Regenerative Technologies Research Articles

Rapid in situ regeneration of phenol-saturated activated carbon fiber by an electro-permonosulfate-ozone process: Performance, operators and mechanism

In this study, a new method that encompasses electricity, permonosulfate (PMS), and ozone (E-PMS-O3) was proposed and applied in the regeneration of phenol-saturated activated carbon fiber (ACF). Compared with traditional regeneration technology, the E-PMS-O3 process simultaneously regenerated exhausted ACF in situ and mineralized the desorbed pollutants effectively (78.67%) with relatively low energy consumption (4.338 kWh m−3). Furthermore, the E-PMS-O3 regeneration process only required 2 h, which was shorter than other well-documented electro-advanced oxidation processes (EAOPs), such as the E-O3 process lasting for 3 h, the E-persulfate process for 6 h, and the E-Fenton process for 6 h. Possible pathways in the regeneration process include direct electron transfer, ozone oxidation, PMS oxidation, non-radical reactions, and reactive oxygen species (ROS) oxidations. Two main ROS — hydroxyl radical (O•H) and sulfate radical (SO4•−) were probed and their contribution ratio was approximately 1:1. An external electric field visibly enhanced the recovery adsorption capacity of ACF and accelerated the decomposition of PMS. Interestingly, additional experiments revealed that adding two different oxidants (PMS/O3) provided a better protection effect on the properties of ACF against oxidation of oxidants and ROS. It's important to mention that the maximum concentration of byproducts remained below 5 mg g−1, which effectively minimized the potential for subsequent pollution. In the end, multiple regeneration cycles demonstrated that the regeneration efficiency was nearly 60% even after 6 cycles. Hence, the E-PMS-O3 process was promising for further exploration and discussion when applied in regeneration of exhausted AC materials.

Laboratory investigation on the properties of warm mixing-recycled asphalt containing waste oil and plastics

ABSTRACT The integration of warm-mix and regeneration technologies is gaining momentum due to its dual advantages: enhancing the utilization of recycled asphalt and promoting environmental sustainability. In this study, these technologies by leveraging waste materials were synergized. Specifically, kitchen waste oil underwent chemical treatment to serve as a rejuvenator, while waste low-density polyethylene was transformed into pyrolysis wax, a beneficial additive for the asphalt mix. Utilizing these waste components, a sustainable warm mixing-recycled asphalt blend was formulated. This blend’s efficacy was meticulously evaluated through viscosity tests, rheological assessments, four-component analyses, and FT-IR evaluations. Optimal results emerged when incorporating 5% waste pyrolysis wax and 3.3% waste oil into warm recycled asphalt, notably improving viscosity reduction, high-temperature performance, rutting resistance, and fatigue life at 25 °C. Moreover, the four-component test shows the component of aged asphalt after adding the optimal combination is basically consistent with that of the neat asphalt. Importantly, FT-IR tests affirmed that pyrolysis wax bolstered the blend’s oxidation resistance. Through gray correlation analysis, we deduced that asphalt’s component changes are intricately linked with rheological property variations. Notably, the carbonyl index exhibited a pronounced negative correlation with rutting and fatigue life.

Comparative Analysis of Hyaline Cartilage Characteristics and Chondrocyte Potential for Articular Cartilage Repair.

This study aimed to compare the histological, biochemical, and mechanical characteristics of hyaline cartilage in different regions and evaluate the potential of chondrocytes extracted from each region as donor sources for articular cartilage repair. The cartilage tissues of the femoral head and knee joint, ribs, nasal septum, thyroid, and xiphoid process of adult Bama pigs were isolated for histological, biochemical, and mechanical evaluation and analysis. The corresponding chondrocytes were isolated and evaluated for proliferation and redifferentiation capacity, using biochemical and histological analysis and RT-PCR experiments. Compared with articular cartilage, non-articular hyaline cartilage matrix stained more intensely in Safranin-O staining. Glycosaminoglycan and total collagen content were similar among all groups, while the highest content was measured in nasal septal cartilage. Regarding biomechanics, non-articular cartilage is similar to articular cartilage, but the elastic modulus and hardness are significantly higher in the middle region of costal cartilage. The chondrocytes extracted from different regions had no significant difference in morphology. Hyaline cartilage-like pellets were formed in each group after redifferentiation. The RT-PCR results revealed similar expressions of cartilage-related genes across the groups, albeit with lower expression of Col2 in the xiphoid chondrocytes. Conversely, higher expression of Col10 was observed in the chondrocytes from the rib, thyroid, and xiphoid cartilage. This study provides valuable preclinical data for evaluating heterotopic hyaline cartilage and chondrocytes for articular cartilage regeneration. The findings contribute to the selection of chondrocyte origins and advance the clinical translation of technology for cartilage regeneration.

