A low-temperature co-treatment of diethylhexyl phthalate-rich polyvinyl chloride and waste copper catalyst by subcritical water (hydrothermal treatment): Dechlorination, recovery of diethylhexyl phthalate and copper.

As one of the most widespread plastics in the world, the recycling of diethylhexyl phthalate-rich polyvinyl chloride (DEHP-rich PVC) faces great challenges because of the high levels of Cl and plasticizers. On the other hand, waste copper catalyst (WCC) discharged from various industrial processes is not effectively recycled. In this study, a significant synergistic effect between the DEHP-rich PVC and WCC was found in a subcritical water (SubCW) medium, and a co-treatment of the DEHP-rich PVC and WCC was developed by the SubCW process. The introduction of WCC significantly improved the dechlorination efficiency of the DEHP-rich PVC to 96.03 % at a low temperature of 250 °C. Under the optimal conditions, the leaching of copper from WCC reached a maximum of 81.08 %. Oil products included DEHP (55.7 %, GC peak area%), 3-methyl-3-heptene (37.3 %, GC peak area%), and 2-ethyl-1-hexanol (7.0 %, GC peak area%). The dechlorination pathways of the DEHP-rich PVC included hydroxyl substitution and direct dechlorination. HCl released from the DEHP-rich PVC led to a decrease in the pH of the system and significant copper leaching from the WCC. DEHP was decomposed by hydrolysis, dehydration, and rearrangement reaction by the SubCW co-treatment process. The enhancement mechanism of the WCC for the dechlorination of the DEHP-rich PVC was based on that the conversion of copper species in the SubCW promoted the formation of hydroxyl radicals and the hydroxyl substitution for chlorine in PVC molecular chain. The proposed SubCW low-temperature co-treatment could be a prospective strategy for the low-energy and synchronous recovery of the two different wastes of the DEHP-rich PVC and WCC.

Exposing the pitfalls of plastics mechanical recycling through cost calculation.

The plastic industry needs to match the recycling goals set by the EU. Next to technological hurdles, the cost of plastics mechanical recycling is an important modality in this transition. This paper reveals how business economic cost calculation can expose significant pitfalls in the recycling process, by unravelling limitations and boundary conditions, such as scale. By combining the business economic methodology with a Material Flow Analysis, this paper shows the influence of mass retention of products, the capacity of the processing lines, scaling of input capacity, and waste composition on the recycling process and associated costs. Two cases were investigated: (i) the Initial Sorting in a medium size Material Recovery Facility and (ii) an improved mechanical recycling process for flexibles - known as the Quality Recycling Process - consisting of Additional Sorting and Improved Recycling. Assessing the whole recycling chain gives a more holistic insight into the influences of choices and operating parameters on subsequent costs in other parts of the chain and results in a more accurate cost of recycled plastic products. This research concluded that the cost of Initial Sorting of flexibles is 110,08-122,53 EUR/t, while the cost of subsequent Additional Sorting and Improved Recycling ranges from 566,26 EUR/t for rPE Flex to 735,47 EUR/t for rPP Film, these insights can be used to determine a fair price for plastic products. For the Quality Recycling Process it was shown that rationalisation according to the identified pitfalls can reduce the cost per tonne of product by 15-26%.

Estimation of the uncertainty of metal content in a batch of waste printed circuit boards from computer motherboards.

Electronic wastes are a valuable resource due to their critical and precious metal content. To include these wastes in recycling or recovery chains, it is necessary to precisely determine their metal content. Because analysing the whole sample of a batch of electronic waste is not practical, different preparation and sampling or subsampling steps are necessary. Sampling induces an error in the composition of the final sample compared to that of the initial batch, which finally leads to uncertainty in the final metal content measurement as compared to the "actual" batch metal content. The aim was to characterize the uncertainty in metal content of a batch of 372 kg of WPCB. Thirty-nine metals were analysed and thirty-two were considered: base, precious, rare-earths and critical metals. An empirical method (i.e. replicated measurement tests) was thus applied, based on statistical calculations according to Eurachem Guidelines. Uncertainty arising during the 3 different stages of the preparation process (primary, secondly and tertiary sampling steps) was calculated. For the analysed given weight (0.5 g), the shredding efficiency, which directly affects metal particle size distribution, was found to be the most important factor influencing the uncertainty. Uncertainties in base metal content, which is often concentrated in the coarsest particles, arose mainly from the last preparation step (tertiary sampling). Conversely, precious metals and rare-earths were finely ground during the 3 preparation steps, which led to low uncertainties, despite their low concentration in the waste (<337 mg/t for precious and < 35 mg/t for rare-earths).

