon neutrality

Hydrogen is gaining tremendous traction in China as the fuel of the future to support the country's carbon neutrality ambition. Despite that hydrogen as fuel largely hinges on the supply of platinum (Pt), the dynamic interlinkage between Pt supply challenges, hydrogen development pathways, and climate targets in China has yet to be deeply analyzed. Here, we adopt an integrated assessment model to address this important concern and corresponding strategies for China. The results indicate that the booming hydrogen development would drive China's cumulative demand for Pt metal to reach 4,200-5,000 tons. Much of this demand, met through a limited supply pattern, is vulnerable to price volatility and heightened geopolitical risks, which can be mitigated through circular economy strategies. Consequently, a coordinated approach to leverage both global sustainable Pt sourcing and a robust domestic Pt circular economy is imperative for ensuring cost-effective hydrogen production, aligned with a climate-safe future.

Pollution characteristics and release mechanism of microplastics in a typical end-of-life vehicle (ELV) recycling base, East China

Microplastics (MPs) is a novel and significant pollution due to its eco-environmental hazards and ubiquity. In end-of-life vehicle (ELV) recycling base, MPs are widely distributed but have rare reported in scientific literature. In this study, a comprehensive analysis of MPs was conducted in a typical ELV recycling base. MPs were found in all samples at different sampling sites and environmental mediums. A total of 34 polymer types were detected by μ-FTIR, and the main polymers include PE-PP, ABS, polyester resin, nylon, and PEU plastic. MPs were released from the crushing, tearing, and breaking of plastic parts in ELVs. They were in high content in ground dust, with the abundance of 737-29,021 p/5 g D (the average abundance of 5552 ± 6435 p/5 g D). The abundance, shape, color, and size of MPs are related with functional areas of ELV recycling. Heavy metals could be adsorbed on MPs, and their contents on MPs have a significant correlation with those in the corresponding dust samples. At last, some specific MPs control measures, such as changing transportation mode, using dust-proof cloths, and equipping dust removal equipment, have been put forward.

The Decision-Making Analysis on End-of-Life Vehicle Recycling and Remanufacturing under Extended Producer Responsibility Policy

This research develops a dual-cycle ELV recycling and remanufacturing system to better understand and improve the efficiency of the ELV recycling and remanufacturing businesses. For the flawless operation of this system, the researchers employed evolutionary game theory to establish a game model between original vehicle manufacturers (OVMs) and third-party recyclers with the government involved. This research presents evolutionary stable strategies (ESS) that could promote an ELV recycling and remanufacturing system. Results show that OVMs’ expected profit difference between choosing and not choosing authorization is crucial in their ESS. The licensing fee plays a part of OVMs’ expected profit difference. Based on the results, optimal ESS could be achieved when the OVMs’ expected profit difference between choosing authorization and not choosing authorization and the third-party recyclers’ profit when paying the licensing fee are both positive. Then, the two groups’ involvement in dual-cycle ELV recycling and the remanufacturing system can be ensured. This research implicates the government to devise appropriate reward and punishment strategy to encourage OVMs and third-party recyclers to collaborate for efficient recycling and remanufacturing systems. Particularly, the government is suggested to impose strict restrictions on OVMs to carry ELV recycling and provide support to promote recycling quantity standards. Hence, the ELV recycling and remanufacturing system would be strengthened, thus improving waste management which is crucial for both environmental and resource efficiency.

Characterizing the Changes in Material Use due to Vehicle Electrification

Modern automobiles are composed of more than 2000 different compounds comprising 76 different elements. Identifying supply risks across this palette of materials is important to ensure a smooth transition to more sustainable transportation technologies. This paper provides insight into how electrification is changing vehicle composition and how that change drives supply risk vulnerability by providing the first comprehensive, high-resolution (elemental and compound level) snapshot of material use in both conventional and hybrid electric vehicles (HEVs) using a consistent methodology. To make these contributions, we analyze part-level data of material use for seven current year models, ranging from internal combustion engine vehicles (ICEV) to plug-in hybrid vehicles (PHEVs). With this data set, we apply a novel machine learning algorithm to estimate missing or unreported composition data. We propose and apply a metric of vulnerability, referred to as exposure, which captures economic importance and susceptibility to price changes. We find that exposure increases from $874 per vehicle for ICEV passenger vehicles to $2344 per vehicle for SUV PHEVs. The shift to a PHEV fleet would double automaker exposure adding approximately $1 billion per year of supply risk to a hypothetical fleet of a million vehicles. The increase in exposure is largely not only due to the increased use of battery elements like cobalt, graphite, and nickel but also some more commonly used materials, most notably copper.

Insights from In Situ Studies on the Early Stages of Platinum Nanoparticle Formation

Understanding the formation of nanomaterials down to the atomic level is key to rational design of advanced materials. Despite their widespread use and intensive study over the years, the detailed formation mechanism of platinum (Pt) nanoparticles remains challenging to explore and rationalize. Here, various in situ characterization techniques, and in particular X-ray total scattering with pair distribution function (PDF) analysis, are used to follow the structural and chemical changes taking place during a surfactant-free synthesis of Pt nanoparticles in alkaline methanol. Polynuclear structures form at the beginning of the synthesis, and Pt-Pt pair distances are identified before any nanoparticles are generated. The structural motifs best describing the species formed change with time, e.g., from [PtCl₅-PtCl₅] and [PtCl₆-Pt₂Cl₆-PtCl₆] to [Pt₂Cl₁₀-Pt₃Cl₈-Pt₂Cl₁₀]. The formation of these polynuclear structures with Pt-Pt coordination before the formation of the nanoparticles is suggested to account for the fast nucleation observed in the synthesis.

Emerging anthropogenic circularity science: principles, practices, and challenges

Material depletion over reliance of linear economies and environmental pollution may be resolved by applying the principles and practices of anthropogenic circularity science. Here we systematically review the emergence of anthropogenic circularity science in the interdisciplinary development of green chemistry, supply chain, and industrial ecology at different scales. The first, second, and third laws of circularity chemistry are proposed as forming the basic principles of circularity science. To close the loop on critical materials, these three basic principles have been exemplified in the anthropogenic circularity practices. We highlight the spatial distribution of critical metal, waste generation, and recycling rate. Future opportunities and challenges for a circular economy and urban mining will predominate in anthropogenic circularity. Therefore, anthropogenic circularity science will play an increasing role in enabling a smooth transition to a circular society.

On the facile and accurate determination of the Pt content in standard carbon supported Pt fuel cell catalysts

We introduce a new and straight-forward methodology to accurately determine the Pt content in polymer membrane electrolyte fuel cell (PEMFC) catalysts consisting of carbon supported Pt nanoparticles (Pt/C). The method is based on an indirect Pt proof (IPP) consisting of the oxidative removal of the carbon support, the digestion of the Pt in aqua regia followed by a replacement reaction to form Cu ions (CuCl₂). The Pt content is then determined via the Cu-ions with the help a complexometric indicator using a simple titration. The procedure is fast and does not require any expensive equipment. Thus, it can be implemented in any standard chemistry laboratory. The advantages and disadvantages of the IPP method are evaluated in a comparison to alternative methods for the determination of the Pt content in supported catalysts, i.e. inductively coupled plasma mass spectrometry (ICP-MS) and UV/Vis spectroscopy (UV/Vis). It is demonstrated that the IPP method delivers reliable and accurate results and is less influenced than for example ICP-MS by side effects such as excess in nitric acid or organic impurities. Furthermore, during the procedure up to 60% of the Pt material is recovered during the IPP procedure.