Enhancing high-content recycled asphalt pavement regeneration: A laboratory separation and treatment approach

The escalating costs of aggregates and stringent sustainable development policies have emphasized the significance of effective high-content recycled asphalt pavement (RAP) regeneration technology. This study aims to present a novel laboratory separation and treatment approach for RAP materials, ensuring optimal performance of high-content RAP recycled asphalt mixtures. The proposed method is compared against factory-separated RAP materials in terms of agglomeration evaluation and mixture performance comparison. High- and low-temperature performance of the recycled asphalt mixture were evaluated through wheel tracking and trabecular bending tests. Furthermore, the moisture sensitivity of the recycled mixture was studied through immersion Marshall and freeze-thaw splitting tests. The uniformity and fusion between aggregates and asphalt in the recycled asphalt mixtures were meticulously analyzed using advanced techniques such as Scanning Electron Microscope and industrial Computed Tomography scans. The laboratory separation method encompasses flexible separation for 5–10 mm RAP materials and rigid separation for 10–20 mm RAP materials. Notably, the laboratory separation methods proved more effective in removing aged asphalt from the surface of 10–20 mm RAP materials compared to factory separation, thereby enhancing the adhesion between aggregates and asphalt and ensuring a more uniform recycled mixture. Although the dynamic stability of recycled asphalt mixture was reduced using laboratory separation, it still meets the requirements of relevant specifications. Moreover, the low-temperature maximum flexural tensile strain of the recycled asphalt mixture increased by 16%, with the residual stability and tensile strength ratio rising by 1.33% and 2.69%, respectively. Compared with the factory separation method, the laboratory separation method reduces the porosity percentage of the recycled asphalt mixture cross-section by 3.47%. Overall, the laboratory separation method for RAP materials provides valuable insights for enhancing the factory processing of RAP materials, contributing to the successful application of high RAP content regeneration technology in the pursuit of sustainable and cost-effective road construction practices.

Injectable hydrogels for bone regeneration with tunable degradability via peptide chirality modification.

The degradability of hydrogels plays a pivotal role in bone regeneration, yet its precise effects on the bone repair process remain poorly understood. Traditional studies have been limited by the use of hydrogels with insufficient variation in degradation properties for thorough comparative analysis. Addressing this gap, our study introduces the development of matrix metalloproteinase (MMP)-responsive hydrogels engineered with a tunable degradation rate, specifically designed for bone regeneration applications. These innovative hydrogels are synthesized by integrating MMP-sensitive peptides, which exhibit chirality-transferred amino acids, with norbornene (NB)-modified 8-arm polyethylene glycol (PEG) macromers to form the hydrogel network. The degradation behavior of these hydrogels is manipulated through the chirality of the incorporated peptides, resulting in the classification into L, LD, and D hydrogels. Remarkably, the L hydrogel variant shows a significantly enhanced degradation rate, both in vitro and in vivo, which in turn fosters bone regeneration by promoting cell migration and upregulating osteogenic gene expression. This research highlights the fundamental role of hydrogel degradability in bone repair and lays the groundwork for the advancement of degradable hydrogel technologies for bone regeneration, offering new insights and potential for future biomaterials development.

A novel functionally graded bilayer membrane with excellent barrier function and in vivo osteogenesis promotion for guided bone regeneration.