Contribution of waste management to a sustainable textile sector.

With increasing textile consumption and limited sorting and recycling capacities, the EU faces major challenges in terms of managing its textile waste. This study investigates the environmental and socio-economic impacts of explorative policy scenarios for a more sustainable textile waste management system in Europe. These scenarios differ substantially in the amounts of textile waste generated and separately collected, closed-loop recycling capacities and textile waste exports. Our results show that sustainable textile waste management remains highly relevant for the sector. Still, without addressing in parallel prevention of textile waste generation via production and consumption patterns, a climate-neutral and circular textiles sector will be hard to achieve. Interventions in the waste management of textiles could reduce global warming impacts by up to 22.3 Mt CO2 per year, which translates to an 18% sector-wide impact by 2035. Depending on the intervention(s), the estimated required investment at present amounts to between 7 and 33 billion EUR. The study provides a valuable starting point for evidence-based decisions on future textile policymaking in Europe.

Pyrolysis-induced migration and transformation of heavy metals in sewage sludge containing microplastics.

Stabilizing heavy metals (HMs) in sewage sludge is urgently needed to facilitate its recycling and reuse. Pyrolysis stands out as a promising method for not only stabilizing these metals but also producing biochar. Our research delves into the migration and transformation of specific HMs (Cr, Mn, Ni, Cu, Zn, As, and Pb) during co-pyrolysis under various conditions, including the presence and absence of microplastics (PVC and PET). We examined different concentrations of these plastics (1 %, 5 %, 10 %, and 15 %) and temperatures (300 °C, 500 °C, and 700 °C). Findings reveal that microplastics, particularly PVC, enhance the migration of Zn and Mn, leading to significant volatilization of Zn and Pb at higher temperatures, peaking at 700 °C. The increase in temperature also markedly influences HM migration, with As showcasing notable loss rates that climbed by 18.0 % and 16.3 % in systems with PET and PVC, respectively, as temperatures soared from 300 °C to 700 °C. Moreover, our speciation analysis indicates that microplastics aid in transforming certain HMs from unstable to more stable forms, suggesting their beneficial role in HM stabilization during pyrolysis. This study significantly enriches our understanding of microplastics' impact on HM behavior in sewage sludge pyrolysis, offering new avenues for pollution control and environmental management strategies.

Sustainable management of medical plastic waste through carbon dioxide-assisted pyrolysis.

To address the challenges associated with medical plastic waste and to characterize its heterogeneity, non-recyclability, and potential biohazard risks, this study explored a carbon dioxide (CO2)-assisted pyrolysis process as a sustainable disposal method. Medical plastic waste typically includes polypropylene, polystyrene, and polyvinyl chloride. To experimentally evaluate the functional reactivity of CO2, we employed three pyrolysis setups (one-stage, two-stage, and catalytic processes). The technical advantages of using CO2 over inert gases such as nitrogen (N2) were demonstrated through pyrolysis tests. The results showed that energy production was enhanced under CO2 conditions, with catalytic pyrolysis generating 146% more flammable gases compared to pyrolysis in an N2 environment. The use of CO2 also led to a reduction in the formation of toxic chemicals due to improved thermal cracking. The CO2-assisted pyrolysis process exhibited net negative CO2 emissions when a catalyst was present, as a substantial amount of CO2 was consumed during the process. In conclusion, CO2-assisted pyrolysis of medical plastic waste offers a sustainable management solution that maximizes the utilization of carbon resources.

Recycling of Sewage Sludge: Synthesis and Application of Sludge-Based Activated Carbon in the Efficient Removal of Cadmium (II) and Lead (II) from Wastewater.

