Development of sustainable and efficient recycling technology for spent Li-ion batteries: Traditional and transformation go hand in hand

Clean and efficient recycling of spent lithium-ion batteries(LIBs)has become an urgent need to promote sustainable and rapid development of human society.Therefore,we provide a critical and comprehensive overview of the various technologies for recycling spent LIBs,starting with lithium-ion power batteries.Recent research on raw material collection,metallurgical recovery,separation and purification is highlighted,particularly in terms of all aspects of economic efficiency,energy consumption,technology transformation and policy management.Mechanisms and pathways for transformative full-component recovery of spent LIBs are explored,revealing a clean and efficient closed-loop recovery mechanism.Optimization methods are proposed for future recycling technologies,with a focus on how future research directions can be industrialized.Ultimately,based on life-cycle assessment,the challenges of future recycling are revealed from the LIBs supply chain and stability of the supply chain of the new energy battery industry to provide an outlook on clean and efficient short process recycling technologies.This work is designed to support the sustainable development of the new energy power industry,to help meet the needs of global decarbonization strategies and to respond to the major needs of industrialized recycling.

Effects of electrolyte recycling on desulfurization from bauxite water slurry electrolysis

To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.

Closed-loop cobalt recycling from spent lithium-ion batteries based on a deep eutectic solvent (DES) with easy solvent recovery

Efficient recycling technology for the rapid growth of spent lithium-ion batteries(LIBs)is essential to tackle the resources and environmental crisis.Hydrometallurgical approach has attracted extensive research due to its potential to reduce the consumption of energy and threat to the environment.However,the simultaneous realization of green,efficient and closed-loop recycling is still challenging.Herein,we report a closed-loop and highly efficient approach to recycle lithium cobalt oxide from spent LIBs based on a choline chloride:oxalic acid(ChCl:OA)type deep eutectic solvent(DES).An ultrafast leaching process is observed at 180°C for 10 s with no observable residues.The energy barrier during leaching is calculated to be 113.9 kJ/mol.Noteworthy,the solubility of cobalt ions can be reversibly tuned by simply adding/evaporating deionized water,thus avoiding the addition of precipitant and enabling the easy recovery of the leaching solvent for realizing a closed-loop recycling process.The simultaneous realization of high efficiency,green and closed-loop process is expected to push the DES into practical application for recycling the electrodes of LIBs.

Bond Behavior between BFRP Bars and Hybrid Fiber Recycled Aggregate Concrete after High Temperature

The aim of this study is to improve the bond performance of basalt fiber reinforced polymer(BFRP)bars and recycled aggregate concrete(RAC)after being exposed to high temperatures.The bond behavior(failure modes,bond strength,bond stress-slip curves)between BFRP bars and hybrid fiber recycled aggregate concrete(HFRAC)after being exposed to temperatures ranging from 20℃up to 500℃was studied by using pull-out tests.The effect of high temperatures on mechanical properties of concrete(compressive strength,splitting tensile strength)and tensile strength of BFRP bars was also investigated.The bond strength decreased as the temperature increased and the drop of bond strength between RAC and BFRP bar was larger than that between HFRAC and BFRP bar.As the temperature rises,the key factor affecting the bond strength was gradually transformed from concrete strength to BFRP bar strength.The relationship between bond stress and slip in the dimensionless bond stress-slip ascending section was established,which was in good agreement with the experimental results.

A Simple Mix Proportion Design Method Based on Frost Durability for Recycled High Performance Concrete Using Fully Coarse Recycled Aggregate

Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.

The Development of Recycling Agent for Asphalt Pavement

A type of recycling agent was developed and its use for modifying used asphalt is described.The results show that the viscosity and three main properties of the aged asphalt were remarkably improved.With 5% - 7% content of recycling agent, the main properties of recycled asphalt comported with China GB asphalt standard AH-70 and the recycled asphalt concrete could be used as high grade highway.Furthermore,the recycling mechanism of the aged asphalt is discussed.