Guided bone regeneration (GBR) technology has been widely used as a reliable method to address alveolar bone defects. To improve the clinical effects of GBR approach, there have been attempts to develop barrier membranes with enhanced regenerative properties. However, modifying the material and structure of GBR membranes to integrate physicochemical properties and biological activity remains challenging. The aim of this study was to develop a novel functionally graded bilayer membrane (FGBM) with a gradient structure and composition, and to evaluate its osteogenesis promotion effect for GBR. By combining the phase inversion method and electrospinning method, functionally graded bilayer membranes (FGBM) with gradient structure and composition of poly(lactic-co-glycolic acid) (PLGA), nano-hydroxyapatite (nHA), and gelatin were fabricated in this study. The physicochemical and biological properties of the prepared FGBM, including structural and morphological characterization, mechanical properties, in vitro biodegradation, cell behaviors, and in vivo osteogenic bioactivity, were comprehensively evaluated. The findings demonstrated the successful fabrication of PLGA/nHA/gelatin FGBM with an asymmetric structure, exhibiting enhanced hydrophilic, mechanical, and degradation properties. The incorporation of gelatin not only improved the biological integration, but also enhanced the binding affinity between electrospun fiber layer and phase inversion layer. The FGBM with a 30% nHA mass fraction and a PLGA/gelatin mass ratio of 1:1 exhibited excellent barrier function and osteogenic bioactivities in vitro and in vivo. This work demonstrated the potential of PLGA/nHA/gelatin FGBM in bone regeneration and provided valuable insight for the development of barrier membrane.

Fundamentals of the recycling of spent lithium-ion batteries.

This review discusses the critical role of fundamentals of battery recycling in addressing the challenges posed by the increasing number of spent lithium-ion batteries (LIBs) due to the widespread use of electric vehicles and portable electronics, by providing the theoretical basis and technical support for recycling spent LIBs, including battery classification, ultrasonic flaw detection, pretreatment (e.g., discharging, mechanical crushing, and physical separation), electrolyte recovery, direct regeneration, and theoretical calculations and simulations. Physical chemistry principles are essential for achieving effective separation of different components through methods like screening, magnetic separation, and flotation. Electrolyte recovery involves separation and purification of electrolytes through advanced physical and chemical techniques. Direct regeneration technology restores the structure of electrode materials at the microscopic scale, requiring precise control of the physical state and crystal structure of the material. Physical processes such as phase changes, solubility, and diffusion are fundamental to techniques like solid-state sintering, eutectic-salt treatment, and hydrothermal methods. Theoretical calculations and simulations help predict the behaviour of materials during recycling, guiding process optimization. This review provides insights into understanding and improving the recycling process, emphasizing the central role of physical chemistry principles in addressing environmental and energy issues. It is valuable for promoting innovation in spent LIB recycling processes and is expected to stimulate interest among researchers and manufacturers.

Experimental results of the improved cotton regenerator under production conditions

The research article focuses on the application of an enhanced cotton regenerator in the Independence cotton cleaning technology within the TST AGRO cluster, presenting compelling results. The study assessed various key parameters related to cotton fiber quality to compare the performance of the improved cotton regenerator with the existing technology. Several crucial quality indicators were examined during the research, including the length uniformity index of cotton fiber (Unf), relative breaking strength (Str), the number of impurities in cotton fiber (Cnt), the amount of short fibers (SFI), and contamination with non-fibrous impurities. Additionally, changes in the color index (T) and quality aspects such as the degree of yellowness (+b) of the fiber were thoroughly investigated. The research findings revealed that the quality indicators of cotton fiber produced using the improved cotton regenerator surpassed those achieved with the existing regenerator technology. This suggests that the enhancements made to the regenerator positively influenced critical aspects of cotton fiber quality, including fiber length uniformity, breaking strength, impurity levels, and overall cleanliness. Moreover, the study examined color-related parameters, indicating that the improved regenerator contributed to maintaining or enhancing the fiber's color quality. The results of this research signify the potential benefits of implementing the improved cotton regenerator in the Independence cotton cleaning technology. This advancement has the capacity to positively impact the textile industry by delivering cotton fibers with superior qualities, thereby contributing to the overall improvement of cotton processing and manufacturing processes within the TST AGRO cluster.