The limited supply of drinking water has aroused people's curiosity in recent decades. Adsorption is a popular method for removing hazardous substances from wastewater, especially heavy metals, as it is cheap, highly efficient, and easy to use. In this work, a new sludge-based activated carbon adsorbent (thickened samples SBAC1 and un-thickened samples SBAC2) was developed to remove hazardous metals such as cadmium (Cd+2) and lead (Pb+2) from an aqueous solution. The chemical structure and surface morphology of the produced SBAC1 and SBAC2 were investigated using a range of analytical tools such as CHNS, BET, FT-IR, XRD, XRF, SEM, TEM, N2 adsorption/desorption isothermal, and zeta potential. BET surface areas were examined and SBAC2 was found to have a larger BET surface area (498.386 m2/g) than SBAC1 (336.339 m2/g). While the average pore size was 10-100 nm for SBAC1 and 45-50 nm for SBAC2. SBAC1 and SBAC2 eliminated approximately 99.99% of Cd+2 and Pb+2 out the water under all conditions tested. The results of the adsorption of Cd+2 and Pb+2 were in good agreement with the pseudo-second-order equation (R2 = 1.00). Under the experimental conditions, the Cd+2 and Pb+2 adsorption equilibrium data were effectively linked to the Langmuir and Freundlich equations for SBAC1 and SBAC2, respectively. The regeneration showed a high recyclability for the fabricated SBAC1 and SBAC2 during five consecutive reuse cycles. As a result, the produced SBAC1 and SBAC2 are attractive adsorbents for the elimination of heavy metals from various environmental and industrial wastewater samples.

Comprehensive analysis of bioplastics: life cycle assessment, waste management, biodiversity impact, and sustainable mitigation strategies.

Bioplastics are emerging as a promising alternative to traditional plastics, driven by the need for more sustainable options. This review article offers an in-depth analysis of the entire life cycle of bioplastics, from raw material cultivation to manufacturing and disposal, with a focus on environmental impacts at each stage. It emphasizes the significance of adopting sustainable agricultural practices and selecting appropriate feedstock to improve environmental outcomes. The review highlights the detrimental effects of unsustainable farming methods, such as pesticide use and deforestation, which can lead to soil erosion, water pollution, habitat destruction, and increased greenhouse gas emissions. To address these challenges, the article advocates for the use of efficient extraction techniques and renewable energy sources, prioritizing environmental considerations throughout the production process. Furthermore, the methods for reducing energy consumption, water usage, and chemical inputs during manufacturing by implementing eco-friendly technologies. It stresses the importance of developing robust disposal systems for biodegradable materials and supports recycling initiatives to minimize the need for new resources. The holistic approach to sustainability, including responsible feedstock cultivation, efficient production practices, and effective end-of-life management. It underscores the need to evaluate the potential of bioplastics to reduce plastic pollution, considering technological advancements, infrastructure development, and increased consumer awareness. Future research should focus on enhancing production sustainability, understanding long-term ecological impacts, and advancing bioplastics technology for better performance and environmental compatibility. This comprehensive analysis of bioplastics' ecological footprint highlights the urgent need for sustainable solutions in plastic production.

A comprehensive review of current approaches on food waste reduction strategies.

Food waste is a serious worldwide issue that has an impact on the environment, society, and economy. This comprehensive review provides a detailed description of methods and approaches for reducing food waste, emphasizing the necessity of comprehensive strategies to tackle its intricate relationship with environmental sustainability, social equity, and economic prosperity. By scrutinizing the extent and impact of food waste, from initial production stages to final disposal, this comprehensive review underlines the urgent need for integrated solutions that include technological advancements, behavioral interventions, regulatory frameworks, and collaborative endeavors. Environmental assessments highlight the significant contribution of food waste to greenhouse gas emissions, land degradation, water scarcity, and energy inefficiency, thereby emphasizing the importance of curtailing its environmental impact. Concurrently, the social and economic consequences of food waste, such as food insecurity, economic losses, and disparities in food access, underscore the imperative for coordinated action across multiple sectors. Food waste can also be effectively reduced by various innovative approaches, such as technological waste reduction solutions, supply chain optimization strategies, consumer behavior-focused initiatives, and waste recovery and recycling techniques. Furthermore, in order to foster an environment that encourages the reduction of food waste and facilitates the transition to a circular economy, legislative changes and regulatory actions are essential. By embracing these multifaceted strategies and approaches, stakeholders can unite to confront the global food waste crisis, thereby fostering resilience, sustainability, and social equity within our food systems.

Estimating energy left in discarded alkaline batteries: Evaluating consumption and recovery opportunities.

Each year, a significant number of single-use alkaline batteries with untapped energy are discarded. This study aims to analyze the usage patterns of alkaline batteries based on a dataset of 1021 used batteries, ranging from Size AA to 9V, collected from households in the State of New York. We measure the energy loss resulting from underutilized batteries and examine the corresponding environmental and economic impacts on a national scale. Discarded AA alkaline batteries maintain about 13 % of their initial energy, that results in an estimated annual energy loss of 660 MWh for all AA alkaline batteries in the U.S., and about 40 MWh in New York State. Annually in the U.S., consumers discard AA alkaline batteries with approximately $80 million worth of unused energy, including $4.8 million in New York State alone. We also show that the lifecycle impact of batteries should be multiplied by 1.25 to account for their underutilization. To address these issues, we propose actionable recommendations for improving battery consumption practices and facilitating End-of-Life/Use (EoL/U) recovery processes. The findings show the need for policy interventions to better manage battery usage and disposal toward reducing energy waste and mitigating environmental impacts.

