Closed-loop Process Research Articles

A Periodically Updated Adaptive Sampling Framework for Marine Mobile Observation Platforms

Abstract While numerical models have been developed for several years, some of these have been applied to ocean-state sampling. Adaptive sampling deploys limited assets using prior information; then, observation assets are concentrated in areas of greater sampling value, which is very suitable for an extensive and dynamic marine environment. The improved resolution allows numerical models to be used on mobile platforms. However, the existing adaptive sampling framework for mobile platforms lacks regular interaction with the numerical model. And the observation scheme is easy to deviate from the optimal. This study sets up a closed-loop adaptive sampling framework for mobile platforms that realizes the optimization of model → sampling → model. Linking a coupled model with the sampling points of the mobile platforms, the adaptive method configures key sampling locations to determine when and where the sampling schemes are adjusted. With the aid of a coupled model, we selected an optimization algorithm for the framework and simulated the process under the twin experimental framework. This research provides theoretical technical support for the combination of model and mobile sampling platforms. Significance Statement The ocean is very difficult to observe because it is so vast. How to deploy observing assets is a question worth investigating. We designed an adaptive sampling framework for mobile observing platforms to improve the prediction accuracy of numerical models. This framework uses the prediction to design the observation scheme, then the observation to update the prediction, and then the updated prediction to adjust the sampling scheme, which achieves closed-loop optimization. We first selected an optimization algorithm for this framework by comparing experiments. Based on the optimization algorithm, we simulated the closed-loop optimization process. Simulation results show that this framework can significantly increase the efficiency of long-term ocean observations with mobile devices.

The Application of BOPPPS Teaching Method in the Teacher Education Curriculum

The teacher education curriculum should guide the future teachers to master the necessary educational knowledge and ability. The teaching reform is the core link of the teacher education curriculum reform. Based on constructivism and communicative approach, the BOPPPS teaching model is a closed-loop teaching process model which emphasizes students’ participation and feedback. The BOPPPS teaching model is helpful to realize effective teaching of teacher education courses. The application of the BOPPPS teaching method in the teacher education curriculum is helpful to deepen the theoretical teaching and consolidate the theoretical knowledge of education and teaching.

Technologies of Recycling REEs and Iron from NdFeB Scrap

In recent years, under the background of global low-carbon development, the production of NdFeB magnets has increased dramatically. With the end of magnet life, a large number of discarded products will be produced in the future. At the same time, 6–73% of industrial waste will be produced in the manufacturing process of magnets. The rare earth content (about 30 wt.%) of these magnet scraps is generally higher than that of raw ore, and the recovery of rare earth elements from them helps to stabilize the global rare earth supply chain. In addition, NdFeB scrap contains about 70 wt.% of iron, which is currently unable to be utilized with high added value. If iron can be recycled based on recycling rare earth elements, it is expected to realize the full component recycling of NdFeB waste and reduce the full life cycle environmental load of NdFeB products. This paper summarizes the properties, recycling potential, and existing recycling technologies of NdFeB waste, and it summarizes the principles, advantages, and disadvantages of various recycling methods, such as direct reuse, pyrometallurgy, hydrometallurgy, and electrochemistry. Among them, the electrochemical recovery method was emphatically reviewed as a newly proposed method. On this basis, the future development direction of NdFeB waste recycling has been prospected, and the research idea of avoiding the shortcomings of various recycling methods through the combined process is proposed. It is proposed that low environmental hazards, low energy consumption, and a closed-loop process are the main goals to be achieved in the recycling process.

Blockchain-IIoT-big data aided process control and quality analytics

The literature on quality management system (QMS) assumes that product and process performance data are authentic and easily accessible. This assumption, while ideologically sound, is questionable in practise because the authenticity and accessibility of data cannot be guaranteed in many circumstances. Inaccurate, incomplete, inconsistent, and inaccessible data are common in supply chains and prevent the QMS from achieving its goal: assuring product and process quality to meet customer requirements. This study is one of the first to examine the impact of data quality and data latency on process control and quality analysis which are elemental parts of daily QMS activities, from a supply chain visibility (SCV) perspective. In this study, five propositions are made to show the relationships between technology, SCV, and data issues. More importantly, the study proposes a platform that integrates Blockchain (BC) technology, Industrial Internet of Things (IIoT), and Big Data to solve data problems in SCV and QMS. We further perform fuzzy association rule mining (FARM) to show how the platform can solve quality analysis problems and complete a closed-loop process control cycle in manufacturing. We also explain the contributions of the integrated platform to QMS from four theoretical perspectives. Finally, we discuss the limitations of the platform and provide recommendations for future research.