Unraveling the mystery: Extraction and component analysis of irrecoverable foulants of end-of-life membrane from large-scale MBR

Membrane bioreactors (MBRs) are increasingly employed in municipal wastewater treatment, with membranes inevitably reaching their end-of-life (EOL) primarily due to the accumulation of irrecoverable fouling. Nevertheless, the composition and properties of irrecoverable fouling remain ambiguous due to the lack of appropriate extraction and analytical methods. Herein, we developed a temperature-regulated organic solvent extraction method to extract and analyze irrecoverable foulants in EOL ultrafiltration membranes at various locations within a large-scale MBR for municipal wastewater treatment. The irrecoverable foulants encompassed a high molecular weight fraction not observed in the influent, potentially induced by aggregation from organic-inorganic foulant interaction. The terrestrial humic acid (HA)-like substance dominated the organic components of irrecoverable foulants, and the chelating cation Ca emerged as a dominant inorganic compound. Unexpectedly, we noticed the enrichment of Al, Fe, and Si in the irrecoverable fouling, despite their relatively low rejections by the EOL membrane. The potential complex interactions among HA-like substances, Ca, Al, Fe, and Si were revealed by correlation and cluster analysis. The strong bridging potentials of [Al(OH)4]-, Fe(OH)3 at neutral pH, coupled with the colloidal property of Si, may facilitate the aggregation of organic and inorganic compounds, forming complex irrecoverable foulants with strong affinity for the membrane matrix. Besides, the irrecoverable fouling exhibited an increasing trend along the water flow direction. The mystery of irrecoverable fouling of EOL membrane was, for the first time, systematically unraveled, establishing a foundation for the development of effective membrane cleaning and regeneration technology.

Evaluation of Stability of Performance of Electrochemically Exfoliated Graphene for Electrochemical Double-Layer Capacitors

Energy storage devices are known as supercapacitors. One highlighted characteristic of them is high specific power and cycling long-life. These properties are associated with charging and discharging in short periods of time, especially useful for high demanding systems, such as regenerative technologies, strong acceleration in mobility and radical maneuvers in aeronautics. So, market demands for supercapacitors have been growing fastly. The performance improvement and cost reduction of supercapacitors are essential for the popularization of electromobility all over the world. For this aim, graphene and carbon nanotubes, among others, are materials widely used to such proposes due to their high specific surface area and excellent pseudocapacitive and electrochemical double layer properties. In this work, the use of graphene oxide obtained by electrochemical exfoliation and polyvinylpyrrolidone as active mass of supercapacitor electrodes was studied. The electrodes were prepared using the dip coating technique. To characterize the samples obtained, cyclic voltammetry (CV) and galvanostatic charge and discharge (GCD) were carried out in a 3-electrode cell with a 1 M sulfuric acid solution. CV was used to define the potential window, estimate capacitive profile and observe possible faradic phenomena. After that, GCD was used to study the material’s stability during 1000 operation cycles, at three specific current densities: 1.0; 1.5; and 2.0 A g-1. The voltammograms obtained are shown in Figure 1. It was possible to observe a symmetrical voltammogram with discrete quasi-reversible faradic phenomena (pseudocapacitive effects) defined by the cathodic peak at 0.48 V and anodic peak at 0.22 V. These peaks may be related to the redox reactions of graphene oxide. GCD was carried out to evaluate coulombic efficiency and charge retention such as shown in Figure 2. There was no great damage during the cycles; there was a slight positive change (increase) during 1000 cycles for all current densities. Furthermore, an increase in charge retention was observed for all current densities, this effect can be related to elongation of the polymeric chain due to electrostatic interaction of the binder in acidic media, leading to a higher effect of double-layer. For the 1 A g-1 current density, the increase of charge retention and coulombic efficiency were more relevant. These increases may be associated with gradual and discrete pseudocapacitive processes also observed in cyclic voltammetry measurements. The determined values of capacitance, energy and power densities are shown in Table 1. The values obtained at 1 A g-1 specific current density showed a higher coulombic efficiency and a significant increase in charge retention, despite having presented a lower power density. to this material, it is possible to assert to be a working condition better than others. At specific current densities of 1.5 A g-1 and 2 A g-1 higher values of energy and power density were determined, but lower coulombic efficiency. Figure 1

Electrochemical dissolution of MCrAlY coatings and oxide layers on Ni-based superalloys in 3.5% NaCl and aqua-regia solutions