Modelling and optimization of an innovative facility for automated sorting of aluminium scraps.

The growing demand for aluminium worldwide makes aluminium recycling critical to realising a circular economy and increasing the sustainability of our world. One effective way to improve the impact of aluminium recycling is to develop cost-efficient automated sorting technologies for obtaining pre-defined high-quality aluminium scrap products, thus reducing undesirable downcycling and increasing environmental/economic benefits. In this work, an innovative facility, which includes singulation, sensor scanning, and ejection, is optimised for the automated sorting of aluminium scraps. The sorting facility is computationally studied by a virtual experiment model based on the discrete element method. The model considers particle-scale dynamics of complex-shaped scraps and mimics the automated operation of the facility. Based on virtual experiment modelling, the flow of scrap is optimized by computation, with the feasible operation of the sorting facility being proposed. Accordingly, the sorting facility has been built and model predictions are confirmed in actual operation.

Potential improvement in the mechanical performance and thermal resistance of geopolymer with appropriate microplastic incorporation: A sustainable solution for recycling and reusing microplastics.

The accumulation of microplastics (MPs) has been a major threat to the natural environment and human health. However, incineration and landfilling may not be appropriate for the management of MPs. This paper evaluated the feasibility of incorporating MPs with diverse dimensions (50 to 500 µm) and contents (2.5 % to 10 %) into geopolymer cured under different temperatures (40 and 80 °C). The compressive (fc) and flexural strength (ff) after curing and thermal exposure (200 to 600 °C) were determined. When cured at 40 °C, fc and ff decreased with percentages of MPs incorporated. By contrast, when cured at 80 °C, the addition of 2.5 % MPs increased fc and ff by up to 33 % (from 52.2 to 69.4 MPa) and 18 % (from 8.2 to 9.7 MPa), depending on MPs' sizes. The XRD and TGA results suggested that the observed increases in mechanical properties can be attributed to the formation of more calcium alumino (silicate) hydrates (C-(A)-S-H gels) induced by the incorporation of a small quantity of MPs (2.5 %). The SEM images also showed better adhesion between MPs and geopolymeric products when cured under 80 °C, potentially inhibiting crack development. After being exposed to evaluated temperatures (200 and 400 °C), fc of the specimens with 2.5 % MPs and cured at 80 °C was higher than that without MPs. The fc dropped dramatically due to the degradation of MPs between 400 and 600 °C. The increase in strength and heat resistance (up to 400 °C) of MPs-incorporated geopolymer cured under 80 °C indicated the potential recycling and reuse of MPs for geopolymer materials.

Pharmaceutical residues in plastic tablet containers: Impacts on recycling and the environment.

High-density polyethylene tablet containers are potentially very suitable for recycling, but no data are publicly available on active pharmaceutical ingredients' (API) residues in empty containers and if they affect the recyclability of pharmaceutical packaging. Plastic tablet containers represented 15 % of pharmaceutical primary packages sold in Finland in 2020 and 2021, equalling 350 tons of plastic per year. We studied the residues of six APIs remaining or adsorbed inside plastic tablet containers. The effects of tablet coating and usage in dose-dispensing services versus households on the API residues, and rinsing water's ability to remove the residues were evaluated. Up to 940,000 µg/kg of carbamazepine was detected in a container of uncoated carbamazepine tablets. The residues from coated tablets containing the other five APIs were 2.4-6,100 µg/kg. Ten times higher paracetamol residues were obtained in containers from household use than from a dose-dispensing unit. Rinsing can remove most API residues, but it leads to environmental emissions. For example, rinsing water can double carbamazepine emissions from a Finnish wastewater treatment plant where plastic packaging waste effluents are processed. Considering the API concentrations, decreasing residues by rinsing and dilution with other plastic packaging waste, the residues of the studied APIs are not considered an obstacle to the recycling of plastic tablet containers. However, further research is needed on more toxic APIs and the fate of APIs in the plastics recycling process.

Chemical profiling of paper recycling grades using GC-MS and LC-MS: An exploration of contaminants and their possible sources.