Low-carbon footprint approach to produce recycled compacted concrete

Achieving a closed-loop recycling process with low CO2 emissions remains a challenge for the concrete industry. To improve the recycling of concrete debris, a powder compaction process for concrete waste was designed to obtain recycled compacted concrete (hereinafter referred to as compact) and thermal treatment was proposed to be utilized to improve its strength. However, non-specific investigations of treatment parameters, like-treatment temperature, and duration, do still exist, and the required high production pressure (100 MPa) is impracticable. Therefore, this study aims to evaluate the effectiveness of two novel treatments on compact in improving its strength and reducing its carbon footprint. First, the heat treatment process used in a previous study [1] was expanded by varying immersion durations and treatment temperatures. Second, autoclaving was employed to obtain a stronger compact with different treatment settings. Additionally, in both treatment processes, the efficacy of low production pressure (<100 MPa) was evaluated. For this, eighteen different concrete wastes, having different industrial wastes, like-fly ash, slag, were collected, crushed, and powdered to produce compacts. The treated compacts were characterized based on both compressive strength and carbon footprint to compare the environmental performance of a compact prepared via thermal treatments in the production phase. The test results revealed that increasing water immersion duration (to 48 h) during the heat treatment process improved the compact strength to up to 48 MPa, and autoclaving at higher temperatures (at 220 °C) resulted in a compact strength of up to 98 MPa. Additionally, a strength of 30 MPa was attained even at a low production pressure (10 MPa) after autoclaving. The estimated CO2 emissions of the compact production process developed in this study were as low as 70.6 kg/m3 of compact. At the present stage of the study, it can be deduced that the compact manufactured possesses potential for implementation in various non-structural applications, including the production of pavement blocks and bricks, with lower CO2 emissions.

Ammonia recovery from municipal wastewater using hybrid NaOH closed-loop membrane contactor and ion exchange system

Water scarcity is affected by population growth and increasing nutrients pollution. This study evaluated the integration of ion exchange-natural activated clinoptilolite zeolite (IEX-NZ) and hollow-fibre liquid–liquid membrane contactor (HF-LLMC) as an innovative and sustainable hybrid technology for ammonia recovery from treated urban wastewaters. The process is based on NaOH closed-loop process to i) ensure the extracted concentration of ammonia from the loaded zeolites and ii) enhance the transport of NH3 through the HF-LLMC. Regeneration of the IEX-NZ provided recoveries up to around 92% using 8% NaOH solution with concentration factors between 30 and 60 and a residual ammonium stream below 1 mg NH4+-N/L. Recovery of NH3 from NaOH solutions was carried out by HF-LLMCs using two different membrane chemistries: polypropylene (PP) and poly (4-methyl-1-pentene) (PMP) (>95%). A 1-D model was developed and used to describe the time evolution of NH3 concentration during the recovery process, to determine its mass transfer coefficient (9.5·107 m3/m2·s) and to quantify the undesired water co-transport (5.0·105 m3/m2·s). In addition, the model was used to analyse the influence of operational parameters on the membrane's permeability to maximise the concentration of the ammonium salts recovered as fertilisers. In this case, the 1-D algorithm was used to identify the needed stages to achieve residual levels of NH3 on the treated streams that promoted the NaOH closed-loop recycling to secure economic feasibility.

A mild closed-loop process for lithium–iron separation and cathode materials regeneration from spent LiFePO4 batteries

The recycling and reusing of waste LiFePO4 batteries significantly promote sustainable development and environmental protection. In this study, an innovative process of iron-lithium separation and cathode materials regeneration from used LiFePO4 batteries is proposed. The spent LiFePO4 powder was put into NaH2PO4 and H2O2 combined treatment solution for an oxidation leaching reaction. Under the optimal condition, excellent lithium–iron separation was achieved, with 98.65% leaching of lithium and only 0.028% leaching of iron. The selective separation of lithium ion can be efficiently achieved during the leaching process. Li+ from the leachate was precipitated into Li3PO4 by evaporation crystallization, and the saline solution, after precipitation, was converted into a leaching agent by adding H3PO4 for reusing. The regenerated LiFePO4 from recovered FePO4 displays excellent rate capability and long-term cyclic stability. Through the synergistic effect of NaH2PO4 and H2O2, this work achieves efficient and mild separation of iron-lithium while maintaining the raw material olivine structure, regenerating LiFePO4 cathode material with good electrochemical properties, avoiding the cost of wastewater treatment and forming a stable closed loop.