Superalloys are widely used for aerospace industry. At the same time, more and more superalloy scraps are produced. Therefore, the recycling and reuse of superalloy scraps is of great significance. Purification smelting after surface impurity removal is an application trend of superalloy regeneration technology. Electrochemical methods can be used to remove metal impurities such as oxide layers and coatings. The electrochemical dissolution behavior of a Ni-based superalloy with coating and oxide layer has been studied in 3.5 wt% NaCl solution and aqua regia solution. The results show that pitting corrosion occurs on the surface of the alloy in 3.5 wt% NaCl solution, forming a "occlude corrosion cell" and leaving a lot of pitting corrosion. The oxide layer itself is a passivation film with high stability in 3.5 wt% NaCl solution. However, in aqua regia solution, the alloy underwent strong corrosion, and the surface coating and oxide layer of the alloy fell off in large quantities. The results show that the oxide layer like a “coating” with high corrosion resistance, which prevents the reaction between the alloy and the electrolyte. However, due to the poor density of the oxide layer, the electrolyte flows into the alloy matrix along the oxide layer gap, and electrochemical reaction occurs with the matrix. In aqua regia electrolyte, the oxide layer is thus peeled off. In this study, the dissolution behavior of the coating and the oxide layer in different electrolyte solutions was clarified, and the dissolution model of the coating on the alloy surface and the spalling mechanism of the oxide layer were established.

Methodology of Examination of Patients with Osteoarthritis and Aseptic Necrosis of Hip and Knee Joints when Using Regenerative Interventional Technologies

Background. Diagnosis of osteoarthritis of the hip and knee joints, as of today, would seem to be a well-studied issue. Radiography, magnetic resonance imaging, ultrasonography - each of these methods makes it possible to make a diagnosis. At the same time, the use of new methods of treatment of osteoarthritis requires new approaches to its diagnosis.
 Objective: to develop a methodology for examining patients with osteoarthritis and aseptic necrosis of the hip and knee joints during treatment with regenerative technologies.
 Material and Methods. The material for the study was case histories of 233 patients with osteoarthritis and 58 patients with osteoarthritis of the hip and knee joints. Clinical, laboratory, and instrumental research methods were used.
 Results. The methodology of clinical examination of patients when using regenerative technologies is based on filling out quality of life questionnaires. A feature of the methodology of laboratory examination of patients with osteoarthritis and aseptic necrosis of the hip and knee joints when using regenerative technologies is oncological screening in the case of the use of biotechnological products containing MSCs, with the determination of epigenetic markers of the risk of oncogenesis in the form of miRNA.
 Conclusions. The methodology of the instrumental examination of patients with osteoarthritis is as follows: the key is an X-ray examination with the establishment of the stage of osteoarthritis according to the Kellgren-Lawrence classification and the subsequent ultrasound and MRI examination in order to assess the extent of damage to the soft tissues of the hip and knee joints, subchondral bone and paraarticular structures. In patients with aseptic necrosis of the hip and knee joints, when using regenerative technologies, the key is an MRI study followed by X-ray and ultrasound examination.

Current strategies for regenerative therapy of spinal cord injury

Spinal cord injury (SCI) is a leading cause of death and severe disability amongst young people. The incidence of SCI is 0.6–1.0 per 10,000 individuals. Unfortunately, there are no effective methods of restoring locomotor function for individuals with severe SCI. To address this issue, exoskeleton technology controlled using BCI is actively being developed for prosthetic locomotion. Despite the lack of encouraging data for severe spinal cord injuries, regenerative technologies continue to hold promise for spinal cord repair. The limited options for regenerating the central nervous system in humans necessitate creating new sources of neural stem cells for regeneration. Reprogramming autologous somatic cells neurologically can effectively serve as such a source [1]. Nevertheless, the constitution of neuroglial progenitors, which are necessary for regenerating damaged axons of the pyramidal tract, still requires clarification [2]. Some interesting efforts are underway to directly reprogram glial cells in situ using a variety of biotechnological approaches [3]. Overcoming or preventing the formation of a harsh scar tissue at the injury site is the key obstacle to successful regeneration therapy for SCI. Various scaffolds are being developed to facilitate axon regeneration, and several gene therapy agents are being tested to either knock down scar formation factors or activate extracellular matrix remodeling and reparative regeneration. Neuromodulation shows promise for SCI treatment. Studies indicate that epidural stimulation of the L2-S1 spinal cord in humans and mammals activates SPG neurons, aiding spinal walking generator functions. A potentially successful treatment approach involves scaffolds with reprogrammed cells and neuromodulation [4].