Experimental Study on Compressive Strength of Recycled Aggregate Concrete under High Temperatur

This research aims to study the effect of elevated temperature on the compressive strength evolution of concrete made with recycled aggregate.Demolished building concrete samples were collected from four different sites in Saudi Arabia,namely from Tabuk,Madina,Yanbu,and Riyadh.These concretes were crushed and recycled into aggregates to be used to make new concrete samples.These samples were tested for axial compressive strength at ages 3,7,14,and 28 days at ambient temperature.Samples of the same concrete mixes were subjected to the elevated temperature of 300°C and tested for compressive strength again.The experimental result reveals that the recycled aggregate concrete samples have good quality at ambient and elevated temperatures and are considered fairly close to the concrete made with natural aggregate.However,recycled aggregate concrete at high temperatures showed higher strength degradation than natural aggregate concrete,but with differences that do not exceed 5%to 10%.The concrete samples made from recycled coarse aggregates also reached the design strength.It can be considered acceptable,considering the high variation in the concrete’s thermal response found in the literature.

Recycling valuable cobalt from spent lithium ion batteries for controllably designing a novel sea-urchin-like cobalt nitride-graphene hybrid catalyst: Towards efficient overall water splitting

Along with the continuous consumption in lithium-ion batteries (LIBs), the price of cobalt is inevitably going up in recent years. Therefore, recycling valuable Co element from spent devices, and boosting its service efficiency are becoming two indispensable approaches to promote the utilization of Co in various energy conversion/storage devices. Herein, we realize the recovery of Co from spent LIBs and synthesize a three–dimensional (3D) sea-urchin-like cobalt nitride composite material (labeled as CoN-Gr-2), which is used as a bi-functional catalyst for water splitting. Benefiting from the intrinsic high conductivity, larger surface area and unique 3D sea–urchin–like architecture, CoN-Gr-2 shows an excellent electron transfer efficiency, highly exposed active sites as well as the superior mass transport capacity. The CoN-Gr-2 catalyst exhibits low overpotentials of 128.9 mV and 280 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are comparable to the commercial 20 wt% Pt/C and RuO_(2) catalysts. Moreover, when adopting CoN-Gr-2 as both anode and cathode materials for overall water splitting (in 1.0 M KOH electrolyte), the assembled cell achieves a current density of 10 mA cm^(−2) at 1.61 V, which almost close to that of Pt/C||RuO_(2) benchmark (1.60 V), demonstrating its superior water-splitting efficiency. Meanwhile, the CoN catalysts exhibit strong chemical interaction with the Gr support, suppressing the aggregation of CoN catalysts and maintains their high activity during HER and OER reactions. So, the cell exhibits a high current retention of 97.3% after 40 h. This work successfully develops an industrial chain from recycling Co wastes in spent energy devices to controllably designing 3D sea-urchin-like CoN-Gr with high water splitting efficiency. Therefore, it could further promote the efficient utilization of valuable Co element in various energy devices.

Analytical Case Study on a Dedicated Pigment in Recycling Processes of Polyethylene

The ability to track & trace materials is a key feature in the entire chain, and it ensures circularity principles. Examples from plastic recycling show the enormous added value that analytical technology can have for the circular economy. During polymer production and recycling processes, pigments can be added for different purposes;e.g. as colouring agent of the polymeric product but also as tracer for tracking process development and control in the final recycle products versus possible by-products. An analytical method for tracking the pigment Solvent Blue 15 in input materials, in intermediates as well as in recyclates was developed by tracing and quantifying an indicator metal which is copper (Cu). Therefore, suitable digestion procedures and a quantification method by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) were developed and used for measuring the polymeric digests. The method was tested on relevant samples from chemical recycling processes. The background concentrations in base/raw material are in the range of 0.05 - 0.1 mg·kg-1 Cu. The processing concentrations are in the range of 4.2 to 28 mg·kg-1 Cu, while the pigment starting material (polyethylene, PE) has a concentration of around 50 mg·kg-1 Cu.

Catalytic recycling of plastics into value-added products

The overuse and ineffective management of plastics have led to significant environmental pollution. Catalytic upcycling into value-added chemicals has emerged as a promising solution. This review provides a comprehensive overview of recent advances in catalytic upcycling, focusing on the cleavage of chemical bonds such as carbon-carbon (C-C), carbon-oxygen (C-O), and carbon-hydrogen (C-H) in plastics. It systematically discusses plastics conversion via electrocatalysis, thermal catalysis, and photocatalysis. Additionally, it explores the conversion of plastics into value-added chemicals and functional polymers. The review also addresses the challenges in this field and aims to offer insights for developing sustainable and effective plastics upcycling technologies.