Paper packaging made with recycled paperboard is used to pack various consumer goods that can include amongst others, electronics, toys, food, cosmetics, and stationery. Chemical profiling of the various paper recycling grades used in the manufacture of recycled paperboard was undertaken to investigate possible sources of contaminants and their propagation in the paper recycling chain. Pre-consumer, retail and post-consumer paper-based materials were collected at papermills, corrugators, grocery stores, household waste, solid waste disposal sites and recycling facilities. In the GC-MS analysis, phthalates, long-chain aliphatic compounds, and fatty acids were the most commonly detected compounds whilst phthalates and bisphenols featured most prevalently in the LC-MS analysis. The factors that were identified as likely contributors to the detection of the different chemical compounds included the presence of wood derivatives, the use of certain chemical additives during manufacturing, and exposure of paper to contaminants from consumers, other goods and the environment. Waste mingling, recovery, sorting and reprocessing into recycled paper were also shown to influence the chemical profile of paper materials. Sparse partial least squares-discriminate analysis indicated that newspaper and office paper had unique chemical constituents, whilst cartons were shown to have higher variability. By looking at key stages of paper recycling, this study showed that the possible persistence and transformation of chemical compounds in additives must be evaluated when considering the recyclability of paper-based materials. Further, it highlighted that different separation approaches may be required to reduce contaminant exposure opportunities in post-consumer paper materials.

Waste management from dental clinics: A case study in Belo Horizonte, Brazil.

Healthcare waste management is a critical aspect of public health and environmental protection, particularly in establishments such as dental clinics. This study examined the dental clinic waste (DCW) management processes in clinics within the city of Belo Horizonte, Brazil. Utilizing data from Healthcare Waste Management Plans (HCWMP) provided by the Urban Cleaning Superintendence, the study investigated waste generation, segregation, storage, collection, treatment, and final disposal practices. The results revealed that hazardous DCW represented a significant portion (26.5 %) of waste generated in dental clinics, exceeding the World Health Organization's recommended threshold. Biological waste (22.9 %), mainly consisting of cotton, gauze, and gloves contaminated with blood or body fluids, was the most generated hazardous waste group, followed by chemical (2.2 %) and sharps waste (1.3 %). Incineration was the predominant treatment method for hazardous DCW, raising concerns about environmental impacts and greenhouse gas emissions. Non-hazardous waste, primarily destined for landfills, had limited recycling rates (2.4 %), emphasizing the need for improved waste management strategies to minimize environmental impacts and increase circular economy. Challenges in DCW management included inadequate segregation practices, limited recycling initiatives, and incomplete HCWMPs lacking descriptions of waste management beyond establishment boundaries. Addressing these challenges requires comprehensive training programs, strengthened regulations, and increased environmental awareness among healthcare professionals. In conclusion, improving DCW management in dental clinics is crucial for mitigating occupational and environmental risks. Collective efforts are needed to enhance waste segregation, promote recycling, and ensure compliance with regulations, ultimately safeguarding public health and the environment.

Assessing the resource potential of paper and board in lightweight packaging waste sorting plants through manual analysis and sensor-based material flow monitoring.

The recycling of paper and board (PB) yields economic and environmental advantages compared to primary paper production. However, PB from lightweight packaging (LWP) waste is currently not comprehensively reintegrated into the paper value stream. To develop an adapted recycling process for PB from LWP, PB quantities, qualities, and fluctuations ranges in LWP are required. Currently, no sufficient database is available. Therefore, we developed a methodical approach and conducted a case study to access the PB potential in LWP sorting plants using manual analysis and sensor-based material flow monitoring. Differences resulting from seasonal variations, materials from different settlement structures, and fluctuation ranges in LWP composition over two weeks have been investigated. PB contents in the input of 6.5 wt% (ww) and 5.9 wt% (ww) were determined for winter and summer sampling campaigns, respectively. The PB product stream amounted to 5.7 wt% (ww, winter) and 4.8 wt% (ww, summer). Around 45 wt% (ww) of PB from the PB product stream was classified as misplaced by the consumer and should have been discarded in separate paper collections. Based on the determined PB quantities and qualities, a potential of usable and in the PB product stream available PB in LWP was determined. The technically available and usable PB potential in German LWP waste amounts to 89,000 to 100,000tons per year (average PB yield of around 65 wt% (ww)). The methodical approach can be adapted for sorting plant balances. The results can contribute to developing an adapted recycling process for PB from LWP.