Direct regeneration of spent lithium-ion batteries: A mini-review

Recycling spent lithium-ion batteries (LIB) has emerged as a pressing necessity for addressing resource shortages and mitigating environmental pollution. This article reviews the most advanced spent LIBs recycling technology, namely direct regeneration. Traditional recycling methods have problems with high energy consumption and secondary pollution. In contrast, direct regeneration extends battery life by repairing degraded cathode materials and retains battery energy to the maximum extent. This method includes technologies such as chemical lithiation and recycling of waste graphite. These innovative technologies improve battery cycle life, reduce energy consumption, production costs, and promote sustainable resource management. Direct regeneration technology provides new opportunities to reduce resource waste and reduce environmental pollution. It will promote the sustainable management of spent LIBs and support the development of future renewable energy technologies.

Design of Single-Atom Catalysts for E lectrocatalytic Nitrogen Fixation.

The Electrochemical nitrogen reduction reaction (ENRR) can be used to solve environmental problems as well as energy shortage. However, ENRR still faces the problems of low NH3 yield and low selectivity. The NH3 yield and selectivity in ENRR are affected by multiple factors such as electrolytic cells, electrolytes, and catalysts, etc. Among these catalysts are at the core of ENRR research. Single-atom catalysts (SACs) with intrinsic activity have become an emerging technology for numerous energy regeneration, including ENRR. In particular, regulating the microenvironment of SACs (hydrogen evolution reaction inhibition, carrier engineering, metal-carrier interaction, etc.) can break through the limitation of intrinsic activity of SACs. Therefore, this Review first introduces the basic principles of NRR and outlines the key factors affecting ENRR. Then a comprehensive summary is given of the progress of SACs (precious metals, non-precious metals, non-metallic) and diatomic catalysts (DACs) in ENRR. The impact of SACs microenvironmental regulation on ENRR is highlighted. Finally, further research directions for SACs in ENRR are discussed.

Nanofibers: An Effective Biomedical Tool for Burn Management

Abstract: The largest organ in the body and the organ that interacts most directly with the environment is the skin. As a result, the skin is susceptible to numerous injuries, including burns. Cell types, cytokines, mediators, the neurovascular system, and matrix remodelling work in concert to heal skin wounds. Through re-epidermalization, interactions between epidermal and stromal cells, angiogenesis, and habitation of hypertrophic scars and keloids, tissue regeneration technology significantly improves skin restoration. With the use of several skin substitutes, skin healing success rates for burn injuries have dramatically increased. For the reconstruction of skin tissue, we examine the use of cells, growth factors, scaffolds, or scaffolds seeded with cells in this review. We also compare the high efficacy and affordability of each therapy. We outline the key components, successes, and difficulties of cell-based therapy for minimising scar formation and enhancing the management of burn injuries.

Study on low temperature crack resistance of warm-mixed recycled SBS modified asphalt mixtures

In view of the cold winter in northern China and the large temperature difference between day and night, the asphalt pavement has been in low temperature service for a long time, in addition to experiencing the aging effect of water and salt erosion, jointly leading to a particularly serious pavement cracking phenomenon. Therefore, a quantity of Reclaimed Asphalt Pavement (RAP) is produced for the repair and renovation of old roads. Faced with the problems of inadequate reuse rate of RAP and high energy consumption of thermal regeneration, it is of great practical significance to explore the technology of warm mix regeneration. In order to study the adaptability of recycled SBS modified asphalt mixtures to low temperature after complex environmental erosion (long-term aging, water freeze-thaw cycle, and salt freeze-thaw cycle), two mixing methods, including hot mixing and warm mixing, were selected, and a Semi-Circular Bending Test was performed. SCB and Digital Image Correlation (DIC) techniques were used to evaluate the low temperature properties of recycled asphalt mixtures by fracture toughness, fracture energy and horizontal strain density damage. Combined with an Atomic Force Microscope (AFM) test, the microscopic analysis of recycled asphalt was carried out to verify the mechanism of low temperature cracking. The results showed that the low temperature cracking resistance of the reclaimed asphalt mixtures with warm mix was slightly worse than that with hot mix. The overall low temperature cracking resistance of the reclaimed SBS modified asphalt mixtures decreased with the increase in RAP content. The low temperature performance of the warm-mixed reclaimed asphalt mixtures deteriorated greatly when the RAP content was 80 %. The influencing factors of environmental conditions on the low temperature cracking resistance of the warm-mixed recycled SBS modified asphalt mixtures were listed as below: long-term aging > salt freeze-thaw cycle > water freeze-thaw cycle. The influence of salt on the stress field of crack tip and the microstructure of recycled asphalt after freeze-thaw was greater than that of water erosion. The changes of the microscopic adhesion were in good agreement with the macroscopic test results, which could be employed as the index evaluating the low temperature crack resistance of the warm-mixed SBS modified asphalt mixtures. The addition of warm mixing agent would play a positive role in the low temperature crack resistance of recycled asphalt mixtures with a RAP content of less than 60 % to a certain extent, so warm-mixed recycled asphalt mixtures were more suitable for the application in northern areas.