Developing Sustainable High Strength Concrete Mixtures Using Local Materials and Recycled Concrete

This study presents the development of high strength concrete (HSC) that has been made more sustainable by using both local materials from central Texas and recycled concrete aggregate (RCA), which has also been obtained locally. The developed mixtures were proportioned with local constituents to increase the sustainable impact of the material by reducing emissions due to shipping as well as to make HSC more affordable to a wider variety of applications. The specific constituents were: limestone, dolomite, manufactured sand (limestone), locally available Type I/II cement, silica fume, and recycled concrete aggregate, which was obtained from a local recycler which obtains their product from local demolition. Multiple variables were investigated, such as the aggregate type and size, concrete age (7, 14, and 28-days), the curing regimen, and the water-to-cement ratio (w/c) to optimize a HSC mixture that used local materials. This systematic development revealed that heat curing the specimens in a water bath at 50℃ (122oF) after demolding and then dry curing at 200℃ (392oF) two days before testing with a w/c of 0.28 at 28-days produced the highest compressive strengths. Once an optimum HSC mixture was identified a partial replacement of the coarse aggregate with RCA was completed at 10%, 20%, and 30%. The results showed a loss in compressive strength with an increase in RCA replacement percentages, with the highest strength being approximately 93.0 MPa (13,484 psi) at 28-days for the 10% RCA replacement. The lowest strength obtained from an RCA-HSC mixture was approximately 72.9 (MPa) (10,576 psi) at 7-days. The compressive strengths obtained from the HSC mixtures containing RCA developed in this study are comparable to HSC strengths presented in the literature. Developing this innovative material with local materials and RCA ultimately produces a novel sustainable construction material, reduces the costs, and produces mechanical performance similar to prepackaged, commercially, available construction building materials.

COMPARISON OF RECYCLED GLASS AND RECYCLED CONCRETE AGGREGATES BEARING MORTAR MIXTURES EXPOSED TO HIGH TEMPERATURE,ABRASION AND DRYING

In this study,the effects of recycled glass(RG)and recycled concrete(RC)fine aggregates on the drying-shrinkage,carbonation,high temperature and abrasion resistance of mortar mixtures were investigated comparatively.In addition,durability performance of the mortar mixtures was investigated through micro-structural analysis.For this purpose,9 different mortar mixtures were prepared by replacing 25,50,75 and 100 wt.%of crushed-limestone fine aggregate with recycled glass and recycled concrete aggregates.Except for the abrasion resistance,the RG mixtures showed better durability performance than the control mixture.However,the RC mixtures containing more than 50%recycled aggregate showed lower performance than the control mixture.

Progress in Recycling of Composites with Polycyanurate Matrix

Thermoset based composites are used increasingly in industry for light weight applications, mainly for aircraft, windmills and for automobiles. Fiber reinforced thermoset polymers show a number of advantages over conventional materials, like metals, especially their better performance regarding their strength-to-weight ratio. However, composite recycling is a big issue, as there are almost no established recycling methods. The authors investigate the recyclability of polycyanurate homo- and copolymers with different recycling agents under different conditions. Also the influence of the recycling process on the most important reinforcement fibers, i.e. carbon-, glass-, aramid-, and natural-fiber is investigated. The authors find that: the recycling speed is not only dependent on the temperature, but also is significantly influenced by the particular recycling agents and the polycyanurate formulation. Hence, the stability against the recycling media can be adjusted over a broad range by adjusting the polymer composition. Furthermore, the authors find that the inorganic reinforcement fibers (carbon and glass) are almost unaffected by neither recycling agent at either temperature. Aramid-fibers degrade, depending on the particular recycling agent, from slightly up to extremely strong. This leaves one with the possibility to find a combination of matrix resin and recycling agent, which does not affect the aramid-fiber significantly. In the case of natural fibers, the dependence on the particular recycling media is very strong: some media do not affect the fiber significantly;others reduce the mechanical properties (tensile strength and elongation at break) significantly, and still others even improve both mechanical properties strongly. From the Recyclate, the authors synthesize and subsequently characterize a number of new polyurethane thermosets (foamed and solid samples) with different contents of recyclate, exhibiting Tg in the range of 60°C to 128°C.