Assessment of an eco-efficient process for the optimization of metal recovery in lithium cobalt oxide and lithium nickel manganese cobalt oxide batteries.

The expansion of technology motivates the increase of global demands for critical minerals. In this context, the exploration of secondary sources of these components is expanding. End-of-life batteries can be seen as potential sources of lithium, cobalt, nickel and manganese for electric vehicles or diverse applications in electronic equipments. This paper provides a comprehensive evaluation of the recovery of metals from waste batteries with diverse chemistry composition. Lithium cobalt oxide (LCO) and lithium nickel cobalt manganese oxide (NMC) batteries were co-treated with polyvinyl chloride (PVC) channels under supercritical water, varying reaction temperature (400-600 °C) and PVC/Battery composition (0-3 m/m) in a tubular continuous reactor. Results show high recovery rates for all metals, with up to 90% percentage recovery of lithium and cobalt in all cases. Temperature and feed composition were identified as determining factors for the recovery of lithium from LCO batteries. In the case of cobalt, temperature was identified as the most important factor that affects its recovery. The selected optimal conditions for cobalt recovery in the solid products of reactions were identified for batteries LCO and NMC: temperature of 600 °C and PVC/Battery ratio of 3.0 and temperature of 500 °C and PVC/Battery ratio of 1.5, respectively. Environmental impacts, primarily Global Warming Potential (GWP), were minimal, with 4.71·10-5 kg CO2 eq., indicating the benefits of the process as an eco-efficient and promising route for the recycling of valuable metals.

Preparation of high quality carbon nanotubes by catalytic pyrolysis of waste plastics using FeNi-based catalyst.

Plastic waste pollution is the serious environmental problem, and catalytic pyrolysis of waste plastics is an effective way to solve this problem. Carbon nanotubes (CNTs) are prepared by catalytic pyrolysis of low-density polyethylene (LDPE) waste plastics by one-stage method using iron nitrate and nickel nitrate as catalyst. The growth mechanism of CNTs is analyzed in detail. TPO, XRD, SEM and Raman analyses show that increasing Ni content contributes to the production of CNTs with good morphology and high graphitization degree. While the increasing Fe content contributes to improving the yield of CNTs. The outer and inner diameters of the FeNi12-CNTs-800 are about 21 nm and 8 nm with the length of 18.9 µm, respectively. LDPE pyrolysis gases are analyzed to determine that the primary carbon source required for CNTs growth is C2H4. The C2H4 adsorption and decomposition processes on FeNi alloys are performed to reveal the growth mechanism of CNTs, based on density functional theory calculation. Three kinds of the growth models are proposed to explain the difference of the CNTs tubular shape. FeNi12-CNTs-800 are used to remove microplastics from wastewater due to existence of magnetic. PVC can be quickly removed from wastewater with removal of 100 % at 20 min. This study provides an effective way for recycling and treatment of waste plastic.

Enhanced reducing capacity of citric acid for lithium-ion battery recycling under microwave-assisted leaching.

The management and sustainable recycling of spent lithium-ion batteries (LIBs) holds critical importance from both economic and environmental standpoints. H2O2 and ascorbic acid are widely used inorganic and organic reductants in the hydrometallurgical process for battery recycling. In this study, citric acid, as a reductant, was found to have superior metal leaching efficiencies under microwave-assisted leaching than H2O2 and ascorbic acid. The enhanced performance was attributed not only to the inherent reducing property of citric acid but also to the chelation of citric acid with Cu and Fe, resulting in the formation of reductive radicals under microwave. The effect of acid type, H2SO4 concentration, citric acid concentration, solid-liquid (S/L) ratio, reaction time, and temperature were investigated. 99.5 % of Li, 99.7 % of Mn, 99.5 % of Co, and 99.3 % of Ni were leached from spent lithium nickel manganese cobalt oxides (NCM) battery black mass using 0.2 mol/L H2SO4 and 0.05 mol/L citric acid at 120 °C for 20 min with a fixed S/L ratio of 10 g/L in the microwave-assisted leaching process. Leaching kinetic results were best fitted with the Avrami model, suggesting that the microwave-assisted leaching process was controlled by diffusion. The leaching activation energies of Li, Mn, Co, and Ni were 30.11 kJ/mol, 27.48 kJ/mol, 21.32 kJ/mol, and 33.29 kJ/mol, respectively, providing additional evidence that supports the proposed diffusion-controlled microwave-assisted leaching mechanism. This method provided a green and efficient solution for spent LIBs recycling.