Closed-loop recyclable plastics from poly(ethyl cyanoacrylate).

Ethyl cyanoacrylate is a highly reactive monomer that has been used nearly exclusively to make Super Glue and related fast-setting adhesives. Here, we describe transformation of this highly abundant, readily available monomer into a closed-loop recyclable plastic that could supplant currently used (and often unrecycled/unrecyclable) plastics, such as poly(styrene). We report polymerization conditions, plastic-processing methods, and plastic-recycling protocols for poly(ethyl cyanoacrylate) plastics that make the Super Glue monomer a viable starting material for a next generation of closed-loop recyclable plastics. The processes described are scalable, and the plastics can be recycled in a closed-loop process with >90% yields, even when combined with a heterogeneous mixture of other types of plastic.

Regeneration of raw materials for aluminum electrolysis from spent carbon anodes via a closed-loop environmentally-friendly process based on aluminum–fluorine complexation

Spent carbon anode (SCA) discharged from the aluminum electrolysis industry is an unavoidable solid waste with an estimated production of 700 kilotons in 2021, which has been widely identified as the hazardous solid waste. A new two-stage leaching scheme comprising an aluminum salt leaching and an alkali leaching has been investigated in this study, by which valuable elements have been extracted from SCA. Effect of reaction conditions on the first-stage aluminum salt leaching process was investigated in detail. Under the optimal leaching conditions, the leaching rates of F, Na, and Al reached 98.00%, 94.94%, and 93.94%, respectively, and the recovered carbon purity was 85.84%. The fluorine recovery route was followed by the preparation of aluminum hydroxyfluoride precursor, namely Al2F3.24(OH)2.76 1.65H2O, through the mixing of two filtrates. Then thermogravimetry-differential scanning calorimetry (TG-DSC) curves were used to explore its calcination temperature point in detail. The final product was obtained as a mixture of AlF3 and Al2O3 with 95.94% purity. The characterization results showed that the calcined product was very similar to the commercial aluminum fluoride. Finally, the neutralized filtrate will be prepared by freezing and crystallizing Na2SO4, and the crystallized solution will be returned to the aluminum salt leaching process for recycling, which is the promise of green, recyclable, and high-value technology for realizing the detoxification of SCA and its subsequent utilization.

Sustainable regeneration of high-performance LiCoO2 from completely failed lithium-ion batteries

Utilising the solid-state synthesis method is an easy and effective way to recycle spent lithium-ion batteries. However, verifying its direct repair effects on completely exhausting cathode materials is necessary. In this work, the optimal conditions for direct repair of completely failed cathode materials by solid-state synthesis are explored. The discharge capacity of spent LiCoO2 cathode material is recovered from 21.7 mAh g−1 to 138.9 mAh g−1 under the optimal regeneration conditions of 850 °C and n(Li)/n(Co) ratio of 1:1. The regenerated materials show excellent electrochemical performance, even greater than the commercial LiCoO2. In addition, based on the whole closed-loop recycling process, the economic and environmental effects of various recycling techniques and raw materials used in the battery production process are assessed, confirming the superior economic and environmental feasibility of direct regeneration method.

Deterministic learning-based neural control for output-constrained strict-feedback nonlinear systems