High-Pressure Melting Experiments on Basalt-Peridotite Layered Source (KLB-1/N-MORB): Implications for Magma Genesis in Hawaii

In order to understand the melting processes that occur within recycled oceanic crust and mantle in a heterogeneous plume (e.g., that beneath the Hawaiian Islands), a series of high-pressure-high-temperature layered experiments were performed at 2.9 GPa, 5 GPa, and 8 GPa, from 1300°C to 1650°C, using a fertile peridotite KLB-1 and N-MORB. Our experiments at conditions below the dry peridotite solidus produced melt compositions that ranged from basaltic andesite to tholeiite. An Opx reaction band formed between eclogite and peridotite layers, likely via chemical reaction between a silica-rich eclogite-derived partial melt and olivine in the peridotite matrix. At temperatures at or above the dry peridotite solidus, substantial melting occurred in both basalt and peridotite layers, and fully molten basalt melt and melt pockets from the peridotite layer combined. In our layered experiments, major and minor element contents in reacted melts closely matched those of Hawaiian tholeiite and picrite, except for Fe. Partial melts of anhydrous run products had ~55 - 57 wt% SiO2 at low temperature (i.e., were andesitic) and had ~50 - 53 wt% SiO2 at high temperatures, slightly below the dry peridotite solidus (i.e., were tholeiitic, and similar to those that occur during the Hawaii shield-building stage). Based on the Fe- and LREE-enriched signature in Hawaiian tholeiites, we propose that recycled components in the Hawaiian plume are not modern N-MORB, but are Fe-rich tholeiite;a lithology that was common in the Archaean and early Proterozoic. We have demonstrated that the entire compositional spectrum of Hawaiian tholeiites (basalt to picrite) can be formed by basalt-peridotite reactive melting near the dry solidus of peridotite. Based on these results, we propose that the potential temperature of the sub-Hawaiian plume may be much lower than previously estimated.

Developing Sustainable Ultra High Strength Concrete Mixtures Using Spent Foundry Sand

This study presents the development of ultra high strength concrete(UHSC)that has been made more sustainable by using both local materials from central Texas and spent foundry sand(FS)from the metal casting industry,which has also been obtained locally.This study first describes various trial mixtures tested as well as the specimen preparation techniques investigated that led to the final UHSC-FS mixtures.The developed mixtures were proportioned with local constituents to increase the sustainable impact of the material by reducing emissions due to shipping as well as making UHSC more affordable to a wider variety of applications.The final mixture design constituents were:river sand,locally available type I/II cement,silica fume,and spent FS,which was obtained from a local steel casting company.Multiple variables were investigated,such as the aggregate type and size,concrete age(7,14,and 28-days),the curing regimen,and the water-to-cement ratio(w/cm)to optimize a UHSC mixture that used local materials and FS.This systematic development revealed that heat curing the specimens in a water bath at 50 oC(122 oF)after demolding and then dry curing at 200 oC(392 oF)two days before testing with a w/cm of 0.20 at 28-days produced the highest compressive strengths.Once an optimum UHSC mixture was identified a partial replacement of the fine aggregate with FS was completed at 10%,20%,and 30%.The results showed an increase of compressive strength performance at 10%replacement,followed by no change at 20%,and finally a slight decrease at 30%.Developing this innovative material with local materials and FS ultimately produces a novel sustainable construction material,reduces the costs,and produces mechanical performance similar to prepackaged,commercially,available construction building materials.

Research and Application of an Environmental-Friendly Low-Damage and High Salt-Resistance Slick Water Fracturing Fluid System

The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.

Experimental Study of Post-heated Steel Reinforced Recycled Concrete Columns Repaired with CFRP

The mechanical and thermal properties of steel reinforced concrete columns with CFRP reinforcement were examined after exposure to a high temperature of 500℃. The concrete made with normal and recycled coarse aggregate（RCA） was fabricated and three different RCA replacement ratios（0, 50%, and 100%） were investigated. The fatigue properties of steel reinforced concrete with RCA and CFRP reinforcement were tested for two million cycles at a frequency of 2.5 Hz. The test results show that the failure of strengthened specimens is mainly caused by rupture of CFRP jacket and buckling of inner section steel reinforcement. However, for the unstrengthened specimen, both of inner steel buckling and core concrete cracking are the main contributors to the damage. The load-bearing capacity, deformation and energy dissipation of the specimens during the fatigue test could be strengthened greatly by CFRP reinforcement. However, the CFRP reinforcement has little influence on the improvement of the stiffness of the specimens, which may be caused by a plastic damage accumulation during the early cycles of fatigue tests. Finally, a static test was conducted on the postfatigue specimens, the results showed that a large decrease in stiffness was observed for the specimens subjected to high temperature and fatigue, and the fatigue loading had a higher influence on the specimens than the high temperature.

