ACS Sustainable Resource Management最新文献

The chemical recycling of a fully bio-based thermoset has been investigated by developing an innovative in situ monitoring methodology. Within this study, two distinct recycling pathways utilizing KOH/EtOH or NaOH/water were successfully developed for the solvolysis process of SuccELO, an epoxy/acid cross-linked polymer, by targeting its fragile ester bonds. The solvolysis was monitored by calorimetry, FT-IR, mass loss measurements, and optical microscopy. The kinetic parameters evaluated by calorimetry have been interpreted in terms of solvolysis mechanisms and used to discriminate four stages of the recycling process, beginning with a diffusion-controlled stage. The second step combines both diffusion and solvolysis, the later process corresponding to the formation of carboxylate ions. A third stage was identified and is associated with an autocatalytic step driven by the formation of sodium salts acting as a solubilizer for triglycerides. Finally, the diffusion of small chains is identified as the rate-limiting step at the end of the process. Validation of these findings is reinforced by comprehensive surface analysis using microscopy and FT-IR techniques. Besides the novelty of monitoring solvolysis by calorimetry, a simulation tool was developed based upon this method. These simulations were compared with mass loss measurements, highlighting drawbacks in the procedure used for these mass loss tests. Lastly, it is shown how prediction of the solvolysis at various temperatures not experimentally accessible can be achieved using kinetic modeling, facilitating process design and optimization strategies.

Exaggerated global efforts to endorse a circular economy for resolving environmental concerns along with high energy demand have enhanced interest for the valorization of waste biomass. This study investigates the sustainable utilization of waste biomass through the pyrolysis kinetics of jujube pits. Jujube pits are abundant agricultural byproducts with potential for energy generation and value-added material production. Pyrolysis kinetics elucidate the thermodynamic and kinetic parameters governing the decomposition process, crucial for optimizing pyrolysis conditions and product yields. By optimizing the pyrolysis kinetic parameters, we have thoroughly assessed the potential of jujube pits as biomass fuel, which exhibits a higher HHV (higher heating value) and low activation energy. After controlled pyrolysis, the tailored pyrolytic carbon exhibits excellent electrochemical stability and lithium-storage kinetics because of its microstructure and chemical composition. Additionally, the resultant pyrolytic carbon was employed for lithium-ion storage and delivered high specific capacity (166 mAh g^–1) and an ultrastable cycling performance by retaining almost 100% Coulombic efficiency over 2000 cycles at 2 A g^–1. By elucidation of the pyrolysis kinetics of jujube pit waste and assessment of the electrochemical behavior of its derived carbon products, this study contributes to the advancement of sustainable practices in biomass utilization, contributing to the development of sustainable energy-storage solutions.

A novel low-temperature electrochemical method for rare earth elements (REEs) recovery from spent permanent magnets was investigated at bench scale. First, magnets were completely dissolved in a 2 g sulfuric acid/g magnet powder solution at room temperature. Then, the iron present in the leachate was either oxidized or reduced electrochemically. After that, REEs were separated as double salt precipitates by the addition of sodium sulfate or sodium hydroxide. A sodium sulfate quantity of 5 times the stoichiometric mass amount proved to be adequate for achieving recovery rates of 90–99% for neodymium, praseodymium, and terbium in the acid leachate, while ensuring no iron coprecipitation. Iron speciation (either fully oxidized or fully reduced) was demonstrated to have no apparent effect on REEs recovery. However, 2–7% iron coprecipitation was observed for acid leachate containing fully reduced iron. Finally, iron, the element of higher weight fraction in magnets, was recovered (77.32% in 20 h) in its useful metallic form by a divided electrowinning process at a moderate temperature (70 °C). The purity of the electrodeposited iron layer was determined to be 95.20 ± 3.57%. The novelty of the proposed environmentally friendly method is the recovery of iron in metallic electrolytic form and REEs in sulfate form, avoiding high temperature pyrometallurgical methods (roasting) or the use of additional chemical oxidizers.

We present an environment-friendly circular electrochemical method of recycling REEs from NdFeB permanent magnets. This method reduces solid waste (by recovering iron in metallic form) and minimizes acid waste by regenerating sulfuric acid for recycling.

This paper discusses a sustainable waste management initiative in ASEAN nations, utilizing a unique Quadruple Helix model that includes an international organization as an active fourth actor. This collaboration among academia, government, industry, and the international organization focuses on strategic policy alignment, advanced waste management technologies, and project creation through an interactive multi-stakeholder knowledge-sharing digital platform. The project is leading to a significant reduction in carbon and methane emissions, mitigating approximately 6 million tons of CO₂ equivalent and creating around 1,300 green jobs. Nearly 4 million ASEAN citizens are benefiting from improved access to solid waste management services, enhancing their quality of life and environmental health. Universities play a crucial role by establishing the ASEAN-Korean Integrated Green Technology Platform (AKIGTP), which bridges next-generation research and practical applications. NTU’s contributions in advanced research, knowledge dissemination, and fostering multi-stakeholder partnerships were instrumental in addressing complex challenges and advancing innovation within the Quadruple Helix framework. Taken together, the project not only showcases the potential of the Quadruple Helix model in driving sustainable development but also sets a precedent for similar initiatives globally. This comprehensive approach ensures effective and sustainable solutions to municipal solid waste management challenges, promoting a resilient and environmentally conscious future for the ASEAN region.

Pyrolysis of plastic waste is a key technology for closing the anthropogenic carbon cycle. The energy demand (ED) of this endothermic process is a crucial factor to evaluate its benefits compared to established recycling pathways. The pyrolysis ED can be determined experimentally. However, this is elaborate and limited in transferability. Existing models cover virgin plastics or hydrocarbon thermoplastic mixtures on a laboratory scale. Here, a model for calculating the ED of thermoplastic mixtures based on the superposition of virgin polymer data is developed. The material data, such as heat capacity, phase transition enthalpy, and reaction enthalpy, are determined using differential scanning calorimetry. Pilot-scale experiments are performed in a 1 kg/h screw reactor. These experimental data are compared to model calculations. The feedstock-specific ED for pyrolysis is plastic-type independent. It amounts to approximately 4–6% of the feedstocks’ net calorific value. The validation shows excellent accordance for virgin plastics and hydrocarbon plastics mixtures. The modeled ED of mixtures including heteroatoms is systematically underestimated, which indicates changes in the degradation mechanism. The model allows for resolving several phenomena contributing to the pyrolysis ED. The simple calculation of the ED with in-depth information on occurring phenomena enables more reliable process design, optimization, and evaluation.