This paper studies learning from adaptive neural control of output-constrained strict-feedback uncertain nonlinear systems. To overcome the constraint restriction and achieve learning from the closed-loop control process, there are several significant steps. Firstly, a state transformation is introduced to convert the original constrained system output into an unconstrained one. Then an equivalent n-order affine nonlinear system is constructed based on the transformed unconstrained output state in norm form by the system transformation method. By combining dynamic surface control (DSC) technique, an adaptive neural control scheme is proposed for the transformed system. Then all closed-loop signals are uniformly ultimately bounded and the system output tracks the expected trajectory well with satisfying the constraint requirement. Secondly, the partial persistent excitation condition of the radial basis function neural network (RBF NN) could be verified to achieve. Therefore, the uncertain dynamics can be precisely approximated by RBF NN. Subsequently, the learning ability of RBF NN is achieved, and the knowledge acquired from the neural control process is stored in the form of constant neural networks (NNs). By reutilizing the knowledge, a novel learning controller is established to improve the control performance when facing the similar or same control task. The proposed learning control (LC) scheme can avoid repeating the online adaptation of neural weight estimates, which saves computing resources and improves transient performance. Meanwhile, the LC method significantly raises the tracking accuracy and the speed of error convergence while satisfying of the constraint condition simultaneously. Simulation studies demonstrate the efficiency of this proposed control scheme.

High-efficiency recycling of spent lithium-ion batteries: A double closed-loop process

Due to the scarcity of raw materials and negative environmental effects, it is essential to selectively recover lithium and other transition metals from end-of-life lithium-ion batteries (LIBs). Here, we propose a dual closed-loop process for resource utilization of spent LIBs. As an alternative to strong inorganic acids, deep eutectic solvents (DESs) as green solvents are employed for the recycling of spent LIBs. The DES based on oxalic acid (OA) and choline chloride (ChCl) achieves efficient leaching of valued metals within a short time. Through the coordination adjustment of water, it can form high-value battery precursors directly in DES, changing wastes into valuables. Meanwhile, water as a diluent can achieve the selective separation of lithium ions via filtration. More importantly, DES can be perfectly re-generated and recycled many times, indicating that the process is cost-effective and eco-friendly. As experimental proof, the re-generated precursors were used to produce new Li(Ni0.5Co0.2Mn0.3)O2 (NCM523) button batteries. The constant current charge-discharge test revealed that the initial charge and discharge values of the re-generated cells were 177.1 and 149.5 mAh/g, respectively, corresponding to the performance of commercial NCM523 cells. The whole recycling process is clean, efficient, and environment-friendly, realizing the double closed loop of spent battery regeneration and deep eutectic solvent re-use. This fruitful research demonstrates DES has excellent potential for recycling spent LIBs and provides an efficient and eco-friendly double closed-loop solution for the sustainable re-generation of spent LIBs.

Investigations into the closed-loop hydrometallurgical process for heavy metals removal and recovery from biosolids via mild acid pre-treatment

Biosolids contain heavy metals (HMs), restricting their beneficial reuse in agricultural land. However, these metals can be a valuable resource in many applications if recovered efficiently. Therefore, the removal and recovery of HMs and other limiting contaminants in biosolids without degrading the organic nutrients of the resulting treated biosolids demands holistic investigations. A closed-loop hydrometallurgical treatment process for metal removal and recovery from biosolids was developed in this study. Firstly, mild acid treatment using 3% v/v H2SO4 at 25 °C, 600 rpm for 30 min was performed in a 1 L continuous stirred tank reactor to extract common HMs (such as As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) from biosolids into the aqueous phase. The effects of solids concentration and acid types on the HMs extraction efficiency were studied. Then, the primary acid leachate stream was continuously recycled for metal extraction from biosolids until the dissolved metals in the solution reached saturation concentration. After that, the dissolved metals were recovered in staged NaOH precipitation and adsorption. Low solids contents (<5% w/v) using mineral acids having pH <2 and oxidation-reduction potential (ORP) ∼500 mV (versus SHE) favoured HMs solubilisation from biosolids with an average extraction efficiency of 70%. The dissolution of ferric iron (Fe3+) by H2SO4 and subsequent in-situ formation of ferric sulfate enhanced the metal extraction strength of the spent leachate stream during recycling. However, the solids loading in each leaching process must be kept low to prevent ferric concentration build-up and precipitation as the leachate pH steadily increases above 2 during recycling. Amongst the metal recovery methods investigated, H2O2 oxidation prior to 2-stage NaOH precipitation had the highest efficiency with 75–95% HMs recovery. The clarified stream was used to neutralise the acidic treated biosolids to close the process loop. The complete process flowsheet was developed with mass balances, and the fate of nutrients (mainly C, N, and P) and major per- and polyfluoro alkyl substances (PFAS) were overviewed.