Assessment of Environmental Health Knowledge, Attitude and Behavior among High School Students in a USA Southeast Texas School District

This cross-sectional descriptive study assessed general environmental health literacy among students focusing on their knowledge, skills, attitudes and behaviors regarding the environmental health, stewardship, and sustainability, using a questionnaire consisting of 35 core questions from the Centers for Diseases Control (CDCs). Students (N = 185) from three high schools in the district were asked through their class teachers to voluntarily complete the questionnaire. Results indicated that about 41% (n = 77) of the students lacked knowledge regarding potential sources of radiation exposure and 70% (n = 133) lacked knowledge regarding radon gas being the number one risk factor for lung cancer among non-smokers. Additionally, the ANOVA test indicated significant knowledge differences among school location. Students in school #1, located in the most affluent area, had significantly higher knowledge scores (M = 4.39) than school #2 located in a moderately affluent area (M = 3.50). Furthermore, we found significant differences in ethnicity on the environmental health attitude of the high school students. Black students reported lower positive environmental health attitude (M = 29.86) than White students (M = 32.63), Hispanic students (M = 32.33) and Asian students (M = 33.84). These findings demonstrated knowledge deficiency in some key areas in environmental health particularly the environmental diseases and conditions caused by manmade hazards such as pesticides, chemicals, radiation, air, water, and soil pollution. Targeted educational interventions to increase awareness and understanding of health effects, exposure to environmental hazards and carcinogens as well as risks associated to direct exposure as in this study, radon and radiation, should be provided to high school students. Practical education through tours where students can observe directly and participating in laboratory experiments could empower the students to translate this knowledge into positive environmental health behaviors and practices now and in the future.

Mechanical and Thermal Properties of Recycled Mixed Waste Polymers Reinforced with Reclaimed Newsprint Fibres

This study investigates the mechanical,thermal and morphological properties of rHDPE(Recycled High Density Polyethylene)and a mixture of rPE HD/LD(High and Low Density Polyethylene),both reinforced with rNP(Reclaimed Newsprint Paper)fibres.To enhance the composite properties,the addition of highly grafted maleic anhydride polyethylene wax,as CA(Coupling Agent),and semi crystalline copolymer of propylene and ethylene,as IM(Impact Modifier),was included into the material formulation by a twin-screw extruder.Mechanical and morphological properties were studied on tensile test specimens,prepared by injection moulding,by tensile testing machine and SEM(Scanning Electron Microscope),respectively.Thermal properties,i.e.melting and crystallization behaviour,were investigated by DSC(Differential Scanning Calorimetry).Mechanical analysis showed that the addition of rNP in both composites increased the young modulus and significantly decreased the elongation at break.The DSC results revealed that the addition of the rNP in the rHDPE matrix led to a substantial decrease of crystallinity,which consequently affects the tensile strength of the composite(17 MPa)in contrast to the neat rHDPE(25 MPa).On the contrary,fibre addition in rPE HD/LD matrix had no specific impact on the crystallinity index,but did contribute to the increased tensile strength(26 MPa)when compared with neat rPE HD/LD(16 MPa).SEM photomicrographs of the impact fracture surfaces demonstrated a solid adhesion bond between the natural fibres and the rPE HD/LD matrix.Reclaimed newsprint fibres can thus be considered as a perspective alternative to the inorganic fillers in the rPE HD/LD composite.

Value-added recycling of sludge and sludge ash into low-carbon construction materials:current status and perspectives

Sludge as the by-product of wastewater treatment usually accumulates toxic substances that require specific treatment before disposal.With the increase of sludge production,the safe and economic treatment of sludge has become a global issue.Construction filed provides a solution for consuming huge volumes of sludge and sludge ash owing to the similar chemical composition with cementitious materials.This paper critically reviewed the current status of recycling sludge and sludge ash into low-carbon construction materials and highlighted the future perspectives of sludge-derived construction materials.Furthermore,the immobilization mechanisms of heavy metals in sludge-derived construction materials were elaborated to promote the actualization of sustainable management of sludge and sludge ash.