Direct recovery of degraded LiFePO4 cathode via mild chemical relithiation strategy

With the rapid popularization of LiFePO4 (LFP) based lithium-ion batteries, the rational recycle of spent LFP has become focus in recent years. Direct regeneration of spent LFP has received continuous attention as it can effectively eliminate the capacity attenuation caused by lithium loss and Fe (Ⅲ) phase and maintain the original LFP structure. Here, we propose an efficient approach on basis of mild chemical relithiation combining with appropriate thermal annealing to realize the direct regeneration of spent LFP without high temperature/pressure or extra hazardous chemical. Specifically, subtle reductive hydrogen peroxide in LiOH solution is utilized to remove the structural defects of a degraded LFP cathode, and the restored LFP shows excellent cycling stability and rate capability (a capacity retention of 84.9% after 1000 cycles at 5C). Moderate regeneration conditions guarantee high security and profit of this strategy compared with other regeneration technologies, which reveals a favourable potential of practical application and is expected to the sustainable development of spent lithium-ion batteries.

Peroxymonosulfate activation with CuOX/MnFe2O4 for the regeneration of granular activated carbon after adsorption of organic pollutants

Adsorption is a cost-effective technology for the removal of refractory organic pollutants, and the regeneration of the spent adsorbent is crucial in terms of environmental and economic aspects. Herein, CuOX/MnFe2O4 was synthesized by a two-step precipitation method and investigated as a peroxymonosulfate (PMS) catalyst for the regeneration of granular activated carbon (GAC) saturated with ofloxacin. The influences of reaction conditions on the regeneration of GAC with CuOX/MnFe2O4-PMS and the possible mechanism were explored. The results showed that CuOX/MnFe2O4 exhibited high catalytic activity for the regeneration of GAC via the high mineralization of the adsorbed ofloxacin. Singlet oxygen was the dominant reactive species for organics removal, while O2•− and SO4•− also made a contribution to the degradation of organic intermediates. Under the optimized conditions, the regeneration efficiency of the spent GAC reached 98%, 89%, 87% and 85% for ofloxacin, ciprofloxacin, Orange II and methylene blue, respectively. Moreover, CuOX/MnFe2O4 and GAC exhibited high stability and good reusability in this process, suggesting the potential application of this regeneration technology for removing refractory organic pollutants.

Direct regeneration of cathode materials in spent lithium-ion batteries toward closed-loop recycling and sustainability

The transformation of energy structure is deemed as a paramount strategy in accomplishing the ambition of carbon neutrality. Lithium-ion batteries (LIBs), as one of the most exceptional energy storage and conversion devices available, play a pivotal role in this energy revolution. However, due to the extensive production and limited lifespan of LIBs, the retirements of LIBs are set to boom in the coming years. The proper and timely recycling of these batteries are of paramount importance, from both environmental and economic perspectives. Direct cathode regeneration technology is the most promising solution for the treatment of these waste cathodes, as it enables the healing of spent cathodes with minimal energy and chemical consumption, without compromising the original structure of the cathode. Herein, we analyzed the degraded mechanisms of spent LIBs and found that relithiation and defect reparation are crucial steps for the regeneration of spent cathode materials. Various direct regeneration methods previously reported have been summarized, and their respective advantages and limitations as well as technical challenges when implemented into practical industrial applications are discussed. In addition, possible solutions to these problems are proposed, which guide the future direction for the sustainable development of the battery recycling industry.