Microbial recycling of lithium-ion batteries: Challenges and outlook

Joseph Jegan Roy started his research career at the National Institute of Interdisciplinary Science and Technology (CSIR–NIIST) in Trivandrum, India, and received his PhD from the University of Kerala, India. Currently, he is a senior researcher in the SCARCE program at the Energy Research Institute @ NTU ([email protected]), Nanyang Technological University (NTU), Singapore. His current research centers on recycling spent lithium-ion batteries through biological, direct recycling techniques and waste-for-waste strategies. In addition, he is exploring the possibility of reutilizing recovered materials in novel applications of new electrochemical energy storage. Norazean Zaiden is a graduate of the Singapore Centre for Environmental Life Sciences Engineering (SCELSE, NTU, Singapore). Her interest in applied microbiology leads to biofilm matrix development for bioremediation and resource recovery applications through synthetic biology. In addition, she continues her journey in SCELSE as a research fellow under an industry collaboration studying anti-biofouling agents' effects on biofilms. Minh Phuong Do is a research fellow (materials science) with years-long experience in lithium/sodium ion batteries at Energy Research Institute at NTU, Singapore. She received her PhD from NTU in 2020, specializing in electrochemistry. Phuong uses this expertise in developing and optimizing a safe and stable battery system. Her current research focus is on the green closed-loop hydrometallurgical process for recycling spent lithium-ion batteries using biomass and regeneration of high-quality battery materials. Bin Cao is an associate professor in the School of Civil and Environmental Engineering and a principal investigator at the Singapore Centre for Environmental Life Sciences Engineering, NTU, Singapore. He received his PhD from the National University of Singapore and later worked as a postdoctoral research associate at Washington State University and Pacific Northwest National Laboratory. His research interest centers on biofilm-mediated microbial processes, with the goals of understanding environmental biofilm processes and applying the knowledge and insights to harness the power of beneficial biofilms and combat detrimental biofilms. Madhavi Srinivasan is a professor and executive director of the Energy Research Institute @ NTU ([email protected]) and NTU Sustainability office. Her research focuses on synthesis, fabrication, and application of nanoscale materials/architectures in improving the performance of electrochemical energy storage devices such as advanced lithium-ion batteries, supercapacitors, sodium ion batteries, multivalent aqueous Zn/Al batteries and recycling of e-waste. She is the co-director of SCARCE (Singapore-CEA alliance for research in circular economy), a joint lab, in collaboration with French Alternative energies and atomic energy commission (CEA, France), focusing on recycling of e-waste. Joseph Jegan Roy started his research career at the National Institute of Interdisciplinary Science and Technology (CSIR–NIIST) in Trivandrum, India, and received his PhD from the University of Kerala, India. Currently, he is a senior researcher in the SCARCE program at the Energy Research Institute @ NTU ([email protected]), Nanyang Technological University (NTU), Singapore. His current research centers on recycling spent lithium-ion batteries through biological, direct recycling techniques and waste-for-waste strategies. In addition, he is exploring the possibility of reutilizing recovered materials in novel applications of new electrochemical energy storage. Norazean Zaiden is a graduate of the Singapore Centre for Environmental Life Sciences Engineering (SCELSE, NTU, Singapore). Her interest in applied microbiology leads to biofilm matrix development for bioremediation and resource recovery applications through synthetic biology. In addition, she continues her journey in SCELSE as a research fellow under an industry collaboration studying anti-biofouling agents' effects on biofilms. Minh Phuong Do is a research fellow (materials science) with years-long experience in lithium/sodium ion batteries at Energy Research Institute at NTU, Singapore. She received her PhD from NTU in 2020, specializing in electrochemistry. Phuong uses this expertise in developing and optimizing a safe and stable battery system. Her current research focus is on the green closed-loop hydrometallurgical process for recycling spent lithium-ion batteries using biomass and regeneration of high-quality battery materials. Bin Cao is an associate professor in the School of Civil and Environmental Engineering and a principal investigator at the Singapore Centre for Environmental Life Sciences Engineering, NTU, Singapore. He received his PhD from the National University of Singapore and later worked as a postdoctoral research associate at Washington State University and Pacific Northwest National Laboratory. His research interest centers on biofilm-mediated microbial processes, with the goals of understanding environmental biofilm processes and applying the knowledge and insights to harness the power of beneficial biofilms and combat detrimental biofilms. Madhavi Srinivasan is a professor and executive director of the Energy Research Institute @ NTU ([email protected]) and NTU Sustainability office. Her research focuses on synthesis, fabrication, and application of nanoscale materials/architectures in improving the performance of electrochemical energy storage devices such as advanced lithium-ion batteries, supercapacitors, sodium ion batteries, multivalent aqueous Zn/Al batteries and recycling of e-waste. She is the co-director of SCARCE (Singapore-CEA alliance for research in circular economy), a joint lab, in collaboration with French Alternative energies and atomic energy commission (CEA, France), focusing on recycling of e-waste.

