Journal of advanced manufacturing and processing最新文献

Over 430 million tons of plastic were produced in the year 2022, and 2/3rd of them were of short-term use. Besides good successes in recycling PET (No 1) and HDPE (No 2), most of them end up in landfills or waterways and oceans. Even recycling of plastic by mixing them with virgin plastic has problems, as they contain large amounts of pharmaceuticals and other undesirable chemicals. One of the desirable ways to chemically recycle a plastic is to take it back to its starting monomers, which can then be re-polymerized into virgin plastic—a circular recycling. A polyester (PET) polymer can be hydrolyzed back to diacids and diols, and after cleaning, polymerized back to PET with the same characteristics as the original polymer. There are catalytic pyrolytic ways to produce naphtha (C₄–C₇) that can be a starting material for ethylene and propylene to be repolymerized to PE and PP. Inductively coupled depolymerization of plastic can, under the right conditions (Eco Fuel Technology, US Patent 9 505 901), take the polymer all the way to its monomer (85–90 + % yield). Mixtures of plastic can be reacted, and the resulting ethylene, propylene, or styrene can be separated to get pure monomers that can be re-polymerized. This will be a true circular chemical recycling and this paper will propose ways to scale up the process to industrial scale. This cycle can be repeated indefinitely and the process by itself does not add any CO₂.

Battery-electric vehicles (EVs) are growing exponentially. The demand for these batteries is expected to increase sevenfold by 2035. The EV batteries reach their end of life when the capacity fades to 70%–80% of new, with some being removed from the primary applications with even lower levels of degradation. These batteries can be used in less demanding applications. The disassembly process is currently manual, slow, unsafe, and expensive. Automation is needed to increase the throughput. EV battery packs feature various continually changing designs and form factors, which limit the usefulness of deterministically programmed robotic solutions. The conceptual robotic disassembly of EV batteries has attracted the attention of researchers. However, while many approaches have been proposed, practical implementations are lacking. We review proposed concepts for EV battery disassembly and describe the selected approach, with elements of partial solutions validated in a laboratory setting, including the selection of commercial solutions, the development of custom end effectors, and methodologies for detection, localization, and classification of fasteners. The computer vision tasks employed an overhead 2D camera to detect the type of battery pack and approximate localization of fasteners, and a 3D camera mounted on the robotic arm for precise localization (position and tilt) and classification.

Textiles is a growing waste stream ripe with opportunities for better materials management and promotion of businesses aligned with textile reuse and repair. The California Product Stewardship Council (CPSC) is leading textile policy development and textile recovery projects focused on expanding circular fiber systems with reduced cost burden on local government and taxpayers through extended producer engagement. Innovative fiber identification and pre-processing solutions are needed to enhance the efficiency and efficacy of Materials Recovery Facilities. Various textile scanning technologies are available on the market, with Near-Infrared Spectroscopy (NIR) emerging as the most promising and market-ready option due to its wide use in solid waste and recycling contexts. The article compares multiple NIR-based fiber identification devices tested in CPSC's recent pilot projects to provide a comprehensive overview of the current market landscape. The article discusses the potentials of handheld and tabletop devices in comparison to large-capacity machines, and challenges for accurate fiber identification due to the diverse nature of textile waste, including complex fabric blends, multi-layers, and the presence of disruptors such as prints, embroidery, and zippers. Industry-wide collaboration and the establishment of regulations and standards are required to overcome the current technical and economic challenges in textile circularity. The article will present recommendations for data collection, transparency, and accountability in the industry, and will discuss the role of policy development in creating economic incentives such as financial support, tax incentives, or subsidies for MRFs investing in state-of-the-art scanning solutions to expedite the transition toward more sustainable and efficient circular economy practices.

The emission of methane and carbon dioxide from greenhouse gases and vehicle emissions is a major contributor to air pollution. This research is aimed to convert methane into hydrogen gas through using non-thermal plasma decomposition. Twenty experiments were conducted, and three parameters were manipulated: voltage of the plasma power source, methane gas flow rate and argon gas flow rate which is streamlined to operate the plasma reactor. The best result was found in the experiment at 3 kV, 8 L/min of argon gas, and 75 mL/min of methane gas, producing 635 ppm of hydrogen gas. The study outcomes were incorporated in a model which highlighted the relationship between the power source voltage, flow rate of argon and methane as a function of the hydrogen produced. Additionally, the results disclosed that other gases, such as carbon dioxide, ethylene, and ethane, were also produced during the decomposition process. The results of this research demonstrate the potential of a novel Multi Flying Jet Plasma Torches reactor for efficient, eco-friendly hydrogen production through methane decomposition, offering optimized operational parameters and predictive modeling that enhance process scalability and reduce environmental impact compared to conventional methods.

We have been developing a solvent-based plastic recycling technology called STRAP. The technology is based on dissolving a targeted plastic resin in a specific solvent that does not dissolve other resins. We have demonstrated STRAP in thousands of bench scale experiments for a large variety of wastes. Recently we have demonstrated the technology for PCR, using mixed plastic wastes (MPWs), from a wet Material Recovery Facility (MRF). The process includes (1) infrared (IR) characterization to determine the plastic composition for accurate selection of the solvent to be used for the extraction of the pure resins. (2) Shredding to the right size and aspect ratio required for flowable and fast dissolvable process. (3) Mixing the MPW in the first solvent to dissolve the first resin. (4) Filtration of the solution plastic blend, to separate the nondissolved plastic from the solution. (5) Further filtration of the solution to remove micron-sized particle of pigments and fibers. (6) Cooling for precipitation. (7) Filtration of pure resins. (8) Drying of a pure resin. (9) Extrusion of the resin to pellets. (10) Generating films or other products from the pure resin. Steps 1–10 can be considered as one-cycle that extracted the first resin. (11) A second resin can be extracted with a respective solvent from the plastic that did not dissolve in the first cycle and following steps 1–10 described above. The process also includes characterization of interim and final products. The effort includes building a pilot system at 25 kg/h throughput. We will present specific results for various PCR.