Design and experimental study on closed-loop process of preparing chitosan from crab shells.

The purpose of this article is to design a green and comprehensive utilization process for preparing chitosan from crab shells. Glutamate acid was used as a decalcifying agent for crab shells, and the mixed solution of potassium hydroxide/isopropanol was used for deproteinization and deacetylation to prepare chitosan. Glutamic acid and isopropanol could be recovered for recycling. At the same time, calcium carbonate and protein in crab shells were converted into calcium hydrogen phosphate and compound fertilizer containing nitrogen, phosphorus, and potassium, respectively. The prepared chitosan was characterized by Fourier-transform infrared (FT-IR), differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM), and its deacetylation degree and viscosity average molecular weight were 88.7%±0.68% and 792.1±10.82kDa, respectively. The recoveries of glutamic acid and isopropanol were 95.56%±1.39% and 88.14%±1.13%, respectively. The prepared chitosan has large molecular weight and deacetylation degree, controllable production cost, comprehensive utilization of crab shell components, and greatly reduced waste emissions.

Literature Review on Power Battery Echelon Reuse and Recycling from a Circular Economy Perspective.

Developing new energy vehicles (NEVs) is necessary to grow the low-carbon vehicle industry. Many concentrated end-of-life (EoL) power batteries will cause large-scale environmental pollution and safety accidents when the time comes to replace the first generation of batteries if improper recycling and disposal methods are utilized. Significant negative externalities will result for the environment and other economic entities. When recycling EoL power batteries, some countries need to solve problems about lower recycling rates, unclear division of echelon utilization scenarios, and incomplete recycling systems. Therefore, this paper first analyzes representative countries' power battery recycling policies and finds out the reasons for the low recycling rate in some countries. It is also found that echelon utilization is the critical link to EoL power battery recycling. Secondly, this paper summarizes the existing recycling models and systems to form a complete closed-loop recycling process from the two stages of consumer recycling and corporate disposal of batteries. The policies and recycling technologies are highly concerned with echelon utilization, but few studies focus on analyzing application scenarios of echelon utilization. Therefore, this paper combines cases to delineate the echelon utilization scenarios clearly. Based on this, the 4R EoL power battery recycling system is proposed, which improves the existing recycling system and can recycle EoL power batteries efficiently. Finally, this paper analyzes the existing policy problems and existing technical challenges. Based on the actual situation and future development trends, we propose development suggestions from the government, enterprises, and consumers to achieve the maximum reused of EoL power batteries.

Continuous versus discrete robotic feedback for brain-computer interfaces aimed for neurorehabilitation.

Brain-Computer Interfaces (BCI) can allow control of external devices using motor imagery (MI) decoded from electroencephalography (EEG). Although BCI have a wide range of applications including neurorehabilitation, the low spatial resolution of EEG, coupled to the variability of cortical activations during MI, make control of BCI based on EEG a challenging task. An assessment of BCI control with different feedback timing strategies was performed. Two different feedback timing strategies were compared, comprised by passive hand movement provided by a robotic hand orthosis. One of the timing strategies, the continuous, involved the partial movement of the robot immediately after the recognition of each time segment in which hand MI was performed. The other feedback, the discrete, was comprised by the entire movement of the robot after the processing of the complete MI period. Eighteen healthy participants performed two sessions of BCI training and testing, one with each feedback. Significantly higher BCI performance (65.4 ± 17.9% with the continuous and 62.1 ± 18.6% with the discrete feedback) and pronounced bilateral alpha and ipsilateral beta cortical activations were observed with the continuous feedback. It was hypothesized that these effects, although heterogenous across participants, were caused by the enhancement of attentional and closed-loop somatosensory processes. This is important, since a continuous feedback timing could increase the number of BCI users that can control a MI-based system or enhance cortical activations associated with neuroplasticity, important for neurorehabilitation applications.

How much can chemical recycling contribute to plastic waste recycling in Europe? An assessment using material flow analysis modeling

Plastic recycling rate in Europe is low, urging developments in recycling technology and strategies to increase circularity. Mechanical recycling (MR) has been the reference recycling technology for years, but in the near future chemical recycling (CR) options are expected to contribute to improve plastic circularity. This study uses a material flow analysis (MFA) at European level to provide quantitative estimates of the contribution of CR technologies to plastic recycling. Ten most used polymer types from five sectors are selected. A status quo 2018 scenario is modelled and compared to five potential future scenarios (in 2030) of plastic waste treatment, including one that only looks at improved waste collection, sorting, and MR technologies and four exploring developments of CR options. The so-called ‘missing plastics’, i.e., plastic waste generated but currently not accounted for in statistics, is considered in one of the future scenarios. The MFA results are compared by calculating four circularity indicators namely end-of-life recycling rate (EoL-RR), plastic-to-plastic rate, plastic-to-chemicals rate, and plastic-to-fuels rate. The results indicate that in the most optimistic scenario the EoL-RR in 2030 is 73–80% (sum of plastic-to-plastic and plastic-to-chemical rates, excluding plastic-to-fuel rate), in which 41–46% is plastic-to-plastic from MR, 15–38% is plastic-to-plastic from CR and 19–35% is plastic-to-chemicals. The highest achievable plastic-to-plastic rate is estimated to be 61% (46% from MR and 15% from CR). In all future scenarios, the plastic-to-fuel rate is estimated to be 3–6%. The MFA results are also used to estimate potential recycled content availability in 2030, which suggest that closed-loop recycling and processing the ‘missing plastics’ will be necessary to achieve the targets.

Amorphous Sugar Materials as Sustainable and Scalable Alternatives for Rigid, Short-Term-Use Products

Plastics are the prevailing materials for short-term-use applications, despite being designed to last far longer than often is needed or desired. This article describes a class of materials that are formed from small-molecule sugars, rather than polymers, as a scalable and environmentally friendly replacement for rigid thermoplastics for short-term-use applications. The materials use amorphous isomalt as a matrix and natural additives to tune the mechanical properties. Like plastics, this class of materials is lightweight and can be produced efficiently at low temperatures via injection molding, yet the materials emulate the rigidity and strength of ceramics and stones. Repeated recycling is achieved via a closed-loop process without degradation of the isomalt binder and without loss of mechanical properties. Finally, these materials are resistant to water for hours when coated, yet ultimately dissolve within minutes when broken, with the resulting products being nontoxic small-molecule and degradable bio-based materials. This combination of traits makes amorphous isomalt materials suitable as an alternative to persistent plastics in short-term-use applications.

Efficient leaching and recovery of metallic gold and copper from integrated circuits with the novel bromotrihalide ionic liquids based on the redox mechanism

In order to develop a safe, closed-loop and eco-friendly process for high efficiency leaching and recovery Au and Cu from integrated circuits (ICs), bromotrihalide ionic liquids (ILs) were synthesized as the perfect substitutes for corrosive or toxic leaching agents. Notably, bromotrihalide ILs showed excellent satisfied thermostability, low viscosity and low water solubility traits in green recovery of metallic Au and Cu. The leaching behavior was explored by studying experimental factors, including solid-to-liquid ratio, temperature and leaching methods. In addition, the corresponding kinetics models were established. It was noteworthy that the maximum Au leaching efficiency of 94.6% and that of Cu 100% were reached in the optimal conditions (20 g/L, 45 °C). It suggested that the leaching process of Au was co-controlled by chemical reaction and diffusion, with a corresponding activation energy of 37.4 kJ/mol. For revealing the redox leaching mechanism, XPS, UV–Vis, SEM, EDS-mapping and ICP spectrometry were conducted, and the leaching pathways of Au were triumphantly investigated via DFT-computed transition state energy barrier and ADCH charge. At last, Au nanoparticles and Cu(II) solution were obtained by selective stripping of Au and Cu. And the recovery efficiencies of Au and Cu were 94.6% and 100%. This work suggests a promising approach to recover the Au and Cu from ICs.